Electron Scattering, Isospin Mixing, and the Structure of the 12.71- and 15.11-MeV Levels inC12

Abstract

The structure and the degree of isospin mixing for the ${1}^{+}$ levels in $^{12}\mathrm{C}$ at 12.71 MeV ($T=0$) and 15.11 MeV ($T=1$) are determined from measured 180\ifmmode^\circ\else\textdegree\fi{}-electron-scattering form factors. The resulting charge-dependent isospin-mixing matrix element ranges from 130 to 165 keV depending on the theoretical model of the isoscalar form factor.