Experimental study of isospin mixing in 12C+n→ 13C (T=3/2) and 16O+n → 17O(T=3/2) resonances

Narrow resonances of 13C and 17O have been studied by a measurement of the total neutron cross sections of carbon and oxygen between 3 and 30 MeV. Employing the improved time-of-flight spectrometer at the Karlsruhe Isochronous Cyclotron and precise calibration methods, resonance cross sections were measured with an energy resolution of 1:2100 at 10 MeV and energy accuracies between 10-4 and 10-5. Resonance analyses of the measured data provided parameters for numerous narrow states of both isospins T--1/2 and T=3/2. These data in conjunction with information determine isospin mixing matrix elements. Results were obtained for the first five T=3/2 resonances in 17O and the first T=3/2 resonance in 13C. The obtained mixing matrix elements are compared with previous experimental results and shell-model predictions of this quantity