α decay of 273110: Shell closure at N=162

In bombardments of ²⁴⁴Pu with ³⁴S we discovered the α-decaying nuclide ²⁷³110. We conducted an extensive off-line search of the raw data for event sequences which fit the expected pattern of implantation in a position-sensitive detector and subsequent decay of ²⁷³110 and its descendants. We observed one three-member sequence of genetically linked α decays, resulting in E_α=11.35 MeV, a half-life of 0.3^+1.3_-0.2 ms, and a production cross section of about 0.4 pb for ²⁷³110. Other possible ²⁷³110 event chains were also observed. The measured α-particle energy for the N=163 nuclide ²⁷³110 provides direct evidence for a neutron shell closure at N=162.