Narrow Results

Nuclear masses are calculated using the modified Bethe–Weizsäcker mass formula in which the isotonic shifts have been incorporated. The results are compared with the improved liquid drop model with isotonic shift. Mass excesses predicted by this method compares well with the microscopic–macroscopic model while being much more simple. The neutron and proton drip lines have been predicted using this modified Bethe–Weizsäcker mass formula with isotonic shifts.

K⁻pn and K⁻pp bound states are searched for at SPring-8/LEPS in the d(γ, K⁺) and d(γ, K⁺π⁻) reactions with photon energies from 1.5 to 2.4 GeV. The data was collected during the 2002-2003 run period utilizing liquid hydrogen and liquid deuterium targets. Using the K⁺ and K⁺π⁻ missing mass spectra from the deuteron, we hope to determine upper limits for K⁻pn and K⁻pp bound state production.

We suggest that the three-body force due to the Delta-hole excitation plays a crucial role in determining the neutron drip line of oxygen isotopes. This is one of the consequences of the repulsive effective T=1 force produced by the Delta-hole excitation on the shell evolution. The same mechanism makes effective T=1 interaction more repulsive in general.

After a brief discussion of effective field theory applied to nuclear clusters, I present the aspect of Coulomb interactions, with applications to low-energy alpha-alpha and nucleon-alpha scattering.

In a decade-and-a-half old experiment, Raabe et al. [Nature 431, 823 (2004)], had studied fusion of an incoming beam of halo nucleus ⁶He with the target nucleus ${}^{238}U$. We extract a new interpretation of the experiment, different from the one that has been inferred so far. We show that their experiment is actually able to discriminate between the structures of the target nucleus (behaving as standard nucleus with density distribution described with canonical RMS radius $r=r_0{A}^{\frac{1}{3}}$ with $r_0=1.2$ fm), and the “core” of the halo nucleus, which surprisingly, does not follow the standard density distribution with the above RMS radius. In fact, the core has the structure of a tennis-ball (bubble)-like nucleus, with a “hole” at the center of the density distribution. This novel interpretation of the fusion experiment provides an unambiguous support to an almost two decades old model [A. Abbas, Mod. Phys. Lett. A16, 755 (2001)], of the halo nuclei. This Quantum Chromodynamics based model succeeds in identifying all known halo nuclei and makes clear-cut and unique predictions for new and heavier halo nuclei. This model supports the existence of tennis-ball (bubble)-like core, of even the giant-neutron halo nuclei. This should prove beneficial to the experimentalists, to go forward more confidently, in their study of exotic nuclei.

This study investigates the production of charged particles and the kaonic nuclei $K^{-}pp$ and $K^{+}\bar{p}\bar{p}$ in $\mathrm{\text{Au}}+\mathrm{\text{Au}}$ collisions at $\sqrt{s}=130$ GeV. The parton and hadron cascade model PACIAE 2.1 is used to calculate the yield of charged particles, and the Dynamically Constrained Phase–space Coalescence (DCPC) model is used to calculate the yield of kaonic nuclei. Results showed that the yield of charged particles was consistent with experimental data from the STAR detector at Brookhaven National Laboratory (United States). The data also revealed that the simulated yield of $K^{-}pp$ was greater than the yield of $K^{+}\bar{p}\bar{p}$. The kaonic nuclei $K^{-}pp$ and $K^{+}\bar{p}\bar{p}$ are probably formed by $K^{+}$(or $K^{-}$) directly trapping two protons (or antiprotons).

Charge form factors corresponding to proton density distributions in exotic nuclei, such as ^6,8He, ¹¹Li, ^17,19B and ¹⁴Be are calculated and compared. The results can be used as tests of various theoretical models for the exotic nuclei structure in possible future experiments using a colliding electron-exotic nucleus storage ring. The result of such a comparison would show the effect of the neutron halo or skin on the proton distributions in exotic nuclei.

