Measurement of the neutron total cross sections of Ta and Mo and proton induced reaction cross sections of ^natMo

Abstract
The Pohang Neutron Facility based on an electron linear accelerator was operated for the neutron total cross section measurements by using the pulsed neutrons produced in a water-cooled Ta-target with a water moderator. The neutron total cross sections of Ta and Mo were measured in the neutron energy region from 0.01 eV to 100-200 eV by using the time-of-flight method. A ⁶LiZnS(Ag) glass scintillator with a diameter of 12.5 cm and a thickness of 1.6 cm was used as a neutron detector. The neutron flight path from the water-cooled Ta target to the neutron detector was 12.1 m. The background level was determined by using notch-filters of Co, In, Ta, and Cd sheets. In order to reduce the gamma rays from Bremsstrahlung and those from neutron capture, we employed a neutron-gamma separation system based on their different pulse shapes. The present measurements of Ta and Mo are in general agreement with the evaluated data in ENDF/B-VI. Cross sections for residual radio-nuclide production by proton-induced reactions on natural molybdenum were measured from their respective threshold energies to 42 MeV by using the MC-50 cyclotron at KIRAMS. The activation method and a stacked-foil technique using high-resolution HPGe gamma-ray spectrometry were applied to determine the excitation functions. The reactions induced on Al and Cu foils were used to monitor the parameters of the proton beam. The present results are in generally good agreement with the earlier reported data and with the calculations based on the ACILE-IPPE code.