Reinvestigation of the decay properties of 261,262Bh at the gas-filled recoil separator SHANS2

The isotopes 261,262Bh were reinvestigated by using the cold fusion reaction 54Cr+209Bi. The evaporation residues were separated by the gas -filled recoil separator SHANS2 (Spectrometer for Heavy Atoms and Nuclear Structure -2) and identified by means of the recoil-alpha-correlation method. The alpha-decay properties of 261,262Bh were measured and the results are consistent with the previously reported values. Based on the measured half-lives, the existence of two distinct states of 262Bh was confirmed, whereas 261Bh lacked any isomer with alpha-decay properties. Two spontaneous fission events potentially from 262Bh and/or 261Bh were detected and the production cross sections at beam energies of 264.1 and 270.4 MeV were obtained.