THE STUDY OF THE ODD-PROTON NUCLEUS TA-169 AT HIGH-SPIN

The level structure of 169Ta has been studied using the reactions (Gd( F,5n))-Gd-155-F-19, E = 85.5-100 MeV and (Sn(V,4n))-Sn-122-V-51, E = 2 23 MeV. Four rotational bands of 169Ta have been identified with assig nments 1/2-[541], 9/2-[514], 5/2+[402], 1/2+[41 1 ] and a decoupled ba nd was identified but not assigned to any configuration. Different con figurations are observed to have different band-crossing frequencies a nd these differences are consistent with configuration-dependent defor mation driving effects. The crossing frequency of the band based on th e 1/2-[541] configuration is deduced to be 0.305 MeV/HBAR which is del ayed by about 55 keV in comparison with the yeast bands of its even ne ighbours. The first band crossings of 169Ta are attributed to the alig nment of a pair Of i13/2 quasineutrons, while the second band crossing s may correspond to h11/2 two-quasiproton alignment. The deformation d riving effects of quasiparticle orbitals, B(Ml)/B(E2) values of the 9/ 2-[514] and 5/2+[402] bands and the band crossings in 169Ta are discus sed. [GRAPHICS]