Investigation of the neutron shell structure of the even-even isotopes <Superscript>40–56</Superscript>Ca within the dispersive optical model

Within the method of matching experimental data obtained in the neutron-stripping and neutron-pickup reactions on ^{40,42,44,46,48}Ca isotopes, the single-particle energies and probabilities that neutron states are filled are obtained for the even-even calcium isotopes. These data are analyzed within the dispersive optical model, and good agreement between the calculated and experimental values of the energies of states is obtained. The dispersive optical potential is extrapolated to the region of the unstable ^50,52,54,56Ca nuclei. The calculated single-particle energies of bound states in these isotopes are compared with the results of the calculations within the multiparticle shell model, the latter predicting a new magic number N = 34 for Z = 20 nuclei.     

Study of the νi13/2－1 band in 189Pt

High-spin levels of ^189Pt have been studied with the in-beam T-spectroscopy method via the ^176Yb（^18O,5n） reaction at the beam energies of 88 and 95 MeV. The previously known ＂vi-1 13/2 band has been confirmed, and its unfavored signature branch extended up to the 31/2^＋ state. Within the framework of the triaxial particle-rotor model, the vi-1 13/2 band is suggested to be associated with the 11/2[615] configuration, and to have triaxial deformation.     

Properties of the β-delayed proton decay of 146Ho

The proton-rich isotope 146Ho was produced via the fusion-evaporation reaction ^92Mo （^58Ni, 3p1n）. The β-delayed proton decay of 146Ho was studied by proton-γ coincidence measurements using a He-jet tape transport system. The γ-transitions in ^145Tb following the proton emissions were observed, and the β-delayed proton branching ratios to the final states in the grand-daughter nucleus ^145Tb were determined. According to the relative branching ratios, the ground-state spin of 146Ho has been proposed and the possible configuration discussed.     

Structure of β-emitting nuclei 29P

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 μ_N after diamagnetism correction. It is very close to the calculated value of 1.1009 μ_N 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 2s_1/2 proton in the ²⁹P may lead to the proton-skin structure.     

壳模型对13N Gamow-Teller跃迁的研究

最近的研究表明¹³N的beta衰变对于Ia型超新星爆炸前的电子丰度有着重要的影响.本文在壳模型的基础上,首先计算¹³N基态到基态以及基态到不同激发态的Gamow-Teller(GT)跃迁强度,并将其与实验数据进行了比较.在理论计算的GT强度基础上,对不同温度和密度天体环境下¹³N的电子俘获率进行了细致的计算,并重点讨论基态到激发态的GT跃迁对电子俘获率变化的影响.结果表明,考虑基态到激发态的跃迁后,超新星的电子丰度下降,中微子能量损失增大.基态到激发态跃迁对电子俘获率的影响主要由低激发能级贡献. 关键词： Gamow-Teller跃迁 壳模型 电子俘获 激发态     

丰中子核108Ru的集体带结构

通过对重核²⁵²Cf自发裂变产生的瞬发γ谱的测量, 对丰中子核¹⁰⁸Ru的能级结构进行了研究. 基带、单声子γ振动带和一个二准粒子带分别得到了确认和扩展, 同时识别了一个新的边带, 初步认定为二声子γ振动带. TRS模型计算表明¹⁰⁸Ru核具有三轴形变，其形变参量为β₂～0.29, γ=－22°. 推转壳模型的计算结果表明¹⁰⁸Ru核基带回弯是由h_11/2轨道的一对中子发生角动量的顺排所致. 对二准粒子带的组态特性也进行了讨论.     

Isospin and F-spin symmetry structure in low-lying levels of 48，50Cr isotopes

The low-energy level structure and electromagnetic transitions of ^48.50Cr nuclei have been studied using the interacting boson model with isospin (IBM-3). A sequence of isospin excitation bands with isospin T = Tz, Tz 1and Tz 2 has been assigned, and compared with available data. According to this study, the 2^3 and 2^2 states are the lowest mixed symmetry states in ^48Cr and ^50Cr, respectively. In particular, the present calculations suggest that a combination of isospin and F-spin excitation can explain the structure in these nuclei. The transition probabilities between the levels are analysed in terms of isoscalar and isovector decompositions which reveal the detailed nature of the energy levels. The results obtained are in good agreement with recent experimental data.     

B（E2） value of even-even ^108-112Pd isotopes by interacting boson model-1

This work studies the systematic reduced transition probabilities B（E2）↓, intrinsic quadrupole moments and deformation parameters of Pd isotopes with even neutrons from N =62 to 66. The downward reduced transition probabilities B（E2）↓from gamma transition 8^＋to 6^＋, 6^＋ to 4^＋, 4^＋ to 2^＋ and 2^＋ to 0＋states of even-even108 112Pd isotopes were calculated by the Interacting Boson Model（IBM-1） and compared with the available previous experimental results. The ratio of the excitation energies of the first 4＋and the first 2＋excited states, R4/2, is also studied for the classification of symmetry of these nuclei. Furthermore we have studied systematically the transition rate R = B（E2： L＋ →（L 2）＋）/B（E2 ： 2＋ →0＋） of some of the low-lying quadrupole collective states in comparison with the available experimental data. The associated quadrupole moments and deformation parameters have been calculated. The results of this calculation are in good agreement with the corresponding available experimental data. The108 112Pd isotopes show the O（6） symmetry.     

