alpha-Decaying neutron-deficient nuclei At-195g,At-195m

New neutron-deficient isotopes At-195g,At-195m, which are far away from the S-stability line, have been produced in the Er-164(Ar-36,p4n)At-195g,At-195m(E-lab = 199 MeV) reaction. The reaction products recoiling out of the Er-164 (62.4% enriched) target were separated from the incident Ar-35 beam by using a gas-filled-type recoil separator (GARIS) and were implanted onto a double-sided position-sensitive silicon detector (PSD) placed at the focal-plane of the GARIS after traversing a large micro-channel plate (MCP) assembly. The large-area MCP assembly was set 60.8 cm upstream from the PSD to measure the time of flight (TOF) and to roughly estimate the masses of the reaction products. A pulsed beam with a repetitive mode of 5-ms Beam-On and 5-ms Beam-Off was used. The fusion evaporation products were identified on the basis of genetic correlations in the evaporation residue-initiated alpha-decay chains. As a result, the new activity with a half-life of 84(-14)(+20) ms and an alpha-energy of 7089 +/- 30 keV is assigned to the decay of the ground state of At-195 (At-195g). Another new alpha line with a half-life of 26(-9)(+31) ms and an alpha-energy of 7185 +/- 30 keV is assigned to the decay of an isomeric state in At-195 (At-195m).