ALPHA-DECAY PROPERTIES OF PB-181

The isotope Pb-181 was produced in Mo-92 bombardments of Zr-90 and, to gether with other reaction products, was passed through a recoil mass separator and implanted in a double-sided silicon strip detector for a lpha-particle assay. The half-life and energy of the main Pb-181 alpha transition were determined to be 45 (20) ms and 7065 (20) keV, respec tively. This Pb-181 E(alpha) agrees with one previously measured value [7044 (15) keV], but not with the one [7211 (10) keV] used as input t o the 1993 Atomic Mass Evaluation. The 6180-keV alpha transition assig ned to Tl-181 by Bolshakov et al. was observed, but the 6566-keV alpha particles ascribed to a 2.7-ms level in Tl-181 by Schneider were not.