8th High Power Targetry Workshop (HPTW2023)

6 Nov 2023, 08:30 → 10 Nov 2023, 17:00 Asia/Tokyo

Administrative Headquarters 2F conference room (RIKEN Wako campus)

Hiroki Okuno (RIKEN Nishina center for accelerator-based science)

The 8th High Power Targetry Workshop  (HPTW2023), which RIKEN and J-PARC will host, will take place at RIKEN Nishina Center for Accelerator-based Science, Wako, Saitama, Japan, from Nov. 6th to Nov. 10th, 2023. The HPT Workshop brings together scientists and engineers from the international community for particle accelerator targetry.  Applications include neutrino facilities, neutron facilities, radioactive ion beam facilities, material irradiation facilities, accelerator driven systems, and precision experiments for rare processes.

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Dear All

We have decided to hold the next HPTW on November 6-10, 2023. The Covid-19 restrictions on entry into Japan have been greatly eased. We look forward to seeing you all in person.

Best regards,

Hiroki OKUNO and Shunsuke Makimura on behalf of the LOC of HPTW2023

230527 HPTW2023 1st announcement_SPC .pdf

2nd announcement of HPTW2023_v2.pdf

poster-web-2023r3.pdf

program_distributed.pdf

Monday 6 November ¶

08:30 Registration

08:50 Announcement

Opening Session¶

Convener: Yong Dai

1 Welcome talk¶

Speaker: Hiroyoshi Sakurai (RIKEN Nishina Center for Accelerator-Based Science)

HPTW-sakurai.pptx

2 Target activities at RIBF¶

Speaker: Hiroki Okuno (RIKEN Nishina center for accelerator-based science)

230923 HPTW2023 RIKEN plenary okuno v2.pptx

231030 HPTW2023 MondayAnnouncement.pptx

3 Proton Irradiation Facility at J-PARC¶

Speaker: Shin-ichiro Meigo (J-PARC/JAEA)

meigo_HPTW2023_irad_fac.pptx

Topic3-1¶

Convener: David Senor (Pacific Northwest National Laboratory)

4 First-of-a-kind autopsy of the Large Hadron Collider external beam dump¶

The CERN's Large Hadron Collider (LHC) is equipped with two external beam dumps, designed in order to absorb the entire energy of the accelerator, which reached 320 MJ/dump during LHC Run2 (2015-2018). During that period several operational challenges were encountered in the operation of the dumps; several mitigation measures were implemented in the spare dumps during Long Shutdown 2 (2019-2021), while the old operational dumps were removed from service. Following a core endoscopic inspection on the latter, damage was observed in some of the absorber components, specifically in some high-density disks of extruded graphite. Given the importance of the potential impact on LHC operation during Run3 as well as in view of the High Luminosity LHC upgrades, it was therefore decided to execute a complete dump autopsy in order inspect in detail the core components. An ad-hoc area has been designed to this purpose and two different & independent methods developed to access the internal core.

The following contribution will summarize the observations, the technical infrastructure put in place to autopsy the dump, the cutting procedure and return of experience as well as the early observations, including implications for the operational dumps as well as for the construction of the spares.

Speaker: Mrs Ana-Paula Bernardes (CERN)

APB_HPTW2023VF1.pptx

5 Recent spallation materials researches performed at PSI¶

Spallation materials researches have been performed at PSI for more than 20 years. The activities are dominated by the SINQ Target Irradiation Program (STIP) and the post-irradiation examination (PIE) of STIP specimens. In the past five years, the 8th irradiation experiment of STIP (STIP-VIII) has been successfully carried out and some irradiated specimens of steel, tungsten, zircaloys and Al-alloy were investigated.
Due to the failure of SINQ Target-11 in 2016, heightened safety measures have been implemented since then. STIP-VIII, performed during 2018-2020, has to comply with the new safety requirement. Instead of placing specimens in a high proton and neutron flux region, the STIP-VIII specimens were irradiated in the upper part of Target-13, where the proton and neutron fluxes are much lower. In addition, tungsten specimens and liquid metal capsules were greatly limited in order to reduce risks. However, the irradiation condition of STIP-VIII is more relevant to fusion and fission reactors since due to lower the helium and hydrogen production. Therefore, materials from nuclear fission and fusion material programs are the majority in STIP-VIII. In this contribution, the details of STIP-VIII will be presented.
This contribution will also highlight the PIE results of steel, tungsten, zircaloys and Al-alloy specimens irradiated in previous STIP experiments and in STIP-VIII, including those from mechanical tests (tensile, 3-point bending (3PB) and small punch tests), microstructural analyses (transmission electron microscopy – TEM, and atom probe tomography – APT), and thermal diffusivity measurements. The results of 3PB testing on ferritic/martensitic steels in liquid lead-bismuth and APT analysis of spallation transmutation elements in tungsten will be described in more detail.

Speaker: Yong Dai (Paul Scherrer Institute, Switzerland)

20231106, HPTW, Dai.pptx

20231106, HPTW, Dai.pptx

10:30 Coffee Break

Topic8-1¶

Convener: Hiroshi Imao (RIKEN)

6 The Muon Collider Study: Challenges and perspectives¶

Following the 2020 update of the Strategy for Particle Physics, CERN initiated, under the auspices of the European Large National Laboratories Directors Group (LDG) a new International collaboration to progress on the feasibility studies of a Muon Collider at 10+ TeV with the goal of publishing a pre-CDR report in time for the next ESPPU at the end of the decade. The Collaboration elaborated a detailed resource loaded R&D roadmap necessary to prove the technologies involved, and is addressing the most urgent points on both the machine and detectors. The Collider aims at producing an integrated luminosity of 10 ab-1 at 10 TeV, with an intermediate step at 3 TeV delivering 1 ab-1. The muon collider presents several challenges, starting from a production target that will have to sustain a deposited power of 2÷4 MW, Superconducting Solenoids with large field on axis (5÷40 T) and subject to heavy irradiation, RF acceleration in magnetic fields, fast acceleration to cope with the short lifetime of muons, and finally the need to keep under control the neutrino radiation on surface. In this talk I will give a brief overview of all those challenges with particular emphasis on beam intercepting devices.

Primary author

Speaker: Roberto LOSITO (CERN)

Muon Collider HPTW23.pptx

7 Production of astatine-211 for targeted α-particle therapy at RIBF¶

Astatine-211 with the half-life of T1/2 = 7.214 h is one of the promising radionuclides for targeted α-particle therapy (TAT) [1]. The 5.87- and 7.45-MeV α-particle emissions occur in intensities of 41.8% and 58.2%, respectively, associated with the 211At decay. Due to the proper ranges of these α-particles in tissue, the 211At-labeled medicine is effective in killing cancer cells. 211At is produced in the 209Bi(α,2n)211At reaction. Since 2015, we have been developing an 211At production system on the beam line of the RIKEN AVF cyclotron [2-5]. The metallic 209Bi target (20 mg/cm2) is irradiated by the 28-MeV α beam from AVF. The typical beam intensity is 25 particle μA (pμA). Under our current experimental condition, 1.2 GBq of 211At can be produced in 1-h irradiation. The irradiated 209Bi target is placed in a quartz tube and heated up to 850°C. 211At sublimated from the target is transported from the quartz tube to a cold PFA tube (–96°C) by O2 gas flow (10 mL/min). After the distillation, the PFA tube is washed with CHCl3 (300–400 μL) which is then dried up by N2 gas (100 mL/min). The typical chemical yield of 211At is 80%.
We are distributing 211At to about 20 universities, research institutes, and companies, where radiolabelling and animal experiments are ongoing to develop novel radiopharmaceuticals for cancer therapy. Our 211At has been supplied to Osaka University Hospital since 2016, and in 2022, the Japan's first clinical trial of TAT for refractory differentiated thyroid cancer has been initiated.
In January 2020, RIKEN heavy-ion Linear ACcelerator (RILAC) was upgraded with the 28-GHz superconducting ECR ion source and the superconducting RILAC (SRILAC) [6]. SRILAC is expected to generate high intensity α beams of >100 pμA. We are developing a large-scale production technology of 211At using a liquid 209Bi target in a rotating cup in collaboration with Metal Technology Co. Ltd., Japan.

References
[1] Y. Feng and M. R. Zalutsky, Nucl. Med. Biol. 100–101, 12 (2021).
[2] S. Yano et al., RIKEN Accel. Prog. Rep. 50, 261 (2017).
[3] N. Sato et al., RIKEN Accel. Prog. Rep. 50, 262 (2017).
[4] Y. Wang et al., RIKEN Accel. Prog. Rep. 53, 192 (2020).
[5] H. Haba, Drug Deliv. Syst. 35, 114 (2020) (in Japanese).
[6] N. Sakamoto and T. Nagatomo, Nucl. Phys. News 32, 21 (2022).

Speaker: Hiromitsu Haba (Nishina Center for Accelerator-Based Science, RIKEN)

231106 HPTW 2023 Haba (25+5 min) for OPEN.pdf

8 Present status and upgrade plan of RI production target in SCRIT electron scattering facility¶

Electron-beam-driven RI separator for SCRIT (ERIS) [1] was constructed as an online isotope separator (ISOL) system that is dedicated to produce a radioactive isotope (RI) beam for the SCRIT (Self-Confinement RI Target) electron scattering facility [2] at RIKEN RI Beam Factory. Electron scattering is one of the best ways to accurately understand the internal structure of atomic nuclei. The aim of this facility is realization of electron scattering experiment with unstable nuclei, for which the target nuclei of 108 ions/s are required.
In ERIS, the photofission of uranium driven by the electron beam is used for the RI production. 43 self-made uranium-carbide disks are stacked to be the target. The disk is approximately 1 mm thick and 18 mm in diameter. The amount of uranium is approximately 0.65 g/disk. The uranium-carbide disks are irradiated by 150 MeV electron beam accelerated by a microtron. Recently, the yields of ${}^{132}$Sn and ${}^{137}$Cs beams extracted from ERIS were achieved to 2.6$\times$10${}^5$ ions/s and 6.3$\times$10${}^6$ ions/s with 15-g and 28-g uranium targets and a 10-W electron beam, respectively [3], and, in particular, the ${}^{137}$Cs beams were used for the world’s first electron scattering experiment with online-produced unstable nuclei.[4]
For further experiments, we plan to upgrade the power of electron beam by a factor of 100 to 2kW in order to increase the yield of RI beam. Therefore, a high-power resistant system for ERIS is required, such as a production target itself, a remote handling system for irradiated targets, radiation shields, and so on.
In this contribution, we will report the present status and an upgrade plan of ERIS.

References
[1] T. Ohnishi et al., Nucl. Instrum. Methods Phys, Res. B 317, 357 (2013).
[2] M. Wakasugi et al., Nucl. Instrum. Methods Phys. Res. B 317, 668 (2013).
[3] T. Ohnishi et al., Nucl. Instrum. Methods Phys. Res. B 541, 380 (2023).
[4] K. Tsukada et al., Phys. Rev. Letters, in press. (2023).

Speaker: Yasushi Abe (RIKEN)

20231106_HPTW_YAbe_web.pdf

9 The ISAC facility secondary irradiation and PIE upgrades¶

The ISAC facility’s RIB production scheme enables the irradiation and PIE of secondary (parasitic) targets under high power beam conditions (500 MeV, 100 μA), with potential for a wide range of investigations. Over recent years, ISAC has successfully commissioned and routinely operated secondary targets, seamlessly integrating a secondary irradiation program into the primary RIB target schedule. Moreover, the facility has established hot-cell and radioactive material handling procedures for secondary irradiated materials, while also expanding its PIE capabilities. Presently, the primary focus of the secondary irradiation program has been investigations of radiation damage in materials employed for both beam intercepting and auxiliary components within accelerator facilities, as well as studies in collaboration with the nuclear power field. Additionally, the developed capabilities open the possibility to examine long-irradiated stored components, including old ISAC beam windows, the harvesting of long-lived isotopes from secondary targets and the implementation of online monitoring systems. This overview provides a comprehensive summary of ISAC’s experiences with secondary targets, encompassing both commissioning and online operation phases. It highlights outcomes from the secondary irradiation studies and offers insights into future system upgrades to unlock additional research.

Speaker: Ferran Boix Pamies (TRIUMF)

HPTW2023_FBP_06_11_2023.pptx

12:30 Lunch Break

Memorial session for Nick SImon¶

Topic2-1¶

Convener: Shunsuke Makimura (J-PARC/KEK)

10 Overview of Radiation Materials Science and Radiation Damage Modeling¶

To understand and reliably predict the irradiation performance of materials, it is important to understand the fundamental effects of radiation on materials at the atomic scale. At the most basic level, radiation effects are caused by the creation of point defects including interstitial defects, substitutional defects and vacancies. Point defects are created when an incident particle or a displaced atom interacts with an atom located on a lattice position. Incident radiation typically creates a series of atomic displacement events called a displacement cascade. Most of the point defects created during the displacement cascade will be annealed very quickly by finding their way back to appropriate lattice positions, but some of the defects will remain. The motion of the defects through the radiation-damaged lattice is determined by the material characteristics, applied stress, and temperature. A variety of radiation damage microstructures can evolve including radiation-induced segregation, formation of dislocations, creation of voids or bubbles, and changes in phase composition such as second-phase precipitation and amorphization. The resulting microstructures can be evaluated in the irradiated materials by a variety of methods, but most commonly by transmission electron microscopy. The presence of radiation-damaged microstructures will affect the properties and hence the performance of irradiated materials. Changes in material properties can include irradiation hardening and embrittlement, irradiation growth and swelling, enhanced creep rate, irradiation-assisted stress corrosion cracking, and degradation of thermal properties.

Developing computational models to predict the effects of radiation on material properties is a significant challenge. To predict effects from first principles, a variety of tools are needed, operating on multiple scales in both space and time. The initial displacement cascade happens over Angstroms to nanometers and tenths of picoseconds. A few picoseconds after the cascade, there is a thermal spike caused by the motion of the displaced atoms through the lattice on the nanometer scale. After about 100 picoseconds, the defects that have not been annealed will begin to evolve, forming a variety of radiation damage microstructures. As radiation dose proceeds over subsequent hours, days, or years, these microstructures can grow to tens or hundreds of nanometers and significantly affect the bulk properties of the material. At the smallest length scale and shortest time scale, atomistic modeling techniques are typically used, from first-principles density functional theory to molecular dynamics methods that permit larger simulation sizes, albeit at reduced computational accuracy. At the mesoscale, techniques such as kinetic Monte Carlo, phase field and rate theory can be used to describe microstructural evolution. Finally, output from these various techniques can be used as input for continuum modeling methods like finite element or finite volume to evaluate the effects of radiation damage on bulk properties over days to years.

The presentation will include an overview of radiation materials science fundamentals, coupled with a discussion of radiation damage modeling techniques that can be used to inform post-irradiation microstructural characterization, plan experiments, and ultimately, predict irradiation performance of materials at space and time scales relevant to engineering applications.

Speaker: David Senor (Pacific Northwest National Laboratory)

Radiation Materials Science Overview.pdf

11 Irradiation damage of diamond by ion implantation¶

Diamond is expected to be applied to next-generation power electronics and quantum sensor, due to its excellent and unique physical properties. As in the field of semiconductor device industry with other materials, ion implantation technology is indispensable for realizing diamond devices because of its design flexibility, where depth and concentration can be controlled by ion energy and dose, respectively. A lot of research has been carried out since the 1960s. However, irradiation damage is simultaneously introduced, that degrades electronic properties and device performances. In addition, the accumulation of defects induces graphitization and prevents from returning to crystalline diamond.
As for the doping technique, boron, the most promising p-type dopant, was successfully ion-implanted to show p-type characteristics from an early stage, although sufficient electronic properties for device applications have not yet been achieved. On the other hand, clear n-type properties have not been shown by ion implantation. A key issue is how to eliminate the influences of irradiation damage.
On the contrary, there are fields in which point defects by ion implantation can be effectively utilized. For example, a great deal of attention is recently paid on research on applications to quantum sensing devices using magnetic resonance related to the vacancy complexes with additive elements such as nitrogen (N-V center) in diamond. Here, it is necessary to control the position so that a vacancy should be located next to an ion-implanted additive element.
This presentation will introduce the research on controlling defects as irradiation damage caused by ion implantation into diamond semiconductor for the purpose of applying diamond to various devices.
Acknowledgment: This work was partially supported by JSPS KAKENHI Grant Number JP20H02139.

Speaker: Dr Masahiko Ogura (AIST/Japan)

12 Capabilities of the FLUKA particle transport code for the design and operation of high-power targetry systems¶

FLUKA [1-3], developed and maintained by the FLUKA.CERN Collaboration, is a general-purpose code for the Monte Carlo (MC) simulation of radiation transport. It is capable of accurately accounting for the transport and interaction of over 60 particle species (photons, leptons, hadrons, and ions) in complex material geometries on a broad energy range, from the keV (meV for neutrons) up to the TeV, and even up to the PeV if linked to DPMJET III [4]. FLUKA is applicable to problems in radiotherapy, cosmic ray physics, dosimetry, neutronics and, especially, to the design and operation of particle accelerators. Specifically, FLUKA has been extensively used to assess radiation effects in the design and operation of high-power targetry systems, and in general of beam-intercepting devices under energetic and intense radiation fields at CERN and other labs, in the course of which regular benchmarks against experimental data and other MC codes have been performed [5].

In this contribution, the capabilities of FLUKA to assess radiation effects in materials shall be demonstrated, showing by way of example its scoring capabilities for physical observables of relevance for short- and long-term radiation damage effects, including dose deposition, the production of H and He, as well as displacements per atom (DPA), employing a recent implementation of a state-of-the-art athermal recombination efficiency [6]. Finally, the capabilities of FLUKA to assess the production of single-event effects in electronics under intense radiation fields shall be showcased.

[1] https://fluka.cern

[2] C. Ahdida, D. Bozzato, D. Calzolari, F. Cerutti, N. Charitonidis, A. Cimmino, A. Coronetti, G. L. D’Alessandro, A. Donadon Servelle, L. S. Esposito, R. Froeschl, R. García Alía, A. Gerbershagen, S. Gilardoni, D. Horváth, G. Hugo, A. Infantino, V. Kouskoura, A. Lechner, B. Lefebvre, G. Lerner, M. Magistris, A. Manousos, G. Moryc, F. Ogallar Ruiz, F. Pozzi, D. Prelipcean, S. Roesler, R. Rossi, M. Sabaté Gilarte, F. Salvat Pujol, P. Schoofs, V. Stránský, C. Theis, A. Tsinganis, R. Versaci, V.
Vlachoudis, A. Waets, M. Widorski,
"New Capabilities of the FLUKA Multi-Purpose Code",
Frontiers in Physics 9, 788253 (2022).

[3] G. Battistoni, T. Boehlen, F. Cerutti, P.W. Chin, L.S. Esposito, A. Fassò, A. Ferrari, A. Lechner, A. Empl, A. Mairani, A. Mereghetti, P. Garcia Ortega, J. Ranft, S. Roesler, P.R. Sala, V. Vlachoudis, G. Smirnov,
"Overview of the FLUKA code",
Annals of Nuclear Energy 82, 10-18 (2015).

[4] https://github.com/DPMJJET

[5] N.V. Mokhov, I.L. Rakhno, I.S. Tropin, F. Cerutti, L.S. Esposito, A. Lechner,
"Energy deposition studies for the high-luminosity Large Hadron
Collider inner triplet magnets",
Phys Rev ST Accel Beams 18, 051001 (2015).

[6] K. Nordlund, et al.,
"Improving atomic displacement and replacement calculations with physically realistic damage models",
Nature Commun., 9:1084 (2018)

Speaker: Dr Vasilis Vlachoudis (CERN)

FLUKA_HPTW_2023.pptx

13 Measurement of displacement cross section for high-energy protons and future plan for material damage using 0.4 GeV protons at J-PARC¶

Material damage index of displacement per atom (dpa) is calculated by the particle flux and the displacement cross section. Since the experimental data of the displacement cross section was scarce, the measurements using protons were conducted, and so far, the experimental data of protons up to 30 GeV have been obtained in J-PARC and other Japanese facilities. The displacement cross section was almost constant regardless of the projectile proton energy above several GeV, which is against the expectation because the heat deposition given by the proton increases as projectile energy due to the relativistic theory. The experiment with 120 GeV protons at Fermi National Laboratory (FNAL) was conducted to obtain the data for high-energy regions. In this talk, the experimental data will be presented. To extend the energy region, the experiment with 430-GeV protons at HiRadMat in CERN is planned for the following year.
Additionally, a new beam irradiation facility plan at J-PARC with 0.4-GeV protons to study material radiation damage will be presented in this talk. In 2022, the user community of the facility was established. New users, especially those outside of Japan, will be welcomed.

Speakers: Shin-ichiro Meigo (J-PARC/JAEA), Dr Shin-ichiro Meigo (JAEA/J-PARC)

meigo_HPTW2023_dpa.pdf

15:15 Coffee Break

Topic5-1¶

Convener: Dohyun Kim (Brookhaven National Laboratory)

14 Charge stripper ring for RIBF¶

The RIKEN RI beam factory (RIBF) is promoting the future upgrade plan to increase the intensity of heavy-element beams, especially uranium beams which are particularly important in unstable nuclear physics research in the midst of global research competition. At the RIBF, the overall charge conversion efficiency of two strippers, He gas and rotating graphite sheet disk strippers, used for uranium acceleration is less than 5%, which creates a severe bottleneck for the intensity upgrade. We have proposed using charge stripper rings (CSRs) as a cost-effective way to enhance the charge stripping efficiency at the RIBF. The overall charge conversion efficiency will be increased from 5% to 50% (10 times of the current level) with CSRs. The design and development status of CSRs will be discussed.

