Stability of oblate shapes in the vicinity of $N = Z = 34$ $^{68} Se :$ Bands in $^{69} Se$ and $^{67} As$

The

γ

-ray decay schemes of

^{69} Se

and

^{67} As

have been considerably extended using the

^{40} Ca (^{32} S {, 2 p n)}^{69} Se

and

^{40} Ca (^{32} S, α {p)}^{67} As

reactions at 100 MeV and

^{40} Ca (^{36} Ar, α {2 p n)}^{69} Se

and

^{40} Ca (^{36} Ar, 2 α {p)}^{67} As

reactions at 145 MeV, with the aim of studying oblate bands arising from the strong coupling of a valence

g_{9 / 2}

particle (or hole) to the oblate deformed ground state band of

^{68} Se .

A new

T_{1 / 2} = 12 \pm 2 ns J^{π} {= 9 / 2}^{+}

isomeric bandhead was identified in

^{67} As .

A transitional quadrupole moment of

Q_{0} = - 2.7 (6) e b

was deduced for the band built on the

{9 / 2}^{+}

isomer in

^{69} Se,

corresponding to a rigid oblate deformation of

β_{2} = - 0.4 (1),

consistent with theoretical predictions. However, it appears that the relevant oblate configurations in

^{69} Se

and

^{67} As

are not nearly so favored as they are in

^{68} Se,

and are rapidly crossed by prolate configurations that form the high spin yrast lines.

This publication has 16 references indexed in Scilit:

Stability of oblate shapes in the vicinity ofN=Z=3468Se:Bands in69Seand67As