Benzine
BENZINE GA EVAL-DEC69 KOPPEL,HOUSTON,BORGONOVI
REF.1 (1978) DIST-MAY10 20100309
----JENDL-4.0 MATERIAL 40
-----THERMAL NEUTRON SCATTERING DATA
------ENDF-6 FORMAT
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The data were taken from ENDF/B-VI.8.
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TEMPERATURES = 296 350 400 450 500 600 800 1000 DEG K.
HISTORY
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THIS EVALUATION WAS PRODUCED AT GENERAL ATOMIC IN 1969 USING
THE GA CODE GASKET (SEE REF.1). IT WAS CONVERTED TO
ENDF-6 FORMAT AT LOS ALAMOS IN 1989. THE ONLY CHANGES
MADE TO THE CONTENTS WERE ADJUSTMENTS OF CROSS SECTIONS
TO MATCH THE ENDF/B-VI VALUES.
THEORY
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THE BENZINE MOLECULE HAS AN HEXAGONAL PLANAR STRUCTURE WITH
SYMMETRY D6H, CARBON-CARBON BOND LENGTH OF 1.39 ANG, AND
CARBON-HYDROGEN BOND LENGTH OF 1.08 ANG. IN CONSTRUCTING A
MODEL FOR THE ATOMIC VIBRATIONS, IT WAS ASSUMED (REF.2) THAT
THERE IS NO INTERACTION BETWEEN VIBRATIONAL AND ROTATIONAL
STATES OF THE MOLECULE, AND THAT THE HINDERED ROTATIONS THAT
DESCRIBE THE INTERACTIONS OF MOLECULES IN THE LIQUID CAN BE
REPRESENTED BY TRANSLATIONS OF THE WHOLE MOLECULE WITH AN
EFFECTIVE MASS. CONTINUOUS FREQUENCY DISCTRIBUTIONS WERE THEN
OBTAINED FOR THE HYDROGEN AND CARBON ATOMS USING METHODS
DESCRIBED IN (REF. 3). THE CLUSTER OF FREQUENCES CLOSELY
SPACED AROUND 0.38 EV WAS LUMPED INTO A SINGLE OSCILLATOR.
THE GASKET CODE WAS THEN USED TO COMPUTE SEPARATE S(ALPHA,BETA)
FUNCTIONS FOR HYDROGEN AND CARBON. THE SCATTERING LAWS WERE
COMBINED AND ADJUSTED TO BE USED WITH THE HYDROGEN FREE-ATOM CROS
SECTION. THE CARBON FREE-ATOM CROSS SECTION HAS BEEN PROVIDED
FOR USE WITH THE SHORT-COLLISION-TIME APPROXIMATION (SCT).
THUS, THE THERMAL CROSS SECTION COMPUTED FROM EITHER S(ALPHA,
BETA) OR BY THE SCT APPROXIMATION GIVES AN ASYMPTOTIC LIMIT OF
APPROXIMATELY 6*20+6*4.7 BARNS.
REFERENCES
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1. J.U.KOPPEL AND D.H.HOUSTON, REFERENCE MANUAL FOR ENDF THERMAL
NEUTRON SCATTERING DATA, GENERAL ATOMIC REPORT GA-8774
REVISED AND REISSUED AS ENDF-269 BY THE NATIONAL NUCLEAR
DATA CENTER, JULY 1978.
2. D.SPREVAK, G.M.BORGONOVI, J.M.NEILL, AND G.W.CARRIVEAU,
NUKLEONIK 11, 233(1968).
3. D.SPREVAK, G.M.BORGONOVI, G.W.CARRIVEAU, AND J.M.NEILL,
"NEUTRON THERMALIZATION IN BENZINE," GENERAL DYNAMICS
REPORT GA-8185 (AUGUST 1967).