skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Some Notes on Neutron Up-Scattering and the Doppler-Broadening of High-Z Scattering Resonances

Abstract

When neutrons are scattered by target nuclei at elevated temperatures, it is entirely possible that the neutron will actually gain energy (i.e., up-scatter) from the interaction. This phenomenon is in addition to the more usual case of the neutron losing energy (i.e., down-scatter). Furthermore, the motion of the target nuclei can also cause extended neutron down-scattering, i.e., the neutrons can and do scatter to energies lower than predicted by the simple asymptotic models. In recent years, more attention has been given to temperature-dependent scattering cross sections for materials in neutron multiplying systems. This has led to the inclusion of neutron up-scatter in deterministic codes like Partisn and to free gas scattering models for material temperature effects in Monte Carlo codes like MCNP and cross section processing codes like NJOY. The free gas scattering models have the effect of Doppler Broadening the scattering cross section output spectra in energy and angle. The current state of Doppler-Broadening numerical techniques used at Los Alamos for scattering resonances will be reviewed, and suggestions will be made for further developments. The focus will be on the free gas scattering models currently in use and the development of new models to include high-Z resonance scattering effects.more » These models change the neutron up-scattering behavior.« less

Authors:
 [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1396101
Report Number(s):
LA-UR-17-28809
TRN: US1800078
DOE Contract Number:  
AC52-06NA25396
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; RESONANCE SCATTERING; NEUTRONS; MONTE CARLO METHOD; RESONANCE; neutron up-scattering; Doppler-Broadening temperature dependent scattering cross sections

Citation Formats

Parsons, Donald Kent. Some Notes on Neutron Up-Scattering and the Doppler-Broadening of High-Z Scattering Resonances. United States: N. p., 2017. Web. doi:10.2172/1396101.
Parsons, Donald Kent. Some Notes on Neutron Up-Scattering and the Doppler-Broadening of High-Z Scattering Resonances. United States. doi:10.2172/1396101.
Parsons, Donald Kent. Thu . "Some Notes on Neutron Up-Scattering and the Doppler-Broadening of High-Z Scattering Resonances". United States. doi:10.2172/1396101. https://www.osti.gov/servlets/purl/1396101.
@article{osti_1396101,
title = {Some Notes on Neutron Up-Scattering and the Doppler-Broadening of High-Z Scattering Resonances},
author = {Parsons, Donald Kent},
abstractNote = {When neutrons are scattered by target nuclei at elevated temperatures, it is entirely possible that the neutron will actually gain energy (i.e., up-scatter) from the interaction. This phenomenon is in addition to the more usual case of the neutron losing energy (i.e., down-scatter). Furthermore, the motion of the target nuclei can also cause extended neutron down-scattering, i.e., the neutrons can and do scatter to energies lower than predicted by the simple asymptotic models. In recent years, more attention has been given to temperature-dependent scattering cross sections for materials in neutron multiplying systems. This has led to the inclusion of neutron up-scatter in deterministic codes like Partisn and to free gas scattering models for material temperature effects in Monte Carlo codes like MCNP and cross section processing codes like NJOY. The free gas scattering models have the effect of Doppler Broadening the scattering cross section output spectra in energy and angle. The current state of Doppler-Broadening numerical techniques used at Los Alamos for scattering resonances will be reviewed, and suggestions will be made for further developments. The focus will be on the free gas scattering models currently in use and the development of new models to include high-Z resonance scattering effects. These models change the neutron up-scattering behavior.},
doi = {10.2172/1396101},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2017},
month = {9}
}

Technical Report:

Save / Share: