E2andM1Matrix Elements inB10

Abstract

$\ensuremath{\gamma}$-ray decay of the ${\mathrm{B}}^{10}$ 2.15- and 3.59-MeV levels was studied following population via the ${\mathrm{B}}^{11}({\mathrm{He}}^{3}, \ensuremath{\alpha}){\mathrm{B}}^{10}$ reaction at ${E}_{{\mathrm{He}}^{3}}=2.6$ MeV. The $\ensuremath{\gamma}$ rays were detected in coincidence with $\ensuremath{\alpha}$ particles observed in an axially symmetric silicon detector centered at 180\ifmmode^\circ\else\textdegree\fi{} to the beam. $\ensuremath{\gamma}$-ray branching ratios were extracted for both levels. From the angular distributions of the decay $\ensuremath{\gamma}$ rays, results were obtained for the $\frac{E2}{M1}$ mixing ratios $x$ of the decay of the ${2}^{+}$ 3.59-MeV level to the ${3}^{+}$ ground state, the ${1}^{+}$ 0.72-MeV level, and the ${1}^{+}$ 2.15-MeV level, respectively, as follows: $+0.31<x<+2.1$, ${x}^{\ensuremath{-}1}=+(0.11\ifmmode\pm\else\textpm\fi{}0.10)$, $x=\ensuremath{-}(0.38\ifmmode\pm\else\textpm\fi{}0.09)$, all pertaining to $\ensuremath{\Delta}T=0$ transitions. For the decay of the 2.15-MeV level to the 0.72-MeV level, $x=\ensuremath{-}(0.29\ifmmode\pm\else\textpm\fi{}0.05) or \ensuremath{-}(3.39\ifmmode\pm\else\textpm\fi{}0.55)$. Combining these results with previous work gives information on the magnitudes as well as the relative phases of the $M1$ and $E2$ matrix elements considered. These results are compared with the predictions of the independent-particle model.