Jing Ye Zhang

First observation of a rotational band in odd 50Sn nuclei: 111Sn.

Proton particle-hole excitations across the {ital Z}=50 closed shell are responsible for inducing low-lying prolate deformation in even-{sub 50}Sn nuclei. Although related rotational bands have been studied in odd-{sub 51}Sb isotopes involving the coupling of a valence proton, none had been found in odd-{sub 50}Sn nuclei. Using the {sup 96}Ru({sup 19}F,3{ital pn}) reaction, a decoupled band has been observed in {sup 111}Sn extending to a spin-parity of (67/2{sup {minus}}) and feeding out at 23/2{sup {minus}} into spherical states. This band is interpreted as the {nu}{ital h}{sub 11/2} valence orbital coupled to the deformed [({pi}{ital g}{sub 7/2}){sup 2}{direct_product}({pi}{ital g}{sub 9/2}){sup {minus}2}] {sup 110}Sn core. The extracted band properties are compared to those in {sup 111}Sb with the same deformed core.