Spin-dependent interactions play essential roles in nuclear structure and reactions. One of the best known examples is the spin asymmetry found in nucleon elastic scattering, which is a direct manifestation of the spin-orbit interaction. Since the spin-orbit interaction is expected to work in the surface region, it is natural to expect that such interaction could be strongly modified by the...
Observation of high 2$^{+}$ excitation energy in $^{68}$Ni (Z = 28, N = 40) had drawn a clear signature of double magic character in this nucleus [1]. And while $^{68}$Ni can be described as spherical isotope, 2$^{+}$ excitation energy of $^{66}$Fe drops significantly [2], indicating deformed shape of $^{66}$Fe. $^{67}$Co isotope is in between $^{68}$Ni and $^{66}$Fe nuclei and found to share...
The level structure of neutron rich $^{93,94,95}$Sr were studied via the \dtsr{94,95,96}, one neutron pickup reactions at TRIUMF. Excited states were populated when $^{94,95,96}$Sr beams of 5.5 AMeV bombarded a 0.5 mg/cm$^2$ CD$_2$ target. The de-exciting $\gamma$-rays and outgoing charged particles were detected by using the TIGRESS and SHARC arrays, respectively. The level scheme was...
The atomic nuclei have dual features, the single-particle shell nature and collective modes, which are competing with each other to express the actual nuclear structure. Here we demonstrate the precision analysis of this competition by focusing on the magnetic moment of an isomeric state of a neutron-rich nucleus 75Cu, where an intriguing shell evolution has been reported.
The experimental...
It is well known that N=20 shell gap disappears in the "island of inversion" and thus strong deformation appears.
The one-neutron halo nucleus 31Ne, located in the island of inversion, has attracted much attention because it is the first example of a deformation-driven halo nucleus.
Recent experimental studies on 31Ne revealed that it has low separation energy Sn=0.15(+0.16)(-0.10)MeV, and...
The study of nuclei far from stability is one of the most active and challenging areas of nuclear structure physics. One of the most exotic neutron-rich nuclei currently accessible to experiment is 40Mg [1], which lies at the intersection of the nucleon magic number N=28 and the dripline, and is expected to have a large prolate deformation similar to that observed in the neighboring lighter...
South of 48Ca in the nuclear chart, the erosion of the neutron magic number 28 and the onset of collective behavior have been observed.
Especially the ground-state deformation, the shape coexistence, and the high-K isomerism in 44S have been discussed both experimentally and theoretically.
In this region these phenomena related to the deformation of the nucleus are thought to originate from...
There is a renewed interest in single and double charge-exchange reactions due to its connection with the Fermi and Gamow-Teller transitions and double beta decay. It has given origin to different campaigns mainly at RCNP and RIKEN in Japan and at the LNS-INFN Catania in Italy. This last one is focused on the connection of double charge-exchange and the neutrinoless double-beta decay which...
Pairing correlations, influencing almost every feature of ground and low-lying states in nuclei, lie at the heart of nuclear physics. Understanding the mechanism of neutron-proton (np) pairing in N=Z nuclei has been a long-sought goal in nuclear structure since the early sixties. Despite large efforts in both theoretical and experimental studies, the fundamental nature and the interplay...
An efficient way to explore the nuclear structure is the effective use of transfer reactions. Two different physical aspects are being investigated with the use of transfer reactions on 56Ni, which is a N=Z unstable doubly magic nucleus.
(i)To probe the gap of N=28, we study the spectroscopy of the N=29 and N=27 isotones by the (d,t), (p,d) and (d,p) one nucleon transfer reactions on 56Ni...
The nucleus 8He is the most neutron-rich nucleus known. Its structure, consisting of a 4He core surrounded by four neutrons makes it an ideal case to study phenomena in highly neutron-proton asymmetric systems and neutron correlations at the nuclear surface.
The effects of the valence neutrons were investigated experimentally using proton elastic and inelastic scattering of 8He at the IRIS...
It is well known that neutron rearrangement may play an important role in nuclear reactions. The aim of this work is the investigation of the reactions with light nuclei having different external neutron shells. A series of experiments on measurement of total cross sections for reactions 4,6,8He + Si and 6,7,9,11Li + Si in the beam energy range 5–50 AMeV was performed at Flerov Laboratory of...
Guided by the formalism developed for studies of single-nucleon transfer reactions in deformed nuclei [1], we have analyzed spectroscopic factors data in the Islands of Inversion at N=8 and 20, in the rotational strong-coupling limit.
Based on the fact that intruder deformed configurations dominate the low-lying structure of nuclei within the Islands of Inversion, the Nilsson formalism...
The nuclear driplines are defined by instability with respect to particle emission, and therefore the entire spectra of the systems beyond the driplines are continuous. The first emission threshold in the light even systems is often, due to pairing interaction, the threshold for two-neutron or two-proton emission, and therefore one has to deal with three-body continuum. Such continuum provides...
The structure of neutron-deficient nuclei plays a vital role in nucleosynthesis via the rp process. Near the proton drip line, the Q values of (p,g) reactions are low and the reaction rates are dominated by single resonances and direct capture. We present here studies of 25Si and 26P produced through one-neutron knockout and charge exchange at the National Superconducting Cyclotron Laboratory...
Charge-exchange reactions at intermediate beam energies have been a powerful tool for studying spin-isospin responses of nuclei. They become even more powerful when rare isotope beams are utilized or when combined with gamma-ray spectroscopy, as they gain new spin-isospin selectivities that are not possible with conventional reaction probes, or allow for pinning down specific excitations with...
