Study Of Antimagnetic Rotation In ^107,109,111Cd Using A Particle Number Conserving Method Based On Cranked Shell Model

The lowest negative parity bands of odd-A nuclei 107,109,111Cd in A～110 mass region are investigated by using the cranked shell model with pairing correlation treated by the particle-number-conserving method.The experiment moments of inertia J(1)and alignments ix can be reproduced well by the present calculation,the systematic features of the backbanding area in vh11/2 bands with the increase of neutron numbers are shown as well.By comparing the experiment values and the calculation values in the present work,the vh11/2 band in 107Cd observed by experiment is confirmed as the second backbending caused by neutron alignment,while the first backbending appears in the rotational frequency about 0.47 MeV which is caused by a pair of d5/2 neutrons.The change of the occupation probability of energy levels near the Fermi surface with rotational frequency and the contribution of the orbitals to the alignments are also calculated.The present calculated results manifest the backbending of the vh11/2 bands in 107,109,111Cd are all caused by a pair of aligned h11/2 neutrons.The backbending in 107,109Cd is mainly caused by[550]1/2-and[541]3/2-orbitals,while the backbending in 111Cd is mainly caused by[541]3/2-and[532]5/2orbitals.In order to further explore the antimagnetic rotation in 107,109,111Cd,the change of the electric quadrupole transition reduced probability B(E2)values in three nuclei has been calculated in the present work.The calculated B(E2)values decrease with the increasing rotational frequency,which are consistent with the experimental characteristic of antimagnetic rotation.The present study also calculates the angular momentum vectors of the proton hole and the neutron particle in 107,109,111Cd vh11/2 bands,and investigates the two-shears-like mechanism in these three nuclei.According to the antimagnetic rotation characteristic manifested by the backbending of the vh11/2 band in 107Cd as well as the systematic features in odd-A Cd isotopes,the part after the backbending in 107Cd vh11/2 band with the πg9/2-2(?)vh11/23 configuration is suggested as a candidate antimagnetic rotation band.