Speaker: Hiroshi Imao (RIKEN)

HPTW23_imao_ul.pdf

15 Facility Design of the COMET Experiment at J-PARC¶

Construction of the COMET Experiment is underway at J-PARC. It aims to discover a phenomenon of muon to electron conversion, which can prove an existence of the new physics. To achieve and overcome the current experimental record, we will generate high-intensity muon beam by injecting J-PARC 8-GeV primary proton beam to the target. The beam power will be 3.2 kW at the first stage and will be upgraded to 56 kW. The target will be very thick and have length of ~700 mm. We will start the experiment with a graphite target and plan to change it to tungsten in the future. The target will be installed inside a superconducting solenoid magnet. Generated charged pions and muons can be captured by the strong solenoidal field and they will be transported to the experimental area. The irradiation of the high-intensity proton beam to the thick target will generate huge amount of the radiation. To prevent quench of the superconducting coil by the radiation from the target, a heavy shield will be installed between the target and coil. The target room, where the beamline apparatus including the target and superconducting magnet will be installed, must be shielded with sufficient thickness to protect workers who will stay on the top of the beamline. One of the difficulty of the COMET facility design is to efficiently shield the radiation which will be widely distributed due to the thick target. In this presentation, we will introduce the current design of the COMET experimental facility.

Speaker: Yoshinori Fukao (KEK IPNS)

COMET_facility.pdf

16 ORNL Second Target Station Preliminary Design Update¶

The Second Target Station (STS) is currently in the preliminary design phase at the Oak Ridge National Laboratory (ORNL). STS will significantly expand the existing capabilities of the Spallation Neutron Source (SNS) at ORNL by constructing a new target station that utilizes the Proton Power Upgrade (PPU) enhanced SNS accelerator to make STS the world-leading peak brightness source for cold neutrons.
Since the completion of the conceptual design phase in 2021, significant advances in the design of the Target Systems components have been made and some of these advances will be presented. Considerable R&D design, prototyping and testing has been completed validating novel moderator manufacturing. Substantial cost control actions have also been implemented and more are in progress, including cryogenic moderator system simplification, reduction of component cooling loops and monolith shielding composition changes.
The STS technical systems have made excellent progress towards the start of preliminary design reviews scheduled in 2024. Key decisions and design choices have been made. The cost savings identified do not affect the STS Key Performance Parameters (KPPs). Looking ahead, STS is committed to seek efficiencies and scope optimization to limit cost growth while maintaining technical capabilities of the new facility.

Speaker: Michael Strong (Oak Ridge National Laboratory)

HPTW_STS_Prelim_Design_ Update_Nov2023.pptx

17 ORNL Second Target Station Vessel Systems Preliminary Design Update¶

The Second Target Station (STS) is currently under preliminary design at Oak Ridge National Laboratory (ORNL). STS will significantly expand the existing capabilities of the Spallation Neutron Source (SNS) at ORNL by constructing a second target station that utilizes the existing SNS accelerator and provides a world leading source of cold (long wavelength) neutrons. The Target System design of STS differs significantly from the SNS First Target Station design due to the use of a rotating Tungsten target wheel. In order to accommodate the target wheel design, a unique vessel and shielding system is being developed. I will present an overview of the STS target monolith, followed by the preliminary design and analysis of the Vessel Systems components, and share several trade studies that have been undertaken to make critical design choices.

The Vessel Systems scope within STS consists primarily of the Core Vessel, Core Vessel Shielding and Core Vessel Nozzle Extensions. The Core Vessel surrounds the STS Target and Moderator Reflector Assembly (MRA) and provides an optimal environment for Neutron production and transport. Core Vessel shielding is comprised of an assembly of liquid cooled and uncooled shield blocks contained within the Core Vessel that absorb radiation from the spallation process and cool the areas surrounding the Target and MRA. Core Vessel Nozzle Extensions extend radially from the outside diameter of the Core Vessel to the outside diameter of the target monolith in the instrument bunker. Each nozzle extension houses a monolith insert that makes up the first section of optical guide between the MRA and the neutron instruments.

Significant advances in the preliminary design of the Vessel Systems components have been made over the past three years, and some of these advances will be presented. The overall design and fabrication approach of the Core Vessel will be presented, with a focus of Core Vessel simplification to reduce manufacturing complexity and cost. The results from preliminary thermal and structural analyses will also be presented. A design study of a core vessel cooled shield block will be presented that shows a number of concept designs and compares their cooling performance and pressure drop under expected operating conditions. Finally, the results of a Nozzle Extension trade study will be presented that highlights the design, construction approach and connection method to the Core Vessel.

Speaker: Dr Christopher Anton (ORNL)

HPTW ORNL STS Anton Presentation.pptx

18 Design of Rotating Tungsten Target with Segmented Modules for Replacement¶

The Second Target Station will be a world-leading neutron facility with cold neutron brightness an order of magnitude better than the ORNL Spallation Neutron Source First Target Station. This facility aims to produce world-class brightness neutrons to advance fundamental science.

A rotating 1.2m diameter target disk of 59mm thick Tungsten water-cooled bricks has been selected for the Second Target Station. The disk is attached to a 5m long shaft. A drive system is attached to the top of the shaft that provides rotation and cooling water. Tungsten has a long history of successful spallation target operation; however, little is known regarding the irradiated fatigue limits of tungsten material. The STS design has developed two approaches for developing a high-reliability rotating tungsten target encased under 5m of shielding: 1) improve the reliability of the target by utilizing a design that accommodates tungsten failures and 2) improve the recovery time after a target failure by segmenting the circular disk so that sections that can be removed through a small opening in the shielding.

The solid tungsten target design for the STS employs an encased construction of Inconel 718, copper, and tungsten. Water is routed within the tubing attached to the Inconel housing. The separation between water and spallation material provides significant protection against crack propagation and isolates the tungsten from contaminating the cooling water. Geometry, fabrication techniques, current R&D results, and analysis demonstrate the reliability of the selected target design.

To address the concerns over increased risk and the increased complexity required to change a full target disc, a segmented concept has been chosen for STS. The chosen segmented design splits the target disc into 20 individual sections. Each segment is independent and when placed in a circular array on the rotating shaft makes up a complete circular disc. The segments are removed through a narrow opening in the shielding located downstream of the rotating shaft. To remove more than 1 segment, the shaft is rotated; sequentially bringing each segment into the removal position. All connections, fasteners, and remote handling operations are accomplished above the core vessel shielding with long-handled tooling. It is estimated that a segment may be removed in 10 days, whereas a disc replacement was estimated to take 50 days.

This talk will present the current state of the target design along with a brief overview of the design evolution for the Second Target Station.

Speaker: Aaron Jacques

PRES-ORNL-23-11-4 HPTW Current Status of the STS target Segment & Analysis.pptx

17:00 Announcement

Tuesday 7 November ¶

08:30 Registration

08:50 Announcement

Topic2-2¶

Convener: Shunsuke Makimura (J-PARC/KEK)

19 RaDIATE Collaboration Status and Recent Results on Material Studies¶

A high-power target system is a key beam element to complete future High Energy Physics (HEP) experiments.
In the recent past, major accelerator facilities have been limited in beam power not by their accelerators, but by the beam intercepting device survivability. The target must then endure high power pulsed beam, leading to high cycle thermal stresses/pressures and thermal shocks. The increased beam power will also create significant challenges such as corrosion and radiation damage that can cause harmful effects on the material and degrade their mechanical and thermal properties during irradiation. This can eventually lead to the failure of the material and drastically reduce the lifetime of targets and beam intercepting devices.
In order to operate reliable beam-intercepting devices in the framework of energy and intensity increase projects of the future, the RaDIATE collaboration (Radiation Damage In Accelerator Target Environment) managed by Fermilab, brings together existing expertise from 20 international institutions to execute a coordinated strategy for high power targetry R&D.
After presenting an overview of RaDIATE R&D program in support of High Power Targetry development we will provide recent results on material studies and the prospective towards future irradiation campaign.

Speaker: Frederique Pellemoine (Fermilab)

HPTW2023-RaDIATE Collboration - Pellemoine.pptx

20 Novel Materials R&D for Next-Generation Accelerator Target Facilities¶

High-Entropy Alloys and Electrospun Nanofiber materials are two novel classes of materials that can offer improved resistance to beam-induced radiation damage and thermal shock. Research to develop these new materials specifically for multi-megawatt accelerator target applications, such as beam windows and particle-production targets, are ongoing at Fermilab, within the scope of a DOE Early Career Research Program. The research program combines in-beam experiments with complementary simulations to tailor the microstructures of these novel materials for use in next-generation accelerator target facilities. Iterative simulations to optimize the material composition, physics performance and beam-induced thermomechanical response will guide the material design and fabrication processes based on established figures of merit. Ensuing material irradiation experiments using low-energy ions and prototypic high-energy protons, followed by extensive post-irradiation material characterization, will then assess and qualify the selected novel materials. This talk will provide an update on the activities to develop these novel targetry materials.

Speaker: Kavin Ammigan (Fermilab)

HPTW2023-Ammigan.pptx

21 Computational Exploration of High Entropy Alloys as Promising Materials for Future Beam Windows¶

Beam power and runtime in high energy particle accelerators face limitations due to targets and beam windows, experiencing thermal shock, fatigue, and irradiation damage from the beam. To achieve higher beam power and extended runtime, the development of new materials is crucial, with High Entropy Alloys (HEAs) emerging as a promising solution due to their exceptional properties, including high strength, ductility, and radiation resistance. This study proposes an integrated approach that combines computational techniques, including CALPHAD, density functional theory (DFT), and molecular dynamics (MD), to comprehensively investigate defect properties of suitable HEAs, offering potential alternatives for the next generation of beam windows. Starting with a previously studied single-phase BCC CrMnV ternary alloy, small quantities of Ti were introduced as an impurity getter, and Al was added to decrease density while, in conjunction with added Co, promoting a coherent B2 phase to strengthen the material with minimal embrittlement. CALPHAD is employed to conduct approximately one hundred thousand simulations, facilitating the identification of potential HEA compositions. Subsequently, a DFT-informed machine learning potential is being developed to analyze the defect properties of the narrowed HEA compositions, and machine-learned potentials will be utilized for running molecular dynamic (MD) simulations to study defect properties in these alloys. This research not only outlines the CALPHAD approach and highlights the importance of DFT in developing HEAs but also demonstrates the promising role of machine learning in this context. The findings from this study hold the potential to significantly advance materials used in high energy particle accelerator components, ultimately leading to increased beam power and improved runtime.

Speaker: Gaurav Arora (Postdoc Research Associate)

HPTW2023.pptx

22 Evaluation of β-phase based titanium alloys¶

Titanium materials have been applied to beam window materials and beam dumps in large accelerator systems because of their low specific gravity, high corrosion resistance, strength, and other advantages. As beams become more powerful, there is a growing demand for higher irradiation resistance and other properties. We have been further characterizing titanium alloys based on the β-phase, and have found that the Ti-15-3-3-3 alloys have excellent irradiation resistance properties when subjected to ion irradiation. In order to investigate the cause of this, we are also evaluating the microstructure and point defects of this material and related materials by TEM, positron lifetime measurement, and stress-induced changes. In addition, we have recently begun to evaluate the properties of titanium-based high-entropy alloys based on β-titanium, which have been attracting worldwide attention and are being developed as high-entropy alloys. The properties of this material have been investigated, and it is becoming clear that it has considerably higher strength than conventional iron- and titanium-based materials.

Speaker: Eiichi Wakai

10:00 Coffee Break

Topic6-1¶

Convener: Katsuya Yonehara (Fermilab)

23 NuMI Record Beam Power Experiences¶

This talk will contain an overview of the measures taken to set a new beam power record (960kW) for the NuMI experiment, with focus on the target system. Target design upgrades, operational parameter changes, and target hall monitoring systems will be discussed. Additionally, challenges encountered along the way will be discussed such as a Horn 2 failure. Future plans to achieve higher beam power will also be discussed.

Speaker: George Lolov (Fermilab)

NuMI Record Beam Power Experiences HPTW2023.pptx

24 Current developments of the LBE spallation target for the CiADS project¶

To demonstrate the future Accelerator Driven System (ADS), a large-scale scientific facility - China Initiative ADS (CiADS), is now being constructed in Huizhou City by the Institute of Modern Physics, Chinese Academy of Sciences (IMP-CAS). CiADS consists of an linear accelerator, a spallation target and a sub-critical reactor. Lead-bismuth eutectic (LBE) will be adopted as the spallation material/coolant for the spallation target and the reactor. As one of the key acceptance indicators, continuous proton beam with a power of 250 kW and an energy of 500 MeV will be injected into the spallation target to produce neutrons to drive the sub-critical reactor. Thereafter, the proton beam power will be gradually upgraded to 2.5 MW to meet the final design value of CiADS.

In the CiADS project, there is a cylindrical space at the center of the reactor, into which the spallation target will be inserted. However, the space is extremely limited, and it makes a great challenge to design and install the target in such a narrow space. To solve this issue, a compact target concept is adopted, as can be seen in Fig.1. The heat exchanger of the cooling system and the electromagnetic pump (EMP) are both installed within the target.

To realize the 250 kW LBE spallation target in engineering, a prototype LBE target has been developed to verify system integration and key thermal-hydraulic characteristics, which had been operated over 400 hours; Moreover, to mainly investigate the soundness of the target beam window and the low power accelerator-target coupling technology, a Target Window Test Loop is under construction, and the target head of which will be bombarded by an accelerator (named CAFE2) in IMP-CAS.

In addition to the above works, R&Ds are being conducted to develop key components and technologies to support the construction of the target, such as the target flow channel design, EMP techniques, abnormal diagnostic techniques, etc..

In the presentation, the current development status of the CiADS LBE spallation target will be briefly introduced.

Speaker: Tao Wan

Current developments of the LBE spallation target for the CiADS project-upload.pptx

25 Upgrades, fabrication and quality assurance of 1.3MW HyperK target¶

The T2K target has operated successfully since the start of beam in 2010. During this time two targets have been installed and operated without failure. The second target has accumulated 3.1e21 protons on target (POT) at 510kW beam power. With the current upgrade plans the beam power will be 1.3MW by 2026 which will push the target even harder. At this beam power the heat load on the target will be significantly higher and require a higher flow rate of helium to cool it. It addition the levels of radiation damage in the materials will equal the current experience in less than 1 years operation. A prototype HyperK target has been constructed to operate at elevated pressure to increase the cooling capacity. Further improvements are being implemented in the next operational targets to improve the quality and de-risk the manufacturing process. Another key issue for the HyperK targets are the ceramic isolators and seals on the helium pipes. In addition to the temperatures, pressure and radiation in operation, they are also exposed to rapid thermal cycles during beam trips. An extensive testing campaign is underway to validate and select suitable components before implementing them in the target station.

Speaker: Mike Fitton (UKRI - STFC)

2310250004.mp4

5p2_weld_CT2.avi

HPTW2023_HK_Target_MDF.pptx

26 Large Hadron Collider (LHC) Beam Dumps: a high-power, high energy beam absorber: evolution from LHC construction towards High Luminosity LHC¶

Two 6-tonne beam dumps, each constituted by a graphite core encapsulated in a high-strength stainless-steel vessel, are employed to absorb the energy of the two Large Hadron Collider (LHC) intense 7 TeV/c proton beams during operation of the accelerator.

The beam dumps were initially conceived to repeatedly absorb up to around 300 MJ/dump. This has increased over the lifetime of the LHC as a result of upgrades to increase the physics reach of the machine. For the High Luminosity LHC (HL-LHC) era, the dumps will have to repeatedly absorb up to 700 MJ/dump, during beam extractions lasting 90 microseconds. Several upgrades and post-irradiation examination interventions have been carried out since the first installation of the dumps, including modifications of the outer vessel and supporting structure, along with improvements to online instrumentation. Major developments in simulation techniques have also been deployed in order to better understand the dynamics of the high-energy beam absorption and the resulting thermo-mechanical effects.

The contribution will present the design, operational experience, and evolution of the Large Hadron Collider main absorber, from its early inception to the most recent operational experience, including the perspectives for a major upgrade in view of the increased demands of HL-LHC.

Speaker: Marco Calviani (CERN)

MCa_ID26_HPTW_LHC_TDE_Nov2023.pptx

27 Positron source and target in KEK¶

There are several project using positron sources in KEK.
KEK electron positron injector LINAC has been operating and developing positron sources for high energy collider experiments more than 30 years from Tristan to SuperKEKB.
The source for SuperKEKB is world's most intense and high efficiency positron source now in operation.
To further increase the positron production efficiency and the electron beam transport, a rotating target mounted on a water cooled axis is under development.

Slow positron facility is another world's most intense positron source in this field, which is located in the same tunnel as SuperKEKB positron source.
Recently hundred times intensity upgrade of the facility has been under consideration.
In this project, primary electron beam power will be hundred times increased from 0.5 kW to 50 kW.
A new water cooled rotating target will be designed and installed.
A lot of technologies and experiences obtained in the SuperKEKB project will be fed-back to its design.
And new experiences will again fed-back to the development of the positron source for ILC project which is also a task in KEK.

In the presentation, progress, upgrade plan experiences and challenges on positron sources for each project, SuperKEKB, slow positron facility and ILC, will be summarized to facilitate the collaboration with researchers from other high power particle sources.

Speaker: Yoshinori Enomoto (KEK)

231107-HPTW-enomoto-v1.pptx

28 Development of ILC positron production target¶

In the electron-driven positron source of the ILC (International Linear Collider), positrons are obtained by injecting 3-GeV electron beam into tungsten target. The average heat load of the tungsten part is about 20 kW, and a rotating target structure is adopted to disperse this heat load. For this target, it is necessary to design both a rotating structure and vacuum performance. Also, for cooling, tungsten requires bonding with a copper alloy. Brazing and hot isostatic pressing are available as joining methods for tungsten and copper alloys, but this time we are considering joining by Spark Plasma Sintering (SPS). In the SPS method, an intermediate layer is formed between tungsten and a copper alloy to bond them. By adjusting the mechanical properties of the intermediate layer, the thermal stress at the tungsten/copper alloy interface can be reduced. This time, we introduce the outline of the design of the ILC electron-driven positron source, the ongoing model test and the SPS bonding test of tungsten/copper alloy.

Speaker: Yu Morikawa (KEK)

12:15 Lunch Break

Topic6-1a¶

29 LBNF Absorber Design Status and Assembly Planning¶

This will be an overview of the purpose and present design of the LBNF Hadron Absorber followed by discussion of assembly considerations. The Absorber intercepts the residual proton beam after it interacts with the LBNF target and travels through the decay pipe. The Absorber Final Design Review is scheduled for early 2024, and to close out the design a detailed assembly plan is being created. Component delivery sequencing, stacking of shielding elements, tolerance stack-up, and worker safety in the absorber bunker are all of concern.

Speaker: Jonathan Williams (Fermilab)

HPTW LBNF Absorber Status Talk.pptx

Topic4-1¶

Convener: Chris Densham (RAL)

30 LBNF Target Status¶

The pion production target for the Long Baseline Neutrino Facility is being designed and manufactured by the High Power Targets Group at Rutherford Appleton Laboratory UK as a contribution in kind. The design of the first prototype target has now been completed. This talk will give an overview of the design and prototyping work to date, and ongoing plans for manufacturing, commissioning, and operation. An extensive programme of irradiated material research is being carried out in parallel with the prototype target manufacture, in order to inform the design of future production targets.

Speaker: Mr Dan Wilcox (Technology, Science and Technology Facilities Council, UK Research and Innovation)

Wilcox - LBNF Target Design - Final.pptx

31 PREDICTION OF BUBBLE SIZE DISTRIBUTION IN HIGHLY TURBULENT TWO-PHASE LIQUID METAL SWIRL FLOW¶

Injection of helium microbubbles at the Oak Ridge National Laboratory (ORNL)-Spallation Neutron Source has proven to be a stress mitigation mechanism that may extend fatigue lifetime of liquid mercury target vessels. The production of bubbles with average diameters of less than 0.150 mm is achieved using highly turbulent swirl flow in a liquid metal facility undergoing high radiation conditions. The design of the bubble injector device includes four swirl bubbler units working together in a counter-rotating fashion. In this work, the commercial Ansys-CFD code was used to predict the bubble size distribution obtained nearby the outlet of the bubble injectors and its evolution through the whole target vessel is tracked down to obtain average bubble size distribution vs distance from the injection site un mercury. Bubble production and bubble interactions are calculated using the interfacial area concentration transport method. The current methodology accounts for bubble interaction mechanism in the form of coalescence due to random collisions driven by turbulence, breakage due to the impact of turbulent eddies and coalescence due to wake entrainment. The results show reasonable agreement with experimental data obtained in previous studies. The current predictions provide complementary information about expected bubble size distribution by location, however current comparisons with experimental data have been limited due to experimental data available. Further details about the assumptions and limitations of the proposed two-phase flow methodology using mercury as the liquid phase and Helium gas as the secondary phase will be discussed. It is expected that validated bubble size distribution predictions serve as an input parameter for the current strain prediction models used at the SNS.

