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Persistent URL http://purl.org/net/epubs/work/29642
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Record Id 29642
Title The Optimisation of Analyser Geometry for a Near Back-Scattering Spectrometer - IRIS on the ISIS Pulsed Source
Abstract This report describes the upgrade of the pyrolytic graphite (PG) analyser bank on the IRIS high-resolution inelastic spectrometer at ISIS from 1350 graphite pieces (6 rows by 225 columns) to 4212 crystal pieces (18 rows by 234 columns). The new analyser array will achieve a three-fold increase in area and in addition the graphite crystals will be cooled close to liquid helium temperature to reduce thermal diffuse scattering, thereby further improving the sensitivity of the spectrometer. For an instrument such as IRIS, with its analyser out of exact back-scattering geometry, optical aberration and variation in the time-of-flight of the analysed neutrons is introduced as one moves out from the horizontal scattering plane. To minimise such effects, the profile of the analyser array has been redesigned. The concept behind the design of the new analyser bank and the factors that effect the overall resolution of the instrument are discussed. Results of Monte Carlo simulations of the expected resolution and intensity of the complete instrument are presented and compared to the current instrument performance.
Organisation CCLRC
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Language English (EN)
Type Details URI(s) Local file(s) Year
Report RAL Technical Reports RAL-TR-1999-044. 1999. raltr-1999044.pdf 1999