Incorporation of epithermal proton chemical binding effects in HAMMER Page: 2 of 36
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NOTICE
This report was prepared as an aaount of ork
sponsored by the United States Government. N dher
the United States not the United States I energy
Research and Developmen' Administration, nor any of
their employees, nor any of their contractors,
subcontractors, or their employees, makes any
warranty, express or implied, or assumes any legal
INCORPORATION OF EPITHERMAL PROTON Liability or responsibility for the accuracy, complteness
CHEMICJ. BINDING EFFECTS IN HAMhER* or nsefulrem of any information, appararos, ptodact or
QIU4IAL BIDINGprocess disclosed, or represents that its ose wold ntea
Iinfringe privately owned rights.
Arthur Buslik and John Herczeg
I. Introduction
This reports those chang.rs to the hydrogen epithermal library
in HAMMER, and those changes to the HAMER program ' itself, which are
required to incorporate the effects of the chemical binding and thermal
motion of the protons in water on the epithermal neutron flux and reaction
rates. The changes to the hydrogen epithermal library required are changes
to the slowing-down power tos, the Greuling-Goertzel parameter y, and the
P-1 component of the scattering cross-section - . These changes are based
(3)
on the kernel developed by Cady, Kirouac and McInerney.
The changes to the HAMMER program which are required consist of changes
to the program to ensure that the slow.ng-down power tas and the Greuling-
Goertzel parameter y for hydrogen are used in all of the subroutines
(HAMMER at present assumes in certain of its subroutines that the hydrogen
slowing-down power Ss is equal to the P-0 component of the scattering
cross-section aso, and that the parameter y for hydrogen is equal to unity).
In addition, changes are required to modify the Dancoff factor used in the
Pu-240 1 eV resonance treatment and the cosine current calculation of the
lattice escape probabilities used .n the resonance absorption calculation.
These changes are along the lines discussed in references 7 and 8.
Another approach to obtaining cross-sections for hydrogen which ac-
count for epithermal chemical binding effects is to obtain values of gc,
by multigroup so as to reproduce the Corngold asymptotic expansion fluxes
exactly for plain water, and to leave the value of the Greuling-Goertzel
parameter y equal to unity. This is the approach used by J. Hardy, Jr.(6)
as suggested by E. M. Clbard. However, by also varying y (as is done in
the method presented here), one would hope to get better accuracy in cases
of heavy absorption. Moreover, this is more consistent with the changes
made in the resonance absorption treatment for the Pa-240 1 eV resonance.
*Research carried out at Brookhaven National Laboratory under contract with
the U. S. Atomic Energy Commission.
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Buslik, A. & Herczeg, J. Incorporation of epithermal proton chemical binding effects in HAMMER, report, November 1, 1974; Upton, New York. (https://digital.library.unt.edu/ark:/67531/metadc1022786/m1/2/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.