Strong effect of isospin mixing inO16

Abstract

The intensity ratio of the ground state (${2}^{\ensuremath{-}}$) to the 0.30 MeV (${3}^{\ensuremath{-}}$) state of $^{16}\mathrm{N}$ as measured in the $^{17}\mathrm{O}(d,^{3}\mathrm{He})$ reaction and the intensity ratio of their analog states at 12.97 and 13.26 MeV in $^{16}\mathrm{O}$ as measured in the $^{17}\mathrm{O}(d,t)$ and $^{17}\mathrm{O}(^{3}\mathrm{He},\ensuremath{\alpha})$ reactions consistently differ by about 50%. A largely model independent analysis of this isospin mixing effect in $^{16}\mathrm{O}$ suggests \ensuremath{\ge} 17% mixing of the ${2}^{\ensuremath{-}}$ states at 12.97 ($T=1$) and 12.53 MeV ($T=0$) as its dominant source, in which case a lower limit of the isospin mixing matrix element of (155 \ifmmode\pm\else\textpm\fi{} 30) keV is obtained.NUCLEAR REACTIONS $^{17}\mathrm{O}(d,^{3}\mathrm{He})$, $^{17}\mathrm{O}(d,t)$, $E=52$ MeV; $^{17}\mathrm{O}(^{3}\mathrm{He},\ensuremath{\alpha})$, $E=36$ MeV. Measured $\ensuremath{\sigma}(\ensuremath{\theta})$ and relative population of the ground state (${2}^{\ensuremath{-}}$) and the 0.30 MeV (${3}^{\ensuremath{-}}$) state of $^{16}\mathrm{N}$, and their analog states in $^{16}\mathrm{O}$ at 12.97 and 13.26 MeV, respectively.NUCLEAR STRUCTURE $^{16}\mathrm{O}$, deduced isospin mixing of the ${2}^{\ensuremath{-}}$ states at 12.97 MeV ($T=1$) and 12.53 MeV ($T=0$).