The study of the odd-proton nucleus 169Ta at high spin

Abstract

The level structure of 169Ta has been studied using the reactions 155Gd( 19F,5n), E = 85.5–100 MeV and 122 Sn( 51 V,4 n), E = 223 MeV . Four rotational bands of 169Ta have been identified with assignments 1 2 −[541] , 9 2 −[514] , 5 2 +[402] , 1 2 +[411] and a decoupled band was identified but not assigned to any configuration. Different configurations are observed to have different band-crossing frequencies and these differences are consistent with configuration-dependent deformation driving effects. The crossing frequency of the band based on the 1 2 −[541] configuration is deduced to be 0.305MeV/ħ which is delayed by about 55 keV in comparison with the yrast bands of its even neighbours. The first band crossings of 169Ta are attributed to the alignment of a pair of i 13 2 quasineutrons, while the second band crossings may correspond to h 11 2 two-quasiproton alignment. The deformation driving effects of quasiparticle orbitais, B( M1)/ B( E2) values of the 9 2 −[514] and 5 2 +[402] bands and the band crossings in 169Ta are discussed.