Scan profiles for neutron spectrometers. III. Rectangular-profile elements by numerical methods

Abstract

Newly developed re¯ecting neutron collimators promise increased detector count rates in a ®eld where most work is intensity-limited. The effects of such elements on instrument resolution are complicated and appear to be even more subtle than previously imagined. Numerical tests using the McSTAS ray-tracing program (http://neutron.risoe.dk/mcstas) are reported which support and extend the recent analysis of these effects. If re¯ecting collimators are used in all instrument positions they give unusual scan pro®les. Using re¯ecting collimators only before the monochromator and immediately before the detector has no deleterious resolution effects and increases count rates by a factor of more than two on powder diffractometers.

Scan profiles for neutron spectrometers. II. Rectangular-profile elements by acceptance-diagram methods

“…It remains to be numerically and experimentally con®rmed if large gains can be achieved in practice. Numerical simulations appear well adapted to con®rming these results and to continuing this discussion (Cussen & Wildes, 2003).…”

Scan profiles for neutron spectrometers. I. Gaussian-profile elements by acceptance-diagram methods

“…That work will be tackled in the second work in this series . The results will be tested using a numerical simulation in the third work (Cussen & Wildes, 2003).…”

“…The ®rst part, presented here, attacks the ®rst new result, namely a description of Gaussian elements in the acceptance-diagram formalism, which may prove useful in its own right. Two accompanying papers complete the comparison Cussen & Wildes, 2003).…”