Low-background ultrahigh-purity aluminium window for small-angle neutron scattering using monochromatic cold neutrons

単色中性子を用いた中性子小角散乱実験に向けた低バックグランド超高純度アルミニウム窓の開発

熊田 高之   ; 元川 竜平   ; 岩瀬 裕希*

Kumada, Takayuki; Motokawa, Ryuhei; Iwase, Hiroki*

We found that intensity of small-angle neutron scattering (SANS) from ultrahigh-purity aluminium (5N-Al) was lower than that from aluminium alloys by a factor of 40 in maximum, and thus replaced a 500 mm-diameter aluminium alloy neutron window by the 5N-Al window at SANS-J. We succeeded in decreasing the intensity of background in range of the magnitude of scattering vector Q between 0.02 and 0.2 nm by a factor of 10 in maximum. This result indicates that, the 5N-Al window, which is made thicker to compensate lower tensile strength, generates much lower background than the aluminium alloy windows. The 5N-Al window is suitable for large-diameter neutron window in SANS diffractometers and windows in their environmental apparatus, which cannot be made of single crystalline silicon due to its poor fracture strength, processability, and/or affinity with metallic materials.