Speaker: Dr Elvis Dominguez-Ontiveros (ORNL)

Final_SNS_HPTW_Dominguez-Res.pptx

32 Overview of the design status of IFMIF-DONES Lithium Target System¶

IFMIF-DONES will be a unique research infrastructure for the irradiation of materials to be used in future fusion reactors. The facility consists of an accelerator-based neutron source capable of providing an intense neutron flux of $1-5\times {10}^{14}$ $n/c{m}^{2}s$ with an energetic broad peak around 14 MeV, allowing to recreate the radiation effects expected in a fusion environment.
This source is produced through the nuclear interaction between an accelerated deuteron beam (40 MeV, 125 mA) and a flowing liquid lithium Target. As a result, a significant power, about 5MW, is deposited continuously in the Target, which is evacuated by its high-speed liquid lithium jet injected at 15 m/s and 300ºC. A closed lithium loop is in charge of continuously supplying this liquid lithium in optimal conditions.
The Target System, which generates and manages the lithium jet, has undergone intensive R&D and design efforts during the last few years. Some of the most relevant challenges include: designing and optimizing the nozzle and back plate, where the lithium jet is generated and offered to the beam; controlling the hydrodynamic stability and pressure gradient of the lithium jet, minimizing wave perturbations on the free surface, which may affect the integrity and performance of the Target; integrating the diagnostics; and optimizing the quench tank, where the lithium is collected and quenched at the outlet of the Target.
Furthermore, the Target System is exposed to extremely harsh working conditions, leading to significant irradiation damage (~25 dpa per full power year under nominal beam conditions). To ensure safety and reliability, a regular yearly replacement strategy for part of the Target System has been established. The implementation of this strategy requires the development of a series of Remote Handling compatible systems for the installation and alignment of the replaceable parts.
This contribution provides an overview of all these aspects, as well as the current engineering design status and related R&D activities.

This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreements No 633053 and 101052200 — EUROfusion). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them.

Speaker: Dr Jorge Maestre (University of Granada, Spain)

IFMIF DONES presentation_v1.pptx

33 Multiphysics analysis of LBE windowless target design under high-power electron beam¶

Los Alamos National Laboratory (LANL) supported Niowave Inc. as a part of the National Nuclear Security Administration (NNSA)’s Molybdenum-99 (Mo-99) program [1], where USA establishes a reliable domestic supply of Mo-99 production through cooperative agreements between industries and national labs. The decay product of Mo-99, technetium-99m, is essentially used in various medical procedures. LANL helped Niowave develop, design, and evaluate a lead-bismuth-eutectic (LBE) windowless target used to produce neutrons (so-called neutron converter) by electron irradiation at a beam power of 200 kW with a beam energy of 40 MeV. Two superconducting electron accelerators are used to irradiate two neutron source converters embedded in an uranium target assembly where Mo-99 is produced by fission reactions. The neutron converter is designed such that there is a thin stainless steel (SS) housing surrounding LBE flow in vacuum. The LBE layer falls, driven by gravity, and forms free-surface in vacuum. The heat deposited on the irradiated LBE target and SS housing is removed through forced convection by LBE flow. At high incident electron beam power, high-fidelity simulation is essential to ensure the target in-beam survival and the integrity of the target system.

21-GPM LBE enters the converter at 200℃. The design of the converter was optimized by 2D/3D computational fluid dynamics (CFD) hydraulic analysis using ANSYS Fluent [2] volume-of-fluid model to obtain uniform and stable LBE layer formed with the maximum velocity of 1.96 m/s with a favorable pressure gradient avoiding wall separation. LBE velocity is under velocity limitation of 2 m/s to prevent LBE-SS interface erosion issues. Positive pressure over the LBE volume assures no cavitation in LBE flow near ultra-high vacuum conditions.

Attila4MC software [3] was used to import a customized SolidWorks [4] geometry of the discrete LBE, vacuum, SS volume and to generate unstructured meshing for Monte Carlo N-Particle (MCNP) 6.2 code [5]. Volumetric heat deposition by an electron beam on the LBE and SS was obtained by MCNP radiation transport calculations. The direct mapping of data from MCNP to CFD enables high-resolution 3D multiphysics analysis.

Conjugate heat transfer analysis was performed to obtain the 3D temperature profile for the LBE and SS. The LBE maximum temperature reaches 363 ℃, below the LBE evaporation initiative temperature, 450 ℃. The LBE-SS interface temperature reaches up to 346 ℃, which has low risk of severe SS corrosion problems.

Acknowledgment
This research is supported by Department of Energy NNSA.

References
1. NNSA’s Molybdenum-99 Program: Establishing a Reliable Domestic Supply of Mo-99 Produced Without Highly Enriched Uranium https://www.energy.gov/nnsa/nnsas-molybdenum-99-program-establishing-reliable-domestic-supply-mo-99-produced-without.
2. Ansys® Fluent 2021 R2, ANSYS, Inc.
3. Attila4MC 10.2 Overview of Core Functions, Silver Fir Software, Inc., 2020, Gig
Harbor, WA, USA, SFSW-UR-2020-OCF102.
4. SolidWorks® 2021, Dassault Systèmes.
5. C. Werner, et al., MCNP® User’s Manual, Code Version 6.2, Los Alamos National Laboratory, 2017, LA-UR-17-29981.

Speaker: Jee Hyun Seong (Los Alamos National Laboratory)

HPTW23_Jee.pdf

34 Coupling mercury/ bubble material model in the pulse simulation to predict strain on the Spallation Neutron Source target vessel with gas injection¶

SNS targets have been operating with helium microbubble gas injection since 2018. The measurements during in situ testing showed that the strain response of the mercury target vessel significantly decreased with gas injection. Strain reductions range from 40% to 75% for targets operating with gas-injection rates between 2-3 standard liters per minute (SLPM). These strain reductions are expected to significantly improve the fatigue life of the mercury target vessel. The achieved suppression of pulse response and cavitation damage with gas injection is a cornerstone of the upgrade basis to the redesigned mercury vessel for 2MW operations coming with the Proton Power Upgrade (PPU) project.
Development of simulation techniques that account for the benefits of gas injection adds a considerable challenge over the current technique used to simulate a target without gas. A combined mercury/bubble material model based on the Rayleigh–Plesset (R-P) equation was developed to improve simulation of the response of a structure containing liquid and gas by incorporating bubble growth volume feedback. This talk will detail the implementation of the mercury/bubble material model in the pulse simulation of a jet-flow target design. The newly developed simulation technique combines the current no-gas mercury material model for no-gas regions and the mercury bubble material model for the regions with gas bubbles together. The results of the strain response simulation are promising with the new techniques for the targets operating with gas injection. The challenges of the technique development will also be discussed, for example, the bubble size distributions are crucial for the simulations but are still an area of active research.

Speaker: Dr Hao Jiang (ORNL)

HPTW 2024_HJ.pptx

15:15 Coffee Break

Topic1-1¶

Convener: Frederique Pellemoine (Fermi National Accelerator Laboratory)

35 High Power Target R&D needs for muon colliders¶

The Muon Collider will serve as the discovery machine for various mysteries raised in the modern physics, while also facilitating collider experiments for the beyond standard model. The high power target system will be the central part of the collider. The performance of the system will determine the deliverable collider beam parameters, like a luminosity and collision energy. Therefore, making a strategic plan for high power target R&D is an important milestone. Our approach for the R&D is following three items:
Material Discovery: The first part of our R&D initiative on identifying a material which is enough to withstand the intense, short-bunched proton beams. The designed proton beam is the energy range of 5-20 GeV, an RMS bunch length of 1-2 ns, intensity per bunch from 1014 to 1015, and repetition rate of 5-10 Hz. RaDIATE is an international collaboration, which has been established to address the material challenge.
Optimizing Muon Yield: The second aspect involves optimizing the target system to maximize muon production in the system. Collaborative efforts between the International Muon Collider Collaboration (IMCC) hosted by CERN and the US Muon Collider design groups are the central body in designing an efficient target system. It also includes experimental efforts, like proposing the yield measurement by using an existing technologies such as EMPHATIC and NA61/SHINE spectrometers which are used for neutrino oscillation measurements.
Integration: The final piece of the plan lies in the integration of the system. The infrastructure and remote handling systems play a critical role in the maintenance and operation of the target system. The beam instrumentations for diagnose the target and assure the quality of muon beams are also included.

In my presentation, I will provide an overview of the muon collider target R&D including the Accelerator Complex Evolution (ACE) plan at Fermilab. I will also highlight each item.

Speaker: Katsuya Yonehara (Fermilab)

MC_Target_HPTW23_KYonehara.pptx

36 Fabrication of Li-doped diamond by nuclear transmutation¶

Diamond is a wide bandgap semiconductor with excellent physical properties, such as breakdown voltage and thermal conductivity. It is expected to achieve performance beyond existing devices if it is applied as an electronic device. For this purpose, it is necessary to fabricate n-type semiconductors that can operate at room temperature, using lithium as a dopant. However, this has yet to be put to practical use due to the physical properties of lithium and the problems associated with ion implantation.
In this study, we propose using the nuclear transmutation of 7Be, a radioactive isotope of beryllium, to fabricate Li-doped diamonds without lattice detects. Be would diffuse into the diamond by thermal annealing, and if it is injected into the surface layer, it can be distributed throughout the diamond without damaging the diamond lattice. Furthermore, 7Be converts to the stable isotope 7Li by an electron capture reaction and does not emit ionizing radiation which can break the lattice. Therefore, if 7Be is injected into the surface layer of the diamond with enough energy to prevent lattice defects and then thermally diffused, it is possible to fabricate a diamond with a distribution of 7Be without lattice defects. Since the half-life of 7Be is 53 days, a Li-doped diamond will be obtained several periods after implantation of 7Be.
In this presentation, we will overview our research and report on the results of ion implantation and thermal diffusion experiments using 9Be.

Speaker: Dr Yasuto Miyake (RIKEN Nishina Center)

20231107HPTW2023_miyake.pptx

37 Thermal hydraulic characteristics studies of upward spiral flow windowless target (UST)¶

Accelerator driven subcritical system (ADS) is an attractive solution to nuclear wastes disposal. Spallation target is the key coupling component between accelerator and subcritical core in ADS, which plays very important role in adjusting the operation power of the overall system and maintaining security and stability. Liquid metal windowless spallation target is considered to have more potential advantages in thermal transport. The formation and regulation of free surface is crucial and challenging in windowless target, which affects the distribution of the internal flow field, and then constrains the heat transfer performances in beam-target coupling region.

A type of liquid metal windowless target based on upward spiral flow (referred to as upward spiral flow target, abbreviated as UST) has been investigated in our previous work [1]. UST employs a stationary impeller to generate upward spiral flow, which sprays outward under centrifugation and forms a free surface. By studying the regulation effects of UST structures on the distributions of flow field and stagnation zone below the free surface, two types of optimized targets (UST-A & UST-B) are finally established based on the preferred target structures and the corresponding structural parameters. Compared with the initial target, the optimal targets have smaller stagnation zone and better thermal transport performances. As shown in Fig.1(a) and Fig.1(b), UST-A has lower deposition heat power density and lower temperature rise than those of UST-B under the equivalent power level of the beam. As shown in Fig.1(a) and Fig1(c), UST-B has a lower temperature rise than UST-A under the equivalent density of the deposition heat power. The current research achievements have foundational signification for further engineering design and development.

References:
[1] Yang W F, Qiang C W, Wang F, Li L, Deng W P, and Zhang X Y. Three-dimensional CFD simulations to study the effect of impeller geometry on internal flow field in ADS upward spiral flow target[J]. Journal of Nuclear Science and Technology, 2018, 55(12): 1381-1392.

Speaker: Weifeng Yang (Institute of Modern Physics, Chinese Academy of Sciences)

WeifengYang_HPTW2023_1107.pdf

38 Innovative material developments for target backings¶

A new generation of instruments dedicated to the study of superheavy elements has just been com- missioned in several laboratories around the world. One can cite the SPIRAL2 accelerator in GANIL, the SHE-Factory in FLNR and the new RILAC2 in RIKEN which are designed to reach beam intensities up to 10 pμA with heavy ions as 48Ca, 50Ti, 51V or 54Cr. Under these conditions, with more than 6.1013 ions per second interacting with the target, the beam spot power will be unsustainable for the usual Titanium backings that we are using for decades. The development of a new generation of materials especially designed for these specific conditions becomes of paramount importance for the future of SHE studies.
With the support of an USIAS (University of Strasbourg Institute for Advanced Study) grant, we are exploring the current possibilities at IPHC. For these developments, we face two major problematics : the heat dissipation and the structural defaults induced by high dose effects. Moreover, we are still constrained by the target backing thickness (μm order of magnitude) and by the mass of the chosen material (as low Z as possible).
These requirements have pushed us to consider Carbon-based foils as very promising leads, and especially graphite, diamond-like carbon and multilayer-graphene. We worked on different materials with a special interest for the graphene structure. This pure Carbon material consisting of single layers of atoms arranged in a two-dimensional honeycomb lattice nanostructure shows amazing thermal and mechanical properties. Although this innovative material seems to be very promising, the production of foils with a few μm thickness requires a state-of-the-art collaboration between chemistry, material physics and nuclear physics. We produced three types of graphene foils which are currently under study to measure their mechanical properties. Nevertheless, it will be mandatory to test these foils under real conditions to measure the dose effects induced by irradiation.
In parallel, we are also considering to test different Titanium-based alloys, which are well-know and widely used in the aerospace industry. In this context, we are building a laboratory fully dedicated to these studies in IPHC with the ambition to produce and to characterize μm foils of these alloys with different compositions, crystalline phases and cooking methods. Indeed, the design of an alloy especially dedicated to our studies could allow us to customize it on purpose. Complementary, we are developing multilayer materials in order to take the benefit of the specific properties (tensile strength, flexibility, thermal conductivity...) associated to different materials in the same backing foil.
The first part of this talk will be dedicated to the characterization of the extreme conditions these materials will encounter at the target plane. Then, our first materials and some preliminary results will be presented and we will finish by a discussion on the possibility to test these innovative foils under real conditions; as close as possible to the operational conditions of the future experiments performed with such intense beams.

Speaker: Kieran Kessaci (IPHC / Université de Strasbourg)

Riken_2023_KKessaci.pptx

39 Development of Beam Target Cooling System Using Two-Phase Flow Natural Circulation¶

In recent years, beam power in particle accelerator facilities has been increasing to explore new physics. Accompanying this trend, the heat generation density of beam target is also increasing. Traditionally, pumped water cooling system have been used to cool high heat generation density beam targets. However, these systems require multiplexed pumps and equipment with high safety features.
In this study, we are developing a new type of beam target cooling system using two-phase water flow natural circulation without using pumps and electric power.
The cooling system consists of a loop pipe consisting of two vertical pipes and two horizontal pipes, a target at the bottom of one vertical pipe, and a condenser (heat exchanger) at the top of the other vertical pipe. The water boils to cool the beam target due to the high heat generation density in the target, and water and vapor (two-phase flow) flows upward in the vertical pipe. The two-phase flow reaches the condenser in the other vertical pipe, where the vapor is condensed by heat exchange in the condenser. Thus, single-phase water flows down the vertical pipe. There is the density difference between the two-phase flow (water and vapor) in one vertical pipe and the single-phase water flow in the other vertical pipe. This density difference makes the driving force of the natural circulating water flow. Since this cooling system operates without electricity, it is expected to be a highly reliable cooling system even in emergencies such as power outages. It can also cool the decay heat of the target in such a situation.
In this presentation, we report the detailed conceptual design of this cooling system, and the result of experiment with cartridge heater which emulate the beam target, and result of a natural circulation test of a water/air system that supplies air to the test section with a compressor to simulate the steam generated by the beam target.

Speaker: Naoya Kamei (J-PARC/KEK)

oral_final.pdf

Poster session¶

40 ISIS Target Station Two Horn Water Pre-Moderator Failure, Investigation, and Redesign¶

The ISIS Target Station Two (TS2) Horn (water) Pre-Moderator is an integral part of the Target-Reflector and Moderator (TRaM) assembly. It is a vital component in the process of moderating neutrons to the required energy for instruments on the west side of the Target Station. The original pre-moderator, made from a 2000 series aluminium alloy, failed within the first year due to corrosion. The replacement was manufactured from the 5083-aluminium alloy for improved corrosion resistance and ran for six years before being replaced during a reflector upgrade in 2014.
The third pre-moderator began leaking toward the end of 2021. This became apparent when the Target Operations Group became aware of an increase in moisture levels detected by the residual gas analyser within the TRaM void vessel, alongside an indicated decrease in the header tank cooling water level. The spare pre-moderator was fitted while investigations began on the source of the leak. Redesign and manufacture were urgently needed; if the spare failed before a replacement was ready, then TS2 would need to be shut down until a replacement could be installed. Manufacture would be in excess of six months.
Finite Element Analysis performed in ANSYS highlighted stress concentrations where the lid was bonded to the ribs of the main structure. Design changes have been made to eradicate this weakness, with electron beam welding trials performed to validate the design for manufacture. This assembly is now in manufacture.

Speaker: Mark Telkman (STFC)

HPTW 2023 - ISIS TS2 Horn Pre-Moderator Redesign Introduction Slide.pptx

HPTW 2023 Poster - Horn Water Pre-Moderator Failure, Investigation, and Redesign.pdf

41 Optimisation Procedures for ISIS-II Targets¶

ISIS-II, the successor to the UK’s pulsed neutron and muon source, will require two newly-designed spallation targets [1]. This work is still at the conceptual design stage, with a range of possible target designs still under consideration. To evaluate these concepts, it is necessary to produce a range of well-optimised target designs in sufficient detail to understand all the issues involved. Trade-offs must often be made between the competing requirements of neutronic performance and engineering reliability.
This poster will present details of the optimisation procedures applied to various aspects of the target design, including selecting the number of target plates and designing the outer pressure vessel. These processes were automated as much as possible, allowing a large number of design concepts to be evaluated in detail.

References
[1] Initial Target Concepts for ISIS-II – D. Wilcox HPTW2023

Speaker: Mr Daniel Wells Calvo (Technology, Science and Technology Facilities Council, UK Research and Innovation)

ISIS II Neutron Target and Pressure Vessel Design.pptx

42 Initial Target Concepts for ISIS-II¶

Conceptual design studies are now underway for ISIS-II, the successor to the UK’s pulsed neutron and muon source. Appropriate target technologies must be selected for each of the two proposed neutron target stations, to achieve a balance between neutronic performance and engineering reliability.
An essential choice early in the design process is between a stationary solid target or a rotating wheel; therefore it is necessary to understand the limits of achievable beam power on a stationary solid target. Safe operating limits must be defined for direct beam on target, as well as residual decay heat in a Loss of Coolant Accident (LOCA) scenario. Decay heat rather than direct beam has been found to be the limiting factor in some recent facility designs.
This talk will present the current status of preliminary designs for an ISIS-II target concept which enables the highest possible beam power on a static solid target. Detailed optimisation procedures will be presented elsewhere at this conference [1]. Strategies to mitigate the severity of a LOCA scenario were considered from the conceptual design phase. Alternative designs for rotating target wheels will also be presented. The selection of candidate core and cladding materials for ISIS-II targets in still in the early stages. A broad overview will be given of the current status of irradiated material studies, knowledge gaps and plans to address these.

References
[1] Optimisation Procedures for ISIS-II Targets – D. Wells-Calvo HPTW2023

Speaker: Mr Dan Wilcox (Technology, Science and Technology Facilities Council, UK Research and Innovation)

HPTW Poster - Target Concepts for ISIS-II.pptx

HPTW_2023_Poster_Intro_Initial_Target_Concepts_for_ISIS-II_Dan_Wilcox.pptx

43 Simulated and Measured Performance of ISIS TS1 Project Target¶

As part of the ISIS TS1 Project [1], a new design of spallation target has been installed and operated at ISIS TS1. Detailed Finite Element Analysis (FEA) simulations were used to guide the design process and predict target performance. Since the TS1 Project target began operation in November 2022, operating data has been collected and used to validate the target simulation approach.
Relatively quickly after receiving beam, it was noted that the temperature of the front target plate was elevated compared to predictions and compared to the other plate temperatures. Because the installed target was now too radioactive to permit hands-on inspection, FEA simulations became a vital tool to understand the possible causes and safety implications of this anomalous behaviour.
The elevated temperature appears to be confined to the front target plate only, indicating a highly localised effect. The other nine target plate temperatures agreed closely with FEA simulations of both steady-state and transient behaviour. This gives confidence in the overall simulation approach, while also ruling out several proposed causes of the elevated front plate temperature.
Recent reports [2] [3] have shown a significant reduction in the thermal conductivity of tungsten after irradiation. The installation of a new, fully instrumented TS1 Target offered an opportunity to observe this effect in-situ on a working spallation target. Detailed records were kept of plate temperatures over time, and compared to FEA simulations which included irradiation-degraded material properties.