142Ce的新激发态及其经验壳模型研究

利用420MeV⁸²Se轰击¹³⁹La引起的深部非弹反应和在束γ谱学方法研究了¹⁴²Ce的中高自旋激发态.识别出了激发能为2625,2995和3834keV的3个新能级,自旋、宇称分别被指定为8⁺,9^(－)和11^(－).发现这些能级非常好地符合N=84偶偶核转晕能级的系统性.利用经验壳模型计算了¹⁴²Ce的中高自旋激发态的激发能,计算结果比较好地重现了实验值.对它们的结构进行了讨论,表明在¹⁴²Ce的中高自旋激发态中以单粒子激发为主     

Investigation of the [лh9/2vi13/2－1] 10－ Isomer in 206At

The high-spin states of ²⁰⁶At have been studied in the ¹⁹⁷An (¹²C, 3n)²⁰⁶At reaction at ¹²C energies from 60 to 80 MeV using technique of in-beam γ-ray spectroscopy. Measurements of Tray excitation functions, γ-γ-t coincidences, and y-ray angular distributions were performed. A level scheme for ²⁰⁶At, including a 10^－ isomer with a measured half-life of 908±400 ns, was established for the first the. The characteristics of the 10^－ isomers in doubly edd ²⁰⁶At nuclei were stressed.     

Structure of the even-even ~(78-84)Kr isotopes within SD-pair shell model

The collective properties in the even-even ~(78-84)Kr isotopes have been studied within the framework of the SD-pair shell model. It is found that the collectivity of low-lying states in the even-even Kr isotopes can be described very well.     

Structure of the even-even ~(78-84)Kr isotopes within SD-pair shell model

The collective properties in the even-even 78-84Kr isotopes have been studied within the framework of the SD-pair shell model.It is found that the collectivity of low-lying states in the even-even Kr isotopes can be described very well.     

SD对壳模型下原子核形状相变（英文）

在SD 对壳模型的理论框架下讨论了原子核形状相变模式。研究结果表明,该理论模型可以把相互作用玻色子模型中U（5）-SU（3）以及U（5）-SO（6） 形状相变模式再现出来,相互作用玻色子模型中有关临界点对称性的特征也可以很好地描述。本文同时也发现原子核从振动到转动的形状相变可以通过改变相互作用强度来实现。The nuclear shape phase transitional patterns were studied in the SD-pair shell model. The results show that the transitional patterns similar to the U(5)-SU(3) and U(5)-SO(6) transitions in the interacting boson model can be produced. The signatures of the critical point symmetry in the interacting boson model are also produced approximately. It is also found that the shape phase transitional pattern between vibration and rotation can also be produced by changing the interactional strength.     

利用SD对壳模型讨论偶偶Mo核的集体性质(英文)

利用SD对壳模型讨论了偶偶Mo核低激发谱的集体性质。发现当SD对按照如下方法来确定，即对于两核子体系，通过对角化表面δ相互作用哈氏量，将SD对取为01^＋态和21^＋态，该模型可以合理的描述偶偶Mo核低激发态的集体性质。The SD-pair shell model was applied to study the even-even^94 Mo-^100 Mo. It is found that with the SD pair determined as 01^＋ and 21^＋ states of a two-valence-nucleon system with a Hamiltonian, which contains the single particle energy term and the Surface-Delta interaction （SDI） between like nucleons, the collectivity of low-lying states can be described reasonably.     

SD对壳模型：对结构对原子核集体性质的影响

在SD对壳模型的理论框架下, 利用变分法及TDA近似确定SD对结构. 结果发现利用上述方法确定SD对比以往通过对角化表面δ相互作用来确定SD对结构的方法可以更好地再现原子核低激发谱的集体性质.     

SD配对壳模型对质量数A~130区原子核的形状渡越研究(英文)

利用SD配对壳模型研究了质量数A~130区原子核的低激发态性质。为了减少参数,模型采用了等强度对力,取质子和中子对力强度等同近似,而非同类核子间的四极-四极相互作用强度取为同类核子间四极-四极相互作用强度的两倍。计算结果显示,模型的振动-转动和振动-γ不稳定运动的形状渡越特征与相互作用玻色子模型对应的形状相变特征基本吻合,从而说明SD配对壳模型是壳模型的一种合理近似。The SD-pair shell model is applied to analyze the evolution of low-lying states of even-even nuclei in A~130 mass region. In the model, the pairing and the quadrupole-quadrupole interactions are taken into account. The results show that there are clear signatures of the crossover from vibrational to rotational or from vibrational to the γ-soft shape phase.     

Studies of low-lying states of even-even Xe isotopes within the nucleon pair approximation

We study the relevance of nucleon pairs with higher spins, in addition to spin-zero and spin-two pairs (i.e., S D pairs), in low-lying states of even-even Xe nuclei. By including those higher-spin pairs in our configuration, we recalculate energy level schemes, elec trical quadrupole moments, magnetic moments and electric quadrupole transition rates, for low-lying states of even-even 128-142Xe nuclei. The agreement between our calculated results and the experimental data is substantially improved in compari...     

Level statistics for the even-even Yb isotopes

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.     

Level statistics for the even-even Yb isotopes

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.     

Systematic study of odd-mass 151-161Pm and 154,156Pm isotopes using projected shell model

Inspired by the availability of recent experimental as well as theoretical data on the energy levels of odd-mass ^151-161Pm and odd-odd ^154,156Pm, we applied the theoretical framework of the projected shell model to further understand the nuclear structure of these nuclei. The calculations closely reproduced the experimental data reported for the yrast bands of these isotopes by assuming an axial (prolate) deformation of ~0.3. Other properties along the yrast line, such as transition energies and transition probabilities, have also been discussed. Band diagrams are plotted to understand their intrinsic multi-quasiparticle structure, which turn out to be dominated by 1-quasiparticle bands for the odd-mass Pm isotopes and 2-quasiparticle bands for the doubly-odd Pm isotopes under study. The present study not only confirms the recently reported experimental/theoretical data, but also extends the already available information on the energy levels and adds new information regarding the reduced transition probabilities.