Untersuchung des Niveauschemas von Nb93 durch Messung der Gammastrahlung nach der inelastischen Streuung schneller Neutronen

Fast neutrons from a nanosecond-pulsedD(d, n)He³ neutron source were scattered from Nb⁹³. The gamma spectrum arising from inelastic scattering was measured in a high resolution Ge(Li)-spectrometer. In order to obtain low background a time gate technique was used. About 44 gamma lines could be found between 150 keV and 2.2 MeV in the single spectrum. In addition gamma-gamma-coincidences were investigated with a NaJ- and a Ge(Li)-detector. By these means it was possible to identify almost all gamma transitions and to receive a nearly complete level scheme of Nb⁹³ up to 2.2 MeV. The experimental cross sections for the population of the levels by the (n, n′)-reaction were compared with the results of the Hauser-Feshbach theory using the optical model transmission coefficients of Lindner and Meldner. From this and from the observed gamma transitions proposals for spin- and parity-assignments of the energy levels are given.