Structure of 𝐴 ∼130 nuclei in La–Ce region

Pramana

Tumpa Bhattacharjee1¹ 

[1] Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata 700 064, India$$

关键词: Clover detector array;    measured 𝐸𝛾;    𝐼𝛾;    DCO (directional correlation of oriented states);    polarization;    lifetime measurement with Dopper shift attenuation method;    reduced transition probability 𝐵(𝑀1);    shell model;    Tilted Axis Cranking calculation;    total Routhian surface calculations;    backbending;    magnetic rotation bands.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

The variety of shapes and structures, observed in light rare earth $A ∼ 130$ nuclei, have been discussed in view of different angular momentum coupling schemes and their interplay that comes into effect at high spin. The 𝑁 = 79 and 80 isotopes in La–Ce region, produced via fusion evaporation reaction, have been studied using the Indian National Gamma Array (INGA) consisting of 18 clover HPGe detectors. Two nearly degenerate 𝛥 𝐼 = 1 bands have been observed at high spin of 137Ce and a triaxial deformation of 𝛾 = ± 30°$ has been assigned to the bands, from the total Routhian surface (TRS) calculations. The high-spin candidates of the yrast band of 138Ce show signature splitting both in energy and 𝐵(𝑀1)/𝐵(𝐸2) values. The bandcrossing due to the alignment of a pair of ℎ11/2 proton particles has been conjectured at ħ ω ∼ 0.3 MeV, from the single-particle Routhians obtained from TRS calculations. Lifetime measurements by Doppler shift attenuation method (DSAM) has been carried out and from the estimated reduced transition probability 𝐵(𝑀1), the 𝛥 𝐼 = 1 band in 138Ce has been characterized as a magnetic rotation (MR) band. The rise in the values of 𝐵(𝑀1), for the higher spin candidates of the band, has been conjectured as the reopening of a different shear at the top of the Band B1. The characteristic of the MR bands in 𝐴 ∼ 130 region has been discussed in the light of a phenomenological calculation and compared to the MR bands in other mass regions.

【 授权许可】

Unknown