Layout and performance of the polarizing guide system for the J-NSE spectrometer at the FRM II

✍ Scribed by O. Holderer; M. Monkenbusch; G. Borchert; C. Breunig; K. Zeitelhack

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 160 KB
• Volume: 586
• Category: Article
• ISSN: 0168-9002
• DOI: 10.1016/j.nima.2007.11.038

✦ Synopsis

The neutron spin-echo instrument, J-NSE, that has been moved from the ELLA guide hall at the FRJ-2 in Ju¨lich to the guide hall of the new FRM II reactor, needs an intense beam of polarized neutrons. Polarization of the short wavelengths is achieved in a bent section of about 8 m and radius 160 m, with a m ¼ 3 FeSi multilayer coating. Due to the total reflection of FeSi, longer wavelengths ðl ' 10220 ÅÞ pass unpolarized and need an additional short polarizer at the entrance of the instrument. After the bent section within a 10 m straight guide section a turn of vertical polarization to longitudinal guide field is performed and a selector is inserted. Then about 10 m of tapered 58 Ni covered guide follows, which end with a cross-section of 60 Â 60 mm 2 . We present the design criteria and first measurements on the performance of this guide concept.