References
[1] ISIS TS1 Project summary – S. Gallimore et al 2018 J. Phys.: Conf. Ser. 1021 012053 DOI 10.1088/1742-6596/1021/1/012053
[2] Thermal diffusivity of tungsten irradiated with protons up to 5.8 dpa – J. Habainy et al., Journal of Nuclear Materials, 2018
[3] Thermal diffusivity degradation and point defect density in self-ion implanted tungsten – A. Reza et al., Acta Materialia, 2020

Speaker: Mr Dan Wilcox (Technology, Science and Technology Facilities Council, UK Research and Innovation)

HPTW Poster - Simulated and Measured Performance of TS1 Project Target.pptx

HPTW_2023_Poster_Intro_TS1_Simulated_and_Measured_Dan_Wilcox.pptx

44 ISIS Target Station 2, Post Irradiation Examination of W-Ta Target no 4¶

The ISIS Synchrotron operates two Target Stations (TS). TS1 is the oldest and has been operating for nearly 40 years. TS2 came onstream in 2009 adding an additional suite of instruments for scientific research.
Both Target Stations have solid Tungsten Targets clad in Tantalum, which are water-cooled. TS1 Target receives beam power of 160µA at 800 MeV and has proved to be very reliable with a service life of around 5 years. Even though TS2 Target receives only a quarter beam power (40µA) it has a shorter service life of around 2 years. A gamma spectroscopic analysis (gamma spec) is taken during regular maintenance periods to look for evidence of W187 leaching into the cooling water. This is the trigger for changing the Target.
The failure mode is believed to be a breach in the tantalum cladding allowing cooling water to contact the tungsten core. There are several mechanisms that could cause or contribute to this failure.
Post Irradiation Examination (PIE) of a used TS2 Target will provide valuable information regarding the primary mechanism for failure and will focus attention on how to mitigate the problem and extend the service life of the target towards the design goal of 5 years.
Planning for the PIE operation is at an advanced stage with the bespoke tooling having been designed, built, and tested. Full mock tests in the offline Remote Handling Facility have been carried out in preparation for the operation to take place in January 2024.
This presentation will describe in detail the design of the bespoke tooling and the experience gained through offline Remote Handling trials in cutting the end from a mock (tantalum) target to expose the inner surfaces for visual inspection and evaluation.
The severed end cap will be packaged separately from the remainder of the target with the intention of carrying out materials analysis at some point in the future to increase our knowledge of tantalum’s material properties in a highly irradiated state.

Speaker: Leslie Jones (UKRI-STFC Rutherford Appleton Laboratory)

HPTW2023 - Poster Oral TS2 Post Irradiation Examiniation.pptx

45 COLLIMATORS FOR THE HIGH LUMINOSITY LHC AT CERN¶

The collimation system of the CERN Large Hadron Collider (LHC) has been designed to ensure that beam losses in superconducting magnets remain below quench limits in all operational phases. Their jaws constrain the relativistic, high-energy particles to a very small transverse area and protect the machine aperture.
Collimators are organised in families. Primary (TCP) collimators define the collimation cut; secondary (TCS) collimators intercept beam particles scattered by TCPs, and shower absorbers (TCLAs) intercept the most forward secondary particles from TCPs and TCSGs. Tertiary collimators (TCT) offer local protection to the inner triplets (ITs) in IR1, IR2, IR5 and IR8, and reduce the background to the experimental detectors.
More than 100 collimators are installed in the LHC, of different types and functions and with more than 400 degrees of freedom for precise positioning with respect to the LHC beams. The present collimation system features momentum cleaning, located in the insertion region 3 (IR3), and betatron cleaning, located in IR7 with the last stages in the experimental IRs for local protection. By safely disposing of the particle losses, the collimators protect the delicate elements of the machine, help reduce the total dose on the accelerator equipment and optimize the background for the experiments.
Overall, this contribution provides a comprehensive overview of the role, functions, and upgrade requirements of the LHC collimation system in the context of the HL-LHC project. It outlines the challenges and objectives related to collimator design and implementation.

Speaker: Antonio PERILLO MARCONE (CERN)

HPTW23_Collimators_Poster_slide.pptx

46 OPERATIONAL EXPERIENCE OF CERN SUPER PROTON SYNCHROTRON BEAM DUMP¶

Within the scope of the LHC Injectors Upgrade (LIU) project at CERN, a significant redesign of the Super Proton Synchrotron (SPS) beam dump has been undertaken, accompanied by a relocation within the accelerator. The new device has been installed during the Long Shutdown 2 (LS2) in 2019-2020 and has been successfully operating since May 2021.
The revamped beam dump was designed to effectively absorb proton beams with energies ranging between 14 and 450 GeV/c, carrying a beam power of up to 270 kW.
Following LS2, the accelerator started operation with the average beam power intercepted by the dump increasing gradually up to approximately 100 kW.
The device’s design and construction incorporate features engineered to efficiently dissipate the thermal power deposited by the beam. Furthermore, an array of temperature sensors has been strategically positioned throughout the core of the dump to monitor its behaviour under diverse operational scenarios, thereby providing a basis for validating the numerical models employed for simulating the dump's performance.
This contribution consists in an overview of the main design features of this device, and the return of experience of operation. Specifically, the temperature readings at different locations and under different beam conditions will be compared with the values obtained from numerical simulations.

Speaker: Antonio PERILLO MARCONE (CERN)

Operational_Experience_TIDVG5_slide.pptx

47 Beam Intercepting Devices for the High Intensity upgrade in CERN’s SPS North Area facility¶

CERN’s Super Proton Synchrotron North Area (NA) is set to house a new high-intensity fixed-target facility, to be installed in the existing ECN3 Experimental Cavern. Beam delivery to this area relies upon several beam-intercepting devices located in various branched transfer lines from the SPS. These include the transfer line ‘TED’ dump and ‘TCSC’ splitter protection collimators in the NA beamlines, followed by primary production target systems of beryllium plates and subsequently by a combined collimation, attenuation and dump device made from a set of aluminium, copper and iron blocks and known as a ‘TAX’ (Target Attenuator [for] eXperimental areas).
These protection-devices which must be capable of withstanding a few high intensity pulses are to be refurbished or installed as new elements. These may operate in a range of configurations depending on experimental needs. Future operational regimes with higher beam intensities (increased from a current specification of 1.5 × 10^13 to 4.0 × 10^13 𝑝+/pulse), shorter pulse times (4.8 s reduced to 1.2 s), greater repetition rates (14.4 s cycle time reduced to 7.2 s) and ten times the annual intensity place more stringent thermo-structural demands beyond their original specification.
This contribution provides an overview of the different beam-intercepting devices and the respective engineering challenges associated with the high-intensity upgrade proposed for CERN’s North Area ECN3.

Speakers: Rui Franqueira Ximenes (CERN), Dr Marco Calviani (CERN), Jean-Louis Grenard (CERN)

ID92_(slide)_Beam Intercepting Devices for the High Intensity upgrade in CERNs SPS North Area facility.pdf

ID92_Beam Intercepting Devices for the High Intensity upgrade in CERNs SPS North Area facility_print.pdf

48 Target Systems at the Front end of the International Muon Collider¶

Muon colliders offer enormous potential for research of the particle physics frontier. Leptons can be accelerated without being subjected to large synchrotron radiation losses. The International Muon Collider Collaboration is considering 3 and 10 TeV (CM) machines for a conceptual stage.

At the front end of the Muon Collider facility lays a MW class production target system, which will absorb a high power (1.5 to 3 MW) proton beam to produce muons via pion decay. The target must withstand high dynamic thermal loads induced by 2 ns high intensity pulses at a 5 Hz repetition rate. The target system comprises other critical components such as the proton beam windows, subjected to substantial radiation damage, and a surrounding 600 kW tungsten shielding to protect the magnets from neutrons and the electromagnetic radiation. Operational reliability must be guaranteed to reduce target exchanges to a minimum, in an area where all the systems will have to be integrated inside a SC Solenoid cryostat.

This contribution provides an overview of the target systems design and engineering assessments related to a carbon target baseline, along with alternative target concepts involving liquid lead and fluidized tungsten powder, for the International Muon Collider Project.

Speaker: Dr Marco Calviani (CERN)

ID91_(slide)_Target Systems at the Front end of the International Muon Collider.pdf

ID91_Target Systems at the Front end of the International Muon Collider_print.pdf

49 LINAC3 SLITS CONSOLIDATION¶

The CERN’s Linac3 is a linear accelerator responsible for providing ion beams to the CERN accelerator complex. The Linac3 slits serve various functions, including charge state separation, diagnostics, and emittance measurement. However, the currently installed five slits exhibit differing specifications, functions, and positions along the beam line, making maintenance and management of spare parts complex.

The installed slits date back to around 1970 and were originally designed for CERN’s Linac1. Unfortunately, there is a lack of comprehensive documentation and spare parts for their maintenance. Moreover, only one slit is equipped with a survey reference, and the beam parameters have undergone changes over the years.

This contribution will provide a detailed account of the Linac3 slits consolidation program's progress, which started one year ago. The aim is to identify and design new sub-components using commercially available parts while concurrently updating the documentation and increase machine reliability. A thorough study has been conducted on heat dissipation and mechanical characteristics, including practical thermal contact conductance and conductivity characterization. The poster will also present an initial conceptual design of the new system.

Speaker: Jean-Louis Grenard (CERN)

2023_LINAC3SLITS_POSTER.pdf

LINAC3 slits CONS (slide).pptx

50 ISOLDE Beam Dumps Exchange: A challenging consolidation, from buried dumps to flexible access¶

The CERN ISOLDE Facility is the radioactive beam facility dedicated to the production, study and research of nuclei far from stability, currently employing the 1.4 GeV/c beam from the Proton Synchrotron Booster (PSB). ISOLDE is offering the largest variety of post-accelerated radioactive beams in the world. The installation is equipped with two uncooled iron blocks acting as beam dumps, buried below 10 meters of earth in 1991 during ISOLDE construction. They were not initially designed to be accessible or serviced by remote handling.
A study has been launched to evaluate the possibility of changing the ISOLDE beam dumps during CERN’s Long Shutdown 3 to guarantee the long-term reliability of the installation and prepare for the 2 GeV/c upgrade. The consolidation would also allow compatibility with the 2 GeV/c and 6 uA beam intensity instead of the current 1.4 GeV/c and 2uA. This major modification will open new opportunities and maintain research at ISOLDE at the forefront in the fields of nuclear physics.
This contribution will detail the challenges of the project and the path being proposed to tackle them.

Speaker: Mrs Ana-Paula Bernardes (CERN)

07112023_IBDRS poster.pdf

APB_Poster_IBDRS.pptx

51 The Shielding Flask System at Super-FRS¶

The Super Fragment Separator Facility (Super-FRS) at the Facility for Antiproton and Ion Research (FAIR) project in Darmstadt, Germany shall be a state-of-the-art particle accelerator facility, with planned commissioning for early science in 2027. The Super-FRS target area components (plugs) will be activated due to the production of rare isotopes of all elements up to uranium via fission or fragmentation in flight. The primary beam interaction with the target area beamline components will activate them. Ensuring the smooth operation of the facility and enabling remote maintenance of the target area will be critical. To achieve this, the remote transfer and maintenance of the plugs will be essential. The shielding flask (i.e. SFRS flask) will ensure the safety and protection of operators, infrastructure, and the environment from the effects of radiation during Super-FRS beamline component (e.g., target plug) maintenance and the internal transport of irradiated beamline components. The SFRS flask will transport spent components from the heavily shielded target area beamline through the target hall to the hot cell facility for repairs/replacement and install the new components vice versa. The SFRS flask will be lifted by the 80-ton overhead target hall crane and positioned using the support platform, park cell frame, and sliding lid to dock with the beamline plugs, park cells, and hot cell, respectively. The SFRS Flask interfaces with various areas of Super-FRS, and these interfaces have been finalized. They are currently at different stages of construction and procurement. The SFRS flask, along with the support platform and park cell frame, enables remote-controlled transport, lifting, and lowering of 21 different plugs across the beamline, park cells, and hot-cell areas. A total of 96 remotely controlled hoisting sequences are defined for all plugs, taking into account both the set-down level of the plugs and their respective weights.
This contribution provides an overview of the design of the SFRS flask system and its entities, offering insights into the intended operation of the SFRS flask.

Speaker: Dr Faraz Amjad (GSI Helmholtz Centre for Heavy Ion Research)

SFRS_Flask_poster_info.pptx

The Shielding Flask System at Super-FRS-Poster.pdf

52 The Muon Science Facility of MLF J-PARC¶

The muon experimental facility called the Muon Science Establishment (MUSE) is the user facility at J-PARC MLF in addition to the neutron facility.
The muon production target, which is 2 cm thick graphite consuming about 5% of 3 GeV proton beam and located 30 m upstream from the neutron mercury target, produces high-intensity muon beams to be utilized in versatile muon science studies. Four secondary muon beamlines are extended from the muon target and
deliver the muon beam to the experimental apparatus. Each beamline has unique features and provides an intense muon beam with suitable properties, i.e., energy, polarity, etc., for an intended study like material science, elemental analysis, fundamental physics study, etc.
In the presentation, we present the current status of MUSE, separately reporting on the muon production target.

Speaker: Naritoshi Kawamura (J-PARC, KEK)

MUSE_20231028.pdf

53 ANALYSIS OF ROTATIONAL VIBRATION OF MUON PRODUCTION TARGET AT J-PARC MLF¶

The muon production target of the J-PARC MLF adopts a rotating graphite wheel to disperse radiation damage and heat load due to proton beam injection. The target is installed in a beamline vacuum, and the target is driven by a rotary drive transmission system using a drive-line component. Data on the rotational torque and speed of the target are monitored, and the interlock is introduced to stop the rotation and the beam in case of an anomaly. However, even if an anomaly is detected, immediately replacing or repairing the target is difficult in a high-radiation environment. Therefore, preventive detection and identification of the location of the abnormality are necessary.
We confirmed that an FFT analysis of the rotational torque and the rotational speed could detect the vibration in the bearing of the rotary induction motor. This means that the location of abnormalities is identified even from the multiple bearings in the drive system. In addition, we found the existence of minute vibration patterns from the kurtosis and skewness of the signal during low-torque vibration, confirmed that the vibration in the bearing was gradually increasing. In the future, we plan to develop a diagnosis system to determine the lifetime of the bearing using long-short time memory (LSTM).

Speaker: Hikaru Sunagawa (J-PARC, KEK)

HPTW2023_Slide.pptx

54 Development of radiation-resistant distance-sensor for rotating-disk-type target at J-PARC Hadron Experimental Facility.¶

At J-PARC Hadron Experimental Facility, 30-GeV primary proton beam up to 95 kW irradiates the fixed-type target to produce secondary particles for the particle and nuclear experiment. In order to increase the beam intensity up to 150 kW, a rotating-disk-type target is now under development. Although the rotating target is advantageous in terms of cooling capability and long lifetime compared to the current fixed target, it is challenging to monitor the temperature, rotation speed, and eccentricity of the target in long period without maintenance under the high radiation environment. Thus, we have been developing a radiation-resistant capacitive-type distance sensor. In this poster, the design and the development status of the distance sensor are presented.

Speaker: Fumimasa MUTO (KEK)

HPTW2023_poster#16_Short_oral_presentations.pptx

55 Brookhaven Linac Isotope Producer status and Pre/Post-irradiation characterization and analysis capabilities at BNL¶

The characterization of material microstructure and macrostructure effects due to radiation and extreme conditions utilizes proton/ion beam irradiation facilities, Brookhaven Linac Isotope Producer (BLIP) and beams from a Tandem van de Graff facility, extreme temperature studies at the Center of Functional Nanomaterials (CFN), and effects due to extreme (high dose rate) x-ray environment at special beamlines at the National Synchrotron Light Source (NSLS-II) at BNL. The co-location of these facilities at BNL enables comprehensive characterization of material effects under the extreme conditions enabled by these facilities.

The Brookhaven Linac Isotope Producer (BLIP) operations have been ongoing for over fifty years for isotope production augmented with proton and spallation-based fast neutron irradiation studies of particle accelerator and nuclear materials. The program has maintained the handling and characterization capabilities of highly radioactive materials. Specifically, capabilities within the BNL hot cell laboratory, essential for nuclear material studies, include photon spectra and isotopic analysis using high-sensitivity detectors, radioactivity measurements and high precision weight loss or gain assessment. Also, the program is supporting the RaDIATE collaboration and the U.S.-Japan Science and Technology Cooperation Program in High Energy Physics. In the very near future an intensity upgrade will be under way at BNL to increase the 200 MeV Linac up to 250 μA peak current it can deliver after its upgrade.
The Center of Functional Nanomaterials (CFN) has hosted a broad range of research investigations in nanoscience since its inception in diverse research areas, such as efficient catalysts, fuel cell chemistries and architectures, and photovoltaic (solar cell) components. The CFN consists of 7 facilities that provides access to state-of-the-art material characterization and synthesis tools to a scientific community (currently on unirradiated materials).
• Advanced Optical Spectroscopy and Microscopy
• Advanced UV and X-ray Probes
• Electron Microscopy Facility
• Materials Synthesis and Characterization Facility
• Nanofabrication Facility
• Proximal Probes Facility
• Theory and Computation
The National Synchrotron Light Source II (NSLS-II) has developed world-class x-ray capabilities for studying complex and heterogeneous materials, including robotics, that allow it to work with radioactive materials with dose rates up to 100 mrem/h at the XPD beamline. Furthermore, BNL is working with DOE-Nuclear Energy on a concept for a beamline with an end station separated from the ring building, controlled access, special capabilities to receive and study radioactive materials with higher dose limits than at any synchrotron beam line within the DOE complex. The initial scope of this special beam line facility will be on structural analysis and tomography but will have the ability to be upgraded to include chemical imaging.

Speaker: Dohyun Kim (Brookhaven National Laboratory)

8th HPTW_DKim_RIKEN.pdf

56 Novel materials irradiation and pre-characterization plans for high-power targetry applications¶

The multi-megawatt proton beams that will be employed at future accelerator complexes introduce many new challenges for next-generation targetry systems, primarily due to the increased levels of beam-induced radiation damage combined with thermal shock effects during a beam pulse. Novel material classes, such as high-entropy alloys and electro-spun nanofibers are currently being investigated as materials that will be more tolerant of these effects in high beam power applications. Low-energy ion irradiation will be used for pre-screening and down selecting candidate novel materials prior to prototypic high-energy irradiation studies. Specific nano and micro-scale characterization techniques will be used to evaluate the radiation damage and thermal shock resistance of the new materials. Irradiation induced lattice spacing alteration and defect concentrations, as well as mechanical and thermal properties of the novel materials will be measured and compared to those of conventional targetry materials. This poster will detail plans for initial low-energy ion irradiation tests, and the post-irradiation examination techniques that will be used to develop and screen these novel target materials.

Speaker: Abe Burleigh (Fermilab)

HPTW2023-short_pres.pptx

57 Testing high-DPA irradiated titanium alloys for high-cycle fatigue¶

The LBNF-DUNE experiment is expected to use a titanium beam window, immediately upstream of the pion-producing target and directly cooled by helium. This window will receive 2.5 DPA/yr from the proton beam and will experience significant cyclic loading due to beam heating, as well as operating at elevated temperature. To ensure beam window failure via high cycle fatigue is not a limiting factor on target life, a program of material testing has commenced to determine the effect of radiation damage on the fatigue life of various titanium grades.
The poster will detail current work at the Materials Research Facility at Culham, Oxfordshire, involving the static bending and ultrasonic fatigue testing of 3 grades of mid-scale fatigue samples at low DPA (0.1-1), obtained from the BLIP irradiation experiments at Brookhaven. It will also describe ongoing work to produce and install 6 more grades of samples for high-DPA, high-current irradiation at University of Birmingham’s MC40 facility, up to 3 DPA, in a nitrogen-cooled environment at temperatures similar to in-beam conditions. The application of the sample environment design and experimental techniques to other materials such as tungsten or stainless steel will be discussed through additional future use cases.

Speaker: Richard Cowan (STFC RAL)

Testing Irradiated Titanium for High-Cycle Fatigue - One Slide Presentation v2.pptx

Testing Irradiated Titanium for High-Cycle Fatigue - Poster.pdf

58 Mechanical Properties Testing, Characterization and Modeling of Proton-irradiated Ti-base Alloys and Beryllium¶

Titanium-base alloys and beryllium are currently used as beam windows in multiple accelerator facilities due to their limited interaction with the beam, high strength, and radiation damage tolerance. The Tokai-to-Kamioka neutrino beamline at J-PARC uses the two-phase (alpha+beta) alloy Ti-6Al-4V as the material for both its primary beam window and target containment beam windows. The hadron facility at J-PARC and the Long Baseline Neutrino Facility at Fermilab are both planning to use beryllium windows for the primary beam and/or decay pipe. Planned upgrades to beam power above 1.3 MW would push these materials beyond their current operational experience. Relatively little is known about how Ti-base alloys or beryllium would respond to higher beam power and dose (dpa).

Irradiation studies on alpha-Ti alloys and alpha+beta Ti alloys such as Ti-6Al-4V have been conducted in fission reactors and low energy ion accelerators, but high energy proton irradiation data are limited. Ion irradiations are useful to observe microstructural evolution and micro-mechanical property changes to very high dose, but they are not useful for determining bulk material properties due to limited depth of ion penetration. Neutron irradiation data show effects such as hardening, increased strength, loss of ductility, and swelling. There are suggestions that there may be fundamental differences in irradiation response between alpha-Ti alloys, alpha+beta Ti alloys and the less-investigated metastable beta-Ti alloys. However, effects from neutron irradiation can be quite different than those from high energy protons where damage rate and gas production are much higher.

Beryllium has been used in research and test reactors and there is good understanding of its performance during low-temperature fission neutron irradiation. However, there is little data available for beryllium from elevated temperature high-energy proton irradiation. One phenomenon clearly observed in fission reactor irradiation is swelling caused by production of helium and tritium. The gas production rates in high-power proton accelerators can be up to ten times higher than in fission reactors. Understanding how helium and hydrogen behave in beryllium at prototypic beam window conditions is important, as is understanding the effects of gas production on mechanical properties.

