Measurement of thermal neutron cross section and resonance integral for 148Nd(n,γ)149Nd reaction by using a 55Mn monitor

Thermal neutron cross section and resonance integral for the 148Nd(n,γ)149Nd reaction have been measured by the activation method using 55Mn monitor. The analytical grade MnO2 and Nd2O3 mixed with Al2O3 powder samples were irradiated in an isotropic neutron field of the 241Am-Be neutron source with and without a Cd-shield case. The activities produced in the samples were measured by a high resolution gamma ray spectrometry with a calibrated n-type Ge detector. The necessary correction factors for gamma ray self-attenuation, true coincidence summing effects, thermal, resonance neutron self-shielding effects and epithermal spectrum-shape factor were taken into account. Thermal neutron cross section and resonance integral for the 148Nd(n,γ)149Nd reaction were obtained relative to the reference values, σ0 = 13.3 ± 0.1 b and I0 = 14.0 ± 0.3 b for the 55Mn(n,γ)56Mn reaction. The thermal neutron cross section was measured to be 2.51 ± 0.13 b, and according to the definition of Cd cut-off energy at 0.55 eV, the resonance integral cross section was obtained to be 14.6 ± 1.3 b for the 148Nd(n,γ)149Nd reaction. These results are discussed and compared with previous measurements and the evaluated data. Thermal neutron cross section for 148Nd(n,γ)149Nd reaction is in good agreement with some experimental results and the evaluated data in JENDL-3.3 and JEFF-3.1.1. The existing experimental and evaluated data for the resonance integral are distributed from 10.5 to 48 b and the discrepancies between present result and some of old experimental data is within about 3-28%.