Primary gamma transitions in 159Gd after isolated resonance neutron capture

Abstract

Energy levels and transitions in 159Gd were studied by means of radiative capture of resonance neutrons at 12 isolated resonances of 158Gd. The time-of-flight technique was used on an enriched target at the IBR-30 reactor at JINR Dubna. A total of 80 primary gamma-transitions were recorded and their absolute intensities were determined resulting in the observation of 1 2 ±, 3 2 ± levels up to 2.4 MeV. The observed level density is described in terms of the constant temperature Fermi gas model. The neutron binding energy was determined at (5943.1±0.2) keV. The photon strength is derived and compared with a giant dipole resonance of standard Lorentzian shape for E1 and M1 radiation. The sum of observed gamma-ray intensity amounts to about 30% of the total gamma width. The remaining gamma-ray intensity above 2.4 MeV is estimated by extrapolating the level density and photon strength models to high excitation energies.