An experimentally constrained equation-of-state (EoS) of neutron-rich matter is one of the fundamental goals in nuclear physics that has not been reached yet.The asymmetry term of the EoS is usually expressed by the symmetry energy, with its parameters representing its value $J$ and slope $L$ at saturation density. To date, in particular the parameter $L$ is still poorly known. One method to...
The nuclear magic numbers, as we know in stable nuclei, consist of two different series of numbers. The first series -- 2, 8, 20 -- is attributed to the harmonic oscillator potential, while the second one -- 28, 50, 82, and 126 -- is due to the spin-orbit (SO) interactions. The spin-orbit interactions are known to be significant and responsible for the large (spin-orbit) splitting of the...
A new 11Be(d,p)12Be transfer reaction experiment was carried out in inverse kinematics at 26.9 MeV/nucleon, with special efforts devoted to the determination of the deuteron target thickness and of the required optical potentials from the present elastic scattering data. In addition, a direct measurement of the cross section for the 02+ state was realized by applying an isomer-tagging...
Nuclear structure study for exotic nuclei far away the stability is one of major topics in today’s nuclear physics research. In particular, the neutron-rich nuclei beyond 132Sn provide a pivot region to explore the exotic nuclear structure because 132Sn is doubly magic and locates far away the stability. In this region, two phenomena in nuclear structure have attracted much attention in recent...
It is now well known that the magic numbers are not universal across the nuclear landscape and that new shell closures may emerge in nuclei far from stability. In particular, a new subshell closure at N=34 has been reported in 54Ca. While the systematics of the E(2+) of the Ti isotopes does not show any evidence for the existence of the N=34 subshell closure, the significant 2+ excitation...
The dispersive optical model (DOM), originally conceived by Claude
Mahaux [1], provides a unified description of both elastic nucleon scattering and structure information related to single-particle properties below the Fermi energy [2]. Extensions of this framework have introduced a fully non-local implementation for 40-Ca [3,4]. For the first time properties below the Fermi energy like the...
A microscopic optical potential for intermediate energies is derived using ab initio translationally invariant nonlocal one-body nuclear densities computed within the no-core shell model approach utilizing two- and three-nucleon chiral interactions. The optical potential is obtained at first-order within the spectator expansion of the non-relativistic multiple scattering theory by adopting the...
The optical model potential has an aspect of useful tool to analyze the nuclear reaction data of the non-elastic scattering. Therefore, the construction of the optical model potential is developed. Nowadays, the microscopic description based on the realistic nucleon-nucleon interaction is advanced to construct the optical model potential. The microscopic optical potential is success to...
Halo nuclei exhibit an uncommon nuclear structure with a larger matter radius compared to stable nuclei [1]. This large size is qualitatively understood as due to the loose binding of one or two valence neutrons, which have then a high probability of presence at a large distance from the other nucleons. They thus form a sort of halo around the compact core of the nucleus. The best known...
In the mid-80s, the development of Radioactive-Ion Beam (RIB) has enabled the study of nuclei away from stability. Indeed, these very short-lived nuclei cannot be studied through usual spectroscopic techniques but information about their structure can be deduced from reaction measurements. To conduct a precise analysis, an accurate reaction model coupled to a realistic description of the...
Neutron-rich systems are associated with a variety of important and still open questions such as: the location of neutron drip lines, the thickness of neutron skins, and the structure of neutron stars. Common to these diverse situations is the equation of state (EoS) of neutron-rich matter, namely the energy per particle in isospin-asymmetric matter as a function of density (and other...
A POSSIBLE NUCLEAR SOLUTION TO THE 18F DEFICIENCY IN NOVAE
M. La Cognata1, R. G. Pizzone1, J. José2,3, M. Hernanz3,4, S. Cherubini1,5, M. Gulino1,6, G. G. Rapisarda1,5, and C. Spitaleri1,5
1 INFN - Laboratori Nazionali del Sud, Catania, Italy
2 Departament de Física, EEBE, Universitat Politècnica de Catalunya, E-08019 Barcelona, Spain
3 Institut d’Estudis Espacials de Catalunya,...
X-ray bursts are the most frequent stellar explosions to occur throughout the cosmos and as such, represent key research environments for the field of nuclear astrophysics. These cataclysmic binary systems are known to exhibit distinctive light curves, which have now been observed with unprecedented sensitivity, that provide a detailed reflection of the underlying nuclear physics processes...
Nucleosynthesis of the p-nuclei is one of the remaining unsolved puzzles in nuclear astrophysics. One possible mechanism for production of p-nuclei is the νp-process, which is thought to occur in the ejecta of core-collapse supernovae. A recent study found that the p-p chain breakout reaction 7Be(α,γ)11C...
Classical novae are one of the most energetic stellar events in the Universe. In this site, intense γ-rays due to the beta decay of 18F produced are emitted by the HCNO cycle. The amount of 18F is determined by two destructive channels 18F(p,α)15O and 18F(p,γ)19Ne[1]. The reaction rates of the two destructive channels affect to the novae calculation model[2,3]. For this reason, many...
I will discuss the foundation of the Trojan Horse Method (THM) within the Inclusive Non-Elastic Breakup (INEB) theory. This work demonstrates that the direct part of the INEB cross section, which is of two-step character, becomes, in the DWBA limit of the three-body theory with appropriate approximations and redefinitions, similar in structure to the one-step THM cross section. I will also...
Recently, proton-induced nucleon knockout reactions, (p,pN), have been utilized for the nucleon spectroscopy of nuclei, for unstable nuclei in the inverse kinematics in particular. In this study the benchmarking of the three reaction theories for describing the (p,pN) reaction has been done. The momentum distributions calculated with the distorted wave impulse approximation (DWIA) and the...
