2009 Vol. 33, No. S1


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Triaxial rotation in atomic nuclei
CHEN Yong-Shou, GAO Zao-Chun
2009, 33(S1): 1-4. doi: 10.1088/1674-1137/33/S1/001
The Projected Shell Model has been developed to include the spontaneously broken axial symmetry so that the rapidly rotating triaxial nuclei can be described microscopically. The theory provides an useful tool to gain an insight into how a triaxial nucleus rotates, a fundamental question in nuclear structure. We shall address some current interests that are strongly associated with the triaxial rotation. A feasible method to explore the problem has been suggested.
Research on some superheavy nuclei
DONG Tie-Kuang, REN Zhong-Zhou, XU Chang
2009, 33(S1): 5-8. doi: 10.1088/1674-1137/33/S1/002
Studies on some superheavy nuclei are performed. The α decay energies are calculated by an improved local binding energy formula, and the α decay half-lives are calculated by the Viola-Seaborg formula. Good agreements between theoretical and experimental results are reached.
Shape transitions in proton-rich Ho and Tm isotopes
ZHU Jian-Yu, QI Chong, LIU Meng-Xi, CUI Xiao, XU Fu-Rong
2009, 33(S1): 9-11. doi: 10.1088/1674-1137/33/S1/003
Total Routhian Surface (TRS) calculations have been performed for even-even nuclei along proton drip line to study nuclear ground-state deformations, as well as the odd proton nuclei Ho and Tm isotopes. The drip line nuclei show the expected shape transition with the shell effects. Ground-state shape changes from prolate to oblate at 143Ho and 145Tm in these two isotopes, which is due to the γ instability around N=76.
Renormalizability and nonrenormalizable interactions
YAO Hai-Bo, WU Shi-Shu
2009, 33(S1): 12-14. doi: 10.1088/1674-1137/33/S1/004
Arguments are provided which show that extension of renormalizability in quantum field theory is possible. By an appropriate choice of effective Lagrangian, a dressed Feynman propagator is obtained. In this scheme, higher order Feynman diagrams become self-convergent and nonrenormalizable interactions become renormalizable. As an example, the vacuum fluctuation effects on ρ meson mass for the vector-tensor coupling model is discussed. It is found that the result can agree with the experimental value when coupling constant is adjusted.
Shears mechanism in two-dimensional cranking relativistic mean field approach
PENG Jing, XING Li-Feng, MENG Jie
2009, 33(S1): 15-17. doi: 10.1088/1674-1137/33/S1/005
Using the new two-dimensional cranking relativistic mean field (RMF) approach, the shears mechanism of magnetic rotation based on configuration πh211/2⊙νh-211/2 in 142Gd is microscopically and self-consistently examined by investigating the aligning angular momenta of the valence nucleons.
Contributions of qqqq q components to nucleon spin structure
WAN Meng, TIAN Wei-Zhao, CHEN Hong
2009, 33(S1): 18-20. doi: 10.1088/1674-1137/33/S1/006
The spin structure of nucleons is presented in the framework of an extended quark model which in addition to the conventional qqq structure also takes into account qqqq q admixtures in the nucleon wave functions, where the qqqq q components are in colored quark cluster configurations. The axial vector weak coupling constant and spin distributions for polarized nucleons as well as spin content are obtained for the lowest positive parity qqqq q configurations in flavor-spin dependent interaction. In particular, the contributions of the down and strange quarks to the proton spin and the sum rule for polarized neutron are negative, in agreement with recent experiments.
Restoration of rotational symmetry in deformed relativistic mean-field theory
YAO Jiang-Ming, MENG Jie, Pena Arteaga, Ring Peter
2009, 33(S1): 21-23. doi: 10.1088/1674-1137/33/S1/007
We report on a very recently developed three-dimensional angular momentum projected relativistic mean-field theory with point-coupling interaction (3DAMP+RMF-PC). Using this approach the same effective nucleon-nucleon interaction is adopted to describe both the single-particle and collective motions in nuclei. Collective states with good quantum angular momentum are built projecting out the intrinsic deformed mean-field states. Results for 24Mg are shown as an illustrative application.
Level statistics for the even-even Yb isotopes
CHEN Fang-Qi, SUN Yang, ZHOU Xian-Rong
2009, 33(S1): 24-26. doi: 10.1088/1674-1137/33/S1/008
The level statistics of the even-even Yb isotopes are studied by using the energy levels calculated by the projected shell model. The spectrum of intrinsic states and band energies are also studied to discuss the generation of chaoticity. The energy dependence of the chaoticity is investigated, and a chaos to order transition is found.
Low-lying spectra and E2 transition rates in 160-170Er isotopes in the interaction boson model
ZANG Jin-Fu, LÜ Li-Jun
2009, 33(S1): 27-29. doi: 10.1088/1674-1137/33/S1/009
Spectra and E2 transition rates for the 160-170Er isotopes are studied in the framework of the interaction boson model. A schematic Hamiltonian able to describe their spectra and B(E2) transition is used. It is found that the 160-170Er isotopes are in the transition from the vibrational limit to rotational limit.
Study on the formation of the composite system of 238U+238U
WU Xi-Zhen, TIAN Jun-Long, ZHAO Kai, ZHANG Ying-Xun, LI Zhu-Xia
2009, 33(S1): 30-32. doi: 10.1088/1674-1137/33/S1/010
Strongly damped reactions of 238U+238U, at Ecm= 680—1880 MeV have been studied based on the improved quantum molecular dynamics model. We find that at a certain energy region the entrance channel potential is weakly repulsive and the dissipation is very strong after touching configuration, these two effects make the time delay of re-separation for colliding system. The single particle potential well of the transiently formed composite system has Coulomb barrier about 15—20 MeV high at the surface, which makes the excited unbound protons being still embedded in the potential well and moving in a common mono-single particle potential for a period of time and thus restrains from quick decay of the composite system.
Superfluid nuclear matter in BCS theory and beyond
CAO Li-Gang
2009, 33(S1): 33-36. doi: 10.1088/1674-1137/33/S1/011
Medium polarization effects are studied for 1S0 pairing in nuclear matter within BHF approach. The screening potential is calculated in the RPA limit, suitably renormalized to cure the low density mechanical instability of nuclear matter. The self-energy corrections are consistently included resulting in a strong
depletion of the Fermi surface. The self-energy effects always lead to a quenching of the gap, whereas it is almost completely compensated by the anti-screening effect in nuclear matter.
