Spin-Orbit Splitting Of C-13(Lambda)

The gamma -rays from the 1/2(-) and 3/2(-) doublet states at similar to 11 MeV to the ground state in C-13(Lambda) were successfully measured by using 72 NaI detectors to obtain the spin-orbit splitting energy with high precision. The (K-, pi (-)) reaction on an enriched C-13 target was used at the Brookhaven Alternate Gradient Synchrotron. The energy resolution for the 11 MeV gamma -rays is 340 keV FWHM which is much better than those obtained by using magnetic spectrometers (similar to2 MeV FWHM). The obtained small splitting energy of the 1/2- and 3/2- doublet states in C-13(Lambda) is about 150 keV (preliminary).