Electromagnetic transition properties and isospin excitation in the cross-conjugate nuclei 44Ti and 52Fe

The interacting boson model with isospin (IBM-3) is applied to study the band structure and electromagnetic transition properties of the low-lying states in the cross-conjugate nuclei 44Ti and S2Fe. The isospin excitation states with T=0, 1 and 2 are identified and compared with available data. The E2 and M1 matrix elements for the low-lying states have been investigated. According to this study, the 2+3 state is the lowest mixed symmetry state in the cross-conjugate nuclei 44Ti and 52Fe. The excitation energy of the second 0+2 and 2+2 states with T=0 in the nucleus 52Fe are identified. The agreement between the model calculations and data is reasonably good.     

Shell-model studies of isomeric states in 51,52,53Fe

The yrast bands of ^51,52,53Fe have been studied with a microscopical effective Hamiltonian derived from the charge-dependent Bonn NN potential. Calculations obtain satisfactory agreements with experimental data, reproducing the observed isomeric states. The possible origins of the isomers are discussed.     

Radial Expansion Flow in Reactions of 40Ca+58Fe and 40Ca+58Ni

By means of using an isospin-dependent Boltzmann-Langevin equation which includes isospin-dependent symmetry energy, Coulomb energy, isospin-dependent nucleon-nucleon cross sections, Pauli blocking, and initialization, the radial expansion flow of reaction systems ⁴⁰Ca+⁵⁸Ni and ⁴⁰Ca+⁵⁸Fe at 53, 100, 150, and 200 MeV/u in the central collisions were studied. It has shown that the more neutron rich system exhibits smaller radial expansion flow. It was found that the neutron rich system had smaller threshold energy which may provide a new method to determine the isospin dependent nuclear equation of state from calculated result and linear fitting result.     

Mixed symmetry states and isospin excitation in the N=Z nucleus 28Si

The interacting boson model with isospin (IBM-3) has been used to study the isospin excitation states and mixed symmetry states at low spin for ²⁸Si. The theoretical calculations are in agreement with experimental data. The theoretical results show that the 8⁺₁ energy is 14.73 MeV.     

Pair neutrino energy loss for nuclei 56Fe at the late stages of stellar evolution

Based on the Weinberg-Salam theory, the pair neutrino energy loss rates for nuclei ⁵⁶Fe are canvassed for the wide range of density and temperature. The results of ours (Q_LJ) are compared with those of Beaudet G, Petrosian V and Salpeter E. E's (Q_BPS), and it shows that the pair neutrino energy loss rates of Q_BPS are always larger than Q_LJ .The Q_BPS is 12.57%, 12.86%, 14.99%, 19.80% times higher than Q_LJ corresponding to the temperature T₉=0.385, 1.0, 5.0, 10, respectively.     

Angular Momentum Projected Deformed HF Spectra of 46Ti and 48Cr With MSDI

Taking the modified surface delta interaction (MSDI) and using a spherical shell model basis set, we carry out the deformed Hartree-Fock (HF) calculation for the even-even nuclei ⁴⁶Ti and ⁴⁸Cr in the fp shell, and construct the deformed HF intrinsic states which are the Slater determinants from the HF single-particle states.The angular momentum projection program is then carried out and the reasonable results are obtained.     

Neutrino Energy Loss by Electron Capture on Nucleus ^56Mn, ^56Fe, ^56Co and ^56Ni in Strong Electron Screening

Based on the p-f shell model, the neutrino energy loss rates for nucleus ^56Mn, ^56Fe, ^56Co and ^56Ni in the electron capture process are canvassed in and not in a strong electron screening. The results show that the neutrino energy loss rates for ^56Mn, ^56Fe, ^56Co and ^56Ni decrease about 15%, 10%, 60% and i order of magnitude correspondingly at the temperature T9 = 15 and even debase 2 orders of magnitude at the temperature T9 = 1.     