πg9/2⊙νh11/2 doublet bands in A~100 mass region
WANG Shou-Yu, ZHANG Shuang-Quan, QI Bin, MENG Jie
2009, 33(S1): 37-39. doi: 10.1088/1674-1137/33/S1/012
Using the model with one particle and one hole coupled with a triaxial rotor, the πg-19/2⊙νh11/2 doublet bands in the A~100 mass region are studied, and compared with the πh11/2⊙νh-111/2 doublet bands. It is found that the calculated results for the configuration of πg-19/2⊙νh11/2 are very similar the results for a pure h11/2 proton particle and a neutron quasiparticle with λn5. After including the pair correlation, the model describes the candidate chiral doublet bands in 106Rh successfully, which supports the interpretation of chirality geometry.
Isospin structure in 68Ge
BAI Hong-Bo, DONG Hong-Fei, ZHANG Jin-Fu, LÜ Li-Jun, CAO Wan-Cang, LI Xiao-Wei, WANg Yin
2009, 33(S1): 40-42. doi: 10.1088/1674-1137/33/S1/013
The interacting boson model-3(IBM-3) has been used to study the low-energy level structure and electromagnetic transitions of 68Ge nucleus. The main components of the wave function for some states are also analyzed respectively. The theoretical calculations are in agreement with experimental data, and the 68Ge is in transition from U(5) to SU(3).
Chiral doublet bands and energy-level crossing
QI Bin, MENG Jie, ZHANG Shuang-Quan, WANG Shou-Yu, PENG Jing
2009, 33(S1): 43-45. doi: 10.1088/1674-1137/33/S1/014
Different definitions for chiral doublet bands based on excitation energies, B(E2) and B(M1) respectively are discussed in the triaxial particle rotor model. For the ideal chiral geometry, the selection rules of the electromagnetic transitions in different band definitions are illustrated. It is also shown that the energy-level crossings between chiral doublet bands may occur.
Mixed symmetry states and isospin excitation in the N=Z nucleus 28Si
Khudair Falih, ZHANG Jin-Fu, BAI Hong-Bo
2009, 33(S1): 46-48. doi: 10.1088/1674-1137/33/S1/015
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.
Density effect of the neutron halo nucleus induced reactions in intermediate energy heavy ion collisions
CAO Xi-Guang, CHEN Jin-Gen, MA Yu-Gang, FANG De-Qing, TIAN Wen-Dong, YAN Ting-Zhi, CAI Xiang-Zhou
2009, 33(S1): 49-51. doi: 10.1088/1674-1137/33/S1/016
Using an isospin-dependent quantum molecular dynamics (IQMD) model, we study the 15C induced reactions from 30—120 MeV/nucleon systematically. Here the valence neutron of 15C is assigned at both 1d 5/2 and 2s 1/2 states respectively in order to study the density effect of reaction mechanism. It is believed that the existent neutron halo structure at the 2s 1/2 state of 15C will affect the light particle emission evidently. In our calculation, the different density distributions of 15C at two states are calculated by relativistic mean field (RMF) model and introduced in the initiation of IQMD model, respectively. It is found that some observables such as emission fragmentation multiplicity, emission neutron/proton ratio and emission neutrons' kinetic energy spectrum are sensitive to the initial density distribution.
Dependence of multiplicity and transverse energy distributions on nuclear geometry at RHIC
FENG Sheng-Qin, DU Xiao-Chao
2009, 33(S1): 52-54. doi: 10.1088/1674-1137/33/S1/017
We study the dependence of multiplicity and transverse energy on nuclear geometry at RHIC at √sNN=19.6, 130, and 200 GeV basing on ellipsoidal decay model. It is found that the ellipsoidal decay model can describe the data well.
Shell-model studies of the N=14 and 16 shell closures in neutron-rich nuclei
YUAN Cen-Xi, QI Chong, XU Fu-Rong
2009, 33(S1): 55-57. doi: 10.1088/1674-1137/33/S1/018
Shell-model studies on the N=14 and 16 shell closures in neutron-rich Be, C, O and Ne isotopes are presented. We calculate, with the WBT interaction, the excited states in these nuclei. The calculations agree with recent experiment data. Excited energies and B(E2) values are displayed to discuss the shell closures. Our results support the N=16 shell closure in these isotopes, while indicating a disappearance of N=14 shell closure in Be and C isotopes.
Description of all observed rotational bands in 128Pr
DONG Bao-Guo, GUO Hong-Chao, MA Hai-Liang, YAN Yu-Liang
2009, 33(S1): 58-60. doi: 10.1088/1674-1137/33/S1/019
The configuration-dependent cranked Nilsson-Strutinsky approach was used to investigate the rotational structures in 128Pr and signature splittings of some observed bands could be well described quantitatively at high spin. Its modified model was used to calculate special configurations in order to distinguish the N=4 d3/2s1/2 and g7/2d5/2 orbitals. All observed bands were compared with the calculated configuration assigned to the band and the agreement between experiment and theory is remarkable.
Deconfinement phase transition in neutron star matter
LI Ang, PENG Guang-Xiong, Lombardo U
2009, 33(S1): 61-63. doi: 10.1088/1674-1137/33/S1/020
The transition from hadron phase to strange quark phase in dense matter is investigated. Instead of using the conventional bag model in quark sect, we achieve the confinement by a density-dependent quark mass derived from in-medium chiral condensates, with a thermodynamic problem improved. In nuclear slot, we adopt the equation of state from Brueckner-Bethe-Goldstone approach with three-body force. It is found that the mixed phase can occur, for reasonable confinement parameter, near the normal saturation density, and transit to pure quark matter at 4—5 times the saturation, which is quite different from the previous results from other quark models that pure quark phase can not appear at neutron-star densities.
Towards Lambda-nucleon coupling constants in relativistic mean field theory
YAO Jiang-Ming
2009, 33(S1): 64-66. doi: 10.1088/1674-1137/33/S1/021
New parameter sets for Λ-nucleon coupling in relativistic mean field theory are proposed based on nucleon-nucleon effective interaction PK1. Hypernuclear properties are described well through a systematical study. Effects of hyperon tensor coupling term on spin-orbit splitting are also investigated self-consistently.