Proton and neutron separation energies are calculated using the extended Bethe–Weizsäcker mass formula. This modified Bethe–Weizsäcker mass formula describes minutely the positions of all the old and the new magic numbers. It accounts for the disappearance of some traditional magic numbers for neutrons and provides extra stability for some new neutron numbers. The neutron and proton drip lines are predicted using this extended Bethe–Weizsäcker mass formula. The implications of the proton drip line on the astrophysical rp-process and of the neutron drip line on the astrophysical r-process are discussed.

The experimental search for the formation of the lithium isotope ¹⁰Li was carried out in the inclusive ¹¹B(π^-, p)X and correlation ¹²C(π^-, pp)X, ¹⁴C(π^-, pt)X, ¹⁴C(π^-, dd)X measurements in the stopped π^--meson absorption reactions. Excited states of ¹⁰Li with the resonance energy E_r = 6.1 ± 0.1 MeV, 7.9 ± 0.2 MeV and 10.1 ± 0.1 MeV were observed for the first time.

The structure of exotic nuclei sheds new light on the linkage of the nuclear structure to the nucleonic interaction. The self-consistent mean-field (SCMF) theories are useful to investigate this linkage, which are applicable to many nuclei covering almost the whole range of the nuclear chart without artificial truncation of model space. For this purpose, it is desired to develop effective interaction for the SCMF calculations well connected to the bare nucleonic interaction. Focusing on ground-state properties, I show the results of SCMF calculations primarily with the Michigan-three-range-Yukawa (M3Y)-type semi-realistic interaction, M3Y-P6 and M3Y-P6a to be precise, and discuss in detail how the nucleonic interaction affects the structure of nuclei including those far off the $\beta$-stability. The central channels of the effective interaction are examined by the properties of the infinite nuclear matter up to the spin dependence and the isospin dependence. While experimental information of the infinite matter is obtained by extrapolating systematic data on finite nuclei in principle, it is not easy to constrain the spin dependence and the isospin dependence without connection to the bare nucleonic interaction. The noncentral channels play important roles in the shell structure of the finite nuclei. The tensor force is demonstrated to affect $Z$- or $N$-dependence of the shell structure and the magic numbers, on which the spin–isospin channel in the central force often acts cooperatively. By using the M3Y-P6 interaction, the prediction of magic numbers is given in a wide range of the nuclear chart, which is consistent with almost all the available data. In relation to the erosion of magic numbers in unstable nuclei, effects of the tensor force on the nuclear deformation are also argued, being opposite between nuclei at the $\ell s$- and the $jj$-closed magicities. Qualitatively consistent with the $3N$-force effect on the $\ell s$-splitting suggested from the chiral effective field theory, the density-dependent LS channel, which is newly introduced in M3Y-P6a, reproduces the observed kinks in the differential charge radii at the $jj$-closed magic numbers and predicts anti-kinks at the $\ell s$-closed magic numbers. The pairing correlation has significant effects on the halos near the neutron drip line. A new mechanism called “unpaired-particle haloing” is disclosed.

The proton emission in neutron deficient nuclei with $Z=53\text{–}83$ has been investigated within the framework of axially deformed relativistic mean field (RMF) theory using NL3 and density-dependent DD-ME1 and DD-ME2 parameters. The quasi-bound states from which the proton emission is probable are determined. The RMF densities are folded with the M3Y effective nucleon–nucleon interaction to obtain the nuclear potential. The total interaction potential consisting of nuclear, Coulomb and centrifugal potentials is used to calculate the proton decay half-lives using the Wentzel–Kramers–Brillouin (WKB) approximation. For this, we have used the $Q\text{-value}=-{𝜖}_p$, ${𝜖}_p$ being the single-particle energy of the decaying proton near the Fermi surface. The calculated proton decay half-lives for different nuclei are in consonance with experimental data.

High intensity accelerators for nuclear and hadronic physics are reviewed. The frontier of nuclear and hadronic physics with these accelerators is discussed with its perspectives. J-PARC is a world-leading accelerator of this kind and has just started its operation. As a good example, J-PARC and its physics program are reviewed.

