Effects of Rotation, Blocking and Octupole Deformation on Pairing Correlations in the U and Pu Isotopes

转动、堵塞效应和八极形变对U和Pu同位素对关联的影响

including octupole correlations in the Nilsson potential,the ground-state rotational bands in the reflection-asymmetric(RA)nuclei are investigated by using the cranked shell model(CSM)with the monopole and quadrupole pairing correlations treated by a particle-number-conserving(PNC)method.The experimental kinematic moments ofinertia(Mols)for alternating-parity bands in the even-even nuclei ^(236,238)U and ^(238,240)Pu,as well as paritydoublet bands in the odd-A nuclei 237U and 239Pu are reproduced well by the PNC-CSM calculations.The higher J(1)for the intrinsic s=-i bands in ^(237)U and ^(239)Pu,compared with the s=+1 bands in the neighboring even-even nuclei ^(236,238)U and ^(238,240)Pu,can be attributed to the pairing gap reduction due to the Pauli blocking effect.The gradual increase of J(i)versus rotational frequency can be explained by the pairing gap reduction due to the rotation.The Mols of reflection-asymmetric nuclei are higher than those of reflection-symmetric(RS)nuclei at low rotational frequency.Moreover,the inclusion of a larger octupole deformation 8,in the RA nuclei results in more significant pairing gap reduction compared with the RS nuclei.

通过在Nilsson势中引入八极关联,基于推转壳模型(CSM)下处理对相互作用的粒子数守恒方法(PNC),研究了反射不对称原子核的基态转动带。PNC-CSM的计算结果重现了轻锕系区偶偶核^(236,238)U和^(238,240)Pu的交替宇称带,以及奇-A核^(237)U和^(239)Pu的宇称双重带的转动惯量实验值。奇-A核^(237)U和^(239)Pu的s=-i内禀转动带的转动惯量较相邻偶偶核^(236,238)U 和^(238,240)Pu的s=+1转动带显著增加,这主要归因于泡利堵塞效应导致中子体系的对关联衰减。U和Pu同位素中,转动惯量随着转动频率缓慢增加则是由于对关联随着角频率的增加而衰减所造成的。在低频率区,反射不对称原子核的转动惯量明显高于相对应的反射对称原子核的转动惯量。并且与反射对称原子核相比,较大的八极形变将导致反射不对称原子核体系的对关联衰减更加明显。