Spectroscopy and reduced transition probabilities of negative parity bands up to band termination in 45Ti
MA Hai-Liang, YAN Yu-Liang, ZHANG Xi-Zhen, ZHOU Dong-Mei, DONG Bao-Guo
2009, 33(S1): 67-69. doi: 10.1088/1674-1137/33/S1/022
The negative parity high spin states in 45Ti have been investigated with the interacting shell model including the full fp shell and the configuration dependent cranked Nilsson-Strutinsky approach. Generally, the shell model has successfully reproduced the energy levels of negative parity bands, especially has a good description of the signature inversion at 17/2. The reduced electric quadrupole transition probabilities of high spin states are calculated by the two models and compared with the experimental results. Reasonable agreement between theories and experiment are obtained, while the shell model can give more fine structures. The large differences of elctromagnetic moments between the shell model calculation and observation call for more elaborate effective interaction and more active shells.
Thermal protoneutron stars with hyperons
YU Zi, LIU Guang-Zhou, ZHU Ming-Feng, DING Wen-Bo, ZHAO En-Guang
2009, 33(S1): 70-72. doi: 10.1088/1674-1137/33/S1/023
The properties of thermal protoneutron star matter including hyperons are investigated in the framework of the relativistic mean field theory (RMFT). In protoneuron star matter, with the increase of the temperature, the critical densities of hyperons decrease, the sequence for appearances of hyperons change, the abundances of hyperons as well as neutrinos increase, and the strong interactions between baryons get weaker. Meanwhile, the abundances of isospin multiple states for nucleons, Σ, and Ξ become identical, leading to isospin saturated symmetric matter, respectively. Moreover, if a protoneutron star is born with higher temperature, it is less likely to convert to a black hole.
Neutron star equation of state in density dependent relativistic Hartree-Fock theory
SUN Bao-Yuan, MENG Jie
2009, 33(S1): 73-75. doi: 10.1088/1674-1137/33/S1/024
The equation of state of neutron stars is studied in the newly developed density dependent relativistic Hartree-Fock (DDRHF) theory with the effective interaction PKO1 and applied to describe the properties of neutron stars. The results are compared with the recent observational data of compact stars and those calculated with the relativistic mean field (RMF) effective interactions. The maximum mass of neutron stars calculated with PKO1 is about 2.45 M, which consists with high pulsar mass from PSR B1516+02B recently reported. The influence of Fock terms on the cooling of neutron stars is discussed as well.
Deeply bound kaonic states in nuclei
LI Yi-He, WU Shi-Shu
2009, 33(S1): 76-78. doi: 10.1088/1674-1137/33/S1/025
Using a new phenomenological KN interaction which reproduces Λ(1405) as an I=0 bound state of KN, we have investigated K3 He(T=0) and K4 He(T=1/2) within the framework of the Brueckner-Hartree-Fock(BHF) theory. Our calculations show that the above kaonic nuclear systems are both deeply bound. The binding energy BK- is 124.4 MeV(94.1 MeV) and the width Γ is 11.8 MeV(25.8 MeV) for K3He(T=0) (K4He(T=1/2)).
Calculation of astrophysical reaction rate of 82Ge(n,γ)83Ge
WANG Mian, CHEN Yong-Shou, LI Zhi-Hong, LIU Wei-Ping, SHU Neng-Chuan
2009, 33(S1): 79-81. doi: 10.1088/1674-1137/33/S1/026
The neutron capture reaction on a neutron-rich near closed-shell nucleus 82Ge may play an important role in the r-process following the fallout from nuclear statistical equilibrium in core-collapse supernovae. By carrying out a DWBA analysis for the experimental angular distribution of 82Ge(d, p)83Ge reaction we obtain the single particle spectroscopic factors, S2,5/2 and S0,1/2 for the ground and first excited states of 83Ge=82Ge⊙n, respectively. And then these spectroscopic factors are used to calculate the direct capture cross sections for the 82Ge(n, γ)83Ge reaction at energies of astrophysical interest. The optical potential for neutron scattering on unstable nucleus 82Ge is not known experimentally. We employed a real folding potential which was calculated by using the proper 82Ge density distribution and an effective nucleon-nucleon force DDM3Y. The neutron capture reactions on neutron-rich closed-shell nuclei are expected to be dominated by the direct capture to bound states. We will show that the direct capture rates on these nuclei are sensitive to the structure of the low-lying states.
Properties of deformed Λ hypernuclei
ZHOU Xian-Rong
2009, 33(S1): 82-85. doi: 10.1088/1674-1137/33/S1/027
The properties of Be and B isotopes and the corresponding Λ hypernuclei are studied by using a deformed Skyrme Hartree-Fock approach with realistic nucleonic Skyrme forces, pairing correlations, and a microscopically determined lambda-nucleon interaction based on Brueckner-Hartree-Fock calculations of
hypernuclear matter. The results suggest that the core nuclei and the corresponding hypernuclei have similar deformations with the same sign.
Production mechanism of superheavy nuclei in massive fusion reactions
FENG Zhao-Qing, JIN Gen-Ming, LI Jun-Qing, Werner Scheid
2009, 33(S1): 86-88. doi: 10.1088/1674-1137/33/S1/028
Within the concept of the dinuclear system (DNS), a dynamical model is proposed for describing the formation of superheavy nuclei in complete fusion reactions by incorporating the coupling of the relative motion to the nucleon transfer process. The capture of two heavy colliding nuclei, the formation of the compound nucleus and the de-excitation process are calculated by using an empirical coupled channel model, solving a set of microscopically derived master equations numerically and applying statistical theory, respectively. Fusion-fission reactions and evaporation residue excitation functions of synthesizing superheavy nuclei (SHN) are investigated systematically and compared them with available experimental data. The possible factors that affecting the production cross sections of SHN are discussed in this workshop.
