High Resolution Gamma-Ray Spectroscopy at the RIBF

Session

Proposals

11 Apr 2019, 09:00

Conveners

Proposals: Physics I

• Heather Crawford (Lawrence Berkeley National Laboratory)

Proposals: Physics II

• Nori AOI (RCNP, Osaka Univ.)

Proposals: Physics III

• Thorsten Kroell (TU Darmstadt)

Proposals: Physics IV

• Peter Reiter

Proposals: Physics V

• Anna Corsi (CEA Saclay)

Proposals: Physics VI

• Volker Werner (TU Darmstadt)

7. Shape coexistance in the N=Z nucleus ${}^{80}$Zr

Jose Javier Valiente Dobon (LNL-INFN)

11/04/2019, 09:00

State-of-the-art beyond mean field methods with the Gogny D1S interaction has predicted for the N=Z ${}^{80}$Zr nucleus five 0${}^{+}$ states corresponding to different nuclear shapes within 2.25 MeV, where several rotational and γ-bands are built upon those five 0+ states [1]. We propose to study the rich low-lying energy spectrum of ${}^{80}$Zr, by using a 1n and 2n knock-out reaction from...

5. Study of multiple shape coexistence in 80Zr and isospin symmetry breaking of its vicinity

Jeongsu Ha (Seoul National University)

11/04/2019, 09:15

Nuclear physicists have kept their attention to the nuclei that the proton number (Z) and the neutron number (N) are same, i.e. N=Z, because they are interesting for several reasons. First, they provide a test ground of exchange symmetry between protons and neutrons. Approximately, the nuclear force acting between nucleons does not distinguish the kind of nucleons. However, each proton has a...

30. T=0 pairing along the N=Z line in the g9/2 region

Michael Bentley (University of York)

11/04/2019, 09:30

Enhanced neutron-proton (np) pairing correlations can arise when both particle types occupy the same orbitals. In addition to the T = 1 np pairing phase, the opportunity for isoscalar (T = 0) correlations is also present, especially on the N=Z line. Competition between these np-pairing mechanisms is of much interest. Recent work on ${}^{92}$Pd [1] has indicated the possibility for the existence...

28. MED and TED in the rotational A=78, 82 T=1 triplets

Silvia M. Lenzi (University of Padova and INFN)

11/04/2019, 09:45

D. Bazzacco, A. Goasduff, S.M. Lenzi, S. Lunardi, R. Menegazzo, D. Mengoni, A. Montaner-Pizá, G. Pascualato, F. Recchia, D. Testov
Dipartimento di Fisica e Astronomia, Università di Padova and INFN Sezione di Padova, Padova, Italy
T. Bayram, A. Illana, G. de Angelis, D. Brugnara, M.L. Cortés, F. Galtarossa, A. Gottardo, E. Gregor, T. Marchi, D.R. Napoli, J.J. Valiente-Dobón, I. Zanon
*INFN...

39. Test of nuclear collectivity above 100 Sn

Jose Javier Valiente Dobon (LNL-INFN)

11/04/2019, 10:00

Collectivity in nuclei in the vicinity of the N = Z line may be enhanced by neutron-proton
interactions occupying similar orbits near the Fermi level. Therefore, information on single-particle
energies and residual interactions with respect to the 100 Sn core are extremely important. The region
of 100 Sn has been extensively investigated due to unusual B(E2;0 + →2 + ) values observed for light...

26. Spectroscopy of 100In with neutron knockout reactions

Joochun (Jason) Park (Lund University)

11/04/2019, 10:15

The robustness of the proton and neutron shells for the doubly magic nucleus ${}^{100}$Sn has been studied in $\beta$-decay experiments, resulting in the smallest log $ft$ value for the decay of the ${}^{100}$Sn ground state to the $(1^{+})$ state in ${}^{100}$In. A decay spectroscopy experiment at the RIBF has improved the statistical uncertainties on the corresponding Gamow-Teller decay strength...

