A Phoswich Detector System to Measure Sub-Second Half-Lives using ICF Reactions

The $^{\mathrm{3}}$H(t,$\gamma )^{\mathrm{6}}$He cross section has not been measured at any bombarding energy due to the difficulties of simultaneously producing both a tritium beam and target at accelerator labs. ~An alternative technique may be to use an ICF tt implosion at the OMEGA Laser Facility. The $^{\mathrm{3}}$H(t,$\gamma )^{\mathrm{6}}$He cross section could be determined in situ by measuring the beta decay of $^{\mathrm{6}}$He beginning a few milliseconds after the shot along with other ICF diagnostics. A dE-E phoswich system capable of surviving in the OMEGA target chamber was tested using the SUNY Geneseo pelletron to create neutrons via $^{\mathrm{2}}$H(d,n)$^{\mathrm{3}}$He and subsequently $^{\mathrm{6}}$He via $^{\mathrm{9}}$Be(n,$\alpha )^{\mathrm{6}}$He in a beryllium target. The phoswich dE-E detector system was used to select beta decay events and measure the 807 ms half-life of $^{\mathrm{6}}$He. It is composed of a thin, 2 ns decay time dE scintillator optically coupled to a thick, 285 ns E scintillator, with a linear gate to separate the short dE pulse from the longer E tail. Funded in part by a grant from the DOE through the Laboratory for Laser Energetics.