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

Precise measurements of lifetimes in the picosecond range of excited states in the stable even-A Sn isotopes ¹¹²,¹¹⁴,¹¹⁶,¹¹²Sn have been performed using the Doppler shift attenuation technique. For the first excited 2⁺ states in ¹¹²Sn, ¹¹⁴Sn and ¹¹⁶Sn 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.