Measurements of neutron total cross-sections and resonance parameters of niobium using pulsed neutrons generated by an electron linac

Abstract

We measured neutron total cross-sections of natural niobium in the neutron energy region from 0.05 to 300 eV by using the time-of-flight method at the Pohang Neutron Facility, which consists of an electron linear accelerator, a water-cooled tantalum target with a water moderator, and a 12-m long time-of-flight path. A (6)Li-ZnS(Ag) scintillator with a diameter of 12.5 cm and a thickness of 1.6 cm was used as a neutron detector, and a high purity natural niobium metallic disc with a diameter of 8.0 cm and a thickness of 15.0 mm thickness was used for the neutron transmission measurement. Notch filters composed of Co, In, Cd were used to estimate the background level and to calculate the length of neutron flight path. In order to reduce the gamma-ray background from bremsstrahlung and from neutron capture, we used a neutron-gamma separation system based on their different pulse shapes. The present measurement was compared with the existing experimental and the evaluated data. The resonance parameters of (93)Nb isotope were obtained from the transmission by using the SAMMY code and were compared with other previous results.