First confirmation of the discovery of element 106

Abstract

We have confirmed the 1974 report of the discovery of element 106 by Ghiorso et al. The 0.9-s $^{263}106$ was produced at the Lawrence Berkeley Laboratory 88-Inch Cyclotron via the $^{249}\mathrm{Cf}$${(}^{18}$O,4n${)}^{263}$106 reaction using a beam of 95-MeV $^{18}\mathrm{O}$ ions. Positive identification of $^{263}106$ was made by observing its \ensuremath{\alpha} decay followed closely in time by the \ensuremath{\alpha} decay of the $^{259}\mathrm{Rf}$ daughter. Our rotating wheel system was used in a special parent-daughter mode with six pairs of detectors. The $^{263}106$ half-life, \ensuremath{\alpha}-decay energy, and production cross section are consistent with those measured by Ghiorso et al. The half-life and \ensuremath{\alpha}-decay energies of the $^{259}\mathrm{Rf}$ daughter events are also consistent with those previously published.