2. Gamma spectroscopy near 78Ni

S Franchoo (IPN Orsay)

11/04/2019, 11:00

We propose the $\gamma \gamma$ spectroscopy of ${}^{77,79}$Cu, which is of paramount interest for tracing the evolution of proton single-particle levels near ${}^{78}$Ni. Despite the limited resolution of the Dali-2 scintillators during the Seastar campaign, a level scheme could be constructed for ${}^{79}$Cu. The $\pi f_{7/2}$ strength turned out to be fairly fragmented, resulting in a level...

25. Competition between core excited and single-particle proton and neutron states out of 78Ni studied via lifetime measurements.

Francesco Recchia (INFN LNL)

11/04/2019, 11:15

D. Bazzacco, S. Lenzi, S. Lunardi, D. Mengoni, A. Montaner-Piza’,
A. Goasduff, R. Menegazzo, G. Pasqualato, F. Recchia, D. Testov
Dipartimento di Fisica, Universita’ di Padova and INFN (Italy)

P. Doornenbal, K. Wimmer
RIKEN Nishina Center (Japan)

T. Bayram, D. Brugnara, L. Cortes, G. de Angelis,
A. Gottardo, E. Gregor, A. Illana, D.R. Napoli, I. Zanon, J.J. Valiente Dobon
INFN Laboratori...

46. Detailed spectroscopy of 78Ni

Pieter Doornenbal (RIKEN)

11/04/2019, 11:30

Detailed spectroscopy of 78Ni

44. Lifetimes of the 4+ states in 72 and 74Ni

Jose Javier Valiente Dobon (LNL-INFN)

11/04/2019, 11:45

The seniority scheme was introduced by Racah, initially to identify multiparticle configurations in the atomic spectrum, latter was extended for the atomic nucleus, where is useful to classify the jn states in the jj-coupling. The concept of seniority in bound to the pairing. The seniority is generally conserved up to a large extend and it is well known the conditions that need to satisfy the...

35. Coulomb excitation in neutron-rich isotopes around Ni

Martha Liliana Cortes (RIKEN Nishina Center)

11/04/2019, 12:00

A main focus of nuclear physics nowadays is the study of the evolution of shell structure in exotic isotopes. An interesting region of the nuclear chart to test shell evolution is around the Ni isotopic chain. For this chain, $B(E2;0_{\mathrm{g}.\mathrm{s}.}^{+}\to 2_1^{+})$ measurements have shown a behavior that differs, not only from the seniority scheme, but also from different theoretical...

12. Coulomb Excitation of ${}^{70}$Fe

Heather Crawford (Lawrence Berkeley National Laboratory)

11/04/2019, 12:15

One of the most compelling regions of the nuclear chart within reach of current experimental facilities is that of the N=40 isotopes near ${}^{64}$Cr. Due to the strong effect of the pn interaction between the protons and neutrons at the Fermi surface, the removal of $f_{7/2}$ protons below Ni effectively alters the $f_{5/2}$ neutron spin-orbit partner energy relative to the $g_{9/2}$ and...

14. Neutron single-particle structure above N=50 towards 78Ni

Freddy Flavigny (IPN Orsay)

11/04/2019, 14:00

We propose to perform the spectroscopy of N=51 isotones of 83Ge and 81Zn. The goal is to use the selectivity of neutron knockout from 84Ge and 82Zn to characterize the evolution of the ν(s1/2-d5/2) energy splitting and to identify for the first time (2p-1h) intruder state (ν(g9/2)-1(sd)+2 ) possible signature of shape coexistence above N=50 close to 78Ni. Such a study is uniquely possible at...

19. E2 Coulex measurements in ${}^{79,81}$Zn to understand nuclear intruder states and shell evolution

Andrea Gottardo (LNL - INFN)

11/04/2019, 14:15

E2 Coulex measurements in ${}^{79,81}$Zn to understand nuclear intruder states and shell evolution

Introduction
Recent work [Delafosse] has pointed out that the physics around the N=50 shell closure close to ${}^{78}$Ni may be driven by the effects of ρ-meson exchange potential. On the one hand, this is causing a reduction of the N=50 gap going towards Z=32, inducing a sudden increase of...

