The β delayed deuteron decay of ${}^6\mathrm{He}$ has been measured at the TISOL facility at TRIUMF. For the β-particle measurement a silicon-germanium telescope array has been used. To separate deuterons from $\alpha$ particles and to obtain the spectral form of the deuteron decay, a $d-\alpha$ coincidence technique has been employed using two opposite silicon detectors. The β branch has been determined from the geometry of the experiment and also by comparison with the well-known $\beta -\alpha$ decay modes of ${}^{16}\mathrm{N}$ and ${}^8\mathrm{Li}.$ A branching ratio of $(1.8\mathrm{}\pm 0.9)\times {10}^{-6}$ above the $\beta$ cutoff (350-keV deuteron laboratory energy) and $(2.6\mathrm{}\pm 1.3)\times {10}^{-6}$ for the entire spectrum has been determined for this decay. In the course of the measurement the half-life of ${}^6\mathrm{He}$ has been remeasured to be $T_{1/2}=0.810\mathrm{}\pm 0.008\hspace{0.5em}\mathrm{s}.$ High statistical accuracy in the deuteron spectrum has been obtained that allowed a comparison of the shape of the deuteron spectrum to theoretical predictions.

• Received 19 September 2001

DOI:https://doi.org/10.1103/PhysRevC.65.034310