Facility and method for studying two-step γ cascades in thermal neutron capture

A dedicated facility for γ-γ coincidence studies of (n,γ) reactions at thermal neutron energies is described. The facility and the adopted method of data acquisition make it possible to determine intensities of two-step γ cascades proceeding from the neutron capturing state to a set of selected low-lying levels via resolved and unresolved intermediate levels occurring between the neutron capturing state and a final level of interest. A detailed description of the method for accumulating the γ-ray spectra, characterizing these two-step cascades, is given including procedures for corrections of these spectra for various kinds of backgrounds and distortions.