The Mixing Ratio Of Gamma Transition Of Candidate Doublet Bands In 82Br And Systematic Study Of Antimagnetic Rotation Bands

Spontaneous breaking of symmetry is an important phenomenon in nature.Different symmetry breaking in atomic nuclei can lead to different rotational band structures.These new exotic motion modes have become a hot issue in the field of nuclear structure.In this paper,based on the mixing ratio of ΔI=1 gamma transition,the chiral double bands in the nucleus are studied.Besides,the antimagnetic rotation bands reported so far in nuclei are systematically studied,so as to deepen the understanding of exotic motion modes in nuclei.The main research contents include:(1)Calculate the gamma mixing ratio for the candidate chiral doublet bands in 82Br.Chiral symmetry in nuclei was first proposed by Frauendorf and Meng in triaxial deformed nuclei.In the experiment,it appears as a pair of observable rotational bands with the same parity near degenerate ΔI=1,namely the chiral double bands.So far,more than 50 pairs of chiral double bands have been found experimentally in the A～80,100,130 and 190 mass regions.The mixing ratio of gamma transitions has already played an important role in the determination of vibrational and wobbling bands.Therefore,the mixing ratio of 10 gamma transitions in the 82Br chiral double bands is calculated in this paper,and it is found that the mixing ratio is very small,and the E2 component is very small.The proportion is almost zero,the results support the interpretation of the 82Br chiral double bands,and it is also suggested that a small E2 proportion of ΔI=1 gamma transition between the chiral double bands can be a new criterion for the determination of chiral doublet bands.(2)The antimagnetic rotation bands are systematically studied.Since Frauendorf proposed antimagnetic rotation which is similar to the double-shears mechanism,22 candidate antimagnetic rotation bands have been found in 18 nuclei in the A～110 and 140 mass regions.In this paper,a statistic map of antimagnetic rotation nuclei has been produced.The energy spectra,electromagnetic transition properties and configuration of the antimagnetic rotation bands are systematically studied,and it is found that the spin and rotational frequency are almost linearly dependent;the value of B(E2)decreases with the increase of spin,and its value is usually about 0.1(eb)2;the.T(2)/B(E2)value increases with spin and is greater than 100 MeV-1(eb)-2.And it is predicted that there may be neutron holes(particles)in the A～80 mass region as "scissors" of antimagnetic rotation.