Coincidence Studies of the Thermal Neutron Capture Gamma Rays of Chromium

Abstract

The gamma-ray cascades which follow thermal neutron capture in chromium have been investigated by means of the measurement of coincidences between gamma rays detected by a three-crystal pair spectrometer and a single NaI crystal. Samples of normal chromium and chromium enriched in ${\mathrm{Cr}}^{50}$ and ${\mathrm{Cr}}^{53}$ were used. The following assignments of gamma rays to individual isotopes have been made. ${\mathrm{Cr}}^{51}$: 8.499, 7.36, 6.34, 6.12, 5.46, and 5.18 Mev; ${\mathrm{Cr}}^{53}$: 7.929, 7.36, 5.61, and 5.26 Mev; ${\mathrm{Cr}}^{54}$: 9.716, 8.881, 7.097, 6.872, 6.644, 6.31, 6.00, and 4.83 Mev. A number of features of the de-excitation of the energy levels populated by these transitions are established.