New lifetime measurements in the stable semimagic Sn isotopes using the Doppler-shift attenuation technique.

Abstract

Precise measurements of lifetimes in the picosecond range of excited states in the stable even-A Sn isotopes 112;114;116;122 Sn have been performed using the Doppler shift attenuation technique. For the rst excited 2 + states in 112 Sn, 114 Sn and 116 Sn the E2 transition strengths deduced from the measured lifetimes are in disagreement with the previously adopted values. They indicate a shallow minimum at N = 66 in contrast to the maximum at mid-shell predicted by modern shell model calculations.Financial support from the Spanish Ministerio de Ciencia e Innovaci on under contracts FPA2007-66069 and FPA2009-13377-C02-02, and the Australian Research Council Discovery Scheme, grant no. DP0773273.Peer Reviewe