Fast neutron spectra by integral experiments on graphite with a collimated monoenergetic (D,T) neutron beam
Integral experiments with a large graphite stack and fast neutron spectra calculations are described. A well-collimated beam of (14.75 + or - 0.05) MeV (D,T) neutrons from a generator incident on the graphite resulted in a neutron spectrum that strongly correlated with the fine structure of the carbon nuclei, including anisotropy of elastic and inelastic scattering to first levels. This experimental approach is easier and more straightforward from the calculational point of view than one with a neutron source inside of a stack. The neutron spectrum measurement was performed by an NE-213 liquid scintillator using a pulse-shape discrimination technique to reject gamma-ray counts. The unfolding of the proton recoil spectrum was done by the FORIST code. The calculations were performed using the DOT 3.5 two-dimensional discrete ordinates neutron transport code incorporating the ENDF/B-IV cross-section library with the ETOG III group cross-section generating code, Comparison between measured and calculated spectra showed a reasonable agreement in the 1- to 8-MeV energy range. On the other hand, great discrepancies (up to an order of magnitude) are revealed in the range from 8 to 10.5 MeV. Including the angle/energy correlation in inelastic scattering drastically improved the agreement between measurements and calculations in the inelastic scattering range to the first level of the carbon. The calculated spectrum in the 7- to 10.5-MeV range, i.e., in the inelastic scattering range, was found to be very sensitive to the anisotoropy distribution of inelastic scattering to the first level.
- Research Organization:
- Ben-Gurion University of the Negev, Beer Sheva 84 105
- OSTI ID:
- 5373941
- Journal Information:
- Nucl. Sci. Eng.; (United States), Vol. 84:3
- Country of Publication:
- United States
- Language:
- English
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FAST NEUTRONS
TRANSMISSION
GRAPHITE
NEUTRON TRANSPORT
ANISOTROPY
CARBON
COLLIMATORS
COMPUTER CODES
CROSS SECTIONS
DISCRETE ORDINATE METHOD
ELASTIC SCATTERING
INELASTIC SCATTERING
MEV RANGE 01-10
NEUTRON BEAMS
NEUTRON SOURCES
NEUTRON SPECTRA
PROGRAMMING
PULSE TECHNIQUES
BARYONS
BEAMS
ELEMENTAL MINERALS
ELEMENTARY PARTICLES
ELEMENTS
ENERGY RANGE
FERMIONS
HADRONS
MEV RANGE
MINERALS
NEUTRAL-PARTICLE TRANSPORT
NEUTRONS
NONMETALS
NUCLEON BEAMS
NUCLEONS
PARTICLE BEAMS
PARTICLE SOURCES
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SCATTERING
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654003* - Radiation & Shielding Physics- Neutron Interactions with Matter