α decay of a new isotope 209Th

The new neutron deficient isotope 209Th has been produced in the reaction of 32S on 182W at beam energy of 171 MeV. Evaporation residues were separated in flight from beam by a JAERI recoil mass separator, and implanted in a position sensitive strip detector. The genetic correlation of α-decay events, their energies and half-lives has been used to identify isotopes. An α-decay energy and a half-life of 209Th have been determined to be 8.080(50) MeV and 3.8-1.5+6.9 ms, respectively. copyright 1996 The American Physical Society