Impact parameter and beam energy dependence for azimuthal asymmetry of direct photons and free protons in intermediate energy heavy-ion collisions
LIU Gui-Hua, MA Yu-Gang, CAI Xiang-Zhou, FANG De-Qing, SHEN Wen-Qing, TIAN Wen-Dong, WANG Kun
2009, 33(S1): 89-91. doi: 10.1088/1674-1137/33/S1/029
Hard photon emitted from energetic heavy ion collisions is of very interesting since it does not experience the late-stage nuclear interaction, therefore it is useful to explore the early-stage information of matter phase. In this work, we have calculated the impact parameter and beam energy dependence for azimuthal asymmetry, characterized by directed transverse flow parameter F and elliptic asymmetry coefficient v2, of direct photons and the corresponding free protons in intermediate energy heavy-ion collisions. It is further shown the anti-correlated azimuthal asymmetry between direct photons and free protons.
Doubly magic properties in superheavy nuclei
HUANG Ya-Wei, ZHU Jian-Yu
2009, 33(S1): 92-94. doi: 10.1088/1674-1137/33/S1/030
A systematic study of global properties of superheavy nuclei in the framework of the Liquid Drop Model and the Strutinsky shell correction method is performed. The evolution equilibrium deformations, TRS graphs and α-decay energies are calculated using the TRS model. The analysis covers a wide range of even-even superheavy nuclei from Z=102 to 122. Magic numbers and their observable influence occurring in this region have been investigated. Shell closures appear at proton number Z=114 and at neutron number N=184.
Alpha decay half-lives of heavy nuclei within a generalized liquid drop model
ZHANG Hong-Fei, WANG Zu-Kai, CHENG Xi-Meng, LI Jun-Qing
2009, 33(S1): 95-97. doi: 10.1088/1674-1137/33/S1/031
Theoretical α-decay half-lives of the heaviest nuclei are calculated using the experimental Qα value. The barriers in the quasi-molecular shape path is determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the Density-Dependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulae. The calculations provide consistent estimates for the half-lives of the α decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time.
Deformation constrained relativistic mean-field approach with fixed configuration and time-odd component
LI Jian, YAO Jiang-Ming, MENG Jie
2009, 33(S1): 98-100. doi: 10.1088/1674-1137/33/S1/032
Deformation constrained relativistic mean-field (RMF) approach with fixed configuration and time-odd component has been developed and applied to investigate magnetic moments of light nuclei near doubly-closed shells. Taking 17O as an example, the results and discussion are given in detail.
Single-particle resonance states of 122Zr in relativistic mean-field theory combined with real stabilization method
MEI Hua, CHEN Hong, YAO Jiang-Ming
2009, 33(S1): 101-104. doi: 10.1088/1674-1137/33/S1/033
Single-particle resonance states of 122Zr are studied in the real stabilization method within the framework of relativistic mean field theory. Two efficient methods are adopted to extract the resonance energy and width of 122Zr. The results are compared with those obtained from the analytic continuation in the coupling approach and scattering phase-shift methods.
Triaxial deformation in 104Rh of the chiral doublet bands
XIAO Xian-Wen, CHEN Hong
2009, 33(S1): 105-108. doi: 10.1088/1674-1137/33/S1/034
Triaxial relativistic mean field (RMF) approaches are used to study the properties of 104Rh. The existence of multiple chiral doublets is suggested for 104Rh based on the triaxial deformations and their corresponding proton and neutron configurations.
Understanding of the dissipation mechanism in ternary fission for the system 197Au+197Au
TIAN Jun-Long, LI Xian, WU Xi-Zhen, LI Zhu-Xia, YAN Shi-Wei
2009, 33(S1): 109-112. doi: 10.1088/1674-1137/33/S1/035
The mass number distributions of three fragments from the ternary fission of the system 197Au+197Au are reproduced rather well by using the improved quantum molecular dynamics (ImQMD) model without any adjusting parameter. It is found that the probability of ternary fission evidently depends on the incident energy and the impact parameter, and the two-body dissipation is the main mechanism responsible for the formation of the third fragment with comparable mass.
First attempt to overcome the disaster of Dirac sea in imaginary time step method
ZHANG Ying, LIANG Hao-Zhao, MENG Jie
2009, 33(S1): 113-115. doi: 10.1088/1674-1137/33/S1/036
Efforts have been made to solve the Dirac equation with axially deformed scalar and vector Woods-Saxon potentials in the coordinate space with the imaginary time step method. The results of the single-particle energies thus obtained are consistent with those calculated with the basis expansion method, which demonstrates the feasibility of the imaginary time step method for the relativistic static problems.
Properties of Zr hypernuclei in deformed Skyrme Hartree-Fock approach
WEI Ning, ZHOU Xian-Rong, CHEN Fang-Qi
2009, 33(S1): 116-118. doi: 10.1088/1674-1137/33/S1/037
Properties of the even-N Zr isotopes and their corresponding single-Λ and double-Λ hypernuclei are studied in the deformed Skyrme-Hartree-Fock approach. Binding energy, the two-neutron separation energies, radii are studied from beta-stable zone to the neutron drip line in this paper. The neutron drip line nuclei predicted with SLy4 and SkI4 interactions are 122Zr and 138Zr, respectively. The neutron drip line of single-Λ and double-Λ hypernuclei are 139ΛZr and 142Zr with SkI4 interaction, respectively. The predicted hyperon drip line hypernuclei with 80Zr and 138Zr cores are 10020ΛZr and 18850ΛZr, respectively.
Temperature dependent fission fragment distribution in the Langevin equation
WANG Kun, MA Yu-Gang, ZHENG Qing-Shan, CAI Xiang-Zhou, FANG De-Qing, FU Yao, LU Guang-Cheng, TIAN Wen-Dong, WANG Hong-Wei
2009, 33(S1): 119-122. doi: 10.1088/1674-1137/33/S1/038
The temperature dependent width of the fission fragment distributions was simulated in the Langevin equation by taking two-parameter exponential form of the fission fragment mass variance at scission point for each fission event. The result can reproduce experimental data well, and it permits to make reliable estimate for unmeasured product yields near symmetry fission.
An analysis of nuclear charge radii based on the empirical formula
LI Ru-Heng, HU Yong-Mao, LI Mao-Cai
2009, 33(S1): 123-125. doi: 10.1088/1674-1137/33/S1/039
Several nuclear charge radii had been calculated based on the law of A1/3 and isospin dependence Z1/3 formula which had been used to describe the charge radii data. It is achieved that the isospin dependence Z1/3 formula is superior to the generally accepted A1/3 law through mean root square deviation analysis, that is, the Z1/3 formula is more effective to describe the charge radii data.
