Parity Conservation in Nuclear Reactions: Search forαDecay of the 8.88-Mev State inO16

Abstract

A search has been carried out for the parity-nonconserving $\alpha$ decay of the 8.88-Mev ($2^{-}$) state in ${\mathrm{O}}^{16}$ by examining the alpha-particle spectrum following ${\mathrm{N}}^{16}$ $\beta$ decay. An upper limit of $\left(\frac{{\Gamma }_{\alpha }}{{\Gamma }_{\gamma }}\right)<\mathrm{}2\mathrm{}\times {10}^{-6\mathrm{}}$ was determined which is shown to lead to the estimate that ${\mathfrak{F}}^2\lesssim 2\times {10}^{-12\mathrm{}}$. The alpha-particle group corresponding to disintegration of the broad 9.58-Mev ($1^{-}$) state was observed and the $log\mathrm{ft}$ for the $\beta$ decay to this state found to be 6.8±0.1, the slow transition rate being in accord with a shell-model prediction that the 9.58-Mev state is due to a three-nucleon excitation. The shape of the alpha spectrum was fitted with a Breit-Wigner analysis.