The structure of neutron-rich Ca isotopes have attracted interest from both experimental and theoretical side for a decade. The N=32 sub-shell gap is found to be well established from the measured 2+ energy in 52Ca[1]. Recently, with the availability of intense radioactive beam, the N=34 sub-shell closure was also found experimentally in 54Ca[2]. To quantitatively study the nature of N=34...
Despite the remarkable successes obtained by the cluster models, the physical observables that are directly related to the cluster degree of freedom is not available until very recent studies of α-transfer reactions and α-knockout reactions. We introduce the microscopic structure models into the theoretical frameworks for α-knock out reactions to probe the α-clustering in 10Be nucleus. In this...
We discuss the role of two-neutron transfer processes in the fusion reaction of the $^{9,11}$Li + $^{208}$Pb systems.
We first analyze the $^{9}$Li + $^{208}$Pb reaction by taking into account the coupling to the
$^{7}$Li + $^{210}$Pb channel. To this end, we assume that two neutrons are directly transferred to a single effective channel in $^{210}$Pb and solve the coupled-channels...
Recently, elastic scattering has been of great interest to study the information on the exotic structure and reaction mechanism of the weakly bound nuclei. In the last few years, some of the experimental and theoretical works have appeared for proton as well as neutron-rich nuclei at above and near barrier energies [1-3]. Interesting features have been discovered in the study of the elastic...
A critical problem affecting studies and uses of light weakly-bound nuclei is the suppression of above-barrier complete fusion (e.g. [1]). The cause of suppression is uncertain, particularly for exotic neutron-rich radioactive nuclei. The suppression is thought to be related to their low thresholds for breakup into charged clusters. The observation of fusion suppression in the neutron-rich...
Near-barrier collisions involving light, weakly-bound nuclei exhibit a diverse range of reaction phenomenon, including direct breakup, nucleon transfer, and fusion. The interplay of these different mechanisms is of great interest, since fusion reactions of 6,7,8Li, 9Be and 10,11B have been found to be significantly suppressed, by up to 35% [see 1 and refs. therein]. The root cause of this...
Exploring and understanding the structure of nuclei far from stability is one of the central themes of present day nuclear physics, as evidenced by this workshop. In this presentation, work investigating the structure of the most neutron-rich isotopes of carbon and nitrogen employing high-energy nucleon removal (or “knockout”) will be discussed. These nuclei are of particular interest as they...
The charge-exchange (p,n) reactions at intermediate beam energies and small angles, can selectively excite Gamow-Teller (GT) states up to high excitation energies in the final nucleus. Therefore, (p,n) reactions in inverse kinematics applying the missing mass reconstruction[1,2] provide the best and efficient tool to study the B(GT) strengths values of unstable isotopes in a wide excitation...
The evolution of shell structure toward the driplines is a subject of importance in nuclear physics. For a half decade the p-sd-shell nuclei have been a useful tool for expanding our understanding of shell evolution. 19C is one of those nuclei, well known as the s-wave halo ground state. While the low-lying excited states with 3/2+ and 5/2+ were identified by experimental studies, there exists...
In recent years, there has been rapidly increasing interest in the study of the Borromean nuclei sitting right on the top of neutron driplines and two-neutron decays of unbound systems beyond the neutron dripline. These systems demands a three-body description with proper treatment of continuum, the conventional shell-model assumptions being insufficient. Very recently a high
precision...
The sudden change of the neutron dripline from 24O (N=16) to 31F (N=22), called oxygen anomaly, is one of the exotic phenomena. Recent theoretical studies suggest importance of three nucleon forces on the binding energies of the oxygen isotopes, especially for N>16, while available experimental data are limited because the measurement requires production of extremely neutron rich nuclei.
The...
A measurement was recently performed at the National Superconducting Cyclotron Laboratory on resonant proton scattering of 46Ar in inverse kinematics in the region of isobaric analog states of 47Ar. The experiment was performed using a re-accelerated 46Ar radioactive beam at 4.6 MeV/u from the ReA3 linac after production via the projectile fragmentation of a 48Ca primary beam from the Coupled...
Production of neutron-rich nuclei through one-nucleon knockout (p,2p) reactions has been successfully demonstrated with the MINOS at RIBF. In future RIBF experiments, a method to remove more than one protons with a reasonable rate will be required for production of more neutron-rich nuclei. At present there is no consensus on what is the best reaction for two-proton removal. In this...
Charge-exchange (CE) reactions at intermediary energies serve as a direct method for the extraction of the Gamow-Teller (GT) transition strengths, which are of importance for the estimation of weak-reaction rates for a variety of astrophysical phenomena such as core-collapse supernovae (CCSN) and the crustal heating of neutron
stars. In particular, CE reactions in the $\beta^+$...
A new beam line named OEDO which can degrade the beam energy and squeeze the spatial distribution was installed at RIBF. As the first campaign of the experiments, $^{77,79}$Se(d,p)$^{X}$Se reactions were measured as a surrogate of the $^{79}$Se($n, \gamma$)$^{80}$Se* reaction for the nuclear mutation of the radioactive waste of $^{79}$Se. The $\gamma$ transition probabilities from the unbound...
Experiments employing resonance scattering reactions with radioactive beams have been performed since mid-90s, and originally they were primarily
targeting structure of light weakly bound or unbound proton rich nuclei [1]. Strong scientific potential of resonance reactions as an experimental tool
has been immediately recognized for physics of exotic proton rich nuclei. Unlike for stable...
The structure of $^9$C was studied using $^8$B+p resonance scattering with the newly commissioned Texas Active Target (TexAT) detector system. Recent theoretical developments allow for robust predictions of level structure of light nuclei, including continuum effects, starting from nucleon-nucleon and three-nucleon interactions [1, 2, 3]. High quality experimental data are necessary to...
