Measurements of isomeric cross sections for (n,2n) reaction on 140Ce, 142Nd and 144Sm isotopes around 14 MeV

In this study, activation cross sections were measured for the 140Ce(n,2n)139mCe, 142Nd(n,2n)141mNd and 144Sm(n,2n)143mSm reactions at six different neutron energies from 13.5 and 14.8 MeV. The fast neutrons were produced via the 3H(d,n)4He reaction on SAMES T-400 neutron generator. The cyclic activation technique was used. Induced γ activities were measured by a high-resolution γ-ray spectrometer with a high-purity germanium (HpGe) detector. Corrections were made for the effects of γ-ray attenuation, dead-time and fluctuation of neutron flux. For these reactions, statistical model calculations for which the pre-equilibrium emission effects are taken into consideration were also performed between 13.6 and 14.8 MeV energy range. Theoretical excitation functions and experimental results were plotted together with previous works.