丰中子锰同位素的壳模型计算

利用球形壳模型和投影壳模型两种方法对Z≤28,N=40附近pf壳的丰中子核素的结构进行了一系列的研究。以丰中子的锰同位素为例讨论了对奇奇核58,60Mn的两种壳模型计算结果。结果显示,两种理论方法都很好地再现了58,60Mn实验上观测到的从低激发到高自旋态的能级。在对这两个同位素由中子g_9/2轨道闯入所产生的负宇称转动带进行描述时,两种理论计算也得到了一致的结果。通过对比,阐明了两种壳模型方法及其采用的有效相互作用在该丰中子核区的适用性,特别强调了中子g_9/2轨道的激发对于pf壳Z≤28丰中子核素结构的重要性。Recently,we have carried out a series of studies on the structures of pf shell neutron-rich nuclei around N=40 using the spherical shell model and the projected shell model respectively.As an example,these two types of shell model calculations for the neutron-rich odd-odd isotopes 58,60Mn are discussed in this paper.The results show that both the calculations reproduce the observed experimental energy levels from the lowexcitation states to the high-spin ones in 58,60Mn.Consistent results are also obtained by these two theoretical calculations when describing the negative-parity rotational band derived from the intruder neutron g_9/2 orbital in both isotopes.Through comparison,we show the applicability of these two shell model methods and the adopted effective interactions in the present neutron-rich mass region.The significance of the excitations from neutron g_9/2 orbital to the structures of the neutron-rich nuclei in pf shell with Z≤28 are especially emphasized in this paper.     

投影壳模型研究丰中子奇奇核102,104Nb的转动能谱

运用投影壳模型研究了正常形变丰中子核同位素102,104Nb的低能级能谱, 并指定了它的准粒子组态, 理论计算所得到的能谱曲线与实验给出的能谱曲线非常一致, 说明了投影壳模型对研究重核低能级谱非常有效。 The Projected Shell Model(PSM) is used to study the low energy scheme of the neutron rich normal deformed isotopes of odd odd nuclei 102, 104Nb. The quasiparticle configuration is assigned. The theoretical calculations of the energy band of 102,104Nb could well reproduce the experimental data. It is shown that PSM is a valid method for studying the low energy scheme of heavy nuclei.     

新重丰中子同位素^239Pa的合成

本文简述了新重丰中子同位素＾２３９Ｐａ的首次合成和鉴别，并测定其半衰期为１０６＋３０ｍｉｎ。     

丰中子氮同位素β￣衰变的理论研究

使用壳模型系统地研究了丰中子氮同位素的β￣衰变,并对其衰变子核18,19,20,210的能级结构性质给出理论计算,所得结果与实验符合较好.研究了18,19,20N核的Gamow-Teller允许型β￣衰变的特性,对与近期实验观测不一致之处进行了讨论和分析.预言了21N的β￣衰变及其子核高激发态的能级结构性质.这些计算将对氮同位素的实验研究很有帮助.     

新重丰中子同位素^238Th

利用兰州重离子加速器（ＨＩＲＦＬ）所提供的６０ＭｅＶ／ｕ的＾１８Ｏ离子束照射天然铀靶,通过多核子转移反应生成＾２３８Ｔｈ,由快速放射化学分离技术从铀及其反应产物的合物中分离出钍。使用２台高纯锗（ＨＰＧｅ）探测器对样品的γ（Ｘ）活性进行测量,观测到了＾２３８Ｔｈ的β－衰变子本＾２３８Ｐａ的６３５．０ｋｅＶ和１０６０．５ｋｅＶ２条γ射线峰的增长、衰变行为,利用分析递次衰变的计算机程序对其后一条进行了拟     

丰中子氮同位素β-衰变的理论研究

使用壳模型系统地研究了丰中子氮同位素的β^-衰变,并对其衰变子核^18,19,20,21O的能级结构性质给出理论计算,所得结果与实验符合较好.研究了^18,19,20N核的Gamow-Teller允许型β^-衰变的特性,对与近期实验观测不一致之处进行了讨论和分析.预言了²¹N的β^-衰变及其子核高激发态的能级结构性质.这些计算将对氮同位素的实验研究很有帮助. 关键词： 中子滴线 -衰变')" href="#">β^-衰变 氮同位素 壳模型     

轻丰中子核的壳模型计算

对9≤A≤14,3≤Z≤5的核进行了壳模型计算.以⁸He作为core,选用修正的表面δ相互作用(MSDI)作为残余相互作用,挑选了24个实验能谱数据,定出了MSDI的参数和单粒子能量,并计算了结合能、低激发谱、电磁性质等,得到与实验较符合的结果.并着重讨论了¹¹Be的宇称反转和halo结构的物理机理.计算程序为OXBASH.     

丰中子核素能级结构研究及A～100与A～150区丰中子核形状相变讨论

采用裂变产物-γ-γ符合法,对²⁵²Cf裂变瞬发γ谱进行了研究,扩展了A～100及150区的30种丰中子偶-偶核素的能级结构,最高自旋可达10～14.对某些同位素链的核结构及形状相变特性进行了讨论.     

SD对壳模型与质子中子相互作用玻色子模型

在SD对壳模型理论框架下, 讨论了相互作用玻色子模型下U(5), SO(6)以及SU(3)的经典极限谱. 结果发现SD对壳模型可以很好地再现相互作用玻色子模型中的三种极限谱.     

