Triaxial shape in 129Ce

The high spin states of ¹²⁹Ce have been populated via heavy-ion fusion evaporation reaction ⁹⁶Mo (³⁷Cl, 1p3n) ¹²⁹Ce. The comparison between the signature- and B(M1)-staggering defined by Hagemann and Hamamoto have been showed in the negative-parity band of ¹²⁹Ce. The lifetimes and quadrupole moments Q_t of the high spin states of ¹²⁹Ce have been extracted from the line shape analyses using Doppler shift attenuation method (DSAM). The deformation parameters extracted through the solution of equations for quadrupole transition moments Q_t and collective moments of inertia J_RR.     

Study of Multi-Quasiparticle Excited States in 139Ce

High-spin states in ¹³⁹Ce have been populated using the ¹³⁰Te(¹²C,3n) reaction at beam energy of 50MeV. The level scheme of ¹³⁹Ce has been revised and extended greatly up to E=5765.0keV. The level structure of ¹³⁹Ce shows typical characteristics of spherical nucleus, and the high-spin states were formed by the excitations of valence nucleons. Energies of the yrast and near yrast high-spin states in ¹³⁹Ce have been calculated by the empirical shell model, and the multi-quasiparticle nature of high-spin excited states has been discussed.     

Signature splitting in 129Ce

The high spin states of 129Ce have been populated via heavy-ion fusion evaporation reaction 96Mo (37C1, 1p3n) 129Ce. The γ-γ coincidence and intensity balance used to measure the B(M1; I→I-1)/B(E2; I→I-2) (the probability ratio of the dipole and quadrupole transition) in v7/2[523] rotational band of 129Ce. And the energy splitting (Δe') has been got through the experimental Routhians. The lifetimes and quadrupole moments Qt have been extracted from the lineshape analyses using DSAM. The deformation of the v7/2[523] rotational band of 129Ce was extracted from the Qt and moment of inertia JRR.     

Collective Band Structures in Neutron-Rich Odd-A 145,147Ce Nuclei

Through study of the prompt r-rays emitted in the spontaneous fission of ²⁵²Cf, high spin states of neutron-rich odd-A ^145,147Ce nuclei have been investigated. The levels in ¹⁴⁷Ce have been extended. A collective band in ¹⁴⁵Ce have been identified for the first time. The results from the particle rotor model calculations indicate that the yrast bands in ¹⁴⁵Ce and ¹⁴⁷Ce originate from vi_13/2 orbital coupling and the ground states of ¹⁴⁵Ce and ¹⁴⁷Ce originate from (vh_9/2,vf_7/2) and vh_9/2 configiration, respectively. No obvious octupole deformation was observed in these two isotopes, but a side band obtained in ¹⁴⁷Ce may show some octupole correlations.     

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°.     

High Spin States and Shape Coexistence in 134Ce

high spin states in ¹³⁴Ce nucleus have been studied by using the heavy–ion induced reaction ¹²²Sn(¹⁶O,4n) carried out at china institute of atomic energy. the early level scheme has been extended with spin up to 22. however,our result is different from that in a recent publication,and the magnetic rotation bands reported there have not been confirmed. our observed level structures may be interpreted as shape coexistence. the 10+ state at the backbending with h_11/2 quasineutron configuration has an oblate deformation with an asymmetry parameter γ≈–60°(lund convention),and the 10+ isomer is a yrast trap of prolate deformation with γ≈–120°,whereas the other signature partner bands with h_11/2 and g_7/2 proton configuration probably have a prolate deformation with γ≈0°.     

Band Structures of the Nucleus 129Cs

High-spin states in ^129Cs are populated via the ^122Sn （^11B, 4n） reaction at beam energies of 55 and 60MeV. Two additional bands are placed in the level scheme and the previously known bands are extended to higher spins. The results are compared to the cranked shell model calculations and to the systematics of the adjacent Cs isotpoes. One of the new bands is interpreted as the 7-vibrational band built on the πh11/2 orbital. The possible configuration for another new band is discussed. Upbend caused by （Vh11/2）^2 alignment is observed both in the favored and unfavored sequences of the πh11/2 configuration. The band based on the πgτ/2 configuration at low spins forks around spin 17//2, and the two different S-bands are attributed to （Vh11/2）^2 and （πh11/2）^2 rotational alignments, respectively.     

