Decay Of Tl-178

The isotope Tl-178 was produced in a bombardment of Pd-102 by Kr-78 ions at 340 MeV. Reaction products were separated from the beam by the Berkeley Gas-Filled Separator, and implanted into a silicon strip detector where the subsequent alpha decays were measured. Four distinct alpha transitions from Tl-178 were observed correlated to 6.54 MeV alpha decays from the previously known Au-174 daughter. In some cases, the Au-174 decay was followed by a 5.815-MeV alpha decay. This new transition is tentatively assigned to the decay of the Ir-170 ground state. The half-life of Tl-178 was measured to be 254(-9)(+11) ms. The alpha decay branch of Au-174 was determined to be 90(6)%.