Design of a TOF-SANS instrument for the proposed Long Wavelength Target Station at the Spallation Neutron Source.

Thiyagarajan, P. ; Littrell, K. ; Seeger, P. A.

Technical Information Center Oak Ridge Tennessee

关键词: Neutron sources;    Spallation;    Targets;    Cold neutrons;    Delta function;   

RP-ID  :  DE2001768633

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

We have designed a versatile high-throughput SANS instrument (Broad Range Intense Multipurpose SANS (BRIMS)) for the proposed Long Wavelength Target Station at the SNS by using acceptance diagrams and the Los Alamos NISP Monte Carlo simulation package. This instrument has been fully optimized to take advantage of the 10 Hz source frequency (broad wavelength bandwidth) and the cold neutron spectrum from a tall coupled solid methane moderator (12 cm x 20 cm). BRIMS has been designed to produce data in a Q range spanning from 0.001 to 0.7 (angstrom)(sup (minus)1) in a single measurement by simultaneously using neutrons with wavelengths ranging from 1 to 14.5 (angstrom) in a time of flight mode. A supermirror guide and bender assembly is employed to separate and redirect the useful portion of the neutron spectrum with (lambda) greater than 1 (angstrom), by 2.3(degree) away from the direct beam containing high energy neutrons and (gamma) rays. The effects of the supermirror coating of the guide, the location of the bender assembly with respect to the source, the bend angle, and various collimation choices on the flux, resolution and Q(sub min) have been characterized using spherical particle and delta function scatterers. The overall performance of BRIMS has been compared with that of the best existing reactor-based SANS instrument D22 at ILL.