A=90质量区能级结构与系统学研究  

Structural Investigation in A≈90 Mass Region and Comparison in Its Vicinity

作　　者：吴义恒[1,2] 陆景彬 任臻[1] WU Yiheng;LU Jingbin;REN Zhen(College of Physics,Jilin University,Changchun 130012,China;School of Electronic Engineering and Intelligent Manufacturing,Anqing Normal University,Anqing 246133,Auhui,China)

机构地区：[1]吉林大学物理学院,长春130012 [2]安庆师范大学电子工程与智能制造学院,安徽安庆246133

出　　处：《原子核物理评论》2023年第4期519-526,共8页Nuclear Physics Review

基　　金：国家自然科学基金资助项目(11075064,11775098,12075169,U1867210,2018YFA0404403);安徽省高校自然科学重点研究项目(2023AH050481,2023AH050514)。

摘　　要：在原子核高自旋态的能级结构研究中,处于A≈90质量区的原子核一直是核结构研究的热点,其质子数和中子数分别接近Z=38半幻数与N=50幻数。本工作基于近年来A=90核区实验结果,研究该质量区原子核的单粒子激发,核心激发,高自旋侵入态和同质异能态的特征。通过调研发现,奇-A核素的较低自旋能级可以解释为其相邻偶偶核与一个价核子耦合而成。该核区2_(1)^(+)态能级与E_(4_(1)^(+))/E_(2_(1)^(+))比值的演化特征表明,N=56半闭壳在Z=40(41)核素对能级结构影响显著,随着质子数的增加Z≥42时影响减弱甚至消失。此外,低自旋及中等自旋能级结构中强E2跃迁主要涉及(f_(5/2),p_(3/2),p_(1/2),g_(9/2))轨道耦合,而对于高自旋态能级结构强M1跃迁主要由(f_(5/2),p_(3/2),p_(1/2))轨道质子激发与g_(9/2)轨道中子跨越N=50闭壳跃迁到d5/2轨道耦合产生。奇-A核素的N=50(51)同中子素中的一些同质异能态来源于单中子或单质子与g_(9/2)轨道质子对顺排耦合。In the investigations of the level structure of A≈90 nuclei,whose numbers of protons and neutrons are close to the Z=40 semimagic number and N=50 magic number,have become a hot spot in nuclear physics.The aim of this work is to further probe the characteristics of single-particle excitation,core breaking,high-j intruder states and isomeric states in the A≈90 mass region based on the existing experimental results.Investigations show that the low energy levels of the odd-A nuclei originate from their neighboring even-even nuclei coupled to a valence nucleon.The systematics of the 2_(1)^(+) excitation energies and the values of E_(4_(1)^(+))/E_(2_(1)^(+)) indicate that the N=56 subshell closure may appear at Z=40(41)and disappear for Z>42 nuclei.Furthermore,in this mass region,the strong E2 transitions at low or medium spins are interpreted as the recoupling of the pure protons in(f_(5/2),p_(3/2),p_(1/2),g_(9/2))orbits,and the strong M1 transitions are explicated by moving proton from the(f_(5/2),p_(3/2),p_(1/2))orbits to the g_(9/2) orbit,coupling to a neutron excitation from the g_(9/2) orbit across N=50 closed shell into the d_(5/2) orbit.The isomeric states in odd-A nuclei with N=50(51)can be interpreted as a spin-aligned configuration in which a single neutron or proton couples with a fully aligned proton pair in the πg_(9/2) orbit.

关 键 词：核心激发 壳模型 耦合模型 

分 类 号：O571.6[理学—粒子物理与原子核物理]