20. Secondary knockout reactions and lifetime measurement with the plunger technique

Andrea Gottardo (LNL - INFN)

11/04/2019, 14:30

Secondary knockout reactions and lifetime measurement with the plunger technique

Recent work [Delafosse] has pointed out that the physics around the N=50 shell closure close to ${}^{78}$Ni may be driven by the effects of $\rho$-meson exchange potential. This potential causes a reduction of the N=50 gap going towards Z=32, inducing a sudden increase of across-shell quadrupole coherence in...

22. Onset of collectivity beyond N=50 studied in zinc isotopes

Magdalena Gorska (GSI)

11/04/2019, 14:45

Neutron-rich zinc isotopes will be populated in (p,2p) on the MINOS liquid hydrogen target.

Recently the 2+ and 4+ levels of N=52,54 82,4Zn nuclei were measured at RIKEN within the SEASTAR programme [1]. The energies of the newly observed levels suggest the onset of deformation towards heavier Zn isotopes, which has been incorporated by taking into account the upper sdg orbitals in the...

23. Structural investigation at the boundary of gamma-ray spectroscopy: investigation of extremely neutron rich ${}^{84,86,88}$Ge

Christoph Fransen (Institute for Nuclear Physics, University of Cologne, Germany)

11/04/2019, 15:00

Neutron rich Ge isotopes represent a puzzle so far as the few existing data
yield a contradicting picture. A recently determined large $B(E2;2^{+}\to 0^{+})$
value with a large uncertainty in ${}^{84}$Ge hints for a completely unexpected
shape transition from soft triaxiality in neutron rich Se isotopes with
Z=34 to prolate deformation for neighboring Ge with Z=32 [1]. Such an
"island of inversion"...

34. Intermediate-energy Coulomb-excitation of neutron-rich isotopes at Z<38, N>50

Volker Werner (TU Darmstadt)

11/04/2019, 15:15

The evolution of collectivity, mirrored in B(E2) excitation strength, along the N=52 isotonic line is of special interest toward the Z=28 shell closure. The degree of collectivity depends on the possibility of cross-shell excitations, and on the evolution of shell structure in general. The energies of 21+ states in the N=52 isotones minimize at Z=32 (Ge), only four protons above the Z=28 magic...

29. Approaching the Fifth Island of Inversion from the north

Dr Ryo Taniuchi

11/04/2019, 15:30

Islands of inversion (IoIs) appear close to semi-magic or even doubly magic nuclei and are certain areas of the nuclear chart where the nuclei expected to be spherical in their ground states become deformed. They are interpreted as strong nuclear quadrupole-quadrupole interactions producing a shape transition with highly correlated many-particles-many-holes configurations. When reducing the...

11. Spectroscopic Factors in the Neutron-Rich Ca Isotopes

Heather Crawford (Lawrence Berkeley National Laboratory)

11/04/2019, 16:15

The neutron-rich calcium isotopes have been a focus both experimentally and theoretically, as a key isotopic chain with clear examples of evolving shell structure and a test-bed for microscopically-based interactions and large-space $ab-initio$ calculations. While spectroscopy has extended quite far along the Ca isotopes, out to ${}^{56}$Ca at least, the evolution of single-particle occupancies...

15. Single-particle and collective structure of neutron-rich N=40 nuclei

Kathrin Wimmer (The University of Tokyo)

11/04/2019, 16:30

The increase in collectivity in neutron-rich isotopes around N=40 has been attributed to the enhanced occupation of neutron intruder orbitals from above N=40 [1]. At the center of this island of inversion lies 64Cr. We propose to measure neutron and proton knockout from 64Cr to quantify the neutron g9/2 and d5/2 intruder orbital occupations. The proton knockout will yield the relative location...

13. Spectroscopy of ${}^{63}$V and Spectroscopic Factors in the N=40 Island of Inversion

Paul Fallon (Lawrence Berkeley Laboratory)

11/04/2019, 16:45

We propose proton knockout from ${}^{64}$Cr to ${}^{63}$V. For a deformed ground state (as may be expected) the odd proton can be removed from low-lying Nilsson states for example the $\mathrm{\Omega }=3/2$ levels originating from the $d_{3/2}$ or $f_{7/2}$ shell model states. The spectroscopy will provide an important measure of the relative energies of the proton states, which is sensitive to the...

