Measurement of the total neutron cross-sections and the resonance parameters of natural hafnium at the Pohang Neutron Facility

Abstract

We measured total neutron cross-sections of natural hafnium in the neutron energy region from 0.1 eV to 100 eV by using the neutron time-of-flight method at the Pohang Neutron Facility, which consists of an electron linac, a water-cooled Ta target with a water moderator, and an 11-m-long time-of-flight path. A Li-6-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 natural hafnium metal plate, 5 X 5 cm in area by 0.5 mm in thickness, was used for the neutron transmission measurement. The background level was determined by using notch-filters of Co, In, and Cd sheets. In order to reduce the gamma rays from Bremsstrahlung and from neutron capture, we employed a neutron-gamma separation system based on their different pulse shapes. The present measurement was compared with the previous ones and the evaluated data in ENDF/B-VI. The resonance parameters were extracted from the transmission data by using the computer code SAMMY, which utilizes both Doppler and resolution broadening effects and Bayes' generalized least squares technique.