The half life of the 690 keV first excited state in 72Ge

Abstract

A 5 cm3 trapezoidal wrap-around Ge(Li) detector has been constructed to measure the half life of the 690 keV first excited state in 72Ge. The detector had an energy resolution of 4.7 keV FWHM for the 1332 keV gamma-rays from 60Co. The 690 keV level of 72Ge was excited by fast neutrons from the D(d,n) 3He reaction that impinged on the Ge(Li) detector. The half life of the state was determined from the distribution of time intervals between the detection of the internal conversion electrons from the EO transition of this level and the detection of the associated 3He particle. A value for the half life of 460 ± 13 nsec has been obtained.