In 2018 an international team of researchers from the Radiation Damage In Accelerator Target Environments (RaDIATE) Collaboration, completed irradiation of specimens by 181 MeV protons in the Brookhaven Linac Isotope Producer (BLIP) facility at Brookhaven National Laboratory. Experimental data for a variety of near-alpha, alpha+beta and near-beta Ti-base alloys and two varieties of beryllium included in the BLIP irradiation will be described. For the Ti-base alloys, the data include elastic modulus and tensile results along with complementary fractography, scanning electron microscopy with electron backscatter diffraction and transmission electron microscopy for crystallography, and atomic force microscopy for nanohardness. The presentation also will provide a summary of molecular dynamics modeling of high-energy proton irradiation damage in Ti at the atomic scale to understand fundamental radiation damage mechanisms. For the beryllium samples, elastic modulus, tensile and four-point bend data will be discussed along with complementary fractography and transmission electron microscopy to evaluate the concentration and size of bubbles from gas production.

Speaker: Dr Andrew Casella (Pacific Northwest National Laboratory)

59 Fabrication of W-1.1%TiC with helium bubbles via powder metallurgical route incorporated with helium ambient mechanical alloying¶

Tungsten (W) has attracted great attention as a target material in high-intensity proton accelerator and plasma facing materials/components in future fusion reactors due to its high melting point, low thermal expansion coefficient, high density, etc. In these environments, helium (He) is produced by (n, α) nuclear reaction or spallation in bulk W. He tends to accumulate and precipitates into He bubbles, which may lead to material degradation such as high temperature embrittlement, and blistering. Therefore, many studies have been carried out so far to clarify the effect of He bubbles by introducing He into bulk W samples mainly using high-energy He-ion implantation. In this method, irradiation induced defects such as dislocation loops are also generated via displacement damage. Therefore, it is difficult to know the independent effect of He bubbles. In addition, the irradiated samples become radioactive and difficult to handle in ordinary laboratory experiments.
In order to fabricate W materials containing He bubbles without irradiation inducement, a powder metallurgical route via mechanical alloying (MA) under a He atmosphere, spark plasma sintering (SPS), and grain-boundary-sliding based microstructural modification (GSMM) was employed for the fabrication of W-1.1%TiC. GSMM was compression of the SPSed compact utilizing superplastic deformation due to grain boundary sliding. Microstructure was observed by transmission electron microscopy (TEM) including weak beam dark field method, high-angle-annular-dark-field scanning transmission electron microscopy (HAADF-STEM), and energy dispersive X-ray spectroscopy (EDS). TEM observations revealed that the present fabrication process successfully achieved incorporation of He bubbles in W-1.1%TiC, which had diameters of approximately 6~10 nm or less in as-SPS sintered and GSMM-processed samples. This is the first report on the fabrication of materials such as W alloys that contain He bubbles not by resorting to He implantation or (n, α) reaction by neutron irradiation, hence without radioactivation and irradiation induced defects. The present fabrication of W-1.1%TiC containing He bubbles without irradiation defects can be expected to be useful in fundamental understanding of independent effect of He bubbles on physical and mechanical properties of various materials concerned.

Speaker: Tatsuaki Sakamoto (Ehime University)

Sakamoto_20231105_HPTW2023_ShortPresentation.pptx

60 Recent Progress in development of Toughened, Fine Grained, Recrystallized Tungsten¶

In high-energy proton accelerator facilities, protons accelerated to several hundred MeV to several hundred GeV are irradiated to target materials, and the produced secondary particles are used in experiments to elucidate particle physics, and materials and life sciences. The recent major accelerator facilities have been limited in beam power not by their accelerators, but by target survivability. When secondary particles are transported to the experimental area, the spatial spread of the secondary particle source can be suppressed by increasing the density of the target material, thereby improving the transport efficiency. Therefore, tungsten, hereafter W, is expected to be used as a target material all over the world.
However, W is known to exhibit recrystallization embrittlement and irradiation embrittlement. High Energy Accelerator Research Organization has established an industry-academia, an international, and a domestic collaboration to develop Toughened, Fine Grained, Recrystallized, TFGR W, to surmount the shortcomings of the conventional W materials. TFGR W exhibits grain boundary reinforced nanostructures containing a high density of effective sinks for irradiation-induced point defects, a Ductile-to-Brittle Transition Temperature down to around RT and enhanced resistances against damages by thermal shock/fatigue in the recrystallized state.

Speaker: Shunsuke Makimura (J-PARC/KEK)

poster2.pptx

61 Development of beam window with a large diameter, a thin wall thickness and a large proof pressure for COMET exeperiment through additive manufacturing¶

In next-generation particle accelerators composed of the superconducting magnets, the high proof pressure is required to prepare for a severe accident of liquid helium leakage into the beamline. Furthermore, the beam window should be made of thin and low-density material to reduce loss of the beam through the beam window. It is known that the proof pressure of the sphere-shaped window is higher than that of the plate-shaped window. KEK and Metal Technology Co. LTD. have jointly developed large-diameter, thin, and high-pressure resistant beam windows made of Ti-6Al4V through an additive manufacturing. Currently, we are manufacturing a spherical beam window with a diameter of 260 mm and a thickness of 0.5 mm, which is expected to have a proof pressure of higher than 0.9 MPa according to analysis. After additive manufacturing by laser or electron beam, hot isostatic pressing (HIP) to eliminate the pores remaining in the manufacturing process, and subsequent polishing process was successfully completed. At last, the manufactured beam windows were installed in the beamline at COMET experimental facility. In this presentation, we will report on the status and a future prospect of the COMET beam windows by additive manufacturing.

Speaker: Yutaka Nagasawa (Metal Technology Co.Ltd.)

HPTW2023_ID75_slide.pdf

62 Life cycle of the proton beam window in J-PARC MLF¶

Material and Life science experimental facility (MLF) in J-PARC is Neutron and Muon experimental facility in Japan.[1] 3 GeV pulsed proton beam are injected to the spallation neutron target. Beam power of the MLF reached to 950 kW in the last operation period. The proton beam window (PBW) is the boundary wall between the vacuum space in the proton beam line and the helium atmosphere in the helium vessel where the neutron target is installed. The PBW is made of aluminum alloy. Lifetime of the PBW is estimated to be 10000 MWh and during this summer maintenance period, we are planning 4th PBW replacement in MLF.[2]
Irradiated PBW is replaced to the new one using the shielding cask specially designed to handle the PBW. Used PBW is removed from shielding plug by remote handling in the hot-cell. Then utility pipes connected to the PBW are cut to reduce the volume for storage. The new PBW will be mounted to the shielding plug for the next PBW replacement.
In this presentation, we will present the life cycle of the PBW, the structure of PBW, replacement work, and handling of used one in the MLF.

Speaker: Motoki Ooi (J-PARC)

Poster_ooi_r4.pdf

ShortSlide_ooi_poster24.pptx

63 Moderator and Reflector Fabrication Challenges at the Spallation Neutron Source¶

The inner reflector plug (IRP) at the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) is a 30-ton assembly responsible for moderating neutrons and increasing the yield of useful neutrons at instruments. When operating, it has three cryogenic hydrogen moderators and one water moderator. The assembly uses cadmium, gadolinium, beryllium, heavy and light water, stainless steel, and aluminum to shape the neutron pulses. Historically, the lifetime of the IRP is limited by the burn-up of its neutron poisons. The SNS is currently operating only its second IRP in its history. However, the design presently used would last less than three years in 2 MW operation. Two additional IRPs are currently under fabrication. The SNS has experienced several challenges in fabrication, including a shortage of vendors for specialty operations such as cadmium machining. The SNS is pursuing fabricating the IRPs using a multi-vendor approach. To address some issues, ORNL has found it necessary to develop in-house capabilities while we have located new vendors and methods in others. The desire to increase the lifetime of the IRPs has led to significant challenges in fabricating poison layers of sufficient thickness with the needed quality control. This presentation will discuss the challenges and lessons learned from fabrication, inspection, and quality control for these critical high-power components.

Speaker: Mr Doug Armitage (Oak Ridge National Laboratory)

64 Impact and Lessons Learned from the Mercury System Filling Incident at the Spallation Neutron Source¶

A routine mercury loop filling operation was underway early on the morning of March 21st, 2019. That operation resulted in a severe transient from a previously unidentified accident scenario. Understanding the cause, restoring systems, and addressing the safety issues took time, and the SNS could not resume operations for three months. An undetected leak from a mercury pipe led to high-pressure gas from a storage tank entering the loop and over-pressurizing the process loop. This gas pushed highly radioactive mercury out through the pressure relief and into gas supply lines. Nearly all of the mercury lost from the process loop was safely contained by the shielded service bay, where over 360 liters of mercury was recovered from the collection basin built into the floor. However, some small amount of mercury, though contained, was pushed to an area without adequate shielding. Like all such events, this incident resulted from a confluence of many factors, some of which date back to the fabrication of the SNS. This presentation will provide the history of this event, including the technical explanation and human factors. It will also cover the effects of the event, including the creation of a radiation hazard of 2.3 Sv/hr near our user-occupied space. The presentation will also cover how the root causes were addressed to ensure the facility could be restarted safely. The overarching goal of the presentation is to share lessons learned from this significant event to aid other facilities in avoiding similar incidents.

Speaker: Drew Winder (Oak Ridge National Laboratory)

Slide for Mercury Loop Poster.pptx

65 To realize accelerator driven 80kW class neutron source - defect control and thermal management.¶

Medical accelerator-driven neutron sources are in a unique position. There are many accelerator neutron sources for experimental research, flux up to ~10^8n/s scale, and large-scale spallation-type facilities with high intensity exceeding ~10^13n/s. Accelerator-driven neutron sources for medical use[1], which are now becoming popular, are in a unique position, lying between the two.
At present, excluding the accelerator type, there are a variety of medical accelerator neutron devices such as neutron target materials (Li, Be) and charged particle energies (2.5, 8, 30 MeV)[2].
In addition, about 50 to 80 kW of power is required. Considering that the maximum EBW in widespread use is about 5 kW, a fierce struggle of R&D was expected.
Several types of neutron targets have been published in papers, but blistering, which has been assumed during development, was described by Forton et al. IBA group [3] in INCCT-13. Preliminary experiments with weakened strength require long-term operation, and the strength simulated in practice requires protection against radiation strength. There is a need for an irradiation device that is just now in demand, and more experimental evidence is needed.
We think that two elements, namely defect control and thermal management, are necessary as keywords for the development of this 10^8~10^13n/s neutron source, which should occupy among the existing accelerator-driven neutron sources.
The behavior of protons and hydrogen (atoms) in metals, the dissolution of hydrogen in solids, and the diffusion of hydrogen in beryllium are the subject of research and investigation. It is said that the diffusion of hydrogen in beryllium is slower than in other metals, but what is the rate-limiting part? The BINP group has proposed a blistering threshold, but these various amounts serve as guidelines[4].
After hydrogenating the sample, if it is taken out into the atmosphere, the hydrogen partial pressure in the atmosphere is almost zero, so the hydrogen in the metal should be lost little by little, but in reality this does not happen. It is often thanks to surface barriers that state diagrams have practical meaning. That is, it depends on the conditions at the surface, interface, rather than in the bulk[5].
The discussion of the mean free path in the 2nm process of semiconductor manufacturing and the discussion of Ru instead of Cu are helpful.
Such physics related to material defects, heat treatment of mixed phases of solid phase, liquid phase and gas phase, heat transfer and heat generation not based on diffusion. What is the assumed mean free path? I think that such discussion and consideration will be necessary.
references
[1] IAEA-TECDOC-1223
[2] Reviews of Accelerator Science and Technology Vol. 8 (2015) 181–207
[3] Applied Radiation and Isotopes 67 (2009) S262–S265
[4] Journal of Nuclear Materials 396 (2010) 43–48
[5] EPJ Web of Conferences 231, 03001 (2020)

Speaker: Toshikazu Kurihara (High Energy Accelerator Research Organization (KEK))

HPTW2023_Poster_SLIDE_KURIHARA_27_122.pdf

66 Experimental study of nuclide production cross sections via the natPb(p,X) reaction with GeV-energy proton incidence¶

A variety of research and development related to Accelerator-Driven System (ADS) [1] are in progress spearheaded by Japan Atomic Energy Agency. At the proposed ADS facilities, a high-intensity and high-energy proton beam is supplied to a Lead-Bismuth Eutectic (LBE) alloy target. The neutrons generated by the reactions between incident protons and nuclei of Pb and Bi contained in LBE triggered the transmutation of minor actinides into non-radioactive isotopes or radioactive isotopes with shorter half-lives.
Estimation of residual γ-ray dose rate is important from the viewpoint of radiation safety, as with other accelerator facilities. A nuclide production cross section is key information to evaluate the residual γ-ray dose rate. The activation of the LBE alloy is crucial in ADS facilities. Here, we focus on ${}^{\mathrm{n}\mathrm{a}\mathrm{t}}$Pb, which is one of the constituents of LBE. There are some previous studies to measure the nuclide production cross sections via the ${}^{\mathrm{n}\mathrm{a}\mathrm{t}}$Pb(p,X) reaction[2,3]. However, the total uncertainty of the preceding studies is rather large, which is mainly attributed to the uncertainty of the monitor reactions, such as the ${}^{27}$Al(p,X)${}^7$Be reaction. Thus, further experimental data with as small uncertainty as possible is desired.
To satisfy the demand, a research program was launched at Japan Proton Accelerator Research Complex (J-PARC). The advantage of J-PARC is that the proton intensity can be obtained with smaller uncertainty, due to a high-precision current transformer with an uncertainty of 2% (1σ). We successfully acquired the nuclide production cross sections between primary protons and elements of ${}^{27}$Al, ${}^{55}$Mn, ${}^{\mathrm{n}\mathrm{a}\mathrm{t}}$Fe, ${}^{59}$Co, ${}^{\mathrm{n}\mathrm{a}\mathrm{t}}$Ni, ${}^{\mathrm{n}\mathrm{a}\mathrm{t}}$Zr, and ${}^{209}$Bi [4-8], which are applied to the accelerator components, proton beam window, and neutron-production target at the ADS facilities, with smaller uncertainties compared with previous studies. Thus, we performed a new experiment for the ${}^{\mathrm{n}\mathrm{a}\mathrm{t}}$Pb(p,X) reaction. In the poster, we present the measurement and measured excitation functions. In addition, comparison among the present data, results of nuclear reaction models, and evaluated nuclear data libraries are also reported.

References
1. T. Sugawara, Y. Eguchi, H. Obayashi et al., Nucl. Eng. Des., 331, (2018), 11-23.
2. Yu. E. Titarenko, V. F. Batyaev, E. I. Karpikhin et al., INDC(CCP)-0447, (2009).
3. M. Gloris, R. Michel, U. Herpers et al., Nucl. Instr. Methods B 113 (1996), 429-433.
4. H. Matsuda, S. Meigo and H. Iwamoto, J. Nucl. Sci. Technol., 55 (8) (2018), 955–961
5. H. Takeshita, S. Meigo, H. Matsuda et al., Nucl. Instr. Methods B 511 (2022), 30-41.
6. H. Takeshita, S. Meigo, H. Matsuda et al., Nucl. Instr. Methods B 527 (2022), 17-27.
7. H. Matsuda, H. Takeshita, S. Meigo et al., Proc. 3rd J-PARC Symposium (J-PARC2019), JPS Conf. Proc. 33, (2021), 011047.
8. H. Iwamoto, K. Nakano, S. Meigo et al., Proc. 15th International Conference on Nuclear Data for Science and Technology (ND2022), EPJ Web of Conf. 284 (2023), 01033.

Speaker: Dr Kenta SUGIHARA (KEK)

poster28_sugiharakenta.pdf

67 Graphite enclosure power density experiment¶

The demand for target radioisotopes in the field of target radioisotope medicine is increasing. Next-generation treatment alpha isotopes such as 211At, 225Ac, and 226Ra are at the forefront of this area. During our investigation, we identified the regulations surrounding radioprotection and pollution as a critical issue in the mass production of these isotopes using accelerators.

To address this challenge, we have developed a graphite enclosure structure for the target material. This structure is designed to withstand higher temperatures without fear of melting or the release of gaseous radioactive substances. And the structure can be easily squashed or oxidized in the dry processing stage.

Initial testing of this structure has been conducted using a 30MeV 4He2+ beam with an intensity of 30 euA and a beam sigma of 2 mm. These parameters were chosen to simulate the power density of the project’s goal. The setup was installed in a vacuum chamber with a water cooling plate in contact with the graphite enclosure. The test was conducted for 30 hours, with the graphite enclosure maintained at approximately 210°C. The temperature was measured using a thermocouple probe inserted into a hole in the structure, and the results were quickly responded to by the beam trips.

After the radiation, the induced surface exhibited slight color changes, but no visible effects were observed on the other side. This initial testing demonstrates the feasibility of the graphite enclosure structure for the production of next-generation treatment alpha isotopes.

Speaker: Xuezhi Zhang (Institute of Modern Physics)

zxz-poster.pptx

68 Performance test of Granular flow target¶

The granular flow target is a novel target type for high-power applications. By utilizing granular material as a circulation medium, it combines the advantages of circulation cooling and the use of various solid materials to achieve better performance in both heat removal and neutronics properties.

To evaluate the performance of this target, a system was established that is connected to a low-energy ion beam. A C-shaped elevator served as the circulator, which drove the granular flow target using 1mm ZrO ceramic spheres. An upper storage canister buffered the granules and controlled the mass flow through a gate valve. The flow status formed a channel with an adjustable slope, where the beam bombarded the target material. At the bottom, the flow was collected and cooled by a plate heat exchanger. The granules flowed down along the space between the plates, and the cooling was achieved.

To stabilize the material level in the heat exchanger, a flow control structure was designed to synchronize the flow. The outflow from the heat exchanger entered the elevator and formed a loop. The entire system was vacuumized by mechanical and molecular pumps. The flow achieved through this setup was up to 500g/s, and it was tested using a 210 keV@12 mA proton beam.

The connection was windowless. Though the granular flow system caused slightly vacuum disturbance, the beam line still works well. The beam forms a heat point of about 1cm width, and reaches about 191℃ measured by an inferred thermal imager.

Speaker: Lei Yang (Institute of Modern Physics)

yl-poster.pptx

69 Isotope batch production target design¶

We are pleased to announce the launch of a cutting-edge medical isotope production technology research project in Lanzhou, China. This initiative is designed to address the regional demand for advanced medical radioactive isotopes of the higher quality.
To achieve this goal, the project utilizes a thin metal thorium target, which maximizes specific radioactivity while minimizing total activity, thus simplifying the complex byproduct processing and regulations. The metal thorium is precision cut into 25mm diameter, 1mm thick slices and sealed in a graphite enclosure. These units are placed at a 30 degree angle to the beam direction. The target is cooled through contact cooling in a vacuum chamber, with the graphite enclosure serving as a crucible to prevent the escape of radioactive byproducts and allow for higher temperatures. This design ensures a higher temperature tolerance and enables a significant portion of beam power to be removed through radiation heat transfer, while also leading to increased contact heat transfer to neutralize the disadvantage of a vacuum environment. A dry vacuum chamber is advantageous for beam window design, and an automatic robot handling system is in place to facilitate the transport and retrieval of targets for subsequent processes. The radiation period is set to 10 days, resulting in a final activity of kCi per target unit at the end of the bombardment. With the use of beam point mapping technology, 4×5 targets are radiated as a batch. Although the total activity reaches 20kCi EOB, the radiochemical group does not need to process them at once. Thus, only the target station requires heavy concrete shielding, while the chemical processing can proceed with thinner lead shielding hotcells. The facility will be equipped with state-of-the-art robots and AGVs to facilitate the transport of shielded cells. The building construction is in the process of closing up, and the project is expected to be commissioned within 4 years.

Speaker: Yaling Zhang (Institute of Modern Physics Chinese Academy of Sciences)

zyl-poster.pptx

70 Evaluation on the beam dump activation in the linear IFMIF prototype accelerator (LIPAc)¶

Radiation measurements have been prepared for investigating activation of the 1.1 MW high-power beam dump in the linear IFMIF prototype accelerator (LIPAc). Deuteron beams accelerated up to 5 MeV with a nominal beam current of 125 mA in the current operation phase are stopped in the copper cone in the beam dump located at the end of the LIPAc beam line. In addition to the activation of the copper cone by impinging deuterons, neutrons produced by Cu(d,x) nuclear reactions could activate the other beam dump constituent materials such as the stainless-steel cylinder. It is required to clarify radionuclides mainly contributing to the shutdown dose rate, such as Cu-64 for copper cone and Mn-56 for stainless-steel cylinder, for radiation exposure control during maintenance of the beam dump. A series of beam experiments are planned targeting to increase the beam current from low value (~20 mA) to the nominal, and to achieve continuous wave operations by increasing the duty cycle. By increasing the beam current and the duty cycle, activation of the beam dump could be significant. A NaI (Tl) scintillation survey meter and a CeBr3 detector are used to measure the shutdown dose rate and energy spectrum, respectively, for decay γ rays streamed out from gaps of the radiation shields in the lower part of the beam dump. In addition, a portable high-purity Ge detector is used to measure energy spectrum for back streaming γ rays at the location of around 10 m from the beam dump in the axial direction. The shutdown dose rate calculated with Monte Carlo method was approximately 1 μSv/h right after the beam operation under the beam dump around the gaps of the radiation shields and the location of the Ge detector in a typical condition of the early-stage beam operations, which is 0.1% duty cycle, 8 hours operation for 5 days at the beam current of 125 mA. The present study will report measurement results on radionuclides mainly contributed to the shutdown dose rate and if the calculation results are consistent with the measurement ones.

