Fast neutron angular and energy dependent penetration spectra through water and laminated water--steel slabs: a comparison of experimental and calculated results

Fast-neutron angular penetration spectra were experimentally determined for a fast-neutron spectrum incident on 4-inch, 8-inch, and 12-inch thick water slabs, and on laminated 4-inch water--3-inch steel and 3-inch steel--4 inch water slabs. The experimental spectra were compared with MORSE Monte Carlo calculations using available multigroup cross sections. The source of fast neutrons for the experimental study was the Missouri University Research Reactor (MURR); the incident and penetration neutron spectra were detected by using a 2 x 2 inch NE-213 liquid scintillation spectrometer system. A comparison of the Monte Carlo and experimental results showed excellent agreement for all but the thickest slabs. All of the results showed similar trends and structure, and only for the 12-inch slab did the experimental and calculated results vary by as much as 40% for shallow-angle penetrations. Integrated spectra results are generally within -+ 15% for all reported angles and thicknesses, which is less than the cumulative uncertaintly band of the expermental and calculated results. A modification to the well-known MORSE code was utilized to calculate a group-to-group transfer matrix for each of the experimental geometries. These probabilities were converted to dose and are tabulated to permit calculation of the penetration dose for any incident neutron spectrum for the comprehensive set of angles considered in this work