Nuclear structure of low-lying 0+ states in Ge and Se isotopes

Abstract

The following meanlives of levels in72Se have been measured using the recoildistance Doppler-shift method:Τ(2+, 862 keV)=3.1±0.6 ps,Τ(2+′, 1317 keV)=12.5±2.6 ps,Τ(4+, 1638 keV)=1.2±0.3 ps andΤ(6+, 2469 keV)≦0.7 ps. These meanlives yield sixB(E2) values which are discussed together with the known data of the depopulation of the excited 0+′ state at 937 keV. Systematics of 0+′ states in the mass region 70≲A≲100 show that the low excitation energy of the 0+′ states is correlated with subshell closures. This suggests that the previous interpretation of the 0+′ state in72Se as a rotational band head is questionable.