FAST NEUTRON SPECTROSCOPY AND DOSIMETRY OF THE MIT REACTOR MEDICAL THERAPY FACILITY BEAM.
Scientific rept. no. 3.
MASSACHUSETTS INST OF TECH CAMBRIDGE
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The neutron spectrum was measured using a combination of foil detectors. The absolute thermal flux was measured with gold foils using a beta-gamma coincidence counting technique the epithermal spectrum was measured by taking cadmium ratios with three different resonance foil materials and the fast neutron spectrum was measured with ten different threshold foil materials. The fast neutron spectrum was calculated from the threshold foil data using the Weighted Orthonormal and Weighted Orthonormal Polynomial Methods, which were coded for the IBM-7090 computer. These methods were extensively tested on exact data and on data from the ISPRA-1 Reactor. Finally, a composite neutron spectrum was constructed using the results of the fast, epithermal, and thermal flux measurements. This was used to compute the dose rate in tissue using Snyders Monte Carlo results for a broad beam of neutrons. The calculated gamma-ray dose was then compared to experimental results. Author