Radioactivity of neutron deficient isotopes in the region N>82>Z

The α decay characteristics of 88 decay lines emanating from 74 isotopes are presented, including new α decay lines identified in the neutron deficient nuclides ¹⁵⁸Ta (E_α=5969±8 keV, t_1/2=46±4 ms), ¹⁵⁹Ta (E_α=5516±5 keV, t_1/2=1100±100 ms), ¹⁶⁰Ta (E_α=5313±5 keV, t_1/2=1700±200 ms), ¹⁶⁸Ir (E_α=6323±8 keV, t_1/2=161±21 ms, b_α=82±14%), and ¹⁷⁰Ir (E_α=6083±11 keV, t_1/2=830±300 ms, b_α=36±10%). Their correlations with other decay lines are discussed. The alpha decay of a high-spin isomer in ¹⁵⁷Ta has been discovered, with an energy of 7744±8 keV and a half-life of 1.7±0.1 ms, while the half-life of the corresponding isomeric alpha decay line of ¹⁵⁸W has been measured for the first time as 160±50 μs. First half-life and branching ratio measurements are also reported for the 5454±4 keV ¹⁵⁶Lu line (t_1/2=494±12 ms), ¹⁶²Re (b_α=85±9%), ¹⁶³Os (t_1/2=12_-7⁺¹¹ ms), ¹⁶⁶Ir (t_1/2=12±1 ms), ¹⁶⁷Ir (t_1/2=34±4 ms), the 6227±15 keV ¹⁶⁸Ir line (t_1/2=125±40 ms), and ¹⁷¹Ir (b_α=58±11%). New decay measurements for the proton emitter ¹⁵⁶Ta (E_p=1108±8 keV, t_1/2=375±54 ms, b_p=4.2±0.9%; E_p=1007±5 keV, t_1/2=144±24 ms) are presented. All energies have been measured using a consistent energy calibration procedure for protons and α particles. © 1996 The American Physical Society.