Studies of the structure of neutron rich nuclei are important for exploring shell evolution and the development of theoretical models. While transfer reactions are currently the primary method of studying neutron rich nuclei it is suggested that study of isobaric analogue states through resonance proton scattering could be used as well [1]. We’ve performed a benchmark study of the A=9, T=3/2...
Clustering in light nuclei is a prominent feature that manifests itself through various physical observables, which serve as a guide and constraint for nuclear theory. More precise data on these observables, especially for unstable nuclei, are needed to better constrain nuclear theory and thus give us a more fundamental understanding of what causes nuclei to cluster. In order to obtain more...
Particle-hole excitations near closed shells carry information on single-particle energies and on two-body interactions. The particle-hole excitations near the doubly magic nuclei are of special interest. Information on the charge-changing particle-hole excitations (T= 5 negative parity states) in $^{48} $ Ca is not available. We performed an experiment to establish the level scheme of the...
Isospin symmetry is one of the basic concepts in nuclear physics. One of its consequences is that the level scheme of mirror nuclei, i.e. nuclei with the same number of nucleons but interchanged number of protons and neutrons should be identical. The Coulomb excitation breaks this degeneracy to some extent. It is also known that at the strong interaction level, the symmetry is also broken and...
In the last years special attention has been devoted to the study of the dipole strength at low excitation energy in neutron-rich nuclei, the so called Pygmy Dipole Resonance (PDR). This mode carries few per cent of the isovector EWSR, and it is present in many stable and unstable isotopes with a consistent neutron excess.
It is possible to study these low lying dipole states by using an...
The density dependence of the symmetry energy is one of the keys for understanding the bulk properties of neutron-rich nuclei and astrophysical events, such as supernovae and neutron stars.
Recent theoretical works show that the E1 response of nuclei is well correlated to the density dependence of the symmetry energy close to the saturation density. The dipole polarizability, the inversely...
Reactions induced by neutron halo nuclei have been intensively studied in the last years. The neutron halo structure can affect the dynamic of reactions at energies around the Coulomb barrier producing a significant reduction of the elastic scattering cross section with respect to the Rutherford prediction. This effect can be associated with couplings to breakup channels, since the continuum...
With the radioactive ion beam 17F provided by CRIB (Center for Nuclear Study Radioactive Ion Beam separator), the reactions on the proton-shell closed 58Ni target were measured at four energies around the Coulomb barrier: 46.0, 49.8, 57.9 and 65.1 MeV. A specially designed detector array, which consists of ionization chambers and silicon detectors, was used to identify the heavy and light...
One of the recently developed approaches capable of describing both bound and scattering states in light nuclei simultaneously is the No-Core Shell Model with Continuum (NCSMC). I will present recent NCSMC calculations of weakly bound states and resonances of exotic halo nuclei 6He and 11Be. I will also discuss the 11Be mirror 11N, an unbound 10C+p system, and highlight the role of chiral NN...
Understanding of the roles of three-nucleon forces (3NFs) in nuclear few- and many-body systems is one of the fundamental subjects in nuclear physics. Recently, 3NFs are constructed with chiral effective field theory in which two-, three-, and many-nucleon forces are treated consistently and systematically. The chiral 3NF effects have been analyzed in few-body systems and nuclear matter, and...
The Glauber theory is a powerful and widely used method to describe
high energy nuclear collisions. Since the complete evaluation
of the so-called Glauber amplitude is much involved,
approximate treatment has often been made.
In this contribution, we present our recent developments
of the Glauber model calculations for
nuclear inelastic processes. The Monte Carlo and the factorization...
A basic picture of nuclear excited states can be described by one-particle one-hole (1p1h) excitation. Experimental data of inelastic scatterings of nucleon-nucleus reaction are reasonably reproduced theoretically in this picture. However, it is known that higher-order configurations are important for a better understanding of the excited states. This may apply to the inelastic scattering....
Nucleon removal (p,pn) and (p,2p) reactions at intermediate energies have gained renewed attention in recent years as a tool to extract information from exotic nuclei, thanks to the availability of exotic beams with which to perform these reactions in inverse kinematics. The information obtained from these experiments is complementary to that obtained from nucleon removal experiments with...
Direct nucleon removal has become a tool of choice to study structure and reactions in exotic nuclei [1,2,3]. Despite the pervasiveness of this method, theoretical approaches to describe these reactions remain incomplete. To remedy this, part of the community has focused on experiments with pure proton targets at intermediate energies where the quasifree scattering paradigm may be invoked and...
The shell model remains one of the main building blocks of nuclear structure. Its robustness is well proven for nuclei close to stability, where it successfully explains the occurence of magic numbers. However, these magic numbers are not universal throughout the nuclear chart and their evolution away from stability, observed experimentally over the last decades, has generated much interest....
One of the major focus of modern nuclear physics is to explore which part of the nuclear interaction gives rise to significant shell modifications. Recently, the evolution of the 2s1/2+ and 1d3/2+ single-particle states in odd-A K isotopes attract particular interests. The energy gap between these two states decrease continuously when neutrons fill f7/2 orbit. Inversion of the ordering of the...
Proton inelastic scattering off a neutron halo nucleus, 11Li, has been studied in inverse kinematics at the IRIS facility at TRIUMF. The aim was to establish a soft dipole resonance and to obtain its dipole strength. Using a high quality 66 MeV 11Li beam, a strongly populated excited state in 11Li was observed at Ex=0.80 ± 0.02 MeV with a width of Γ = 1.15 ± 0.06 MeV. A DWBA (distorted-wave...
