Small-angle neutron scattering at pulsed spallation sources
The importance of small-angle neutron scattering (SANS) in biological, chemical, physical, and engineering research mandates that all intense neutron sources be equipped with SANS instruments. Four existing instruments are described, and the general differences between pulsed-source and reactor-based instrument designs are discussed. The basic geometries are identical, but dynamic range is achieved by using a broad band of wavelengths (with time-of-flight analysis) rather than by moving the detector. This allows a more optimized collimation system. Data acquisition requirements at a pulsed source are more severe, requiring large, fast histogramming memories. Data reduction is also more complex, as all wave length-dependent and angle-dependent backgrounds and non-linearities must be accounted for before data can be transformed to intensity vs Q. A comparison is shown between the Los Alamos pulsed instrument and D-11 (Institute Laue-Langevin), and examples from the four major topics of the conference are shown. The general conclusion is that reactor-based instruments remain superior at very low Q or if only a narrow range of Q is required, but that the current generation of pulsed-source instruments is competitive at moderate Q and may be faster when a wide range of Q is required. In principle, a user should choose which facility to use on the basis of optimizing the experiment; in practice the tradeoffs are not severe and the choice is usually made on the basis of availability.
- Research Organization:
- Los Alamos National Lab., NM (USA)
- Sponsoring Organization:
- DOE/AD
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6301817
- Report Number(s):
- LA-UR-90-4095; CONF-9008173-1; ON: DE91004870; TRN: 91-000374
- Resource Relation:
- Conference: 8. international conference on small-angle scattering, Lenvan (Belgium), 6-10 Aug 1990
- Country of Publication:
- United States
- Language:
- English
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75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CRYSTALLOGRAPHY
NEUTRON DIFFRACTION
NEUTRON SOURCES
SMALL ANGLE SCATTERING
DATA ACQUISITION SYSTEMS
LIQUID CRYSTALS
NEUTRON DETECTION
NEUTRON DIFFRACTOMETERS
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