Level Structure of 83Rb in the Projected Shell Model

The projected shell model is applied to the odd-proton nucleus 83 Rb. The results of theoretical calculationsabout the excited positive-parity yrast states and the negative-parity ground-state band are compared with experimentaldata, and the best reproduction of the experiment has been given by this model. In addition, a band diagram calculatedfor the negative-parity g.s. band is also shown in order to extract physics out of the numerical results.     

Neutron Halo and Nuclear Shell Structure in New Nuclide 31Ne

The ground state properties of new nuclide ^31Ne are investigated within the framework of the density-dependent relativistic mean-field theory.One-neutron halo in ^31Ne is predicted.Calculations also show that the ground state of ^31Ne is (3/2)^- and it can be used for the testing of the nuclear shell structure near the neutron-drip line.     

Shell-model Study of Neutron-rich A-hypernucleus 10ΛLi

We investigate a Σ-mixing probability of a neutron-rich A-hypernucleus ~(10)_ΛLi by using microscopic shell-model calculations considering a Λ-Σ coupling in the first order perturbation.The theoretical Σ-mixing probability in ~(10)_Li is found to be about 0.48%,due to the appearance of multi-configuration Σ Nuclear excited states which can be strongly coupled with the A ground state in ~(10)_Li.     

Projected Shell Model Description for the Proton Emitters

Proton radioactivity is an important decay mode for nuclei near the proton drip-line. Studies of this decay mode can reveal valuable information on exotic nuclear structure and provide important information on the stucture of nuclei in extreme conditions. The new experimental data can let us understand the interactions in exotic systems, which motivate further theoretical development. The most recent application of the projected shell model (PSM) for proton emitters is represented. We study the rotational bands of the deformed proton emitter 141Ho by using the PSM. The experimental data are well reproduced. Strongly suppressed γ transition from the low-lying IΠ= 3/2+ state makes this state isomeric. Variations in the dynamical moment of inertia are discussed due to band crossings using the band diagram. The calculated results for proton emitter 151Lu shows it is oblately deformed     

Structure analysis of ~(159)Sm and properties of odd-mass neutron-rich nuclei in mass-160 region

Recent fission experiment data provide interesting structure information for neutron-rich nuclei in the mass A ～ 160 region. We apply the projected shell model to study the strongly-deformed, neutron-rich Sm isotopes. We perform calculations for rotational bands up to spin I = 20 (29/2) for even-even (odd-neutron) Sm isotopes, and analyze the band structure of low-lying states with quasiparticle excitations. Emphasis is given to rotational bands based on one-quasiparticle (1-qp) configurations in the odd-ma...     

Projected total energy surface description for axial shape asymmetry in 172W

The projected total energy surface(PTES)approach has been developed based on the triaxial projected shell model(TPSM)hybridized with the macroscopic–microscopic method.The total energy of an atomic nucleus is decomposed into macroscopic,microscopic and rotational terms.The macroscopic and microscopic components are described with the liquid drop model and Strutinsky method,respectively,and the rotational energy is given by the TPSM,the term beyond the mean field.To test theory,the PTES calculations have been carried out for the yrast states of the well deformed rare earth nucleus172W,and the theoretical results are in good agreement with the experimental data.By using the equilibrium quardrupole deformations(ε2andγ)determined by the PTES,the calculation of the transition quardrupole moment(Qt)in function of spin also reproduces the experimental data.A comparison between the PTES and TRS methods has been made for theoretical and application uses.     

Shell Model Description of Neutron-Deficient Sn Isotopes

The shell model calculations in the sdgh major shell for the neutron-deficient ^106,107,108,109Sn isotopes have been carried out by using CD-Bonn and Nijmegenl two-body effective nucleon-nucleon interactions. The singleshell states and the corresponding matrix elements needed for describing Sn isotopes are reconstructed to calculate the coefficient of fractional parantage by reducing the calculation requirements. This reconstruction allows us to do the shell model calculations of the neutron deficient Sn isotopes in very reasonable time. The results are compared to the recent high-resolution experimental data and found to be in good agreement with experiments.     

Monte Carlo Shell Model Mass Predictions

The nuclear mass calculation is discussed in terms of large-scale shell model calculations. First, the development and limitations of the conventional shell model calculations are mentioned. In order to overcome the limitations, the Quantum Monte Carlo Diagonalization (QMCD) method has been proposed. The basic formulation and features of the QMCD method are presented as well as its application to the nuclear shell model, referred to as Monte Carlo Shell Model (MCSM). The MCSM provides us with a breakthrough in shell model calculations: the structure of low-lying states can be studied with realistic interactions for a nearly unlimited variety of nuclei. Thus, the MCSM can contribute significantly to the study of nuclear masses. An application to N∼20 unstable nuclei far from the β-stability line is mentioned. This revised version was published online in July 2006 with corrections to the Cover Date.     

Nucleon—Pair Shell Model：Magnetic Excitations for Ba Isotopes

Magnetic excitations for Ba isotopes are discussed within the nucleon-pair shell model truncated in the SD subspace.With the SD pair determined by a surface-δ interaction,M1 transitions for ^134Ba are well fitted.The M1 and M3 transitions for ^132Ba and ^130Ba are also predicted.It is shown that the statement,the collective magnetic properties are due to the orbital motion of nucleons,is approximately valid.