Note: Detector collimators for the nanoscale ordered materials diffractometer instrument at the Spallation Neutron Source

Abstract

Five neutron collimator designs were constructed and tested at the nanoscale ordered materials diffractometer (NOMAD) instrument. Collimators were made from High Density PolyEthylene (HDPE) or 5% borated HDPE. In all cases, collimators improved the signal to background ratio and reduced detection of secondary scattering. In the Q-range 10-20 (angstrom)-(1), signal to background ratio improved by factors of approximately 1.6 and 2.0 for 50 and 100 mm deep collimators, respectively. In the Q-range 40-50 angstrom(-1), the improvement factors were 1.8 and 2.7. Secondary scattering as measured at Q similar to 9.5 angstrom(-1) was significantly decreased when the collimators were installed. (C) 2015 AIP Publishing LLC.