Isoscaling behavior studied by HIPSE model
FU Yao, FANG De-Qing, MA Yu-Gang, CAI Xiang-Zhou, GUO Wei, MA Chun-Wang, TIAN Wen-Dong, WANG Hong-Wei, WANG Kun
2009, 33(S1): 126-129. doi: 10.1088/1674-1137/33/S1/040
The isoscaling behavior in the reaction system of 58,64Ni+9Be has been studied by using the heavy-ion phase-space exploration(HIPSE) model. The extracted isoscaling parameters α and β for both heavy and light fragments for HIPSE model calculations are in good agreement with recent experimental data. The investigation shows that the parameters in the HIPSE model have some effect on the isoscaling parameter. The isoscaling parameters for hot and cold fragments have been extracted.
Neutron halos in the excited states for N=127 isotones
SUN Qin, GUO Jian-You
2009, 33(S1): 130-133. doi: 10.1088/1674-1137/33/S1/041
Properties of the ground states and the excited states of N=127 isotones are investigated by using the nonlinear relativistic mean field theory with the interactions PK1. By analyzing the rms of proton and neutron, the single particle energies of valence nucleon and the density distributions of neutron, proton and the last neutron, it can be found that there exists a neutron halo in the excited states of 3d5/2, 4s1/2 and 3d3/2 in 209Pb. It is also predicted that there exists a neutron halo in the excited states of 3d5/2, 4s1/2 and 3d3/2 in 207Hg, 208Tl, 210Bi and 211Po.
Solution to the eigenstates of pairing Hamiltonian in finite nuclei
YU Yi, GUO Jian-You
2009, 33(S1): 134-136. doi: 10.1088/1674-1137/33/S1/042
We apply the algebraic Bethe technique to the nuclear pairing problem with certain limits. We obtain the exact energies and eigenstates, and find the symmetry between the states corresponding to less and more than half full shell. We also proved that the problem of solving BAE can be transformed into the problem of finding the roots of a hypergeometric polynomial, which is much
Number of spin I states for bosons
2009, 33(S1): 137-139. doi: 10.1088/1674-1137/33/S1/043
We study number of spin I states for bosons in this paper. We extend Talmi's recursion formulas for number of states with given spin I to boson systems, and we prove empirical formulas for five bosons by using these recursions. We give number of states with given spin I and isospin F for three and four bosons by using sum rules of six-j and nine-j symbols. We also present formulas of states with given spin I and given F-spin for three and four single-l bosons.
With the alpha-cluster model to explain the change of separating energy
ZHANG Lun-Dong, GUO Jian-You, FANG Xiang-Zheng
2009, 33(S1): 140-141. doi: 10.1088/1674-1137/33/S1/044
It was supposed that, the nucleus was composed of α-cluster, pn-pair, and nn-pair. The reciprocity of the α-cluster, pn-pair, and nn-pair caused the regular change of the separating energy to separate the nn-pair in the exotic nuclei. The regular change was that the separating energy was high behind low to separate the nn-pair in the light and exotic nuclei. This phenomenon must had more profound physical meaning.
EC/β+ decay of six medium-heavy nuclei
XU Shu-Wei, XIE Yuan-Xiang, LI Zhan-Kui, WANG Xu-Dong, PAN Qiang-Yan, YU Yong
2009, 33(S1): 142-144. doi: 10.1088/1674-1137/33/S1/045
Previous experimental results of (EC+β+) decay for the medium-heavy nuclei reported by our group since 1996, including 153Er, 157Yb, 209Fr, 128Ce, 130Ce, and 128Pr have been briefly summarized. The observed low-lying states in their daughter nuclei have been reviewed in a systematic way and compared with different model calculations. Finally, some questions have been put forward for further study and discussion.
Search for chiral bands in A~110 neutron-rich nuclei
ZHU Sheng-Jiang, WANG Jian-Guo, CHE Xing-Lai, DING Huai-Bo, XU Qiang, GU Long, YANG Yun-Yi
2009, 33(S1): 145-147. doi: 10.1088/1674-1137/33/S1/046
High spin states in A~110 neutron-rich 106Mo, 110Ru and 112Ru nuclei have been reinvestigated by measuring the prompt γ-rays from the spontaneous fission of 252Cf. Two similar sets of bands are observed to high spins in each of three nuclei. Through analyzing of characters of the band structures, the chiral doublet bands are suggested in 106Mo, 110Ru and 112Ru.
Structure change of 156Yb at high-spin states
HUA Hui, LI Zhong-Yu, WANG Shou-Yu, MENG Jie, LI Zhi-Huan, LI Xiang-Qing, XU Fu-Rong, LIU Hong-Liang, ZHANG Shuang-Quan, ZHOU Shan-Gui, YE Yan-Lin, JIANG Dong-Xing, ZHENG Tao, ZHU Li-Hua, WU Xiao-Guang, LI Guang-Sheng, HE Chuang-Ye, MA Li-Ying, LU Fei, FAN Feng-Ying, HAN Li-Ying, WANG He, XIAO Jun, LI Xue-Qin, CHEN Dong, FANG Xiao, LOU Jian-Lin, LIU Ying, HAO Xin, PAN Bo, LI Li-Hua
2009, 33(S1): 148-150. doi: 10.1088/1674-1137/33/S1/047
High-spin states of 156Yb have been studied via the 144Sm(16O,4n)156Yb fusion-evaporation reaction at beam energy 102~MeV. The positive-parity yrast band and negative-parity cascade have been extended up to higher-spin states, respectively. The characteristics of the negative-parity sequence above the 25 state may related to the excitation from the nucleon in the Z=64, N=82 core. The E-GOS curve for the positive-parity yrast sequence in 156Yb indicate that this nucleus may undergo an evolution from quasivibrational to quasirotational structure with increasing angular momentum. The Cranked Woods-Saxon-Strutinsky calculations by means of Total-Routhian-Surface (TRS) methods has been made to understand this structure change.