Speaker: Dr Kohki Kumagai (National Institutes for Quantum Science and Technology)

(Slide)_Kumagai_QST_Evaluation on the beam dump activation in the linear IFMIF prototype accelerator (LIPAc)_231020_R1.pptx

71 High-power spallation target for Subcritical Transmutation Accelerated Reactor Technology START: challenges and perspectives¶

Transmutex SA was founded in 2019 in Geneva, Switzerland, to build Accelerator-Driven System (ADS) plants for the safe and sustainable production of carbon-free energy and the transmutation of nuclear waste. The Subcritical Transmutation Accelerated Reactor Technology (START) under development features a high-intensity proton accelerator, a high-power spallation target, a subcritical core, and a fuel reprocessing unit.
The following formula expresses the power generated by an ADS:

P_ADS (MW)=[G_0 (E_beam ) φ^* k_eff/(1-k_eff )+1] P_beam (MW)

where P_ADS is the thermal power produced by the ADS, k_eff is the effective neutron multiplication coefficient of the subcritical core, P_beam is the proton beam power, G_0 (E_beam ) expresses the neutron yield of the target, and φ^* is the coupling of the spallation neutrons with the subcritical core. The planned thermal power of the START pre-industrial plant is 300 MWth, which by design implies a high beam power Pbeam of 4 MW, and, consequently, a high-performance spallation target in terms of intrinsic safety and reliability, neutronics, and thermo-mechanics.
Transmutex is developing a liquid metal cooled spallation target to be integrated into the subcritical core and capable of fulfilling the high-level requirements, while coping with the needed beam power. The main features and challenges of the conceptual design will be discussed, together with the perspectives and R&D proposals.

Speaker: Dr Massimo Barbagallo (Transmutex)

72 Overview of High-Power Targets and Strategies for Remote Handling at TRIUMF - Canada's Particle Accelerator Center¶

TRIUMF laboratory, Canada’s particle accelerator center, currently operates a range of high-power targets across various different facilities. Most target stations are supplied with protons from the cyclotron at the heart of the facility, capable of delivering four independently controllable beams at energies from 70 to 520MeV with a total current of up to 300µA. Along Beamline 1A, there are two target stations (T1 and T2) each operating beryllium targets (12mm and 5cm long respectively) used for pion and muon production. A side-stream off BL1A supplies protons to the Ultra Cold Neutron (UCN) experiment where they collide with a tungsten spallation target. The resulting fast neutrons are slowed in moderators and then reduced to ultra-cold speeds for observation and study. In the ISAC facility, commissioned with first beam in 2001, the proton beam is impinged upon targets made of various materials to produce rare isotope species for studies in different fields such as experimental nuclear physics, astrophysics, material science and nuclear medicine. In the ARIEL facility, which is currently under development, a proton target (APTW) and an electron target (AETE) will be run simultaneously to produce additional rare-isotope species. The proton station will accept up to 50kW at 500MeV from the main cyclotron and the electron target will be supplied by TRIUMF’s new e-Linac with up to 100kW of beam power at 50MeV. The spent targets at all facilities become highlight radioactive during irradiation (producing fields of up to 10Sv/hr at 1m). Remote handling techniques are therefore essential to safely perform target maintenance, replacement, and disposal. In this poster presentation, details and illustrations of the various targets and remote handling strategies for each will be presented.

Speaker: Isaac Earle (TRIUMF)

HPTW Poster - Short Oral Presentation (Isaac Earle, 2023-11).pdf

HPTW Poster - Short Oral Presentation (Isaac Earle, 2023-11).pptx

Wednesday 8 November ¶

08:30 Registration

08:50 Announcement

Topic1-2¶

Convener: Drew Winder (Oak Ridge National Laboratory)

73 DIFFUSION BONDING BY MEANS OF HIP FOR BEAM INTERCEPTING DEVICES AT CERN¶

Beam intercepting devices are typically designed to absorb significant thermal power deposited by the particle beam. In many instances, due to various considerations, the heat deposited within a component is dissipated by cooling another material that is in direct contact with the initial part. The effectiveness of this cooling relies on minimising the thermal resistance at the interface.
It has been observed that diffusion bonding minimises (and in some cases eliminates) the thermal resistance at the interface and additionally establishes a clean (ultra-high vacuum compatible) and mechanically robust junction between two components. This ensures reliable and efficient operation over time, even under demanding environment typically found in beam particle accelerators (such as UHV, radiation, thermal/mechanical fatigue, etc).
In the last years, CERN has studied, tested and implemented diffusion bonding techniques by means of Hot Isostatic Pressing (HIP) on operational devices.
The materials employed at CERN and bonded using this technique can be categorised in two groups: i) Cuprous materials combined with stainless steel and ii) refractory metals (such as tungsten, Mo-alloys, Ta-alloys and Nb-alloys). Different combinations of materials within each group have been studied.
For the first group, diffusion bonding is achieved by subjecting the components to HIP at a temperature of approximately 950°C and a pressure of 100 MPa. Conversely, for the second group, temperatures in the range of 1200-1400°C and a pressure of 200 MPa are necessary to join the different materials.
Specifically, components made of CuCr1Zr with embedded 316L tubes have been produced and employed as heat sinks in the Proton Synchrotron and Super Proton Synchrotron beam dumps. These systems have been operational since 2021.
This contribution presents the development tests and studies conducted at CERN concerning the application of this technique to these two groups of materials. This encompasses the production of multiple prototype components using different HIP parameters, non-destructive examinations, microstructure inspections as well as thermal/mechanical testing of the interfaces of bonded interfaces.

Speaker: Antonio PERILLO MARCONE (CERN)

HIP_BIDs_HPTW23.pptx

74 Isochoric Beam Deposition for Asteroid Deflection¶

The study of asteroid deflection maneuvers show two deficiencies that would make the reliable deflection of large objects (1-3 km in diameter) impossible: Reliability and efficiency of the maneuver. Predicting the deflection from hydrocodes has shown a degree of dependence on the choice of strength model, inhibiting reliable prediction (see Stickle et al. (2019)). For efficiency of deflection (rate of transfer of momentum input to a change of momentum of the deflected object), nuclear devices have been shown to be the first choice. But even classical nuclear devices are so limited in efficiency, that this restricts the achievable $\mathrm{\Delta }v$ to a very narrow band (see Horan IV et al. (2021)).
Our ansatz to solve both problems is isochoric energy deposition by a particle beam. We plan to study this in a fully dynamical scale model, using the CERN hadron beam, where a meteorite sample target mimics the asteroid. Real-world, we will use a proprietary nuclear fusion scheme to realize this. In contrast, impactor mechanical deposition (as applied in NASA’s DART mission in 09/22) is isentropic and needs a less efficient higher pressure level to deposit the same amount of energy (see Pasquali et al. (2019) ). Hence, the isochoric deposition leads to a faster increase in temperature.
The transfer of momentum from the CERN hadron beam to the target consists of many components, ranging from elastic transfer (which already works at low thermal loads) to vaporization or even ionization at high energy deposition per volume. Vaporization or ionization lead to a rocket-like exhaust of the target from ejected material and in this regime should contribute the largest share of momentum transfer.
First results with FLUKA show that beam deposition should be much more efficient in achieving momentum transfer than any classical nuclear device. For the reliability question note that for the specific impulse $I_{sp}$ of the target at vaporization or ionization
$I_{sp}\sim \frac{T}{M_{mol}}$
Here $T$ denotes the temperature at ejection of the material and $M_{mol}$ the molar mass. Since only the temperature at ejection enters, the goal is to show that isochoric heating arises fast enough to lead to heavily reduced dependence on the choice of strength model.
Main goal of the diagnostics is to show the transfer of momentum from beam to target in the different regimes. Key criteria for the choice of diagnostics are e.g. the spatial and temporal resolution to resolve the momentum transfer (since e.g. the phase of acceleration at one bunch of the CERN beam will only be on a nanosecond time scale).

References:

• Stickle et al., Benchmarking impact hydrocodes in the strength regime: Implications for modeling deflection by a kinetic impactor, Icarus 2019
• Horan IV et al., Impact of neutron energy on asteroid deflection performance, Elsevier 2021
• Pasquali et al., Dynamic response of advanced materials impacted by particle beams: the MultiMat experiment, Journal of Dynamic Behavior of Materials 2019

Speakers: Dr Karl-Georg Schlesinger (OuSoCo), Melanie Bochmann (OuSoCo)

HPTW 2023 - Isochoric Beam Deposition for Asteroid Deflection.pdf

75 Tesla-Converter: A high power water cooled Bremsstrahlung converter¶

Targeted alpha-particle therapy is a promising approach for cancer treatment, with ${}^{255}\mathrm{Ac}$ emerging as a potent radionuclide candidate. However, the scarcity of ${}^{255}\mathrm{Ac}$ supply hinders extensive clinical research. In this presentation, we focus on the photo-nuclear route as a potential means to extend the ${}^{255}\mathrm{Ac}$ production. The current bottleneck in this approach is the requirement for a high-power Bremsstrahlung converter.

We introduce a novel concept for a high-power Bremsstrahlung converter capable of handling up to $125\mathrm{kW}$ of beam power, corresponding to an electron pulse energy density of approximately $120{\mathrm{J}/\mathrm{cm}}^3$. The design is based on the Tesla pump concept, employing layered rotating tungsten discs to act as both a shear-force pump and a Bremsstrahlung converter within the same unit. The rotation of the target facilitates effective thermal distribution and coolant flow, allowing for a compact design.

During this talk, we will present the design optimization concerning photon yield, thermal and mechanical considerations, and material and component selection. Additionally, we will discuss the first prototype’s development and testing, including cold tests to validate pumping performance and preliminary cooling experiments conducted with the METAS electron accelerator.

This concept’s successful implementation can significantly contribute to the advancement of targeted alpha-particle therapy research by overcoming the limitations posed by limited radionuclide supply.

Speaker: Matthias Lüthi (Federal Institute of Metrology (METAS))

Telsa-Converter-MLuethi.pdf

Telsa-Converter-MLuethi.pptx

76 New cryogenic helium heat exchanger for the ISIS Target Station 2 Solid Methane Moderator¶

The ISIS Target Station 2 decoupled solid methane moderator is cooled to 40 K using a helium cooling loop inside the methane vessel. However, there is currently a struggle to hold this temperature, with the moderator degrading over the user cycle to reach 65 K. There has recently been an undertaking to improve cooling and use more cooling power available from the cold box by reducing the pressure drop through the heat exchanger and increase the contact surface area for heat exchange. Colder methane temperatures (approximately 30 to 35 K) produce more neutrons at longer wavelengths for the WiSH diffractometer instrument.
This paper will report on the modelling and manufacturing development that has led to an innovative design using a plate heat exchanger. The new heat exchanger will use multiple channels of variable width plus larger cross sections at the inlet and outlet to reduce the pressure drop. Water flow tests and computational fluid dynamics (CFD) analyses provided insight into the design’s performance and highlighted the potential improvements. The CFD models have shown that the plate heat exchanger allows for the mass flow rate to increase from 7 g/s to 10 g/s while maintaining the same pressure drop. This has the cumulative effect of reducing the average temperature of methane from 41 K to 36 K. The new heat exchanger is now in manufacture alongside its integration into the methane moderator assembly with the hope that testing on its performance can begin in late 2024. Meanwhile, further iterations are under development to continually improve and maximise the potential cooling power available.

Speaker: Mark Telkman (STFC)

HPTW 2023 - Design of a new heat exchanger for the TS2 methane moderator V3.pptx

77 Vibration analysis of Mo-100 targets for accelerator based Mo-99 production¶

Production of metastable Technetium-99 (Tc-99m), a decay product of Molybdenum-99 (Mo-99) is vital to the medical imaging community. One method of producing Mo-99 using accelerators is through the irradiation of Mo-100 targets using an electron beam. Los Alamos National Laboratory (LANL) provides support to NorthStar medical Radioisotopes (NMR) on their efforts to produce Mo-99. The NMR target consists of an Inconel window that allows the electron beam to penetrate and irradiate a stack of approximately 70, 24 mm, 0.74 mm thick Mo-100 discs. The discs are separated by 0.25 mm thin cooling channels through which pressurized helium flows and cools the discs during irradiation which generates large amounts of heat. We have found during cold testing of the target system that the Mo-100 discs undergo significant mass loss and disc breakage due to flow induced vibrations. The mass loss is not only undesirable due to monetary loss reduced final quantities of Mo-99, but also due to the hazards associated with radioactive material trapped in the cooling lines and particle filters. This work describes the experimental characterization of the flow induced vibrations and disc mass loss in a reduced scale set-up containing 10 Mo-100 discs. We use high speed imaging, displacement measurements and microphone measurements combined with signal processing to estimate the vibration frequency of each disc. The effect of disc thickness, target fit and duration of testing on the mass loss is described. It is found that for a looser fit, disc rotation leads to more mass loss than disc vibration. For tighter fits, it is found that with longer run times, the overall target fit loosens, leading to both rotation and vibration motion, leading to mass loss. Recommendations for target improvement are also presented.

Speaker: Bhavini Singh (Los Alamos National Laboratory)

HPTW2023-ID25-LANLBhaviniSingh.pdf

10:30 Coffee Break

Topic4-2¶

Convener: Hiroki Okuno (RIKEN Nishina center for accelerator-based science)

78 Mu2e Target Status and Challenges¶

The Mu2e experiment at Fermilab plans to use a a radiation cooled production target to generate pions from an incoming 8kW proton beam. Radiative cooling results in a high surface temperature, requiring a high-Z, refractory metals target material due to its high melting point, high tensile strength and low thermal expansion coefficient. Tungsten is the material of choice for this application. Design of the target cartridge and remote handling machine has been carried out. Challenges of the radiation cooled design and development have focused on emissivity, creep, oxidation, radiation damage resistance, together with alignment stability across a wide temperature range. I will discuss the status of the Mu2e target design and development, including discussion of the emissivity optimization approaches, such as coatings, surface roughness, and fabrication strategy.

Speaker: Zunping Liu (Fermi National Accelerator Laboratory)

Mu2e Target Status and Challenges.pdf

79 Present design status of COMET target at J-PARC¶

At the J-PARC Hadron facility, construction of the COMET project is underway to explore the muon-electron conversion process. An 8 GeV proton beam supplied from the main ring is irradiated to a target in a superconducting capture solenoid magnet, and the generated pions and muons are transported to the experimental area. Graphite material will be used as the target material in Phase 1 (proton beam intensity: 3.2 kW) and high-density materials such as tungsten material in Phase 2 (proton beam intensity: 56 kW). For the target design, cooling methods for the heat generated by proton beam irradiation, transport efficiency of secondary particles, and selection of target materials are being studied, because the COMET target, although the proton beam intensity is not so high, must be installed in a high magnetic field with a superconducting solenoid magnet so that the secondary particle transport path is not disturbed, It is difficult to distribute the heat generation density as in the rotating target system. In addition, the design of the structure must take into account the remote replacement of the activated target. In this presentation, we report on the design status of the COMET target.

Speaker: Shunsuke Makimura (J-PARC/KEK)

COMET target.pdf

COMET target.pptx

80 Surface muon production at J-PARC muon facility¶

At the Muon Science Facility (MUSE) located within the Japan Proton Accelerator Research Complex, there are four beamlines situated around the muon target. The D-line incorporates a superconducting solenoid, while the U-line utilizes an axial-focusing system capable of transporting muons over large solid angles to generate ultra-slow muons. The S-line is dedicated to µSR research, and the H-line primarily serves high-statistics fundamental physics experiments. MUSE operates with a 3 GeV proton beam at 1 MW power, a beam current of 333 µA, and the proton beam is double-pulsed at 25 Hz, delivering 1.87 x 10^15 protons per second. Approximately 90% of these protons are directed from the Rapid Cycling Synchrotron (RCS) to the muon target, where pions are produced as a result of proton interactions with low-Z nuclei materials like graphite. Subsequently, these pions decay into muons. In our work, we will present simulation results divided into two sections. The first section focuses on the muon target area to study muon production, the distribution of scattered particles around the muon target, proton transmission, pion yield, and muon yield. The second section describes the properties of the muon beam at the S-line entrance, including the impact of the leakage field from the H-line.

Speaker: Phanthip Jaikaew (RIKEN)

Design of Radiation Shielding at PCELL.pdf

81 Development of new rotating-disk-type production target at J-PARC Hadron Experimental Facility¶

At J-PARC Hadron Experimental Facility, a wide variety of nuclear and particle physics experiments has been carried out using secondary particles such as kaon and pion, which are produced in a dense-metal target irradiated by slowly extracted 30-GeV proton beam. A current target is a fixed type made of gold, which is jointed to the water-cooled copper block. The current target is designed to be accepted up to 95-kW proton beam for 5.2-s repetition cycle.
In order to increase an acceptable beam power up to 150 kW, development of a new production target is in progress. The new target is planned to be a rotating-disk type, which distribute heat load to circumferential direction. In the plan, direct cooling by helium-gas blowing to the disk is adopted. The disk is a diameter of 346 mm and a thickness of 66 mm with fin shape to increase an amount of heat transfer.
Material of the new target, which should have properties of high density and high thermal conductivity, is under consideration. Candidates of the material are gold, platinum or tungsten. To determine the material, primitive tests such as machining and surface treatment have been examined to tungsten material.
To support the disk rotation, a helium-gas-lubricated bearing, which is basically no life limitation and also capable of rotating at higher speed than widely-used radiation-resistant ball bearings, has been examined with a real-size disk.
In this report, design and development status of the new target are presented.

Speaker: Hiroaki Watanabe (KEK)

HPTW-watanabe-Nov8-r2.pdf

82 Lujan Center 1L Target TMRS Mark IV Upper Target Design and Thermal Hydraulic Analysis¶

Commissioning of the Los Alamos Neutron Science Center (LANSCE) Mark IV Target-Moderator-Reflector System (TMRS) neutron source at the Lujan Center took place during the 2022 run cycle. The Mark IV is comprised of three target stations. A new upper target has been designed to accommodate and enhance the changing experimental needs. While the middle and lower target stations had minimal to no substantial modifications in Mark IV. The main goals of the replacement target, Mark IV, are to improve target performance for nuclear science research while preserving the thermal- and cold-neutron performance for material science. The two-tiered nature of the 1L target and associated beam lines naturally lends itself to this dual mission. The resulting design offers significant improvements in both the resolution and the intensity of medium energy neutrons (keV-MeV) in the upper tier, while preserving the thermal- and cold-neutron performance in the lower tier. Computational models have been developed to simulate the thermal hydraulic performance of the LANSCE TMRS Mark IV Upper Target assembly by coupling particle transport to calculate energy deposition for thermal hydraulic calculations.

Speaker: Mr Eric Olivas (Los Alamos National Laboratory)

hptw2023-ero-laur-23-32368.pptx

83 Optimizing neutron production at ORNL’s Second Target Station¶

Oak Ridge National Laboratory’s (ORNL) Second Target Station (STS) is designed to become the world’s highest peak-brightness spallation source of cold neutrons. Exceptionally bright cold neutron beams will provide transformative capabilities to examine novel materials for advanced technologies in the decades to come. Bright beams will enable new neutron scattering experiments using innovative instruments under more extreme conditions, using smaller samples and shorter irradiation time. A comprehensive optimization study of neutron production is necessary to generate such bright beams. This work presents an automated optimization workflow that combines high-fidelity neutronics modeling with structural stress analyses and modern optimization algorithms. The coupled multi-physics, multi-parameter optimization workflow is essential to completing the STS project successfully. The workflow can be applied in the design process at other neutron, experimental, and accelerator facilities.

The current design of the STS consists of a 700-kW water-cooled rotating tungsten target and two compact pure para-hydrogen neutron moderators at 20 K. The target will be driven by a short-pulsed (<1 us) 1.3 GeV proton beam at 15 Hz from the Spallation Neutron Source’s (SNS) linear accelerator. Neutrons with a broad energy spectrum will be generated in the target via spallation reactions. Some neutrons will enter hydrogen moderators surrounded by a light water premoderator and a beryllium reflector. After their moderation, cold neutrons will exit through small 3x3 cm emission windows and travel towards one of the eventually 18 modern instruments.

A compact arrangement of the target and moderators is key to generating bright neutron beams.
However, arrangements that improve neutronics output typically reduce the structural integrity and thus increase the probability of failure. The goal of the coupled neutronics and structural optimization is to maximize neutron production while maintaining high factor of safety. In the past, one iteration through neutronics and structural analysis took several weeks to months. With the new automated workflow, the duration has been reduced to hours, which allows us to find the optimal solution much faster.

The optimization workflow uses parametrized solid CAD engineering models of the key STS components, such as the target and moderators. The detailed models are converted with Attila4MC into Unstructured Mesh (UM) models for neutronics calculations with MCNP6.2. The automated CAD to MCNP conversion improves the fidelity of the models and minimizes the time necessary for their generation. The high-fidelity energy deposition data from neutronics calculations are extracted together with neutron brightness. Energy deposition serves as input for the calculation of the factor of safety, which automatically evaluates both mean and peak amplitude stress with Sierra. Neutron brightness and factor of safety are passed to the Dakota optimization toolkit, which analyzes the results and proposes a new set of design parameters using one of the state-of-the-art optimization algorithms. This cycle repeats until the optimization workflow converges and the optimal design is found.

This talk reviews the current STS design and the optimization workflow. We will describe individual steps of the workflow, share some practical information about its implementation, and discuss recent results.

