Lifetime measurement in 176Lu and its astrophysical consequences

Because of its temperature-dependent half-life, Lu-176 represents an important thermometer for the slow neutron capture process (s process) which accounts for the origin of about half of the abundances between Fe and Bi. This interpretation of the observed Lu-176 abundance has been improved by a new lifetime measurement of the J(pi) = 5(-) state at 838 keV in Lu-176. The present limit of tau(838) greater than or equal to 10 Ps provides a more stringent constraint for the thermal equilibration between the long-lived ground state (t(1/2)=41 GYr) and the short-lived K isomer at 123 keV (t(1/2)=3.7 h), and, hence, for the resulting estimate of the temperature during shell helium burning in red giant stars. [S0556-2813(98)07210-0].