The transport of 14-MeV neutrons through heavy materials 150 < A < 208
The emission spectra from holmium (0.8 mfp), tantalum (1 and 3 mfp), gold (1.9 mfp), and lead (1.0 mfp) have been measured using the sphere transmission and time-of-flight techniques. The 14-MeV incident neutrons are from the Lawrence Livermore National Laboratory insulated-core-transformer accelerator using the /sup 3/H(d,n)/sup 4/He reaction. These materials were chosen to span a wide range of heavy nuclei, including deformed (holmium and tantalum), spherical (gold), and closed-shell (lead) nuclei. The neutron emission spectra have been measured in the 1- to 15-MeV energy interval and the results compared with Monte Carlo calculations performed using the neutron-photon transport code TART and evaluated neutron cross-section files. An alternative representation of the secondary neutron spectra has been carried out by using model calculations for precompound processes and collective effects in the calculations of the pulsed sphere emission spectra. Their importance in the quality of the agreement between measurements and calculations is discussed. The measurements are compared with the predictions of two evaluated neutron libraries, the ENDF/B-V and evaluated nuclear data library (ENDL). In addition, calculations have been carried out using neutron cross sections calculated directly from well-accepted nuclear models by the ALICE/LIVERMORE 82 and ECIS 79 codes. The quality of the agreements between the measurements and calculations obtained with the latter cross sections and those from the ENDL library is reasonably good for all the targets, and these are systematically better than the results obtained with the ENDF/B-V files. Discrepancies between measurements and calculations as great as 80% are found using the ENDF/B-V files for the emission of neutrons from gold in the 5- to 10-MeV energy range.
- Research Organization:
- University of California, Lawrence Livermore National Laboratory, Livermore, CA 94550
- OSTI ID:
- 5726969
- Journal Information:
- Nucl. Sci. Eng.; (United States), Vol. 92:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GOLD 197 TARGET
NEUTRON REACTIONS
HOLMIUM 165 TARGET
LEAD 208 TARGET
TANTALUM 181 TARGET
TRITIUM TARGET
DEUTERON REACTIONS
ACCELERATORS
COMPUTER CODES
CROSS SECTIONS
EMISSION SPECTRA
HELIUM 4
LAWRENCE LIVERMORE LABORATORY
MEV RANGE 01-10
MEV RANGE 10-100
MONTE CARLO METHOD
NEUTRON TRANSPORT
NEUTRONS
T CODES
TIME-OF-FLIGHT METHOD
BARYON REACTIONS
BARYONS
CHARGED-PARTICLE REACTIONS
ELEMENTARY PARTICLES
ENERGY RANGE
EVEN-EVEN NUCLEI
FERMIONS
HADRON REACTIONS
HADRONS
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MEV RANGE
NATIONAL ORGANIZATIONS
NEUTRAL-PARTICLE TRANSPORT
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEONS
RADIATION TRANSPORT
SPECTRA
STABLE ISOTOPES
TARGETS
US AEC
US DOE
US ERDA
US ORGANIZATIONS
651825* - Nuclear Properties & Reactions
A=150-189
Experimental- Nuclear Reactions & Scattering- (-1987)
651925 - Nuclear Properties & Reactions
A=190-219
Experimental- Nuclear Reactions & Scattering- (-1987)