Speaker: Igor Remec (ORNL)

HPTW2023-Remec-final-11-8-2023.pptx

12:30 Lunch Break

13:30 Transfer to banquet

14:15 Excursion

17:30 Banquet

https://www.princehotels.com/kawagoe/

20:00 Return to Wako

Thursday 9 November ¶

08:30 Registration

08:50 Announcement

Topic7-1¶

Convener: Marco Calviani (CERN)

84 Updates on the operation of the MLF neutron target at J-PARC and perspectives for future operation¶

The high-power pulsed spallation neutron source at Materials and Life Science Experimental Facility (MLF) in the Japan Proton Accelerator Research Complex (J-PARC) started the operation in May 2008, and now it is used as one of the most powerful facilities in the world for the research in the advanced field of material and life science. The beam power for user program is decided to secure the stable operation for long period of scheduled time and that had been raised stepwise every year. In April 2023, the user program resumed after a short outage with the beam power of 840 kW at MLF, which was comparable with that attained in May 2022, but this time the pulse intensity was raised to the highest record of 950 kW for the first time for long term user operation. The pulse intensity corresponds to the beam power at the 3GeV rapid cycle synchrotron (RCS) outlet and is the dominant factor of the pitting damage of the mercury target vessel by pressure waves. This accomplishment means that the goal of the stable operation of the neutron source with 1 MW was almost achieved.
Since the proton beam pulses at RCS outlet are shared between MLF and 30GeV main ring (MR), the beam power at MLF becomes smaller than that at RCS outlet and is changed in accordance with the operation mode of MR. The minimum beam share of MLF is 88.2 % at present and it is planned to be reduced to 86.2 % from 2028, which means that the beam power at MLF is 862 kW even when the power at RCS outlet is 1 MW. In order to achieve 1 MW operation at MLF, the pulse intensity needs to be increased to 1.16 MW, and the mercury target should endure the pulse intensity higher than 1 MW.
In addition to pursuing the higher power operation, there are other requirements to cope with the serious issues of storage space and disposal of the highly radioactivated used target vessels. Now R&D of the mercury target vessel is going on to realize two countermeasures, that is, extending the target operation time and reducing the volume of the used target vessel. Extension of the target operation time with higher power needs a target vessel capable of more effective pitting damage mitigation. Volume reduction of a target vessel needs a new target design which can be disassembled by present remote-handling tools after the beam operation.
In this presentation, present status of the neutron source of MLF and future operation plan will be shown.

Speaker: Dr Katsuhiro Haga (J-PARC/JAEA)

HPTW-2023_Present status and future challenge of neutron source in J-PARC_Haga_Rev2.pdf

85 MUON ROTATING TARGET AT J-PARC MLF¶

The Muon Science Facility (MUSE) at the Japan Proton Accelerator Research Complex (J-PARC MLF) generates intense pulsed muon beams (3 GeV, 25 Hz, up to 0.33 mA), which are used to study various elementary particle and material life. A muon production target is installed on the proton beamline between the 3 GeV synchrotron and the neutron target. The target is made of high-purity isotropic graphite IG-430U (Toyo Tanso), which is exposed to a strong radiation environment and heats up to high temperatures during beam irradiation.
In 2014, the fixed target was replaced by a rotating target, which is now operating smoothly at 800 kW. The ring-shaped graphite, 250 mm in inner diameter, 350 mm in outer diameter, and 20 mm thick, is divided into three sections to prevent failure due to thermal stress caused by thermal imbalance. By introducing a solid lubricant made from tungsten disulfide, we have achieved a long life of the rotating support under high heat, high radiation, and vacuum, which is expected to be about ten years. In the presentation, the current status of the target development and monitoring system will be reported.

Speaker: Shiro Matoba (High Energy Accelerator Research Organization)

MuonTarget_HPTW2023_MATOBA.pdf

86 The High-Power Beam Dump System for the BigRIPS Separator¶

At the RIKEN RI Beam Factory, heavy-ion beams at 345 MeV/nucleon are employed to generate a great variety of exotic nuclei. These exotic nuclei are produced by a fragmentation or in-flight fission reactions of the heavy-ion beams incident on a beryllium target located at the entrance of the BigRIPS separator. The beam ions that remained unreacted at the target are intercepted by water-cooled high-power beam dumps at the downstream of the target. The beam dumps are designed to safely absorb beams with power of 82 kW at the maximum. Presently, operations have been conducted utilizing beams with a maximum power of 20 kW.

In this contribution, we will report the details of the beam dumps and an incident recently we experienced. In addition, the upgrade plan of one of the beam dumps to cope with the higher beam power due to the future RIBF upgrade will be presented.

Speaker: Dr Yasuhiro Togano (RIKEN Nishina Center)

Togano_HPTW2023_20231109.pdf

87 Survivability of proton beam degraders and beam stop: experience at Brookhaven Linac Isotope Producer¶

Brookhaven Linac Isotope Producer (BLIP) operated by Brookhaven National Laboratory (Upton, NY, USA) and funded by US DOE Isotope Program (IP) uses high energy proton beam for isotope production. The proton beam is generated by the Linac and directed to the BLIP target station located 30 feet underground. The incident proton energy is incrementally tunable (30-33 MeV increments) in the range from 0-200 MeV, with the lowest practical incident energy of 66 MeV.
Designed and dedicated solely for isotope production, BLIP continuously receives 200 MeV beam to meet Isotope Program needs. The targets are stacked for irradiation: a typical target stack is comprised of production targets, beam degraders, water channels for cooling, and a beam stop designed to ensure that all 200 MeV is stopped in the stack. The number of targets and degraders in the stack depends on the proton energy required for optimum isotope production. With operational beam currents routinely reaching as high as 165 µA with maximum excursions up to 178 µA, the total beam power deposited in the target stack can reach up to 35 kW (average incident power density 9.1 W/mm2). The heat load on individual components of the stack reaching as high as 5-6 kW.
The above-mentioned operational conditions require a rigorous evaluation approach towards the design of targets and degraders for continuous irradiation. This talk will focus on the current approach toward the design of targets, modeling tools, challenges as well as observed performance of the beam components as related to their suitability as materials to sustain extended irradiation periods.
An upgrade to the entire cooling system is in progress, which will increase the volumetric flow rate and velocity of cooling water over the target faces by a factor of 2.5X. This will double the film heat transfer coefficient to provide a larger safety margin for target survival and allow for future upgrades to beam energy, current, and ultimately increase isotope yield.
Acknowledgement
This work was funded by US DOE Office of Science Isotope Program.
Brookhaven National Laboratory is managed by Brookhaven Science Associates operated by Battelle Memorial Institute (Battelle) and Stony Brook University for US DOE Office of Science under contract DE-SC0012704

Speaker: Dmitri Medvedev (Brookhaven National Laboratory)

DMedvedev_HPTW_final.pdf

88 Operational Experiences of FRIB Linac Beam-Intercepting Devices¶

The Facility for Rare Isotope Beams (FRIB) is a heavy ion accelerator facility aiming to reach 400-kW primary beams, which will extend the heavy-ion accelerator power frontier by more than one order of magnitude. FRIB’s superconducting radio frequency (SRF) continuous-wave heavy-ion linear accelerator can accelerate all the ions up to uranium to energies above 200 MeV/u. The design beam power of 400 kW requires an intense beam, 8.4 particle μA or 5.25 x 10^13 ions/s in the case of uranium.
FRIB’s driver linac uses a charge stripper at a location where the beam energy reaches 17-20 MeV/u, to remove electrons from the primary beam ions, which increases the energy gain of the beam being accelerated, by approximately a factor of two. The linac was designed to accelerate multiple charge states of the stripped beam. But the charge states beyond the acceptance of the linac are intercepted by a device called the charge selector. These are the two main beam-intercepting devices in the FRIB linac.
The major challenges in these devices are ultra-high volumetric heat density and intense radiation damage. FRIB has two types of charge stripper: liquid lithium charge stripper and rotating carbon foil stripper. The liquid lithium stripper is for high power heavy ion beam operations to overcome the above challenges. The carbon stripper is still used for beam operations at the current beam power and will be a back-up of the lithium stripper in the future. The current charge selector uses positional and static slits made of Glidcop AL15. We plan to upgrade it to intercept higher beam power.
In this paper, we report the recent operational experiences of charge strippers and charge selector at FRIB. FRIB beam power has steadily increased from 1 kW to 5 kW since the commencement of user operations in May 2022. The carbon stripper and charge selector supported the recent 10 kW 36Ar and 48Ca beam tests conducted in July 2023.

Speaker: Dr Tomofumi Maruta (Facility for Rare Isotope Beams, Michigan State University)

HPTW23_slides_maruta.pdf

10:30 Coffee Break

Topic3-2¶

Convener: Yong Dai

89 Materials research and dose limits for highly irradiated components at the Spallation Neutron Source¶

High-energy proton and neutron radiation change the microstructure and composition of structural materials during operation. These changes typically cause an increase in the strength and decrease in the ductility of the material with increasing dose. Administrative lifetime limits are applied to components in high-radiation environments at the Spallation Neutron Source (SNS) to limit the risk of failure associated with embrittlement. A post irradiation examination (PIE) program is maintained at the SNS to evaluate the change in mechanical properties of target vessels and proton beam windows (PBW). These results are evaluated to ensure the component lifetime limits are appropriate and the components are operating in a safe condition for the longest lifetime possible. However, peculiar deformation behaviors were recently observed in samples from 316L target vessels and Inconel 718 PBW samples at the SNS. Traveling wave deformation bands were observed in 316L target vessel specimens and an increase in elongations with increasing dose was observed during testing of Inconel 718 specimens. These behaviors complicate lifetime limit evaluations and present a new challenge to establishing appropriate component lifetime limits. This presentation will include a description of the dose limit philosophies used at the SNS, and recent findings from PIE of targets and PBWs will be presented and discussed.

Speaker: David McClintock (Oak Ridge National Laboratory)

HPT8 Presentation - David McClintock - Nov. 8, 2023.pptx

90 Recent Advancements and in-house capabilities in Thermal and Mechanical Characterization of Conventional and Novel Materials¶

In this presentation, we showcase the latest capabilities and breakthroughs achieved in our laboratory using state-of-the-art instruments, namely the dilatometer, differential scanning calorimeter (DSC), and nano-indenter. Through rigorous experimentation, we have examined the thermal and mechanical properties of various materials, including conventional materials such as graphite and titanium alloy, as well as novel materials like High Entropy Alloys (HEA) and ceramic nanofibers. The dilatometer and DSC were employed to evaluate essential thermal properties, such as specific heat and thermal expansion coefficients, of newly developed High Entropy Alloys (HEA). These properties were then compared against simulation results to assess their accuracy and validate the effectiveness of the instruments. Additionally, we present the first-ever evaluation of specific heat for zirconia nanofibers, shedding light on their unique thermal behavior. Moreover, the nanoindenter was utilized to investigate the strain rate dependent hardness properties of ion-irradiated and unirradiated graphite samples. The mechanical response of these samples under varying strain rates provides critical insights into their structural stability and potential applications in radiation-exposed environments. Our findings demonstrate the significance of the acquired capabilities in understanding the fundamental thermal and mechanical characteristics of these novel. The utilization of these advanced techniques allows for more comprehensive and reliable assessments of both conventional and novel materials, opening doors to innovative research and development in high power targetry.

Speaker: Sujit Bidhar (Fermi National Accelerator Lab)

Fermilab-capabilities-Sujit.pptx

91 Thermal diffusivity of tungsten irradiated by protons in spallation environment up to 26.5 dpa¶

Tungsten is chosen as the target material of European Spallation Source (ESS) where it will be irradiated by a high energy (2 GeV) and high power (5 MW) pulsed proton beam to produce neutrons to be used by neutron scattering intruments. For designing a target with a high availability, it is important to determine the development of the temperature and secondary thermal stresses in tungsten during the operation. As irradiation alters material properties, knowledge on the impact of irradiation on thermal diffusivity is crucial to the ESS target design. Using Laser Flash Analysis (LFA) technique, thermal diffusivity of three highly irradiated samples with three different displacement damage doses 9.5, 25.1 and 26.5 dpa were examined. Due to the high radioactivity of the specimens, no surface polishing or blackening could be applied on the samples prior to measurements. Therefore, an attempt was made to study the effect of measured surface roughness on LFA data, and the obtained results for irradiated samples were calibrated accordingly. The data shows a drastic reduction of the thermal diffusivity for all three samples by up to 50%. The thermal diffusivites of the three specimens are overlapping within measurement error uncertainty ranges, independently of the damage dose. Further, the recovery of the thermal diffusivity of irradiated tungsten was also observed after annealing, however this effect was less prounanced compared to the low-dose specimens.

Speaker: Hossein Sina

W Thermal diffusivity_Sina_DY.pdf

92 Tensile properties of SS316LN-EBW after irradiated in STIP-II¶

Austenitic stainless steel is used as a container material for spallation neutron source targets such as the American spallation neutron source (SNS), the Japanese spallation neutron source (J-PARC), and the Chinese spallation neutron source (CSNS), due to its excellent high-temperature performance, welding performance and corrosion resistance. There are some researches on the performance of austenitic stainless steel after proton and neutron mixed irradiation, but few reports on the irradiation performance of austenitic stainless steel after welding. In order to study the mechanical property changes of SS316LN after welding and irradiation, SS316LN and SS316LN electron beam welding (EBW) samples were irradiated in the second experiment of the SINQ Target Irradiation Program (STIP-II) in a dose range of 7.5dpa-19.5dpa and a temperature range of 103-328 °C.
Microscopic morphology observation, hardness and tensile test were conducted on both SS316LN and SS316LN-EBW samples. The microstructure analysis of the welding area shows that the welding center area is composed of fine equiaxed grains, with columnar grains on both sides. The width of the fusion and heat affected zone is approximately 4mm. Compared to the 316LN samples, the total elongation of the welded samples decreased significantly after irradiation at the same dose. However, the tensile strength was similar. At 16.3dpa, the total elongation of the SS316LN-EBW samples decreased to 8% when tested at 250 °C. At 19.5dpa, the total elongation decreased to 6% when tested at 300 °C. For both SS316LN and SS316LN-EBW samples of 11.2-19.5 dpa, the strength and elongation remained no changes when tested at 200-300 °C. Fractography results showed ductile fracture mode for the 19.5 dpa sample tested at 300°C. The size of the ductile dimples on the fracture surface of welded samples is larger than that of non-welding samples.

Speaker: Mr Shaohong Wei (1.Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, China 2.Spallation Neutron Source Science Center, Dongguan, 523803, China 3.School of Materials Science and Engineering, Central South University, Changsha 410083, China)

Tensile properties of SS316LN-EBW after irradiated in STIP-II-V1.pptx

93 Microstructure, strength of Al6061-T6 after irradiation in SINQ Target-13¶

Because of outstanding thermal conductivity of 160-230 W m-1 K-1, high water corrosion resistance and good radiation tolerance, as well as comparably low-radioactivity elements, Al alloys have been used as components in fission reactors [1]. To be noted, the Al–2.7wt%Mg (AlMg3) alloy has been used until now as the beam window material for the safety-hulls of the targets of the Swiss Spallation Neutron Source (SINQ) [2]. Among Al 6xxx series, Al6061-T6 alloys, usually containing Al, Mg, Si and sometimes Cu elements, were fabricated through the artificial aging at ~ 160 – 177 °C for the solid solute solution (also T6 treatment). As a result, Al6061-T6 has the good yield strength of ~ 250 MPa (at room temperature), which is mainly due to the formation of the high-density needle-shaped precipitates during the T6 treatment.
Regarding the radiation tolerance of Al6061-T6, although previous studies focus much on the changes in mechanical properties such as toughness, strength and ductility [1], there is still lack of detailed study of microstructural evolution of Al6061-T6 under neutron irradiation. Considering significant differences between ion and neutron/proton irradiations, in this work, microstructure and strength of Al6061-T6 after neutron/proton irradiations have been investigated mainly by transmission electron microscopy (TEM) and uniaxial tensile testing, respectively.
Dog-bone shaped tensile specimens of Al6061-T6 were irradiated with neutrons and protons in SINQ Target-13 within the STIP-VII irradiation program. The maximum damage level was about 12 dpa. Meantime, about 650 appm helium and 1630 appm hydrogen were produced. The irradiation temperature was around 62 ℃. Tensile tests were conducted at 10-3 s-1 strain rate and at 22, 58 and 152 °C.
The irradiated specimens demonstrated slight irradiation hardening but quite pronounced embrittlement effects. In the unirradiated specimen, needle-shaped precipitates were observed and along the <100> directions of fcc Al matrix. The average length and the number density of which are 22.1 ± 10.3 nm and of (1.7 ± 0.8) × 1022 m-3, respectively. Pretty larger precipitates having a lower density of ~ 1019 m-3 coexisted with needle-shaped ones. In the as-irradiated specimen, most of needle-shaped precipitates were dissolved into Al matrix. Perfect dislocation loops of 1/2<110> and faulted frank loops of 1/3<111> were observed. After annealing at 152 °C/⁓1 h, namely during tensile testing, the density of perfect loops became negligible and frank loops disappeared. However, the needle-shaped precipitates appeared again. High-density He bubbles were found in both as-irradiated and post-irradiation annealed specimens. The annealing caused the growth of He bubbles from 1.7 ± 0.4 nm to 2.5 ± 0.5 nm.

[1]. K. Farrell, 5.07 - Performance of Aluminum in Research Reactors, Elsevier Inc., 2012.
[2]. Y. Dai, D. Hamaguchi, J. Nucl. Mater. 343 (2005) 184–190.

Speaker: Peng Song (PSI)

20231109, HPTW, Peng Song_final.pdf

20231109, HPTW, Peng Song_final.pptx

12:30 Lunch Break

12:30 SPC meeting

Topic5-2¶

Convener: Takashi Naoe (Japan Atomic Energy Agency)

94 Status and Plans for Long Baseline Neutrino Facility Beam Targetry¶

The Long Baseline Neutrino Facility (LBNF) project hosted at Fermilab is building the world’s highest power neutrino beamline for the Deep Underground Neutrino Experiment (DUNE). The new beamline will utilize 120 GeV protons with a time-averaged beam power of 1.2 MW (upgradeable to 2.4 MW) from the Fermilab Main Injector on a graphite target installed within the bore of a magnetic focusing horn operating with a peak current of 300 kA. The LBNF Beam Targetry systems include the target, an upstream protection baffle, a high-flow helium gas cooling system, and a remotely operated target exchange system. This talk will provide an overview of these systems, the challenges associated with the irradiation environment, interfaces with other beamline systems, and the status and future plans for LBNF Targetry.

Speaker: Patrick Hurh (Fermilab)

LBNF Beamline and Targetry Overview HPTW 04Nov23.pptx

95 LBNF Beam Windows Remote Handling and R&D Needs¶

The Long Baseline Neutrino Facility (LBNF) Project, currently under final design, will deliver neutrino beam to the Deep Underground Neutrino Experiment (DUNE) utilizing 120 GeV proton beam on a graphite target at 1.2 MW in 2031 and up to 2.4 MW by 2036. The LBNF neutrino beamline utilizes several beam intercepting devices that are being designed and built to withstand the cyclic thermal shock of the pulsed beam and provide thermal management of the absorbed power. Although operating parameters have been chosen to be within the realm of previous operational experience with neutrino targets (primarily NuMI at Fermilab and T2K at J-PARC), radiation damage effects on critical properties of the chosen materials are still not fully understood, especially effects on fatigue and dimensional stability. Due to this, a key area requiring R&D studies is the Upstream Decay Pipe Window which will experience direct beam downstream of the target. This talk will discuss the R&D needs and challenges for the Upstream Decay Pipe Window, the remote handling procedure and equipment being designed to operate on the window in the inevitable scenario of a window failure, the downstream decay pipe window analysis and design results, and a review of the Primary Beam Window analysis and R&D of the positioning cartridge.

Speaker: Quinn Peterson (Fermilab)

LBNF Beam Windows and Remote Handling R&D Needs.pptx

14:00 Coffee Break (Group photo)

15:30 Lab Tour

Friday 10 November ¶

08:30 Registration

08:50 Announcement

Topic4-3¶

Convener: Alexander Gottberg (TRIUMF)

96 A new spallation-driven two-step target at ISAC-TRIUMF: Design, online irradiations and PIE¶

The ISAC-TRIUMF facility produces Radioactive Ion Beams (RIBs) by impinging a 500 MeV, 50 kW proton beam onto targets of several target materials, and ionizing the outgoing atomic species. A spallation-driven, two-step target has been developed and irradiated at the ISAC-TRIUMF facility, focusing on the production of neutron-rich fission fragments and limiting by design the production of their neutron-deficient isobaric contaminants.
This new target assembly has been designed, tested and commissioned to generate an intense neutron field by impinging the proton beam onto a tungsten spallation target, positioned downstream of an annular uranium carbide volume. The neutrons subsequently induce fission reactions in the actinide material, producing predominantly neutron-rich fission fragments while limiting the production of the neutron-deficient spallation reaction products. In addition to the different distribution of produced isotopes, the thermal decoupling between the tungsten spallation target and uranium carbide volume offers additional benefits that allow high-power irradiations in a more controlled thermal environment.
This contribution presents the optimization process that led to the final target design and focuses on the successful online results obtained at the ISAC-TRIUMF facility from three independent irradiation campaigns. The extensive online beam time dedicated to this target has allowed for precise characterization of its performance by exploring a wide parameter space, improving the purity of some elemental chains by up to a factor 50. Moreover, this prototype has already allowed the delivery of more exotic neutron-rich isotope beams of Rb, Cs, Ba, Zn, Ga and Sn, enabling successful completion of previously unfeasible experiments. Results of the Post Irradiation Examinations (PIE) performed on the three irradiated target units will also be presented, highlighting areas for future improvements.

