Alpha-Decay Properties of the New Osmium Isotopes, 170Os and 171Os

Borggreen and Hyde recently reported the discovery of three new α-emitting osmium isotopes, ¹⁷²Os, ¹⁷³Os, and ¹⁷⁴Os. The present study deals with a search for osmium nuclides with A<172. These osmium isotopes were produced by bombarding ¹⁵⁶Dy with the 160-MeV ²⁰Ne⁶⁺ beam from the Oak Ridge isochronous cyclotron. With the use of α spectroscopy and the helium gas-jet technique, two new α groups were observed. Their mass assignments and decay characteristics are as follows: (1) ¹⁷⁰Os, E_α=5.40+/-0.01 MeV, T₁₂=7.1+/-0.5 sec; and (2) ¹⁷¹Os, E_α=5.24+/-0.01 MeV, T₁₂=8.2+/-0.8 sec.