The first results of the geometry GEANT3 simulation of the three-arm magnetic spectrometer SCAN3 are presented in this article. The possibility of detection of exotic nuclei (such as eta-mesic nucleus) with help of the SCAN3 and the Nuclotron internal target is shown.

Differential cross sections of elastic scattering of ^12,14Be on ¹²C and protons have analyzed within the microscopic model of the optical potential (OP). The microscopic OP consists of the double folding real part and the imaginary part which is constructed using the high-energy approximation theory. The OP depends on the nuclear density distributions of ^12,14Be and thus, their microscopic models have tested in our study.

The isobaric-analog resonances for nuclei around the neutron shell closures at N=20, 50, 82 are treated in the fully self-consistent Density Functional plus Continuum Quasiparticle Random Phase Approximation (DF+CQRPA). The aim is to check how the self-consistency is preserved in the calculations for long isotopic chains. The beta-decay half-lives and delayed multi-neutron emission branching are calculated for the reference Ni isotopic chain. The relative contributions of the GT and first-forbidden transitions are compared with that of the relativistic QRPA and Finite Amplitude Method. The accuracy of the global beta decay calculations performed within FRDM+RPA, DF+CQRPA and RHB+QRPA models are analysed.

Cluster and crystallization forms of nuclei are considered in their manifestation at half-lives and on the parameters of quadrupole nuclear deformation, between which an anticorrelation for elongated spheroids and a correlation for oblate spheroids was found in isotopic chains.

Commissioning of the new fragment separator ACCULINNA-2 at FLNR JINR is accomplished. The separator is destined to expand the possibilities in studies of dripline nuclei performed with the exotic secondary radioactive ion beams (RIBs) at energies of 5 – 50 AMeV. The projected high transmission and purification level were confirmed experimentally for a number of RIBs in last two years. The ACCULINNA-2 setup will become a backbone facility at FLNR for the research in the field of light exotic nuclei. This report shows the current status of the separator, describes the obtained RIB’s parameters and first experiments as well, provides the overview of the developing detection, monitoring and control subsystems.

In this talk, I will overview recent studies on the evolution of the shell structure in stable and exotic nuclei, and will show results of related shell-model calculations. This shell evolution is primarily due to the tensor force. The robust mechanism and some examples will be presented. Such examples include the disappearance of existing magic numbers and the appearance of new ones. The nuclear magic numbers have been believed, since Mayer and Jensen, to be constants as 2, 8, 20, 28, 50, … This turned out to be changed, once we entered the regime of exotic nuclei. This shell evolution develops at many places on the nuclear chart in various forms. For instance, the Island of Inversion picture has been changed considerably.

The structures, the electromagnetic transitions, and the beta decay strengths of exotic nuclei are investigated within an extended cluster model. We start by deriving an effective nuclear Hamiltonian within the S₂ correlation operator. Tensor forces are introduced in a perturbative expansion which includes up to the second order terms. Within this Hamiltonian we calculate the distributions and the radii of A = 3, 4 nuclei. For exotic nuclei characterized by n valence protons/neutrons we excite the structure of the closed shell nuclei via mixed modes formed by considering correlations operators of higher order. Good results have been obtained for the calculated transitions and for the beta decay transition probabilities.

Low-energy quadrupole excitations are analyzed in nuclear Fermi systems. The crust of neutron stars provides a unique framework for studying the evolution of low-lying modes from neutron-rich nuclei to a pure neutron gas. We modelize the crust with Wigner-Seitz cells and focus our attention on the Zr and Sn cells with baryon densities equal to 0.02 fm^-3 and 0.04 fm^-3, respectively. It is shown that the excitations with low multipolarities are concentrated almost entirely in one strongly collective mode which exhausts a very large fraction of the energy-weighted sum rule. Since these collective modes are located at very low energies compared to the giant resonances in standard nuclei, they may affect significantly the specific heat of baryonic inner crust matter of neutron stars.