1h11/2轨道对A～100区偶偶核形状影响的系统研究

采用修正的表面δ相互作用(MSDI),对^102—114Ru,^102—116Pd和^104—116Cd等22个偶偶核分别在gds和gdsh两种不同的组态空间中作了形变HF计算.得到了长、扁椭球等基态或激发态的解.结果表明在质量数为102—116间的原子核存在形状过渡和形状共存现象,且单粒子能级随质量数及组态的不同而不同.两种不同组态空间中的计算结果的对比表明,形变HF计算中1h_11/2轨道的介入及填充与否对A～100区偶偶核的单粒子能谱及形状有较大影响     

三体势对含f玻色子的IBM1的O(6)极限能谱修正

在s–dIBM1的O(6)极限下,引入d玻色子之间相互作用的等效三体势,考虑f玻色子产生的八极态,导出了正负宇称态能谱解析表达式,并对过渡区偶偶核¹¹⁸Xe、¹²⁰Xe进行了能谱计算,得到了与实验能谱符合更好的结果,然后用Staggering指数定量分析了正负宇称态能谱中的Staggering现象.     

偶偶Cd同位素核的形变HF态及负宇称带研究

将具有正宇称的轨道空间扩大到包含具有负宇称的1h_11/2轨道,采用修正的表面δ相互作用(MSDI),对¹⁰⁴Cd,¹⁰⁶Cd,¹⁰⁸Cd,¹¹⁰Cd,¹¹²Cd,¹¹⁴Cd和¹¹⁶Cd等7个偶偶核作了形变HF计算.得到了基态和一些激发态的解.同时,还用近似角动量投影形变Hartree-Fock(PDHF)方法对¹⁰⁸Cd和¹¹⁰Cd进行了能谱计算,得到其正、负宇称带的解,计算结果与实验谱基本一致.     

偶偶Ge和Se同位素核的形变HF态及负宇称带研究

将具有负宇称的fp轨道空间扩大到包含具有正宇称的1g_9/2轨道,采用修正的表面δ相互作用,对⁶⁴Ge,⁶⁶Ge,⁶⁸Ge,⁷⁰Se,⁷²Se和⁷⁴Se等6个偶偶核做了形变HF计算.得到了基态和一些激发态的解.同时,还用近似角动量投影形变Hartree-Fock(PDHF)方法,对⁶⁴Ge和⁷⁴Se进行了能谱计算,得到其正、负宇称带的解,计算结果与实验谱基本一致.     

带三体势的IBM1的O(6)极限对偶偶Pt核的应用

通过在IBMI哈密顿中,引入一种简单的等效三体势,O(6)核能谱可得到不同程度的修正.本文具体计算了^192—198Pt偶偶同位素核的能谱和E2跃迁几率,理论计算值与实验数据符合较好.     

三体势对O(6)极限能谱的修正

本文在IBM哈密顿的基础上,考虑d玻色子之间的三体相互作用,引入了一种简单的等效三体势,探讨它对O(6)对称性的破缺.并实际计算了¹⁹⁶Pt、¹³⁴Ba、¹⁹²Os、^72—76Ge和^124—130Xe等偶偶核的能谱,得到了与实验更加符合的结果.     

近满壳偶偶核闯入态及组态混合的微观分析

本文应用一种描述近满壳偶偶核的闯入态的微观理论,计算了对应于¹¹⁰Cd组态的低能谱及波函数.系统地考察了各种因素对闯入态形成的影响、产生组态混合的机制及强度.通过与唯象工作的比较,考察了微观s-d哈密顿量.     

PDHF方法应用于fp奇A核47Ti、47V、47Cr、49Cr的能谱研究

将近似的角动量投影形变Hartree-Fock(PDHF)方法用于fp壳层区的奇A核:⁴⁷Ti、⁴⁷V、⁴⁷Cr、⁴⁹Cr,计算了它们的能谱,并与实验能谱作了比较,结果是令人满意的,同时,对涉及到的核谱特性结合粒子加转子模型进行了分析,发现这些核的能谱具有无排列极限能谱的特征.     

128—150Ce偶偶核的低能谱和电磁跃迁的相互作用玻色子模型

采用相互作用玻色子模型研究了^128—150Ce同位素核的低能正宇称态的能谱和电磁跃迁.应用简单的哈密顿量很好的描述它们的能谱和E2跃过.研究表明,这些偶偶Ce核是属于U(5)到SU(3)过渡核,而¹⁴⁶Ce以后的核基本是完全的转动核.     

中重核中子辐射俘获γ射线强度函数研究

假设退激过程中除包含巨偶极共振模式外还存在⁶He,⁶Li,⁶Be,⁷Li和⁷Be等粒子集团激发态的退激过程.本文对这一物理假定作了进一步分析.利用据此建立的包括这些过程在内的γ射线强度函数,计算了在核素⁹³Nb,¹⁸¹Ta和天然元素Ag上入射中子能量在0.01—5MeV能区以及在核素¹⁹⁷Au上入射中子能量在0.01—10MeV能区的中子辐射俘获反应截面和γ能谱,得到了与实验数据较好符合的结果.特别是可以较好地解释γ能谱中5.5MeV之后的反常突起.这表明,上述物理假定适用于中重核中子辐射俘获反应.     