33. Single-particle structure of 55Ti and 57Ti

Takuma Koiwai (University of Tokyo)

11/04/2019, 17:00

Beyond the new magic number N = 34, the region around the neutron-rich Ca isotopes, continues to attract a lot of attention. Recently, the energy of the first 2+ state of 56Ca was measured to have an unexpectedly high value [ChePC]. The excitation energies of the 2+ states of the N = 34 nuclei 56Ti and 52Ar indicate that the shell closure occurs only at and below Ca [Liu]. To clarify the...

9. Experiments with the High Resolution gamma-ray Array at RIBF

Marina Petri

11/04/2019, 17:15

Understanding the nuclear structure and dynamics in terms of the underlying fundamental interactions between protons and neutrons is one of the overarching goals of the nuclear science community. To this end, nuclear theory is currently developing nuclear interactions and Hamiltonians derived from chiral Effective Field Theory (EFT) employing 2- (NN) and 3-body (3N) forces. This new approach...

48. High resolution spectroscopy beyond 132Sn

Nori AOI (RCNP, Osaka Univ.)

11/04/2019, 17:30

We will are considering to propose experiments to clarify the anomalous structures in the neutron rich nuclei around and beyond 132Sn in continuation of our previous study.
One of the interests is the decoupling between proton and neutron motion in the low-lying excited states of the nuclei around 132Sn. The other is the evolution of collectivity along Z~50 towards N~90. We are considering...

24. Breaking of the isospin symmetry in the A=71 mirror nuclei: Knock-out reactions in 71Kr-71Br nuclei (and neighbours) using Miniball at Riken.

Francesco Recchia (INFN LNL)

11/04/2019, 17:45

Isospin formalism, which describes the neutron and the proton as two states of the same particle, the nucleon, is amongst the essential descriptive tools of a broad range of nuclear phenomena. The success of the isospin symmetry concept belies its broken nature. Not only is the symmetry broken by the proton-neutron mass difference and the Coulomb interaction, but also by the nucleon-nucleon...

3. Nature of proton and neutron motions in neutron-rich Te isotopes

Dr Byul Moon (Center for Extreme Nuclear Matters, Korea University)

12/04/2019, 09:00

The understanding of the few-nucleon pair motions in an atomic nucleus is one of the ever-evolving topics for the many-body quantum system within a finite potential space. The Te nuclide with $N$ > 82 is the best laboratory to investigate the motion and interaction of a single proton pair in the neutron-rich environment like helium over the robustly closed core of ${}^{132}$Sn. The neutron-rich...

10. Pairing in weakly bound systems

Heather Crawford (Lawrence Berkeley National Laboratory)

12/04/2019, 09:15

The evolution of pairing correlations in exotic nuclei is a subject which has received much attention in recent years, as RIB’s accelerator facilities are providing unique isotopes to study. Of particular interest is the role of pairing in neutron-rich systems where the appearance of a low-density surface may induce a transition from the well known BCS Cooper-pairing mechanism to a BEC...

21. Single-particle states in the N=82 nucleus 129Ag

Zsolt Podolyak (University of Surrey)

12/04/2019, 09:30

129Ag is a single magic N=82 nucleus. With three protons holes below 132Sn is neutron-rich, and any experimental information to be obtained on its structure is directly applicable for the understanding of lighter N=82 nuclei on the r-process waiting path. Proton knockout from 130Cd on the MINOS liquid hydrogen target will be used to populate 129Ag.

130Cd in it is ground-state has two proton...

