Alpha-decay Spectroscopy and Beta-delayed Fission of Neutron Deficient Isotopes 194,196At

A detailed nuclear-decay spectroscopy and the β-delayed fission of the neutron deficient isotopes 194,196At are presented in this work. An isotopic beam was produced using the selective Resonance Ionization Laser Ion Source (RILIS) and ISOLDE mass separator (CERN). The fine-structure α decay of 196At allowed the low-energy excited states in the daughter nucleus 192Bi to be investigated with new states being discovered. The β-decay branch was also derived with a value of b_β (196At)= 2.6(1) %. Further to this, the half-lives of 196At and 196Po were deduced, with values of 0.358(5) ms and 5.8(1) s respectively. Additionally, multipolarities were assigned to some of the γ transitions that were observed in 192Bi. A preliminary α-decay study of 194At was also carried out. A β-delayed fission study of 196At, and a preliminary βDF study of 194At were also performed. A mixture of symmetric and asymmetric fission fragments of mass distributions of the daughter isotope 196Po (populated by β decay of 196At) were deduced, based on the measured fission fragment energies. A βDF probability P_βDF (196At) = 9(1)×10^-5 was determined.