We analyzed the 11Li(p,p’) reaction at 6 MeV/nucleon by using a microscopic continuum-discretized coupled-channels method, in which 11Li is described by a 9Li + n + n three-body model. In this analysis, we found a dipole resonance of 11Li, and the resonance can be interpreted as a bound state in the 10Li + n system, that is , a Feshbach resonance in the 9Li + n + n system. For 11Li, the 10Li +...
One-nucleon removal (p,pN) reactions in inverse kinematics, performed at intermediate energies to increase the mean free path of the proton inside the nucleus, can provide quite clean spectroscopic information on exotic nuclei. The Transfer to the Continuum framework, originally developed for the case of two-body projectiles [1], has been recently extended to describe (p,pN) reactions induced...
Dineutron correlation is one of the phenomena expected to appear in neutron drip-line nuclei. It has been studied using different approaches, such as the transfer reaction and the break up reaction. However, currently available data seem to be insufficient to study the neutron-neutron correlation in terms of (i) the decomposition of high-angular-momentum components, (ii) the extraction of a...
Within the framework of the long-term program of cooperation between JINR, ENU and Institute of Nuclear Physics (INP), joint experiments connected with the peculiarities of the interaction of lithium nuclei (6-9,11Li) at energies near the Coulomb barrier will be conducted on the U-400M cyclotron of G.N. Flerov Nuclear Reaction Laboratory (FLNR JINR) and on the DC-60 accelerator (Astana) of the...
Recent results from RIKEN/RIBF on the low-lying level structure of 29F, and state of the art Shell Model calculations using the SDPF-M effective interaction [1], suggest the extension of the N=20 Island of Inversion to the Z=9 Fluorine isotopes.
In this work we discuss the low-lying excitation spectrum of 29F in terms of a collective picture [2], with a level structure corresponding to the...
Nonlocal nuclear density is derived from the no-core shell model (NCSM) one-body densities by generalizing the local density operator to a nonlocal form. The translational invariance is generated by exactly removing the spurious center of mass (COM) component from the NCSM eigenstates expanded in the harmonic oscillator (HO) basis. The ground state local and nonlocal density of...
Nuclei near the neutron and proton drip lines play a key role in our understanding of astrophysics, weak-interaction physics, and nuclear structure. Weakly-bound or proton-unbound nuclei at the rp-process waiting points, such as the unbound Tz = −1/2 nucleus 73Rb, are critical for constraining calculations and observations of type I x-ray bursts. For instance, the rp process is greatly slowed...
Alpha particle clustering is an important concept in nuclear physics, and it has been used over the years to explain certain features in nuclei, especially for the study of light N = Z nuclei. It proved to be far more difficult to study clustering phenomena in non-self-conjugate N != Z nuclei because of the addition degrees of freedom from the extra nucleons. However, the extra nucleons may...
In present paper, we explored various complexities involved in three-quasiparticle (3QP) Coriolis mixing calculations [1]. The major issues involved in these calculations are:
a)The parallel and anti-parallel coupling of projections of angular momenta of three valence particles on nuclear symmetry axis leads to four different band-heads and hence four different rotational bands for a given...
The empirical spectroscopic properties of unstable nuclei are important input to understanding nucleosynthesis in stars and their explosions, as well as constraining models of nuclear structure. In particular, the spectroscopic factor is a key ingredient in calculating direct-semi-direct neutron capture on weakly bound nuclei, as well as informing the single-particle character of excitations....
Accurate modeling of classical nova nucleosynthesis is fundamentally dependent on the thermonuclear reaction rates of the nuclei involved. In particular it has been shown that the $^{30}$P(p,$\gamma$)$^{31}$S reaction rate is the largest source of uncertainty in the final abundance of nuclei created in a classical nova, involving an ONe white dwarf. The calculation of the...
Jinping Underground lab for Nuclear Astrophysics (JUNA) is designed to directly measure the cross-sections of crucial reactions during the evolution of hydrostatic stars. The extremely low cross-sections of radiative capture reactions within their relevant Gamow peaks require a gamma detector with high detection efficiency. For this reason, we have constructed a 4π BGO array detector composed...
The so-called alpha cluster structure appears in the excited states of light nuclear system, and the structures have been extensively investigated in the N=Z systems. Furthermore, the alpha cluster structures are also discussed in neutron-excess (N>Z) systems extensively.
In the present report, we focus on the mirror systems, which are obtained by replacing neutrons to protons in...
Recent years have seen many important experimental studies for the linear-chain states (linearly aligned 3α particles) in 14C and 16C.
These new data motivated us to perform an analysis and to summarize the calculated and observed properties of the linear-chain bands in carbone isotopes.
In this presentation, the linear-chain states of 14C and 16C and their decay modes are theoretically...
For the experiments of unstable nuclei, the cocktail RI beams produced by the fragmentation of HI beams are often used. It is necessary to identify the RI beam event by event RIBF can provide the high intense RI beam, but we cannot fully utilize it due to the radiation damages of the existing detectors for the particle identification. To get enough data efficiently in a limited time, we need...
The study of exotic nuclei has become a central focus of nuclear structure research. The advent of intense secondary beams has allowed for the production and detailed study of the most extreme nuclear systems. The discovery of halo nuclei and the coupling of these weakly bound systems to the continuum have brought renewed interest in the modelling of nuclear reactions. Reaction studies of...
During the collision of heavy ions, their associated shell structure gets significantly modified, leaving corresponding impact on the dynamics of decaying clusters/fragments. Clustering of nucleons play a significant role in the decay analysis of excited compound systems formed via heavy ion reactions. For an overall understanding of the nuclear dynamics, a collective clusterization model is...