The Exploring of New Collective States ——Mixed-Symmetry States in Nuclei

New collective states with mixed-symmetry character of neutron—proton degrees of freedom is reviewed.In the framework of IBM-2,the mixed-symmtry states have been discussed in detail.The full-symmetry states and mixed-symmetry states of Hg,Gd and Nd isotopes,especially the effect of Majorana parameters on these states and M1 transitions,are calculated and analyzed.The results show that the basic properties of mixed-symmetry states of these nuclei are well described by IBM-2.     

Low-lying states and isospin excitation in the Ge isotopes

The level structure of 64-70Ge isotopes has been studied within the framework of the interacting boson model-3 (IBM-3). The symmetry character in the proton and neutron degrees of freedom of the energy levels has been investigated. The isospin excitation states (T>Tz) have been assigned for the 64Ge (N=Z) nucleus. Some intruder states in these nuclei have been suggested. The calculated energy levels and transition probabilities are in good agreement with recent experimental data. The study indicates that the Ge isotopes are in transition from γ-unstable to vibrational.     

Mixed Symmetry States in Even—Even ^96—108Mo Nuclei

Excitation energies and electromagnetic transition strengths in even-even ^96-108Mo nuclei have been described systematically be using the proton-neutron interacting boson model (IBM-2).It appears that the properties of low-lying levels in these isotopes,for which the comparison between experiment and theory is possible,can be satisfactorily described by the IBM-2 model,provided proper account is taken of the presence at low energy of states having a mixed-symmetry character.It seems possible to identify,in each isotope,a few states having such a character,the lowest ones being either 22^ or 23^ levels.It is found that these nuclei are in the transition from U(5) to SU(3).     

Isospin and Mixed Symmetry Excitations in 60—66Zn Isotopes

The level structure of ^60—66Zn isotopes is studied within the framework of interacting boson model-3 (IBM-3). The mixed symmetry states are investigated in these nuclei by analyzing the wave functions. The isospin excitation states are identified for ⁶⁰Zn (N=Z) nucleus. The calculated energy levels and transition probabilities are compared with available experimental data. The results obtained and the values of parameters used in this calculation indicated that the Zn isotopes are in the transition from vibrational to γ-unstable nuclei.     

Low-lying states and isospin excitation in the Ge isotopes

The level structure of ^64-70Ge isotopes has been studied within the framework of the interacting boson model-3（IBM-3） . The symmetry character in the proton and neutron degrees of freedom of the energy levels has been investigated. The isospin excitation states（T 〉 Tz） have been assigned for the ^64Ge（N = Z） nucleus. Some intruder states in these nuclei have been suggested. The calculated energy levels and transition probabilities are in good agreement with recent experimental data. The study indicates that the Ge isotopes are in transition from γ-unstable to vibrational.     

New algebraic solutions for SO(6) ↔ U(5) transitional nuclei in the interacting boson model

Exact solutions for energy eigenvalues and eigenstates for SO(6) ↔ U(5) transitional (Class C) nuclei in IBM-1 and one case in IBM-2 are found by using an infinite dimensional algebraic method. As examples, the energy spectra and some E2 transition rates and quadrupole moments of the ^100–108Ru and ^102–112Pd isotopes are calculated in IBM-1 and compared with experimental results.     

Shape coexistence in the light Po isotopes

The systematics of the even light Po isotopes (N ⩽ 126) are studied in the framework of the Particle-Core Model. The strong perturbation of the systematics in the very light isotopes is interpreted as arising from the interaction between regular and intruder structures. Results of Potential Energy Surface (PES) calculations and predictions of the Pairing Vibration Model support this interpretation. The mixing between the regular and intruder structures is studied within the IBM-2 and in a simple two-state mixing picture. Matrix elements of the interaction and their spin dependence are extracted. The ‘reconstructed systematics’ show the coexistence of a spherical structure, which varies little with the neutron number, with an intruder band, strongly lowered in energy as the neutron number approaches midshell. The crossing of the two configurations takes place over a few isotopes; the intruder band becomes the ground-state configuration in ¹⁹²Po.     

Tests of interacting boson model wave functions from measured gyromagnetic ratios of states in the even Os isotopes

The gyromagnetic ratios of the 2₁⁺, 2₂⁺, and 4₁⁺ states in ^188,190,192Os were experimentally measured. It is shown that the hamiltonians of standard interacting boson models (IBM-1 and -2) fit to level spectra and B(E2) rates fail to account for either the intra-nucleus or mass-dependent g-factor variations of these states in these Os isotopes.