Beam transport and polarization at TOPAS, the thermal time-of-flight spectrometer with polarization analysis

We present the design for the polarization analysis of the future thermal time-of-flight spectrometer at the Juelich Centre for Neutron Science (JCNS) at the FRM II. TOPAS is a time-of-flight spectrometer covering a range of incident energies 20 meV < Ei < 160 meV and an angular range −3° <...

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Bibliographic Details
Published in:Journal of physics. Conference series 2010-02, Vol.211 (1), p.012032
Main Authors: Voigt, J, Babcock, E, Brückel, T
Format: Article
Language:English
Subjects:
Neutrons
Physics
Polarization
Polarizers
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Summary:We present the design for the polarization analysis of the future thermal time-of-flight spectrometer at the Juelich Centre for Neutron Science (JCNS) at the FRM II. TOPAS is a time-of-flight spectrometer covering a range of incident energies 20 meV < Ei < 160 meV and an angular range −3° < 2θ < 150°. A set of Fermi choppers selects the incoming energy Ei with a resolution up to 3 %. The instrument is optimized for a high flux on small samples using an elliptical neutron guide. The special feature of TOPAS is the polarization analysis. The incident polarization will be realized by means of a 3He continuously pumped polarizer, which is a downscaled version of the device developed for small angle applications at JCNS. The polarization analysis over a wide angular range demands either short distances between the sample and the analyzer or a large volume of polarized 3He. Here we propose the latter alternative to allow the study of magnetic samples and modest magnetic fields at the sample position.
ISSN:1742-6596
1742-6588
1742-6596
DOI:10.1088/1742-6596/211/1/012032