90% background reduction using 99.999% aluminium windows and 30 times enhancement of polarized neutron flux using extended short-focal-length magnetic lenses in SANS-J at JRR-3

熊田 高之   ; 元川 竜平   ; 中部 倫太郎; 廣井 孝介  ; 奥 隆之   ; 岩瀬 裕希*

Kumada, Takayuki; Motokawa, Ryuhei; Nakabe, Rintaro; Hiroi, Kosuke; Oku, Takayuki; Iwase, Hiroki*

We found that SANS intensity from 99.999% aluminium (5N-Al) is much smaller than that from the alloys, and then developed a 500 mm-diameter 5N-Al window for a vacuum tube of SANS-J at JRR-3. Although the center thickness of 5N-Al window (3 mm) was made larger than that of the alloy window used so far (1 mm) to compensate smaller fracture strength, the scattering from the window was reduced by 10 in maximum. We also demonstrated a novel use of the magnetic lenses without polarizer for the scattering measurements at Q larger than 0.2 nm by focusing the incident neutron beam with positive spin polarity on the sample position using extended magnetic lenses. The flux of polarized neutron beam became higher than that with non-focused conventional layout by a factor of 30.