New Nuclide 129Pm Near the Proton Drip Line

The very neutron-deficient nuclide ¹²⁹Pm was produced via the ⁹²Mo(⁴⁰Ca, p2n) reaction and identified for the first time by using the X-γ coincidence in combination with a He-jet tape transport system. From the decay of a 99keV γ ray which corresponds to the 5/2^－→1/2^－ transition in the daughter nucleus ¹²⁹Nd following the (EC+β⁺) decay of ¹²⁹Pm, the half-life of ¹²⁹Pm was determined to be 2.4(6)s.     

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.     

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.     

Optical Potential Parameters for Halo Nucleus System ^6He＋^12C from Transfer Reaction ^11B（^7Li, ^6He）^12C

The optical potential parameters for the halo nucleus system ^6He＋^12C are extracted from fits to the measured angular distributions of ^11B（^7Li, ^6He）12C reaction at energies of 18.3 and 28.3MeV with distorted-wave Born approximation analysis. The characters of the obtained optical potentiM parameters are basically consistent with the results extracted from the fits to the elastic-scattering angular distributions in the literature.     

Identification of a New Band and Its Signature Inversion in ^174Re

High spin states in ^174Re are investigated via the ^152Sm（^27 AL,5nγ）^174Re reaction and γ - γ coincidence relationships are analysed carefully. A new band is identified due to its spectroscopic connection with the known π1/2^-[541] × ν1/2^-[521] band. This band is proposed to be the ground-state band built on the π1/2^-[541]× ,ν5/2^-[512] configuration in view of the low-lying intrinsic states in the neighbouring odd-mass nuclei. It is of particular interesting that the new band exhibits a phenomenon of low-spin signature inversion, providing a new situation for theoretical investigations.     

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.     

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.     

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.     

ON THE TRANSFER MECHANISM OF 16O+24Mg AND 20Ne+24Mg ELASTIC SCATTERING

The mechanism of transfering a cluster of nucleons between two colliding nuclei is considered to explain the backward angle oscillatory rise in the differential cross section of the elastic scattering between certain nuclei, such as ¹⁶O+²⁴Mg or ²⁰Ne+²⁴Mg. The nuclear molecular orbit approximation theory is applied. For one-step transfer, if the parameter involved is assumed to be adjustable, the numerical calculations can be made to fit the experimental results naturally.     

MEASUREMENT OF COMPLETE FUSION CROSS SECTION OF 12C+159Tb,12C+165Ho

Complete fusion cross sections have been measured for ¹²C+¹⁵⁹Tb and ¹²C+¹⁶⁵Ho reactions by using K-X rays of evaporation residues with Si(Li)spectrometer.The half-lives of evaporation residues and its yield distributions as a function of incident energy have also been obtained.The experimental values for the complete fusion cross section were compared with the theoretical ones.     

Further Studies on Halo Nuclei 11Li,14Be and 17B

Based on the three-body model with Yukawa interactions,the halo nuclei ¹¹Li,¹⁴Be and ¹⁷B are further studied by the variation calculation.An analytical expression for the density distribution of the halo neutron is given.The theoretical resultsagree with the recent experimental data.     

SINGLE PROTON TRANSFER REACTION INDUCED BY HEAVY ION 40Ar(11B, 10Be)41K

The angular distribution has been measured for elastic scattering on ⁴⁰Ar with ¹¹B and for the single proton transfer reaction ⁴⁰Ar(¹¹B, ¹⁰Be)⁴¹K at the incident beam energy of 50 MeV. The elastic scattering cross section has been fitted in terms of the optical model. The EFR-DWBA aproach with recoil effect has been used to analyze the differential cross section. The spectroscopic factor was extracted.     

THE MEASUREMENT OF COMPLETE FUSION CROSS-SECTIONS FOR THE REACTIONS 12C+27Al, 12C+209Bi AND 14N+Pb

Mica track detectors were used for the measurement of evaporation residues and fission fragments of compound nuclei formed in ¹²C+²⁷Al, ¹²C+²⁰⁹Bi and ¹⁴N+Pb reactions. The complete fusion cross-sections and excitation functions were then obtained. By using the sharp cut-off model approximation, the values of the critical angular momenta were extracted from the complete fusion cross-sections. The results obtained were compared with the calculations based on current theories for critical angular momentum; they were found to agree within experimental uncertainties.