γ -Ray spectroscopy above the 9+ isomeric state in the N = Z nucleus 66As

Abstract

Excited states above the 9+ isomer in the oddodd N = Z nucleus 66As were studied by employing the 40Ca(28Si, pn) fusion-evaporation reaction at the Accelerator Laboratory of the University of Jyväskylä, Finland. A key method in this study was the use of conversion electrons emitted in the de-excitation of the isomeric state in 66As as a tag for prompt γ rays. Several new states have been added to the 66As level scheme, which was extended up to a tentative spin of 23h¯. The previously reported even-spin yrast band has been reassigned to have odd spin values. The odd spin states above the 9+ isomer are compared with shell-model calculations using the jj44b and JUN45 interactions. Additionally, the recoil-β tagging efficiency of the recently developed scintillator detector named Tuike has been determined experimentally for the first time.