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Neutron long wavelength cut-off filter

2000; Elsevier BV; Volume: 160; Issue: 3 Linguagem: Inglês

10.1016/s0168-583x(99)00612-6

1872-9584

Peter Høghøj, H. Abele, M. Hoffmann, S. Baeßler, J. Reich, V. V. Nesvizhevsky, O. Zimmer,

Nuclear reactor physics and engineering

We report the first use of a long wavelength cut-off filter for a polarized cold neutron beam. If a supermirror polarizer is used, the degree of polarization of neutrons with relatively long wavelengths, say, longer than 1.3 nm, is poor and difficult to determine. The filter we used in this paper separates these undesired neutrons from the beam. The device is 8 mm long and consists of a stack of 118 Si wafers, whose surfaces are covered with m=3 Ni/Ti supermirrors (see Fig. 1)Download : Download high-res image (738KB)Download : Download full-size imageFig. 1. Photograph of the wavelength cut-off filter. The neutron beam enters through the end of the Si wafers. B4C is added around the filter in order to prevent neutrons not filtered from reaching the detector.. The performance of this filter is described. Fig. 1. Photograph of the wavelength cut-off filter. The neutron beam enters through the end of the Si wafers. B4C is added around the filter in order to prevent neutrons not filtered from reaching the detector.