Journal Article

PreJuSER-21221

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png New neutron-guide concepts and simulation results for teh POWTEX instrument

Houben, A. ; Schweika, W.FZJ* ; Brückel, T.FZJ* ; Dronskowski, R.

2012
North-Holland Publ. Co. Amsterdam

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Please use a persistent id in citations: doi:10.1016/j.nima.2012.03.015

Abstract: The POWTEX instrument will be a high-intensity time-of-flight diffractometer at a continuous reactor source. Its design utilizes several new concepts and is suited for small samples. Herein, the optimization of the guide system is presented. It is based on two coupled elliptic neutron guides intersected by the pulse-chopper as an eye of a needle to increase the time resolution and to reduce the background transported from the source. The optical properties of two coupled ellipses are investigated with respect to their design constraints in terms of geometry and regarding the choice of the super-mirror coating. It is shown that low-divergent neutrons are preferentially transported near the pulse-chopper. Accordingly, a numerical optimization is utilized to tailor the coating to the instrument requirements using the back-tracing method that has been developed for the VITESS Monte-Carlo simulation package for virtual instrumentation. The procedure allows for a cost and background optimization because the me-value can be kept as low as needed. For a diffractometer, the homogeneity of the divergence profile is crucial. Herein, the new development of neutron guides with octagonal cross sections is investigated. Appendix A shows a step-by-step description of the newly developed optimization features within VITESS as it was used for POVVTEX. (C) 2012 Elsevier B.V. All rights reserved.

Keyword(s): J ; Neutron guides (auto) ; Neutron optics (auto) ; Super-mirror coating (auto) ; Monte-Carlo simulations (auto) ; POWTEX (auto) ; VITESS (auto) ; Neutron time-of-flight diffractometer (auto)

Note: Jorg Voigt is acknowledged for taking part in discussions about elliptic neutron guides. Klaus Lieutenant and Michael Fromme are acknowledged for their effort on the VITESS software. We acknowledge funding from the German Federal Ministry of Education and Research (BMBF) in the frame of a "Verbundforschungsprojekt".

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Contributing Institute(s):

1. Streumethoden (PGI-4)
2. Streumethoden (JCNS-2)
3. Jülich-Aachen Research Alliance - Fundamentals of Future Information Technology (JARA-FIT)

Research Program(s):

1. Grundlagen für zukünftige Informationstechnologien (FUEK412) (FUEK412)
2. 544 - In-house Research with PNI (POF2-544) (POF2-544)

Experiment(s):

1. POWTEX: High-intensity time-of-flight diffractometer (SR5a)

Appears in the scientific report 2012

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Database coverage:
; Current Contents - Life Sciences ; Current Contents - Physical, Chemical and Earth Sciences ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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