The θ-decays of neutron deficient actinium (218,219Ac) and protoactinium (221Pa) nuclides produced in the 16O-bombardment of 205TI and 209Bi have been studied using a gas-filled recoil isotope separator (GARIS). Their α-decays were detected with a large Si counter placed at a focal plane of GARIS. The α-decay energy of 221Pa has been measured for the first time to be Eα = 9.08 ± 0.03 MeV. The half-lives of 221Pa, 218Ac and 219Ac were determined more precisely than those reported previously; they are 5.9 ± 1.7, 1.06 ±0.09 and 11.8 ±1.5 μs, respectively. The present value for 219Ac is significantly different from the previous measurement. The reduced α-widths of N = 130 isotones are compared with the shell model calculations.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics