Cold Neutron Research Facility begins operating at NIST
Steady-state neutron beams are generally produced by fission in a nuclear reactor, whereas pulsed beams come from spallation neutron sources. Beams from a reactor have a distribution of wavelengths that is roughly Maxwellian, with a peak wavelength that depends on the temperature of the moderator that surrounds the fuel. Cold neutrons can be selected from the low-energy tail of the distribution, but the flux drops as 1/{lambda}{sup 4}. However, by shifting the whole spectrum to longer wavelengths one can dramatically increase the cold neutron flux. This is achieved by replacing part of the core moderator with a cold moderator, or cold source,' such as liquid deuterium (at about 30 K) or D{sub 2}O ice (at about 40 K). Neutrons lose energy to the moderator through collisions, producing a shifted spectrum from which one can select lower-energy neutrons with a roughly ten-fold improvement in the flux. Neutrons exhibit optical behavior such as refraction and total reflection. Thus one can use neutron guides - analogous to optical fibers - to conduct intense beams of neutrons from the reactor into a large experimental hall, dubbed a guide hall,' where background radiation is low. The Cold Neutron Research Facility was finally funded in 1987 and opened its doors this past June. CNRF is located at the 20-MW NIST research reactor, which began continuous operation in 1969. With some foresight, the designers of the original reactor allowed space for the addition of a cryogenic moderator, which is only now being exploited. NIST will develop 10 experimental stations for use by the research science community. Additional help in financing the facility comes from participating research teams made up of groups from industry, academe and government.
- OSTI ID:
- 5663791
- Journal Information:
- Physics Today; (United States), Journal Name: Physics Today; (United States) Vol. 44:9; ISSN 0031-9228; ISSN PHTOA
- Country of Publication:
- United States
- Language:
- English
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BARYONS
COLD NEUTRONS
COST
DEUTERIUM
DEVELOPED COUNTRIES
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
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NEUTRON SOURCES
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NORTH AMERICA
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NUCLEONS
ODD-ODD NUCLEI
OPERATION
PARTICLE SOURCES
RADIATION FLUX
RADIATION SOURCES
REACTOR COMPONENTS
REACTOR EXPERIMENTAL FACILITIES
REACTORS
RESEARCH AND TEST REACTORS
RESEARCH PROGRAMS
RESEARCH REACTORS
STABLE ISOTOPES
TECHNOLOGY ASSESSMENT
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US NBS
US ORGANIZATIONS
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