Stady on the Energy Spectra of fp Odd A Nuclei 47Ti,47V,49Cr With PDHF Method

The approximate angular momentum projected Hartree-Fock(PDHF)method is used to some odd-A nuclei in the fp shell:⁴⁷Ti,⁴⁷V,⁴⁷Cr,⁴⁹Cr.Their energy spectra are calculated and compared with the experimental data.The results are fairly satisfactory.In addition,the characteristics of those spectra are analyzed with the particle-rotor model.It is found that those spectra possess the properties of the no alignment limit Spectra.     

Electron capture of nuclides 52,53,54, 55, 56Fe in magnetars

Based on the theory of relativity in superstrong magnetic fields (SMFs), we have carried out an estimation on electron capture (EC) rates of nuclides ^{52,53,54,55,56}Fe in the SMFs in magnetars. The rates of change of electronic fraction (RCEF) in the EC process are also discussed. The results show that the EC rates increase greatly and even exceeds by 4 orders of magnitude (e.g. ⁵⁴Fe, ⁵⁵Fe and ⁵⁶Fe) in SMF. On the contrary, the RCEF decreases largely and even exceeds by 5 orders of magnitude in the SMF.     

Magnetic moment measurements of mirror nuclei 12B and 12N

The spin polarized β-emitting mirror nuclei ¹²B(I^π=1⁺,T_1/2=20.18 ms) and ¹²N(I^π=1⁺,T_1/2=11 ms) are produced by the low nuclear reactions ¹¹B(d, p) ¹²B and ¹⁰B(³He,n) ¹²N and by selecting the projectile energy and the recoil angle. Their magnetic moments are measured by the β-NMR technique. The magnetic moments obtained after Knight shift correction are μ(¹²B)=1.001(17) μ_N and μ(¹²N)=0.4571(1) μ_N. The calculation using the existing shell model could not reproduce the measured magnetic moments for ¹²B and ¹²N simultaneously.     

Electromagnetic Transition Rates and Deformation Feature in 130Ce

Lifetimes of the excited states in light rare-earth nucleus ¹³⁰Ce have been measured using heavy ion reaction ¹¹⁶Sn(¹⁶O,2n)¹³⁰Ce at beam energy of 73MeV through analyzing the Doppler-broadened line shapes. The reduced transition probabilities B(E2) are extracted from these measurements. The experimental results show that the previously reported anomalously high B(E2) value has not been observed in the present work. The transition quadrupole moment for the yrast band varies with spin and corresponds to a triaxial deformation with γ≈7°.     

质子与~(52)Cr反应数据理论计算与分析

在质子与48Ti,51V和52Cr反应的去弹截面、弹性散射角分布实验数据的基础上,获得了一组入射质子能量在150 MeV以下的质子与52Cr反应的光学势参数。应用光学模型、扭曲波玻恩近似理论、核内级联模型、蒸发模型、带宽度涨落修正的Hauser-Feshbach理论以及激子模型(含改进的Iwamoto–Harada模型)计算得到了质子与52Cr反应的所有截面、角分布、能谱和双微分截面。对理论计算结果与实验数据以及TENDL中的数据进行了比较分析,结果显示,理论计算结果与实验数据符合较好,且反应道截面优于TENDL的结果。     

Electromagnetic excitation and fragmentation of ultrarelativistic nuclei

Electromagnetic interactions of high-energy nuclei in ultraperipheral collisions are considered. Such collisions, which take place without any overlap of nuclear densities, can be considered as irradiation of nuclei by intense photon beams with a broad energy spectrum. This leads to several unusual phenomena, such as mutual electromagnetic excitation of nuclei, including exotic double and triple excitations of giant resonances, and multifragmentation of nuclei. The RELDIS model is presented, which describes fragmentation of nuclei and meson production by equivalent photons. It is shown that the RHIC and LHC colliders provide unique opportunities to study electromagnetic interactions of ultrarelativistic nuclei. The cross sections calculated by the RELDIS model are used in the method of monitoring the LHC luminosity on the basis of neutron emission rates, as well as to simulate interactions of beam nuclei with LHC construction elements.     