The beta-delayed gamma-ray spectroscopy of 123,125Pd are investigated at the Radioactive Isotope Beam Factory of the RIKEN Nishina Center. Neutron-rich nuclei 123,125Pd are produced by in-flight fission of the 238U beam at 345 MeV/nucleon. The 1/2− low-lying beta-emitting isomers in 123,125Ag and gamma transitions feeding into the isomers are constructed for the first time and the results are...
Proton-rich nuclei have received less attention from both theory and experiments when compared to neutron-rich nuclei since proton-halo structure is relatively less pronounced as compared to those of neutron-halos [1,2]. The proton-halo configuration for 8B has already been established by the strong dynamic effects observed in elastic, breakup and fusion measurements [3,4,5]. However, the...
The proton dripline nucleus 9C, with a small two-proton separation energy of 1.43 MeV, can be considered as a two-proton halo candidate. Special attention has been recently devoted to the experimental and theoretical studies of the exotic nature of 9C [1-4]. Elastic scattering angular distributions of proton drip-line isotones 9C impinging on lead target have been measured for the first time...
The spin–independent part of Preston’s equations [1] of alpha-decay radioactivity is used to calculate nuclear radius parameter (r0) of various even–even alpha emitters. In this approach, the r0 parameter is determined by defining the calculated transition probability for an alpha transition from parent's ground state to daughter’s ground state (0+ to 0+) to be equal to the experimental...
In light nuclear systems, it is well known that cluster structures appear in excited states. One of characteristic properties in the cluster structures is a prominent extension of the nuclear radius. Typical examples are the Hoyle 02+ state and its rotational excited state, 22+, in 12C, which are considered to have the developed 3alpha cluster structure. The matter radii of these 3alpha states...
Deuteron-induced one-neutron transfer reactions have been used to extract single-particle properties of nuclei, and the adiabatic (AD) approximation is often used to simply treat the deuteron breakup states.
We examine the validity of the AD approximation for describing the breakup process in the (d,p) reaction systematically.
We calculate the (d,p) cross sections with the...
A single-nucleon transfer reaction is a powerful experimental tool to probe the energies of shell-model orbitals and to study the changes in the energies of these orbitals away from the stable nuclei. In this light, 21F (d,p) 22F and 12B(d,3He)11Be measurements were carried out at the Argonne National Laboratory ATLAS In-Flight Facility. The HELIcal Orbit Spectrometer (HELIOS) was used to...
The total charge-changing reaction cross-sections and the partial cross-sections of projectile fragments(PFs) production for the fragmentation of 12C on C, Al, Cu, Pb and CH2 targets at the highest energy of 400 A MeV are investigated. It is found that the total charge-changing cross-sections and the partial cross-sections of PFs production for the fragmentation are independent of the beam...
It is known that neutron magic number N=20 disappears in the region of Z=10~12. Study of nuclei in this region, called "island of inversion" is important for understanding the evolution of shell structure in neutron-rich region. Neutron-rich F and Ne isotopes are located at the south boundary of the island of inversion. Due to the difficulty in production of these extremely neutron-rich...
The observation of a large permanent electric dipole moment (EDM) would represent a clear signal of CP violation from new physics outside the Standard Model. The 199Hg isotope currently provides the most stringent limit on an atomic EDM, which is converted to a limit on the nuclear EDM via a calculation of the Schiff moment, requiring knowledge of the nuclear structure of 199Hg. Ideal...
The alpha clustering has been one of the main interest in nuclear physics. In order to probe the alpha clustering through reaction observables, the proton-induced alpha knockout reaction, (p,p alpha), is considered in this study. The purpose of this work is to reveal how the alpha cluster amplitude is probed through the (p,p alpha) reactions.
Within the distorted wave impulse approximation...
In this contribution, we will show that isoscalar monopole and dipole transitions are a good probe for cluster states in 24Mg. The cluster states having significant influence on He- and Carbon-burning processes such as 12C+12C and 4He+20Ne are expected in 24Mg according to Ikeda diagram. However, their existences are still ambiguous due to experimental and theoretical difficulties. In this...
I will discuss the Maris polarization effect and its application in quasi-free reactions to assess information on the structure of exotic nuclei. The uncertainties in the calculations of triple differential cross sections and of analyzing powers due the choices of various nucleon-nucleon interactions the optical potentials and limitations of the method are the main focus. Theoretical...
We investigated the effects of three-nucleon force (3NF) from chiral effective field theory on nucleon-nucleus (NA) and nucleus-nucleus (AA) elastic scattering by using g-matrix folding model. To clarify the 3NF effects accurately, we constructed new g-matrix, so called chiral g matrix, from chiral two-nucleon force and 3NF by using Bruckner-Hartree-Fock method and localized the g matrix in...
Nucleon-nucleus (NA) optical potentials are microscopically generated from a fully self-consistent framework of the particle-vibration coupling (PVC), in which the nucleon-nucleon (NN) effective interaction of the Skyrme type is consistently used to describe the Hartree-Fock (HF) mean-field, the small amplitude collective motions of the target, and the particle-collective states coupling. For...
Recently, study on unstable nuclei near the neutron dripline has been attracted by the development of radioactive ion-beam experiments. The optical potential between a projectile and a target is a basic ingredient to describe the elastic scattering. In the neutron-rich region, it is difficult to determine the phenomenological optical potential due to restrictions on experimental data....
Achieving efficient radioactive waste management is only possible in the presence of international cooperation, based on the principles established by the Joint Convention on the Safety of Spent Fuel Management and on the Safe Management of Radioactive Waste and the security recommendations of the International Agency's for Atomic Energy (IAAE) on the safe management of spent fuel and...
