A compact TOF-SANS using focusing lens and very cold neutrons

作者：Yamada Masako^*; Iwashita Yoshihisa; Kanaya Toshiji; Yamada Norifumi L; Shimizu Hirohiko M; Mishima Kenji; Hino Masahiro; Kitaguchi Masaaki; Hirota Katsuya; Geltenbort Peter; Guerard Bruno; Manzin Giuliana; Anderson Ken; Lal Jyotsana; Carpenter John M; Bleuel Markus; Kennedy Shane J

来源：Physica B: Condensed Matter , 2011, 406(12): 2453-2457.

DOI：10.1016/j.physb.2010.12.002

• Focusing lens
• Rot-PMSx
• Pulsed neutron beams
• TOF
• High resolution
• Compact instrument
• VCN
• Focusing-SANS

We are developing a high-resolution small angle neutron scattering instrument for very cold neutrons (VCN). Our concept includes a magnetic lens for focusing of the beam at the detector plane. The lens consists of one permanent-magnet sextupole array rotating outside another stationary sextupole array, to focus a pulsed white beam of neutrons. Thus the instrument operates in time of flight mode. The prototype magnetic lens has a bore of 15 mm diameter and length of 66 mm, producing a magnetic field gradient oscillating from 1.5 x 10(4) to 5.9 x 10(4) T/m(2), with frequency <= 25 Hz. A torque-canceling magnet around the lens suppresses the torque of rotation from the outer array to 1/3.
We have demonstrated the performance of the lens, over wavelength range from 30 to 48 angstrom, on the PF2-VCN beam line at the Institut Laue-Langevin, France. The focused beam image was the same size as the source, without chromatic aberration, with focal length of 1.14 m. We also studied the performance of this configuration for high-resolution SANS, in a compact geometry (just 5 m long). The measurable q range of this system was 0.009 angstrom(-1) <= q <= 0.3 angstrom(-1) or 0.004 angstrom(-1) <= q <= 0.08 angstrom(-1) for sample to detector distances of 100 and 465 mm, respectively. Here, we present the results of our lens characterization study along with the SANS results on a tri-block copolymer (F127 Pluronic) and on a stretched polymer blend (with the Shish-Kebab structure).

• 出版日期2011-6