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CALCULATION OF WIGNER-WILKINS SPECTRA WITH M = 18 KERNEL AND M = 1 SOURCE. PROCEEDINGS OF THE NEUTRON THERMALIZATION CONFERENCE, APRIL 28-30, 1958, GATLINBURG, TENNESSEE

Technical Report ·
OSTI ID:4216925
In an attempt to explain the excellent agreement of measured thermal spectra in water with calculations based on a free monatomic moderator of mass M = 1, a conjecture has been advanced that the calculated spectrum is insensitive to the value of the moderator mass used in the energy change kernel SIGMA (E/sub 1/ yields E/sub f/) of the Wigner-Wilkins integral equation. The truth of this conjecture was investigated by assigning to the protons a mass equal to 18 neutron masses in evaluating the energy change kernel and also in establishing a distribution of initial proton velocities. The source term in the Wigner-Wilkins equation, which represents the neutrons fed into the thermal group from the epithermal region, is, however, calculated with the true proton mass, since the chemical binding is negligible for epithermal neutrons. The integral equation was solved on an IBM-650 computer and the resulting spectra compared with the usual M = 1 spectra. The comparisons indicate that the spectrum is indeed sensitive to the value of the moderator mass used in the energy change kernel. The effcct of thermal-cutoff choice and Doppler effect is also shown. (auth)
Research Organization:
Knolls Atomic Power Lab., Schenectady, N.Y.
NSA Number:
NSA-13-020333
OSTI ID:
4216925
Report Number(s):
ORNL-2739(Paper I-A)
Country of Publication:
United States
Language:
English