Drabkin energy filter for experiments at a spallation neutron source.

Parizzi, A. A. ; Felcher, G. P. ; Klose, F.

Technical Information Center Oak Ridge Tennessee

关键词: Neutron sources;    Spallation;    Time-of-flight method;    Cold neutrons;    Moderators;   

RP-ID  :  DE2001768630

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

We present a new approach for dynamic monochromatization of neutrons suitable for time-of-flight experiments at spallation neutron sources. The method requires polarized neutrons and is based on the Drabkin energy filter. In its initial application, this magnetic resonator device, consisting of a polarizer/analyzer system and a wavelength-dependent spin flipper, was proposed for extracting a narrow bandwidth from a broad bandwidth polarized neutron beam. At a spallation neutron source, wavelength is determined by time-of-flight (TOF) from the source to the detector. However, at each instant a spread of wavelengths is recorded due to the non-zero emission time of the source/moderator system. Particularly, high-intensity moderators for cold neutrons produce long 'tails' in the intensity/time distribution for all wavelengths, degrading the resolution of the experiments. The Drabkin energy filter can be used to cut the neutron tails for all wavelengths, by drifting the resonance condition in synchronization with the TOF. Calculations show that the method is viable, and that substantial resolution gains are obtained by application to a TOF neutron reflectometer.