Focusing cold neutrons using capillary optics for analytical nuclear methods
- National Inst. of Standards and Technology, Gaithersburg, MD (United States); and others
The authors demonstrate improved detection limits and lateral resolution for prompt gamma activation analysis (PGAA) by using a neutron focusing device to increase the neutron intensity. The neutron lens, made of glass fibers with hollow polycapillaries, was designed and constructed by X-Ray Optical Systems, Inc. It has been characterized and used for preliminary experiments at the PGAA station of the Cold Neutron Research Facility (CNRF) at NIST. The lens accepts a polychromatic cold neutron beam (wavelengths longer than 0.4 run) from a neutron guide 50 mm x 45 mm in cross section, and delivers a focused beam of 0.5 mm in diameter (full width at half maximum) at 52 mm from the exit of the capillaries. The average neutron current density at the focus within the FWHM is 80 times higher than that of the direct incident beam. Test samples of 2% gadolinium glass particles of size about 0.1 to 0.2 mm, and cylindrical glass samples of 0.5 mm and 1 mm in diameter containing 15 % boron have been scanned across the focal plane to determine the spatial response as well as the peak count rate. Results from both sets of measurements show promise for higher detection sensitivity on small samples, and for two-dimensional mapping of samples with lateral compositional variation. Problems associated with neutron background will be addressed.
- OSTI ID:
- 191678
- Report Number(s):
- CONF-941098-; TRN: 95:006733-0034
- Resource Relation:
- Conference: FACSS XXI: 21st annual conference of the Federation of Analytical Chemistry and Spectroscopy Societies (FACSS), St. Louis, MO (United States), 2-7 Oct 1994; Other Information: PBD: 1994; Related Information: Is Part Of 21st annual conference of the Federation of Analytical Chemistry and Spectroscopy Societies; PB: 257 p.
- Country of Publication:
- United States
- Language:
- English
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