Rotational properties in even-even superheavy 254-258Rf nuclei based on total-Routhian-surface calculations

High-spin yrast structures of even-even superheavy nuclei ^254-258Rf are investigated by means of total-Routhian-surface approach in three-dimensional (β₂, γ, β₄) space. The behavior in the moments of inertia of ²⁵⁶Rf is well reproduced by our calculations, which is attributed to the j_15/2 neutron rotation-alignment. The competition between the rotationally aligned i_13/2 proton and j_15/2 neutron may occur to a large extent in ²⁵⁶Rf. High-spin predictions are also made for its neighboring isotopes ^254,258Rf, showing that the alignment of the j_15/2 neutron pair is more favored than that of the i_13/2 proton pair.     

Langevin study of neutron emission in the reactions 16O+181Ta and 19F+178Hf

The pre-scission neutrons measured in the reactions ¹⁶O+¹⁸¹Ta and ¹⁹F+¹⁷⁸Hf are studied via a Langevin equation coupled with a statistical decay model. We find that because of the mass asymmetry of different entrance channels, the spin distributions of compound nuclei would be different, consequently, the measured neutrons in these two reactions would also different. This means that the entrance channel will affect the particle emission in the fission process of hot nuclei.     

Angular Distribution of the 12C(6He, 7Li)11B Reaction

Angular distribution of the ¹²C(⁶He,⁷Li)¹¹B transfer reaction is measured with a secondary ⁶He beam of 36.4MeV for the first time. The experimental angular distribution is well reproduced by the distorted-wave Born approximation (DWBA) calculation. The success of the present experiment shows that it is feasible to measure one-nucleon transfer reaction on a light nucleus target with the secondary beam facility of the HI-13 tandem accelerator at China Institute of Atomic Energy (CIAE), Beijing.     

Examining the Chiral Geometry in l04Rh and l06Rh

The criteria for chiral doublet bands based on one particle and one hole coupled to a triaxial rotor have been summarized. Two representative cases in A - 100 odd-odd nuclei, nearly degenerate △I = 1 doublet bands in 104Rh and 106Rh, are checked against these chiral criteria. It is shown that 106Rh possesses better chiral geometry than 104Rh, although the energy near degeneracy is achieved in 104Rh in comparison with the constant energy separation of doublet bands in 106Rh.     

A Three-Body Model of 11Li,14Be and 17B

The nuclei ¹¹Li,¹⁴Be and ¹⁷B are considered as three-body systems composed of the N=2Z core and two outside neutrons.The core-neutron and neutronneutron interactions are assumed to be the attractive exponential potentials.It has been shown that the three-body system can have a bound state although any two constituents of the system cannot have a bound state. The experimental data of the binding energy and extraordinarily large matter root-mean-square radius can be explained in the frame of the three-body model.     

Temporal variation of fundamental constants in 229Th transition

If is there enhanced sensitivity to variations of fine structure constant, nucleon mass and meson masses in the transition between the low energy and long-lived nuclear isomer and ground states? To answer this open problem, we investigate the transition between the long-lived 7.6±0.5 eV isomer and ground states in ²²⁹Th based on the formulae derived from both the Nilsson model and Feynman-Hellmann theorem. Consistent conclusions are drawn by these two method. The sensitivity to relative variation of fine structure constant could be enhanced by 3—4 orders of magnitude, and to variations of nucleon mass and meson masses are enhanced by about 5—6 orders of magnitude in the ²²⁹Th transition.     

Research on High Spin States in 68Ge,65Ga and 67Ga

The high spin states in ⁶⁸Ge,⁶⁵Ga and ⁶⁷Ga were studied through in-beam gamma-ray spectroscopy experiment.The reaction ⁴⁶Ti(²⁵Mg,xpxn) was used with beam energy 68MeV.In ⁶⁸Ge the new multiplicity of band structures,the crossing transitions among the bands and a new band with possible big diformation were observed.The experiment results agree with a new microscopic model calculation (EXCITED FED VAMPIR).In ⁶⁵Ga and ⁶⁷Ga a few band structures with strong collectivity were observed and the new level schemes were given.