SEPARATION OF NEUTRON INELASTIC AND ELASTIC SCATTERING CONTRIBUTION FROM NATURAL IRON USING DETECTOR RESPONSE FUNCTIONS

摘要

Neutrons scattering from a sample of natural iron were measured by the Rensselaer Polytechnic Institute's Neutron Scattering System using the time-of-flight method. Two experiments were required to obtain twelve measurements at seven distinct angles. Scattered neutrons were detected by liquid scintillators (EJ-301), and each event was recorded as a digital waveform and analyzed offline. The primary objective of the experiments was to benchmark iron evaluations such as ENDF, JEFF, and JENDL in the energy region between 0.5 and 20.0 MeV using MCNP. Two techniques that separate the elastic and inelastic scattering contributions were developed and implemented. Both techniques rely on response functions developed from in-beam measurements initially performed to measure the neutron flux shape and each detector's efficiency. The first technique fits two response functions to iron scattering data to determine the inelastic-to-elastic scattering ratio for several energy regions. The second technique eliminates the inelastic scattering contribution by adjusting a discriminator level based on a detector's response function and the incident neutron's time-of-flight. The results from these techniques provide another means to quantify differences between the experimental data and the calculated response from each evaluation.