Shape evolution and test of the critical-point symmetry X(5) in 176Os
HAO Xin, ZHU Li-Hua, WU Xiao-Guang, LI Guang-Sheng, PAN Bo, WANG Lie-Lin, ZHENG Yun, WANG Lei, LI Xue-Qin, LIU Ying, DING Huai-Bo, LI Zhong-Yu
2009, 33(S1): 151-153. doi: 10.1088/1674-1137/33/S1/048
The lifetimes of excited states in the yrast band of 176Os have been measured up to I=20h level using the Doppler shift attenuation method. The high-spin states of 176Os were populated via fusion evaporation reaction 152Sm(28Si, 4n)176Os at a beam energy of 140 MeV. The results support an X(5) structure for 176Os at low spin. This structure disappears at high spin and shows a symmetry rotor character. The shape change of 176Os is similar to that of 178Os.
Extended collective bands in neutron-rich 109Ru
DING Huai-Bo, ZHU Sheng-Jiang, WANG Jian-Guo, CHE Xing-Lai, GU Long
2009, 33(S1): 154-157. doi: 10.1088/1674-1137/33/S1/049
Levels in the neutron-rich 109Ru have been studied by observing the prompt γ-rays following the spontaneous fission fragments of 252Cf. The ground state band and the negative parity bands have been confirmed and extended. A positive parity band with the band head level at 332.5 keV is newly identified and suggested as a single-neutron excitation band built on the 7/2+[404] Nilsson orbital. Some structural characteristics of these bands are discussed.
Observation of a new rotational band in 104Nb nucleus
WANG Jian-Guo, ZHU Sheng-Jiang, DING Huai-Bo, XU Qiang, GU Long, YANG Yun-Yi
2009, 33(S1): 158-160. doi: 10.1088/1674-1137/33/S1/050
The high spin states in neutron-rich 104Nb have been investigated from study of prompt γ-rays in spontaneous fission of 252Cf with the Gammasphere detector array. A new rotational band has been identified for the first time. This band is proposed as a semi-decoupled band based on the configuration π5/2[303]⊙ν1/2[541].
Identification of Time-of-Flight spectra for Isochronous Mass Measurements
SUN Bao-Hua, MENG Jie
2009, 33(S1): 161-163. doi: 10.1088/1674-1137/33/S1/051
The Isochronous Mass Spectrometry (IMS) developed at GSI is a very efficient method for direct mass measurements of short-lived nuclides. By taking a recent IMS experiment as an example, the identification procedure of the Time-of-Flight (TOF) spectrum measured in this experiment is discussed.
Level structure of 159Lu
SHENG Hai-Qing, ZHAI Jian, LI Xian-Feng, MA Ying-Jun, ZHAO Yan-Xin, WANG Ya-Kun, ZHAO Lei, ZHU Li-Hua, WU Xiao-Guang, HE Chuang-Ye, LIU Yin, HAO Xin, LI Xue-Qin
2009, 33(S1): 164-166. doi: 10.1088/1674-1137/33/S1/052
The high-spin states of 159Lu were populated by fusion-evaporation reaction 144Sm (19F, 4n) with beam energy 106 MeV. A new level scheme was established, which consists of the yrast band with negative parity, the octupole vibration band based on the states and quasipartical band with positive parity. The high spin states of 159Lu were discussed by systemic characteristics.
Preparations for the study on the cluster structure of 16C
FAN Feng-Ying, ZHENG Tao, YE Yan-Lin, JIANG Dong-Xing, HUA Hui, LI Zhi-Huan, GE Yu-Cheng, LI Xiang-Qing, SHI Fan, NEI Peng-Xuan, LU Fei
2009, 33(S1): 167-169. doi: 10.1088/1674-1137/33/S1/053
In order to look for a proposed cluster structure of 16C, simulation work was made. The simulation of the reaction dynamics give the resolution of the excitation energy on 16C which was reconstructed prior to breakup. The excitation energy resolution is typically ~200 keV at 2 MeV above the two body decay threshold for 16C→12Be+4He. Moreover,some performances of detectors tested using 241Am α source are also reported.
Study of the structure of borromean nucleus 17Ne
LU Fei, HUA Hui, YE Yan-Lin, LI Zhi-Huan, JIANG Dong-Xing, MA Li-Ying, GE Yu-Cheng, ZHENG Tao, SONG Yu-Shou, LI Xiang-Qing, Qureshi Faisal-Jamil
2009, 33(S1): 170-172. doi: 10.1088/1674-1137/33/S1/054
The 17Ne nucleus is a possible candidate with a two-proton borromean halo structure. Since the theoretical model is difficult to handle the three-body system, it is difficult to determine the two-proton halo structure in 17Ne. In the present research, we try to study the breakup reaction of 17Ne. For the Borromean nuclei, one-proton knockout results in an unstable nucleus which is decaying further by proton emission. This process will result in an angular correlation between the direction of the aligned recoiling unstable nucleus and its decay products. The angular correlations can give us information about the configuration of the valence proton in the 17Ne. Furthermore, theoretical calculations indicate that the momentum distributions of 16F c.m are sensitive to the structure of the halo in 17Ne. Thus the measurement of momentum distributions of 16F c.m may also give us conclusive information on the structure of 17Ne. The present experiment has been done at IMP in Lanzhou using the radioactive beam 17Ne at 30.8 MeV/u on a 43mg/cm2 12C target. The data analysis is under procedure and the primary results are provided.
Lifetime measurements in chiral nucleus 130Cs
WANG Lie-Lin, WU Xiao-Guang, ZHU Li-Hua, LI Guang-Sheng, HAO Xin, ZHENG Yun, HE Chuang-Ye, WANG Lei, LI Xue-Qin, LIU Ying, PAN Bo, LI Zhong-Yu, DING Huai-Bo
2009, 33(S1): 173-175. doi: 10.1088/1674-1137/33/S1/055
The level lifetimes in partner bands of 130Cs have been measured using the Doppler Shift Attenuation method. The high-spin states of 130Cs were populated via fusion evaporation reaction 124Sn(11B, 5n)130Cs at a beam energy of 65 MeV. The absolute M1 and E2 transition probabilities have been deduced. The results indicate that the partner bands of 130Cs manifest the chiral properties.