Speaker: Luca Egoriti (TRIUMF)

Two-step RIBs target-converter_HPTW2023_Luca Egoriti.pptx

97 Large Eddy Simulations of the cooling channels of ISIS Target Station 2¶

We present recent work on the simulation of the turbulence occurring in the cooling channels and the influence of pulsed heating on conjugate heat transfer in Target Station 2 of the ISIS Neutron and Muon Source, which is a water cooled tantalum-clad tungsten target. The simulations performed explore the potential for the influence of thermal fatigue arising from turbulent fluctuations in the cooling channels, as well as pulsed heating from the proton beam on the lifetime of the target. Five case studies of heat transfer modelling are:

1. Conjugate heat transfer of TS2 with Large Eddy Simulation (LES), where steady state heating was applied
2. Conjugate heat transfer of TS2 with Reynolds averaged Navier-Stokes (RANS) turbulence modelling of pulsed heating
3. LES of an untapered version of the cooling channel nearest to the nose of the target
4. LES of pulsed heating applied to the walls of the cooling channel nearest to the nose of the target
5. LES of conjugate heat transfer in a straight channel.

The turbulence models applied are the Smagorinsky form of LES and the elliptical blending Reynolds stress model (EBRSM) for the RANS calculations.

Initial progress on the modelling of thermal stresses within target materials will also be presented.

Speaker: Dr Gregory Cartland-Glover (Scientific Computing, Science and Technology Facilities Council, UK Research and Innovation)

Slides-CartlandGlover_Session4-3_HPTW2023_20231110.pptx

98 ISIS Target Station 2 Update on Target Evolution¶

The ISIS Synchrotron operates two Target Stations (TS). TS1 is the oldest and has been operating for nearly 40 years. TS2 came onstream in 2009 adding an additional suite of instruments for scientific research.
Target Station 2 (TS2) Target receives beam power of 40µA at 800MeV and has a service life of around 2 years. By contrast TS1 target receives beam power of 160µA at 800 MeV and has proved to be more reliable with a service life of around 5 years.
The presentation will show the development of the TS2 Target from the original MK1 design, which had cooling along the outer cylindrical surfaces only and an uncooled front face, through to the current production MK3a, with a water-cooled convex front face, and look forward to the MK4 design.
The MK4 Target is being developed to receive a 50% increase in beam power from 40µA to 60µA.
To handle the increase in beam power the current design will need to change from a single target plate (Tungsten Rod, clad in tantalum) to a multi-plate design with additional water cooling between the plates.
The MK4 will revert to a flat face but will be water-cooled across the front face, unlike the MK1. This will allow for the joining of multiple plates of varying thicknesses with a 2 mm water gap between each plate.
There has been a steady improvement in service life through MK1 to MK3a designs and it is predicted that moving to a flat-face multi-plate design will increase service life further.

Speaker: Leslie Jones (UKRI-STFC Rutherford Appleton Laboratory)

HPTW2023 - ISIS Target Station 2 Update on Target Evolution V2.pptx

99 Computational analysis of energy deposition on beam stoppers for Super-FRS at FAIR¶

At FAIR, pulsed beams of a wide range of heavy ions with energies up to 1.5 GeV/nucleon are anticipated to be used for the projectile fragmentation/fission. Rare isotopes of all the elements up to uranium will be produced and spatially separated at the superconducting fragment separator (Super-FRS) within a few hundred nanoseconds to enable the study of very short-lived nuclei. The beam stoppers are the energy intercepting and dissipating equipment used in the Super-FRS to safely stop the unwanted fragments and the primary beam and dissipate the resulting heat.
Each of the three beam stopper units consists of two shielding plugs each containing a copper absorber and a graphite absorber for the slow and fast extraction modes of operation, respectively. The primary beam specification for fast extraction is ∼ 5× 10^11 particles per spill of 238U of 0.4-1.5 GeV/nucleon which deposits up to 29 kJ energy in the absorbing medium (graphite) in 50-100 ns pulse (spill) duration with the interval between two consecutive pulses being 1.67s. The energy (particle flux) distribution across the beam cross-section is considered to be two dimensional Gaussian. The localized Bragg’s peak in the axial deposition rate curve causes a highly concentrated energy deposition in the absorber medium with the peak energy density reaching as high as ~ 330 J/g for 740 MeV/u. It is expected to induce high magnitude pressure waves in graphite. Simulation of the propagation behaviour of these waves is one of the major design challenges along with the high average thermal power of 17.1 kW at 1500 MeV/u and material degradation due to irradiation of graphite.
The transient coupled thermo-mechanical analysis of the pulsed form deposition of the beam energy is carried out using explicit finite element code LS-DYNA® to study the propagation of pressure waves within the absorber. The simulation results show the generation and propagation pressure wave from the core to the boundary and subsequent reflection at the boundary. The failure of graphite is usually in the form of cracking and spalling and is determined by the maximum and minimum principal stresses generated and the ultimate tensile and compressive strengths of graphite using Coulomb-Mohr failure criterion.
The heat removal performance is studied through the quasi-static thermo-mechanical study. The absorber, which is in the form of a segmented graphite block, is water cooled through copper heat sinks. The entry shape of the absorber is optimized to enable maximum distribution of energy along beam direction, reducing steady state temperature reached from 2200K to ~1500K.

Speaker: Dr Amit Kumar (CSIR-Central Mechanical Engineering Research Institute)

Kumar_beamcatcher-HPTW.pptx

100 Status and R&D of the target and beam dump at FRIB¶

The FRIB accelerator, constructed and commissioned in 2021, serves as a pioneering facility to produce rare isotopes and access elements lying beyond stability. In early 2023, FRIB was successfully operated at 5 kW, employing beams of 36Ar, 64Zn, 36Ar and 124Xe directed onto a rotating single-slice graphite target, while effectively absorbing the remaining beam through an S-Shape static beam dump. The primary beam power is now being increased towards 10 kW. The enhanced single-slice graphite target system and the implementation of a minichannel static beam dump will enable the operation at 10 kW and potentially even higher power.
This paper presents the current status and ongoing R&D efforts focused on the target and beam dump systems.

Speaker: Dr Jeongseog Song (MSU/FRIB)

Song_HPTW.pptx

10:30 Coffee Break

Topic5-3¶

Convener: Patrick Hurh (Fermilab)

101 FRIB Remote Handling – Operations Experience and Future Plans¶

FRIB Remote Handling – Operations Experience and Future Plans*

Michael Larmann, Andreas Stolz, Daniel Cole, Jacob Morris, James Thelen, Jie Wei, Marty Mugerian

Facility for Rare Isotopes Beams, Michigan State University, East Lansing, MI 48824, USA
The Facility for Rare Isotope Beams (FRIB) is a heavy ion accelerator facility aiming to reach 400kW primary beams, which will extend the heavy-ion accelerator power frontier by more than one order of magnitude. FRIB’s superconducting radio frequency continuous-wave heavy-ion linear accelerator can accelerate all ions up to uranium to energies above 200 MeV/u.
FRIB’s Target Hall takes a hybrid approach where personnel access is permitted once beam is turned off and all shielding remains in place. Within the target hall there is a rotating graphite target, water filled beam dump, and energy degrader that require intricate and frequent reconfiguration and maintenance.
At 400kW, the beam impacts the rotating target which absorbs 100kW while the unreacted beam totaling 300kW is dumped into the water filled beam dump. Both the target and energy degrader require reconfiguration to support user experiments at a frequency of up to once per week. Maintenance on the target, energy degrader, and dump outside of experiment reconfiguration occurs annually.
FRIB beam power has steadily increased to 5 kW since the commencement of user operations in May 2022 and is now entering 10kW operations. One of the challenges for remote hanlding will be fulfilling the requirement of reconfiguring both the target and energy degrader within 24hrs for user experiments. The current time to complete the reconfiguration is 48hrs and will require additional assemblies and provisions to reduce to 24hrs.
In this presentation, we report the recent activities and status of remote handling equipment and procedures, how remote handling scope has changed and adapted during power ramp up, and the future remote handling operations at FRIB.

*This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics and used resources of the Facility for Rare Isotope Beams (FRIB) Operations, which is a DOE Office of Science User Facility under Award Number DE-SC0023633.

Speaker: Michael Larmann (FRIB - Facility for Rare Isotope Beams)

FRIB Remote Handling – Operations Experience and Future Plans.pdf

102 HiRadMat: a high power targetry facility at CERN¶

Within the CERN accelerator complex, and towards the high-brightness future of the upcoming HL-LHC upgrade, the exact benchmarking of simulation models and the understanding of the various materials thresholds under the effects of a high-power proton beam is critical. The HiRadMat (High Radiation to Materials) facility of the CERN Super Proton Synchrotron (SPS) was commissioned in 2011 (1) and since then has been serving the accelerator community worldwide as a testbench for such experiments (2).
High-intensity LHC-like proton beam pulses are extracted from the SPS towards HiRadMat, with a maximum stored beam energy of 2.4 MJ and a variable size range of 0.25 – 2 mm. In recent years, the HiRadMat facility has evolved significantly towards a better control of the beam parameters involving automated procedures of logging and beam-based alignment of various experimental setups. A comprehensive upgrade project is currently ongoing to increase the available intensities up to the HL-LHC maximum of 2.3x1011 per bunch, corresponding to a maximum energy of 4.7 MJ, by 2024.
Since the last long shutdown, experiments conducted in the facility have covered a wide range of topics, from various accelerator equipment tests to fundamental plasma physics phenomena research, as well as for materials studies for diverse applications. The HiRadMat facility is available from today until CERN’s Long Shutdown, planned in 2026, to accommodate high-power targetry-related experiments, providing transnational access and financial support in the framework of EURO-LABS to eligible experimental teams. An overview of the facility’s capabilities and the performed experiments are being presented in this contribution.

(1) Efthymiopoulos, I.; Evrard, S.; Gaillard, H.; Grenier, D.; Hessler, C. HiRadMat: A New Irradiation Facility for Material Testing at CERN. Proc. 2nd Int. Particle Accelerator Conf. (IPAC’11) 2011.

(2) Harden, F. J.; Bouvard, A.; Charitonidis, N.; Kadi, Y. HiRadMat: A Facility Beyond the Realms of Materials Testing. J. Phys. Conf. Ser. 2019, 1350 (1), 012162. https://doi.org/10.1088/1742-6596/1350/1/012162.

Speaker: Dr Alice Goillot (CERN)

20231110_HPTW23_HRMT.pptx

103 Target Systems integration for a high intensity facility in the CERN’S North Area¶

A new high-intensity fixed-target facility could be accommodated at CERN by exploiting a proposed increase of the proton flux delivered by the Super Proton Synchrotron (SPS). Multiple physics experiment proposals such as BDF/SHiP, HIKE and SHADOWS are being considered, all requiring high power target systems. Amongst the different possibilities to locate such experiments and their respective target complex at CERN, the ECN3 hall in the North Area has been selected for further study.
This contribution will detail the status of the implementation of the two possible target complexes in the exiting cavern TCC8 as the different experiments require substantially different facilities. To assess the feasibility, a detailed system integration study of the two concepts has been performed. Different aspects were addressed to respect the expected levels of radiation, including radiation protection considerations, remote handling strategy, utilities requirements, installation, operation, maintenance, decommissioning, and sustainability, which are herein discussed.

Speaker: Jean-Louis Grenard (CERN)

ECN3 target station integration.pptx

104 Radiation protection studies for a high intensity facility in the CERN's ECN3 area¶

The ECN3 underground cavern at CERN’s SPS North Area offers unique opportunities in terms of intensity, energy and infrastructure for potential high-impact particle physics programmes that are complementary to the energy frontier and that are in line with the ESPPU 2020 recommendations. There is a strong interest to fully exploit the SPS for Fixed Target physics, which has resulted in the PBC Study Group focusing on siting a future high intensity experimental facility in ECN3. Several proposals for physics experiments including BDF/SHiP, HIKE and SHADOWS are being considered. The given experiments require substantially different facility designs and have, as a consequence, different RP implications and optimization needs.
The implementation of a high intensity facility in ECN3 has therefore undergone a series of exhaustive radiation protection (RP) studies for each proposed experiment and the different modes they operate in. These studies have been aimed at optimising the implementation in TCC8 and ECN3 to ensure that the exposure to radiation of personnel and members of the public, as well as the radiological impact on the environment, would be compliant with CERN’s RP code and as low as reasonably achievable (ALARA). The optimization takes into account the prompt and residual radiation, soil activation and transfer of activation products to groundwater, air/He activation and environmental impact. To assess the above-mentioned radiation protection aspects, extensive simulations were performed with the CERN FLUKA Monte Carlo particle transport code. The status of the RP assessments and design optimization will be presented for the various experiments proposed at ECN3. The present studies will be followed by a Technical Design Report phase after the approval of an experiment.

Speaker: Claudia Ahdida (CERN)

Ahdida_HIECN3_RP_HPTW_2023.pptx

12:30 Lunch Break

Topic7-2¶

Convener: Helmut Weick (GSI Helmholtz Center for Heavy Ion Research GmbH)

105 ISIS Target Station 1, Upgrade Project - Target Station Rebuild Project¶

ISIS neutron source Target Station one (TS1) has been operating for nearly 40 years. To safeguard future reliable operation, a decision was made to upgrade the Target, reflector and, moderators (TRAM) assembly along with the associated plant equipment and controls systems. One of the aims of this project was to take some of the lessons learnt from the construction of the second target station (TS2) that was completed in 2008, to improve remote handling for changing moderators and, to strip back some of the redundant equipment for when uranium targets where used. The aging homemade cryogenic coldbox systems were also replaced to bring them up to modern standards by using off the shelf components and complying with updated flammable gas regulations (DSEAR). This presentation will take you through the journey of challenges undertaken during the strip out of the old equipment such as, the breakdown of the highly active TRAM assembly, sawing of the cantilever support beam, packaging of the active components and, the steps taken for reconstruction and eventual recommissioning.

Speaker: dan coates

HPTW2023 - ISIS TARGET STATION 1 - UPGRADE PROJECT - TRAM REPLACEMENT V2 09112023.pptx

106 Target and cooling system for the high intensity neutrino beams at J-PARC¶

High intensity neutrino beams have been generated using a proton beam power of up to 540 kW at the J-PARC neutrino facility for the long-baseline neutrino experiment since 2009. A 30 GeV proton beam of about 10^14 protons per pulse is injected using fast extraction to the graphite target. The pions generated are focused by the electric magnetic horns, and neutrinos decayed from the pions are utilized for the experiment. A dominant factor that is expected to determine the target lifetime is oxidization, an effect which is related to the target temperature and oxygen concentration in the helium cooling gas. We will report on the design concept of the target and cooling system, the operation results to date, and the upgrades for the 1.3 MW beam power.

Speaker: Tsunayuki Matsubara (KEK/J-PARC)

hptw231110.pdf

107 Upgrades and Progress in Increasing Beam Power Above 1.4 MW at the SNS¶

The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory is currently the world's highest power pulsed neutron spallation source. The SNS first reached its design power of 1.4 MW in 2013 and began operating steadily at 1.4 MW in 2018. Part of the delay in reaching steady, reliable 1.4 MW operation was due to the capabilities of the target systems. We are pleased to report that the SNS is now operating at 1.7 MW and will ramp over time to 2.0 MW. This presentation will provide an update on the recent history of the SNS target systems as they transitioned to steady 1.4 MW operations. It will also provide information about the ongoing Proton Power Upgrade project, which is nearing completion. This project will increase the available accelerator power to 2.8 MW, double the original 1.4 MW design. This beam power will allow for 2 MW operation of the SNS's first target station and provide additional capabilities for a future second target station. Several upgrades will be made to the first target station to ensure reliable operation at 2 MW. This presentation will also describe these upgrades and their current status, including operational unknowns, risks, and risk mitigation strategies.

Speaker: Dr Drew Winder (Oak Ridge National Laboratory)

Upgrades and Progress in Increasing Beam Power Above 1.4 MW at the SNS.pptx

108 Challenges Encountered While Replacing the SNS Ring Injection Dump Beam Stop and Window¶

The Ring Injection Dump (RID) is a high energy beam transport (HEBT) region in the SNS accelerator where extra beam is aborted into a 150 kW water cooled beam stop. The location of the two beams on the adjacent vacuum window is currently not well understood. A new quadrupole magnet is being added to the RID beamline as part of the Proton Power Upgrade (PPU) project, so an imaging system was incorporated into the design to properly steer the beams. The design of the RID Imaging System required it to be located as close as possible to the RID window and to have a new vacuum window with a fluorescent coating on it so that the location of the beams on the window could be seen accurately. To reduce the radiation rates at the imaging system location during installation, the downstream RID vacuum window and beam stop needed to be replaced first. Replacing the RID vacuum window and beam stop are challenging remote handling tasks under normal circumstances. While the beam stop replacement went smoothly, the vacuum window replacement encountered many setbacks that required creative and unconventional methods to successfully complete the job.

Speaker: Ryan Schultz (Oak Ridge National Laboratory)

RID-Challenges-Schultz-Saunders-Willis-HPTW.pptx

109 SNS Target Instrumentation Based on Fiber-Optic Sensors: Development and Application Experience¶

Measurement of the strain waveforms is critical to improving SNS target performance and reliable lifetime, as well as to evaluating the efficacy of strain mitigation techniques such as the injection of helium gas into the mercury flow. As the measurements must take place in a very limited space and in the presence of intense electro-magnetic interference and ionizing radiation, fiber-optic sensors provide an optimum solution. However, off-the-shelf fiber sensors often could not survive the residual radiation dose (~ 10 kGy) experienced by the target before operation and they failed before any measurements of the response to the beam pulse were attempted. Recently, we developed a novel type of fiber-optic interferometric sensors which includes a sensing interferometer using high-radiation-tolerant fluorine-doped single-mode fibers and an all-fiber based, polarization-insensitive, phase-shifted optical demodulator to provide precise and fast signal processing. The sensing mechanism is based on the low-coherence interferometry technique and the signal demodulator uses an all-fiber based Faraday Michelson interferometer. The fiber sensors are installed in the interstitial space between the mercury target vessel and a water-cooled shroud and their outputs are sent to the demodulation system located in the target manipulator’s gallery through 70-ft long relay fiber cables.
The fiber-optic sensors have demonstrated excellent performance in the measurement of both slow and fast (up to MHz) strains in a very high radiation (108 ~ 109 Gy) conditions. Measurements have been conducted at different proton power levels from more than 20 fiber sensors located at different positions on the mercury vessel. In this talk, we will report measurement results particularly in the following aspects.
i) A systematic characterization of the response of the mercury target to the proton pulses with different power levels and as a function of locations on the target vessel.
ii) An in-situ verification of the efficacy of the small-bubble helium gas injection into the mercury flow. The strain measurement directly revealed the clear reduction of the strain magnitude by the gas injection and its dependence on the gas flow rate.
iii) The radiation-induced-attenuation in the optical fiber has been experimentally investigated at both short-term and long-term ranges.
iv) A radiation-induced volume expansion of the adhesive material and its effect on the strain measurement has been studied.
v) Use of the sensors to measure the strain response of solid targets made of tungsten and other materials to a proton pulse.

Speaker: Dr Yun Liu (Oak Ridge National Laboratory)

(5)HPTW23_ID39_YL.pptx

110 Present status of cavitation damage mitigation techniques for the mercury target vessel at J-PARC pulsed spallation neutron source¶

A liquid mercury target system for the pulsed spallation neutron source is installed in the J-PARC. High-power proton beams of 3 GeV 25 Hz is injected to the liquid mercury to produce neutrons. A mercury target vessel made of 316L stainless steel is severely damaged by cavitation which is caused by the proton beam-induced pressure waves. The thickness of beam window is designed to 3 mm to reduce thermal stress. To mitigate the cavitation erosion, we adopted a double-walled structure with a narrow channel expects to disturb the growth of the cavitation bubbles due to the pressure gradient by the high-speed mercury flow.
In addition, gas microbubbles were injected into the mercury to suppress the pressure waves that induces cavitation.
During the beam operation, proton-beam induced acoustic vibration on the mercury target vessel is measured aiming to diagnose the effect of gas microbubble injection on pressure wave mitigation. Operational beam power for the J-PARC mercury target is gradually ramping-up to the 950~kW and achieved its stable operation on the effort of the cavitation damage mitigation techniques.
After the operational period, every year, cavitation erosion facing the mercury with gas microbubble injection and the narrow channel were observed by cutting out the beam window portion using an annular cutter with semi-dry cutting technique. The result showed that the obvious damage mitigation effect by injecting gas microbubble that is predicted through the acoustic measurement was observed. Based on the damage inspection, we are discussing to extend the operational period of target vessel from one year to two years.
In the workshop, present status of the cavitation damage mitigation will be discussed.

Speaker: Dr Takashi Naoe (Japan Atomic Energy Agency)

#33_Naoe_HPTW2023.pdf

15:15 Coffee Break

111 Discussion & Closing remarks¶

Speakers: Dr Alexander Gottberg (TRIUMF), Mr Chris Densham (RAL), Dohyun Kim (Brookhaven National Laboratory), Drew Winder (Oak Ridge National Laboratory), Frederique Pellemoine (Fermilab), Frederique Pellemoine (Fermi National Accelerator Laboratory), Dr Helmut Weick (GSI Helmholtz Center for Heavy Ion Research GmbH), Katsuya Yonehara (Fermilab), Marco Calviani (CERN), Patrick Hurh (Fermilab), Shunsuke Makimura (J-PARC/KEK), Takashi Naoe (Japan Atomic Energy Agency), Dr Yong Dai

231109 Closing session.pptx

231110 Topic8.pptx

2_summary.pptx

HPTW2026_CERN_MCalviani.pptx

Summary of Topic 3_YDai.pptx

summary-topic-7.pptx

summary_topic6_111023.pptx

Topic 1 Closeout Slides_R1.1.pptx

Topic 4 Summary.pptx

Topic 5 Summary.pptx