Structure of Se-72,Se-74 at high spin

Lifetimes of high spin states up to I-pi = 22(+) in the yrast positive pari ty bands have been measured to investigate the shape evolution with increas ing spin in Se-72,Se-74. The Q(t) values derived from these measurements in dicate that prolate shape stabilizes for Se-72, while a triaxial shape deve lops for Se-74 at higher spins. Comparison of the observed trend in Qt with spin for Se-72,Se-74 with that of the corresponding kryptones isotones emp hasizes the stability provided by N = 38 prolate shell gap even at high rot ational frequency.