A CsI(Tl) detector array used in the experiment of the proton-rich nucleus 17Ne
MA Li-Ying, HUA Hui, LU Fei, CHEN Dong, JIANG Xi-Yao, YE Yan-Lin, JIANG Dong-Xing, Qureshi Faisal-Jamil
2009, 33(S1): 176-178. doi: 10.1088/1674-1137/33/S1/056
To investigate the configurations of the valence protons in Borromean nucleus 17Ne, a CsI(Tl) detector array, which consists of 9 CsI crystals (26×26×20mm3) coupled with photodiodes, has been successfully used in the 17Ne experiment to measure the energy of protons. In order to find the optimal working conditions and get the best energy resolutions, several technologies (including various wrapping materials, wrapping and coupling methods) have been used. The testing results showed that the best energy resolution of the CsI(Tl) is about 3.3% using the 241Am α-source. The primary testing results with the proton beam were also provided.
High-spin states in 128I
ZHENG Yun, ZHU Li-Hua, WU Xiao-Guang, LI Guang-Sheng, HAO Xin, WANG Lie-Lin, HE Chuang-Ye, LIU Ying, LI Xue-Qin, PAN Bo, WANG Lei, LI Zhong-Yu, DING Huai-Bo
2009, 33(S1): 179-181. doi: 10.1088/1674-1137/33/S1/057
The high-spin states in 128I have been studied by using in-beam γ-ray spectroscopy with the 124Sn(7Li, 3n)128I reaction at beam energies of 25, 28 and 42 MeV. A new level scheme including 20 new levels and 27 new γ-transitions for 128I has been established preliminarily.
High spin states in neutron-rich 106Tc nucleus
GU Long, ZHU Sheng-Jiang, XU Qiang, CHE Xing-Lai, WANG Jian-Guo, DING Huai-Bo, YANG Yun-Yi
2009, 33(S1): 182-184. doi: 10.1088/1674-1137/33/S1/058
The high spin states of the neutron-rich odd-odd 106Tc nucleus have been reinvestigated by observing prompt γ-rays from the spontaneous fission of 252Cf. A previously known collective band is confirmed and expanded, and a new collective band is newly identified. Several levels in previous report in 106Tc are reexamined and they belong to the members of a band in 107Tc. The total Routhian surface (TRS) calculations show that the 106Tc has triaxial shape. The spins and parities as well as the configurations for these bands have been tentatively assigned according to the analysis of the angular momentum alignments.
High spin band structure in 139Nd
XU Qiang, ZHU Sheng-Jiang, CHE Xing-Lai, DING Huai-Bo, GU Long, ZHU Li-Hua, WU Xiao-Guang, LIU Ying, HE Chuang-Ye, LI Li-Hua, PAN Bo, HAO Xin, LI Guang-Sheng
2009, 33(S1): 185-187. doi: 10.1088/1674-1137/33/S1/059
High-spin states in 139Nd nucleus have been reinvestigated with the reaction 128Te (16O, 5n) at a beam energy of 90 MeV. The level scheme has been expanded with spin up to 47/2 h. At the low spin states, the yrast collective structure built on the νh11 / 2-1 multiplet shows a transitional shape with γ≈32° according to calculations of the triaxial rotor-plus-particle model. Three collective oblate bands with γ~-60° at the high spin states were identified for the first time. A band crossing is observed around hω~0.4 MeV in one oblate band based on the 25/2 level.
Study of magnetic-rotation in 82Rb by g-factor measurements
YUAN Da-Qing, ZHENG Yong-Nan, ZUO Y, FAN Ping, ZHOU Dong-Mei, LIU Meng, WU Xiao-Guang, ZHU Li-Hua, LI Guang-Sheng, XU Guo-Ji, FAN Qi-Wen, ZHANG Xi-Zhen, ZHU Sheng-Yun
2009, 33(S1): 188-190. doi: 10.1088/1674-1137/33/S1/060
Magnetic rotation in 82Rb has been investigated for the first time by g-factor measurement of intra-band states of the magnetic-rotational band built on the 11- state. The g-factors were measured by a TMF-IMPAD method and calculated by a semi-classical model of independent particle angular momentum coupling assumption. The g-factors and deduced shears angles decrease with the increasing of spin along the band, illustrating a step-by-step alignment of the valence protons and neutrons. The rapid alignment of the valence neutrons leads to a decrease of g-factors. The present results vividly reveal the shears mechanism of magnetic rotation.
Gamma decay of the lowly excited states of 189Re
YUAN Shuang-Gui, XU Yan-Bing, DING Hua-Jie, YANG Wei-Fan, XIAO Yong-Hou, NIU Yan-Ning
2009, 33(S1): 191-192. doi: 10.1088/1674-1137/33/S1/061
189W activities were produced via the 192Os(n, α) reaction using irradiation of isotopically enriched 192Os metallic powder of ~100 mg/cm2 with 14 MeV neutrons. The X-γ and γ-γ coincidence measurements were made so as to obtain γ rays from 189W decay and its coincidence relations. A new simple decay scheme of 189W including three γ rays of 210.2, 229.6 and 260.2 keV is proposed. Two new levels of 189Re at 470.4 and 489.8 keV are assigned.
Simulation of the Lanzhou Penning Trap LPT
HUANG Wen-Xue, WANG Jun-Ying, WANG Yue, TIAN Yu-Lin, ZHU Zhi-Chao, XU Hu-Shan, XIAO Guo-Qing
2009, 33(S1): 193-195. doi: 10.1088/1674-1137/33/S1/062
The LPT (Lanzhou Penning Trap) is under construction and its task is to perform direct mass measurement of fusion-evaporation residues and if possible for heavy isotopes. Detailed simulations have been done for a good understanding to the ion's movement and mechanics in the trap. The optimization of the LPT is also performed based on the simulation. With a scale of 0.5 mm per grid used in the simulation and many other limitations a highest mass resolution has been achieved to be 1.9×10-5. An unexpected behaviour in the simulation related to magnetron motion has been found.
