Two-neutron alignment and shape changes in As-69 - art. no. 027303

The nucleus As-69 was Studied using the Ca-40(S-32,3p)As-69 reaction at a b eam energy of 105 MeV. An extension of the band built on the g(9/2) orbital was observed to exhibit a band crossing at a rotational frequency of 0.511 MeV with an associated alignment of 7 (h) over bar. This alignment is inte rpreted as being due to a pair of g(9/2) neutrons. Total Routhian surface c alculations have been carried out which confirm that the shape of this nucl eus changes from oblate at low spin to a triaxial prolate shape at intermed iate spin.