We investigated neutron-proton pairing correlations effects on the shell evolution of ground state energies by the deformation for $N = Z$ nuclei in $sd, pf, dg$-shell. We started from a simple shell-filling model constructed by a deformed Woods-Saxon potential with $\beta_2$ deformation, and included pairing correlations in the residual interaction, which give rise to smearing of the Fermi...
Deep-inelastic processes between complex nuclei were first observed in the 1960s, and in the 1970s the importance of such reaction mechanism was recognized and theoretical concepts were developed. Characteristic features of deep-inelastic collisions include: formation of a dinuclear system which rotates almost rigidly, nucleons exchange governed by N/Z equilibrium, evaporation of nucleons...
Giant resonances provide us important information on nuclear collective properties. For the nuclear density functional theory (DFT), the giant resonance will determine the coupling constants that are not very well constrained from the ground-state properties. In order to assess the giant resonances in a wide region of the nuclear chart, an efficient technique to compute the giant-resonance...
We present recent results of the the neutrino-process in the supernova explosion. In particular, we discuss the neutrino-nucleus reactions by the QRPA formalism. Sensitivity of the reaction on the nucleosynthesis is studied in detail. Also the MSW effects of the neutrino propagation are to be presented for discussions. Finally, other exotic effets on the neutrino propagation, like the neutrino...
The structure of proton-rich Carbon isotopes has been investigated using one-neutron knockout reactions on a ^9Be-target at 1670\,AMeV. The knockout cross section and corresponding momentum distribution of the residue have been measured for the reactions ^9Be(^{12}C,^{11}C)X, ^9Be(^{11}C,^{10}C)X and ^9Be(^{10}C,^{9}C)X. The experimental cross sections were compared to theoretical predictions...
Since the optical model was first applied to describe nuclear scattering and absorptions of neutron on a variety of target nuclei, it has been extensively utilized with great success for the last seven decades and is now considered as one of the most fundamental reaction models in nuclear physics. In general, optical model potentials (OMPs) are extracted by fitting the angular distribution of...
The review presents the latest experimental data on the total reaction cross sections and angular distributions of differential cross sections for elastic scattering of light weakly bound lithium nuclei 6–9,11Li [1].
A review of papers on the interaction of weakly bound (cluster and exotic) 6-9Li and 11Li nuclei published so far and their analysis shows that there are no experimental data on...
Deuteron is the only binding system which consists of two nucleons (a proton and a neutron) in free space.
Recently, theoretical calculation with density functional theory (DFT) suggests that the "deuteron-like" pn pair exists in nuclei.
We propose the (p,pd) reaction to probe the pn pair, and discuss how the (p,pd) cross section reflects the pn pair inside the target nucleus.
We calculate...
Nuclear reaction in extreme condition is one of the attractive topics from the point of view of not only the nuclear structure and reaction but also the nucleosynthesis. Although the electron capture rate in supernova explosion is estimated from the charge exchange reaction with the ground state, the charge exchange reaction with the high-excitation energy state may provide the rate in the...
Nuclear transmutation of long-lived fission products (LLFPs), which are produced in nuclear reactors, is one of the candidate techniques for the reduction and/or reuse of LLFPs. To design optimum pathways of the transmutation process, several nuclear reactions have been studied by using LLFPs as secondary beams. In this study, we report on the proton- and deuteron-induced reactions on 107Pd...
Single-particle structure and nucleon-nucleon correlations are a few topics of the R3B (Reactions with Relativistic Radioactive Beams) research program to be carried out at FAIR. CALIFA (CALorimeter for In-Flight detection of gamma rays and high-energy charged pArticles) is one of the detector systems of R3B. Components of the CALIFA Barrel are currently being assembled and tested. At the...
During the past two decades, chiral effective field theory has evolved into a powerful tool to derive nuclear two- and many-body forces in a systematic and model-independent way. Nowadays, most ab initio calculations of nuclear structure and reactions (including, in particular, exotic nuclei) are conducted with chiral forces. Therefore, it is of interest to have an overview of the status in...
Effects of pairing correlation on s-wave scattering in superfluid nuclei are discussed. In the s-wave, single-particle potential resonance cannot be formed due to no potential barrier, whereas quasi-particle resonance can be formed by the pairing correlation. The quasi-particle resonance is a novel resonance in superfluid nuclei which is predicted by the Hartree-Fock-Bogoliubov (HFB)...
Nuclei in the N=20 island of inversion, located around the neutron-rich 32Mg isotope, have ground-states dominated by deformed and collective configurations arising from neutron-pair excitations across the shell gap (See Ref. [1] for a recent review). Particle-hole sd-pf cross-shell intruder configurations have also been observed in the low-lying level scheme of heavier N = 20 even-even...
Some nuclei in the transitional region exhibit shape coexistence and shape fluctuations (for example $\gamma$-soft) in low-lying energy spectra. To treat such shape fluctuations, quadrupole collective Hamiltonian approach based on energy density functionals (EDF) has often been employed [1]. However, in that approach, the collective inertial functions in the Hamiltonian is derived by the...
Excited states in 63;65;67Mn were studied via in-beam gamma-ray spectroscopy following the knockout reaction from 68Fe. Similar level schemes, consisting of the 11/2-, 9/2-, 7/2- and 5/2- g.s. level sequence, connected by I → I − 1 transitions, were established, the first time for 65;67Mn. Their level structures show features consistent with strongly-coupled rotational bands with K = 5/2....
Neutron-rich Al isotopes (Z=13) lie at the transition point between the classical shell gap N=20 and the Island of Inversion (IoI). Extended spectroscopy of the isotopes 32-35Al was performed at NSCL. Each isotope has been produced via several reaction mechanisms (proton and neutron knockout, fragmentation, charge changing, inelastic scattering) which are sensitive either to the proton or...
