The study of neutron-rich nuclei near132 Sn is interesting and important for both nuclear structure and nuclear astrophysics. For a considerably large model space allowing cross-shell excitations,a new effective Hamiltonian is determined by employing the extended pairing-plus-quadrupole model with monopole corrections. Calculations for two mass regions, for the north-east quadrant of132 Sn with Z > 50 and N > 82 and for the south-west quadrant with Z < 50 and N < 82, have been performed recently. The structure of these nuclei is analyzed in detail, and the role of the monopole corrections can be clearly seen.
A novel method of initiating nuclear fusion reactions in a full plasma environment was suggested, and a proof-of-concept experiment was carried out with the D t D ! n t3 He reaction. In this new approach, two plasma jets generated by high-intensity lasers collide headon-head. The center-of-mass energy of the nuclei increases accordingly, and therefore, reaction products can be significantly enhanced, especially in the sub-Coulomb barrier ranges. As a result of the fusion reaction, up to 7:6 105 neutrons had been observed. This new type of ‘‘plasma collider'' could provide an innovative tool to study nuclear reactions under astrophysical conditions.
Band structure of the Z=104 nucleus256Rf has been a recent research focus in nuclear physics.We performed projected shell model calculations for this and some other neighboring Rf isotopes.Specifically,we studied rotational properties of these nuclei and showed that variations in dynamic moment of inertia were sensitive to single-particle structures,which may be useful information for locating the anticipated island of stability.Electromagnetic transition properties were also calculated,and measurable quantities were predicted for further experimental test.
Zhiyi ZhouYanxin LiuYingchun YangFangqi ChenYang Sun
The N≈Z nuclei in the mass A^80 region has been researched because of an abundance of nuclear structure phenomena.The projected shell model(PSM)was adopted to investigate the structure of high spin state in proton-rich 74,76,78Kr isotopes including yrast spectra,moment of inertia,electric quadrupole transitions and the behavior of single particle.The calculated results are in good agreement with available data and the shape coexistence in low-spin is also discussed.
Deformed odd-mass nuclei are ideal examples where the interplay between single-particle and collective degrees of freedom can be studied. Inspired by the recent experimental high-spin data in the odd-proton nuclide 171 Tm, we perform projected shell model(PSM) calculations to investigate structure of the ground band and other bands based on isomeric states. In addi- tion to the usual quadrupole-quadrupole force in the Hamiltonian, we employ the hexadecapole-hexadecapole(HH) interac- tion, in a self-consistent way with the hexadecapole deformation of the deformed basis. It is found that the known experi- mental data can be well described by the PSM calculation. The effect of the HH force on the quasiparticle isomeric states is discussed.
Nuclear reactions in stars occur between nuclei in the high-energy tail of the energy distribution and are sensitive to possible deviations from the standard equilibrium thermal-energy distribution,the well-known MaxwellBoltzmann Distribution(MBD).Strong constraints on such deviations were made previously with the detailed helioseismic information of the solar structure.With a small deviation parameterized with a factor exp[ δ(E/kT)2],it was shown δ restricted between 0.005 and +0.002.These constraints have been carefully re-examined in the present work.We find that a normalization factor was missed in the previous modified MBD.In this work,the normalization factor c is calculated as a function of δ.It shows the factor c is almost unity within the range 0<δ 0.002,which supports the previous conclusion.However,it demonstrates that δ cannot take a negative value from the normalization point of view.As a result,a stronger constraint on δ is defined as 0 δ 0.002.The astrophysical implication on the solar neutrino fluxes is simply discussed based on a positive δ value of 0.003.The reduction of the7Be and8B neutrino fluxes expected from the modified MBD can possibly shed alternative light on the solar neutrino problem.In addition,the resonant reaction rates for the14N(p,γ)15O reaction are calculated with a standard MBD and a modified MBD,respectively.It shows that the rates are quite sensitive even to a very small δ.This work demonstrates the importance and necessity of experimental verification or testing of the well-known MBD at high temperatures.
Inspired by the recent experimental identification of the new isomer with a half-life of(620±150) ns in the very neutron-rich nucleus 108 Zr, we apply the projected shell model with axially-deformed bases to discuss possible shapes near the ground state and the nature of the isomer. The structure of the new isomer is investigated by restricting the calculation to prolate and oblate shapes. It is shown that the isomer can be understood as a K-isomer. Meanwhile, the calculation predicts more low-lying high-K configurations, which may be confirmed by future experiments.