Dependence of the cross sections for Ir isotopes on the values of Qgg in the heavy ion collision
YANG Wei-Fan, ZHAO Zhi-Zheng, YUAN Shuang-Gui, XU Yan-Bing, LU Xi-Ting
2009, 33(S1): 196-198. doi: 10.1088/1674-1137/33/S1/063
197Au were irradiated with 47 MeV/u 12C ions. Iridium was produced via the multinucleon transfer reactions in bombardments of 197Au with 12C. and was separated radiochemically from Au and the mixture of the reaction products. The γ radioactivities of Ir isotopes were measured by using a HPGe detector. The production cross sections of Ir isotopes were determined from activities of Ir isotopes at the end of bombardment and the other relative data. It has been found that the cross sections for neutron-rich isotopes of iridium show an exponential dependence on the values of Qgg. Our experimental results also demonstrate lack of correlation between the cross sections and Qgg in the case of neutron-deficient isotopes of iridium. The fact can be explained from that neutron-rich isotopes of iridium were produced in the deep inelastic transfer reactions.
High-spin states in neutron-rich 102Mo nucleus
YANG Yun-Yi, ZHU Sheng-Jiang, DING Huai-Bo, WANG Jian-Guo, XU Qiang, GU Long
2009, 33(S1): 199-201. doi: 10.1088/1674-1137/33/S1/064
High-spin states in neutron-rich 102Mo nucleus have been studied by measuring the prompt γ-rays in the spontaneous fission of 252Cf. The previous level scheme has been updated and some new levels and transitions are identified. The one-phonon γ-band is expanded and a band head level of the two-phonon γ-band is proposed. The systematic characteristics of yrast bands, one-phonon γ-bands, two-phonon γ-bands and quasi-particle bands in 102Mo, 104Mo and 106Mo are discussed.
Characteristics of a 4-fold segmented clover detectore
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2009, 33(S1): 202-205. doi: 10.1088/1674-1137/33/S1/065
Four high-purity germanium 4-fold segmented Clover detectors have been
applied in the experiment of neutron-rich nucleus 21N. The performance of those four Clovers have been tested with radioactive sources and in-beam experiments, and the main results including energy resolution, peak-to-total ratios, the variation of the hit pattern distribution in different crystals of one Clover detector with the energy of γ ray, and absolute full energy peak detection efficiency curve, were presented.
Proton alignment in 82Sr investigated by g-factor measurements
FAN Ping, YUAN Da-Qing, ZUO Yi, ZHENG Yong-Nan, ZHOU Dong-Mei, WU Xiao-Guang, LI Guang-Sheng, ZHU Li-Hua, XU Guo-Ji, FAN Qi-Wen, ZHANG Xi-Zhen, ZHU Sheng-Yun
2009, 33(S1): 206-208. doi: 10.1088/1674-1137/33/S1/066
The proton alignment in 82Sr has been investigated by the g-factor measurements of the ground state rotational band levels up to spin I=8+. The g-factors were measured by a transient-magnetic-field ion implantation perturbed angular distribution method. The obtained g-factors increase with the increasing of spin along the band and clearly show the g9/2 proton alignment that starts at I=6+.
Signature splitting in 129Ce
LIU Ying, WU Xiao-Guang, ZHU Li-Hua, LI Guang-Sheng, HE Chuang-Ye, LI Xue-Qin, PAN Bo, HAO Xin, LI Li-Hua, WANG Zhi-Min, LI Zhong-Yu, XU Qiang
2009, 33(S1): 212-214. doi: 10.1088/1674-1137/33/S1/068
The high spin states of 129Ce have been populated via heavy-ion fusion evaporation reaction 96Mo (37Cl, 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 ν7/2[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 ν7/2[523] rotational band of 129Ce was extracted from the Qt and moment of inertia JRR.
Nuclear structure of proton-rich unstable nucleus 28P studied by g-factor measurement
ZHENG Yong-Nan, ZHOU Dong-Mei
2009, 33(S1): 215-217. doi: 10.1088/1674-1137/33/S1/069
Nuclear structure of proton-rich unstable nucleus 28P has been studied by measuring its g-factor for the first time. The g-factor of 28P (Iπ=3+, T1/2=270.3 ms) was measured by means of β-NMR technique combined with the new polarization technique for charge exchange reaction product in the intermediate energy heavy ion collisions. The obtained g-factor of g=0.1028(27) is very much quenched from the Schmidt value, but is well reproduced by the shell model (+0.102). In connection with the magnetic moment of the mirror partner and the β-ray transition probability, the orbital angular momenta and intrinsic spins of protons and neutrons have been determined as 〈lp〉=0.43(29), 〈ln〉=1.85(29), 〈Sp)=0.28(4), and 〈Sn〉=0.44(4).
Structure of β-emitting nuclei 29P
ZHOU Dong-Mei, ZHENG Yong-Nan, ZHANG Xi-Zhen, YUAN Da-Qing, ZUO Yi, FAN Ping, WANG Zhi-Qiang, LUO Hai-Long, XU Guo-Ji, ZHU Sheng-Yun
2009, 33(S1): 218-220. doi: 10.1088/1674-1137/33/S1/070
The extoic structure of 29P was investigated by measuring its magnetic moment in the ground state with β-NMR method. We got the experimental value of 1.2346 μN after diamagnetism correction. It is very close to the calculated value of 1.1009 μN computed with shell model. The shell model calculation also gave a proton density distribution of 29P with a long tail. The present results show that 2s1/2 proton in the 29P may lead to the proton-skin structure.
Shears bands in 112In
LI Xue-Qin, ZHU Li-Hua, WU Xiao-Guang, HE Chuang-Ye, LIU Ying, PAN Bo, HAO Xin, LI Li-Hua, WANG Zhi-Min, LI Guang-Sheng, LI Zhong-Yu, WANG Shou-Yu, XU Qiang, WANG Jian-Guo, DING Huai-Bo, ZHAI Jian
2009, 33(S1): 209-211. doi: 10.1088/1674-1137/33/S1/077
A new level scheme of 112In have been established up to 6.8 MeV in excitation energy and to a tentative spin of (21+) through the reaction 110Pd(7Li,5n)112In at a beam energy of 50 MeV. In-beam measurements involving γ-γ coincidences and directional correlation of oriented states were performed. M1 bands consisting of ΔI=1 dipole transitions have been observed. Possible quasiparticle configurations suggest that these bands are similar to the shears bands observed in Pb nuclei.