68Ni and neighbor nuclei have been extensively studied since, in the nuclear shell-model, a sizeable effect was expected for the addition of the f7/2 proton shell closure Z=28 and the νf5/2 neutron subshell closure N=40. While the energy of the first 2+ state for Ni isotopes reaches a maximum for 68Ni, the evolution of the two neutron separation energy S2n is not significant of a major shell...
The Beijing Radioactive Ion-beam Facility (BRIF) is a large-scale scientific infrastructure, which was commissioned as the national first RIB facility based on the Isotope Separator On Line (ISOL) technique in October, 2016. BRIF is comprised of a high-intensity proton cyclotron, thick-target and ion source system, isotope separator on line and the HI-13 tandem as the post accelerator. The...
The explicit consideration of core degrees of freedom is crucial
in order to obtain an accurate description of the structure and
reactions of light exotic nuclei. In particular, it is important
to consider the role of ground state correlations, respecting
the Pauli principle, and including at the same time the continuum in the calculations (1).
This is possible in the framework of...
As part of the first phase program of experiments utilizing the
SAMURAI spectrometer and NEBULA neutron array, we have undertaken
invariant mass spectroscopy of 18,19,20,21B using the complementary
probes of neutron and proton knockout. After a brief introduction to
the experimental setup and analysis techniques, the results for 18,19B
are discussed where, in addition to substantially...
The strength function Sβ(Е) governs [1,2] the nuclear energy distribution of elementary charge-exchange excitations and their combinations like proton particle (πp)–neutron hole (νh) coupled into a momentum Iπ : [πp νh]Iπ and neutron particle (νp)–proton hole (πh) coupled into a momentum Iπ : [νp πh)]Iπ. The strength function of Fermi-type β-transitions takes into account excitations [πp...
In core He burning and C-shell burning of massive stars, the 22Ne(α,n)25Mg reaction is considered to be a dominant neutron source for the weak s process. The reaction also largely contributes to the neutron production for the main s process in asymptotic giant branch (AGB) stars. While a variety of experimental attempts to determine the rate for this reaction at the Gamow window corresponding...
N. Burtebayev1, Maulen Nassurlla1,2, Zh.K. Kerimkulov1, D.T. Burtebayeva1, E.S. Mukhamedzhanov1, Marzhan Nassurlla1,2, T. Suzuki3, S.B. Sakuta4
1 Institute of Nuclear Physics, Almaty, Kazakhstan
2 Al-Farabi Kazakh National University, Almaty, Kazakhstan
3 Saitama University, Saitama, Japan
4 National Research Center “Kurchatov Institute”, Moscow, Russia
New data of the differential...
It is well established that clustering is an essential aspect of nuclear many-body system. In neutron-rich domains, the valence neutrons in nuclei can exist in molecular orbitals, their role is similar to that of electrons in covalent bonds in atomic molecules, which help to stabilize the unstable multi-cluster states. The AMD plus GCM calculation found that the valence neutrons give richer...
The angular distribution of 12C + 12C scattering at an incident energy of 100A MeV has been measured. The elastic and inelastic scatterings in 12C to the excitation energies of up to ∼15 MeV were measured simultaneously for the first time with the high-resolution Grand Raiden spectrometer at the Research Center for Nuclear Physics (RCNP). The angular distributions of the elastic scattering to...
OEDO (Optimized Energy Degrading Optics for RI beam) is the renovation project of the SHARAQ beamline at RIBF-RIKEN to accommodate a RI beam of with a few tens of MeV/u by energy degrading method. The highly exotic beams with such an energy, which still have been uncharted territory for the existing RI beam facilities, are expected to be achievable by the OEDO beamline. The beamline was...
The magic number 28 appears in the $pf$ shell because of the spin-orbit interaction. However, in some $N \approx 28$ neutron-rich nuclei, the neutron magic number 28 disappears. This leads to the quadrupole deformation of the ground state, the reduction of the excited energies and so on. In what region of the nuclear chart, does the magic number disappear? This is one of the interesting...
Heavy-ion charge exchange reactions at intermediate energies have drawn much attention because they have great advantages for determination of spin-isospin strength with better resolution and selectivity than that with nucleon probes such as (p,n) reaction. Such reactions could be used to extract values of GT strengh which is important for electron capture and beta-decay rates, and electron...
The future ARIEL facility, under development at TIRUMF, Vancouver, BC, will produce radioactive ion beams from photofission with unprecedented purities and intensities in the mass A=100 region. The first stage of ARIEL is the $4.24M CANadian Rare Isotope Facility with Electron Beam Ion Source (CANREB), which will go online in 2019.
Within an international collaboration of the University of...
Transfer reactions are powerful tools to study the structure of atomic nuclei. The recently commissioned OEDO beamline of CNS and RIKEN can provide beams with the necessary intensities at low energies (10-20 MeV/u) offering experimental access to regions of the nuclear chart which were hitherto not accessible for transfer studies.
To utilize OEDO for transfer reactions, a detector array...
Nuclear symmetry energy, temperature and density at the time of the intermediate mass fragment formation are determined using two novel methods, i.e., a self-consistent method and a chemical potential method.
(1) In a self-consistent manner, the yields of primary hot fragments are experimentally reconstructed for multifragmentation events in the reaction system ^64Zn + ^112Sn at 40...
The couplings between single-particle/hole degrees of freedom and collective and non-collective excitations are of primary importance in nuclear physics, as they are responsible for many phenomena observed in atomic nuclei, from the damping of giant resonances, to the quenching of spectroscopic factors and the anharmonicity of vibrational spectra [1].
While such properties have been...
