α decay of the new neutron-deficient isotope 205Ac

The new neutron-deficient isotope ²⁰⁵Ac was synthesized in the complete-fusion reaction ¹⁶⁹Tm(⁴⁰Ca, 4n)²⁰⁵Ac. The evaporation residues were separated in-flight by the gas-filled recoil separator SHANS in Lanzhou and subsequently identified by the α-α position and time correlation method. The α-decay energy and half-life of ²⁰⁵Ac were determined to be 7.935(30) MeV and 20-9+97 ms, respectively. Previously reported decay properties of the ground state in ²⁰⁶Ac were confirmed.