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Title: Metal hydrides as pulsed neutron source moderators and reflectors.

Abstract

No abstract prepared.

Authors:
; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
982616
Report Number(s):
ANL/IPNS/CP-59385
TRN: US201015%%1226
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Conference
Resource Relation:
Conference: 18th Meeting of the International Collaboration on Advanced Neutron Sources ( ICANS-XVIII); Apr. 25, 2007 - Apr. 29, 2007; Dongguan, China
Country of Publication:
United States
Language:
ENGLISH
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; HYDRIDES; MEETINGS; METALS; MODERATORS; NEUTRON SOURCES

Citation Formats

Micklich, B. J., Carpenter, J. M., and Intense Pulsed Neutron Source. Metal hydrides as pulsed neutron source moderators and reflectors.. United States: N. p., 2007. Web.
Micklich, B. J., Carpenter, J. M., & Intense Pulsed Neutron Source. Metal hydrides as pulsed neutron source moderators and reflectors.. United States.
Micklich, B. J., Carpenter, J. M., and Intense Pulsed Neutron Source. Mon . "Metal hydrides as pulsed neutron source moderators and reflectors.". United States. doi:.
@article{osti_982616,
title = {Metal hydrides as pulsed neutron source moderators and reflectors.},
author = {Micklich, B. J. and Carpenter, J. M. and Intense Pulsed Neutron Source},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
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  • The Intense Pulsed Neutron Source (IPNS) started using solid methane moderators in 1985 because of their efficient conversion (about 3.5 times greater than was achieved with a liquid hydrogen moderator) of fast neutrons to long wavelength neutrons. However, the solid methane moderators experienced numerous failures due to pressure surges caused by a combination of (1) the release of stored energy, which occurred when methane radiolytic products recombined, and (2) the expansion of hydrogen, which built up in the solid methane during irradiation. During the ensuing years studies were made to determine how to operate the solid methane moderators without causingmore » failure. The rate at which stored energy built up during irradiation and the temperature at which hydrogen was released during annealing were determined. Since 1993 IPNS has successfully operated the solid methane moderators (at about 30 K) by periodically annealing to the liquid state around 90 K after every roughly three days of irradiation.« less
  • Moderator design for pulsed neutron sources is becoming more and more an interface area between source designers and instrument designers. Although there exists a high degree of flexibility, there are also physical and technical limitations. This paper aims at pointing out these limitations and examining ways to extend the current state of moderator technology in order to make the next generation neutron sources even more versatile and flexible tools for science in accordance with the users' requirements. (auth)
  • We present a progress report on measurements and fitting of pulse shapes for neutrons emerging from one solid and two liquid methane moderators in IPNS. A time-focused crystal spectrometer arrangement was used with a cooled Ge monochromator. Data analysis of one of the liquid methane moderators has shown the need for some generalization of the Ikeda-Carpenter function that worked well for fitting pulse shapes of polyethylene moderators. We describe attempts to model physical insight into the wavelength dependence of function parameters. 5 refs., 7 figs.
  • We report the calculated results of neutronic performance of cold moderators in a reference target-moderator-reflector system at the projected 5 MW pulsed spallation neutron source in Japan Atomic Energy Research Institute (JAERI). The cold neutron intensities in present reference model are about 2.3-2.5 times higher than that from the decoupled solid methane (S-CH 4) and close to the values obtained at other facilities (LANSCE Upgrade, NSNS, etc.). The H 2O premoderator (PM) reduces the energy deposition in a liquid-hydrogen (L-H 2) moderator by about a factor of 2 compared with that in a decoupled L-H 2 moderator. The dependence ofmore » reflector on the neutron intensity and the energy deposition in the cryogenic moderators is also discussed. Although the pulse shapes were not obtained because of time consuming Monte Carlo calculations, we will discuss the pulse shapes based on experiments. (auth)« less
  • The International Workshop on Cold Moderators for Pulsed Neutron Sources resulted from the coincidence of two forces. Our sponsors in the Materials Sciences Branch of DOE's Office of Energy Research and the community of moderator and neutron facility developers both realized that it was time. The Neutron Sources Working Group of the Megascience Forum of the Organization for Economic Cooperation and Development offered to contribute its support by publishing the proceedings, which with DOE and Argonne sponsorship cemented the initiative. The purposes of the workshop were: to recall and improve the theoretical groundwork of time-dependent neutron thermalization; to pose andmore » examine the needs for and benefits of cold moderators for neutron scattering and other applications of pulsed neutron sources; to summarize experience with pulsed source, cold moderators, their performance, effectiveness, successes, problems and solutions, and the needs for operational data; to compile and evaluate new ideas for cold moderator materials and geometries; to review methods of measuring and characterizing pulsed source cold moderator performance; to appraise methods of calculating needed source characteristics and to evaluate the needs and prospects for improvements; to assess the state of knowledge of data needed for calculating the neutronic and engineering performance of cold moderators; and to outline the needs for facilities for testing various aspects of pulsed source cold moderator performance.« less