Decay of the 6.18-MeVJπ=0+Level ofBe10

Abstract

The reaction ${\mathrm{Be}}^9(d, p){\mathrm{Be}}^{10}$ (at $E_d=3.25\mathrm{}$ MeV) has been used to investigate the decay of the 6.18-MeV $J^{\pi }=0^{+}$ level of ${\mathrm{Be}}^{10}$. Both of the $\gamma$-ray transitions 6.18→5.96 and 6.18→3.37 have been observed by means of $\gamma -\gamma$ coincidence experiments using Ge(Li) and NaI(Tl) detectors. The mean life of the 6.18-MeV state is found to be ${1.1}_{-0.3\mathrm{}}^{+0.4\mathrm{}}$ psec from a Doppler-shift measurement on the 6.18→5.96 transition. It is concluded that the 6.18→5.96 transition takes place mainly to the $J^{\pi }=1^{-}$ component of the $J^{\pi }=(1^{-}, 2^{+})$ 5.96-MeV doublet and has an energy of 219.4±0.3 keV. The intensities of proton groups leading to levels of ${\mathrm{Be}}^{10}$ in the ($d, p$) reaction at $E_d=3.25\mathrm{}$ MeV were determined with a Buechner spectrograph By combining the present results with previous measurements on the 6.18-MeV $E0\mathrm{}$ ground-state transition, the branching ratios (in%) from the 6.18-MeV state to the states at 5.96 MeV ($J^{\pi }=1^{-}$), 3.37 MeV ($J^{\pi }=2^{+}$), and 0 MeV ($J^{\pi }=0^{+}$) are found to be 4.6±1.5, 95±2, and 0.24±0.08, respectively. The significance of these results is discussed. Incidental results are a value of 169.25±0.04 keV for the ${\mathrm{C}}^{13}$ 3.85→3.68 transition and a meanlife of 2.0±0.6 psec for the ${\mathrm{B}}^{10}$ 2.15-MeV level.