27. High-resolution spectroscopy around N=90

Radomira Lozeva (CSNSM Orsay)

12/04/2019, 09:45

LoI R. Lozeva

37. γ(γ)-spectroscopy and lifetime measurements in the 132 Sn region following (p,2p) reactions

Thorsten Kroell (TU Darmstadt)

12/04/2019, 10:00

Compared to studies of neutron-rich nuclei (A,Z) employing isomeric decay or Coulomb
excitation which require the isotope of interest as secondary beam or spectroscopy
following β-decay which even requires the more neutron-rich (A,Z-1) isotope, (p,2p)
reactions start from the less exotic isotope (A+1,Z+1). This reaction mechnism has been
exploited successfully already in the SEASTAR campaign...

1. Study of octupole deformation in neutron-rich Ba isotopes using Coulomb excitation at intermediate energies

Andrea Jungclaus (IEM-CSIC)

12/04/2019, 10:15

With this proposal we intend to continue our experimental program to study neutron-rich nuclei in the region around doubly-magic 132Sn using in-beam γ-ray spectroscopy at relativistic energies, which we initiated with experiment NP1306-RIBF98R1 in 2015. In particular, we propose to study the octupole deformation of neutron-rich Ba isotopes by measuring the transition probabilities to the first...

43. Exploring the collectivity around the N = 82 shell closure via relativistic Coulomb excitation of the Z = 50 130,136Sn isotopes

Peter Reiter

12/04/2019, 11:00

We propose to study excited states in the isotopes 130,136Sn the direct neighbors of 132Sn by gamma-ray spectroscopy following relativistic Coulomb excitation. The experiment aims to investigate the evolution of collectivity and nuclear structure around and the magic-shell closure at N = 82 for tin isotopes (Z = 50) via the determination of the reduced transition probabilities, in particular...

6. Disentangling collective and single-particle structures in neutron-rich Se isotopes

Frank Browne (RIKEN Nishina Center)

12/04/2019, 11:15

The quadrant of the nuclear chart north-east of the doubly magic ${}^{78}$Ni is expected to be rife with competition between single-particle and collective degrees of freedom. Of the nuclei in the $28<Z<50$ and $50<N<82$ valence spaces, the neutron-rich Se isotopes have been suggested by theory and experiment to exhibit shape co-existence of spherical, prolate and oblate shapes, and prone...

38. Shape coexistence studies in neutron-rich krypton isotopes around N=60

Andrey Blazhev (Institute for Nuclear Physics, University of Cologne, Germany)

12/04/2019, 11:30

Even-even strontium and zirconium nuclei in the A=100 region show a sudden onset of deformation at N=60 while the lighter isotopes up to N=58 are rather spherical. Unlike, the even krypton isotopes exhibit a smooth onset of collectivity up to N=60 [1]. Recent high-resolution gamma-spectroscopy results on 96Kr [2] following projectile fission confirmed the energy of the yrast 2+ --> 0+...

8. Coulomb and quantum bubbles in heavy nuclei

daisuke suzuki

12/04/2019, 11:45

This is a letter of intent to study the proton shell structure near Z = 82 in the forthcoming Miniball campaign at the RIBF. The depletion of the central proton density, which characterizes the so-called bubble structure, is expected to arise from two different mechanisms. One is for a given atomic nucleus to minimize its Coulomb energy and the other to optimize the nuclear shell energy. While...

49. Single particle structure coupled to the second 0+ state in 32Mg

Nobuaki IMAI (CNS, Univ. of Tokyo)

12/04/2019, 12:00

More than 40 years have passed since the first discovery of the island of inversion [1]. In the
shell model point of view the phenomenon is attributed to the change of the effective single
particle energy, which gives rise to the quenched N=20 shell gap [2]. On the other hand the
single particle structures of 31Mg [3] and 33Mg [4] can be well understood in the Nilsson
diagram, which suggests...

31. Magnetic moments of short-lived excited states at projectile-fragmentation energies. Would the recoil in gas technique work?

Dr Joa Ljungvall (CSNSM, Orsay, France)

12/04/2019, 12:15

Nuclear moment measurements of short lived excited states are in general very challenging due to the requirement to obtain strong enough magnetic fields, capable to provide a sizeable perturbation of the nuclear spin ensemble within the lifetime of the state of interest. Kilotesla’s magnetic fields are usually needed for nuclear states of picosecond lifetimes. Hyperfine fields were often...