21 October 2004 Multiple-stage tapered neutron guide as a broad band focusing system
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Neutron guides are widely used for improving the angular aperture of neutron scattering instruments in a broad band of wavelength. However, the usual guides are not effective enough in the short wavelength range. This is especially critical for time-of-flight instruments, which cannot take advantage of focusing techniques designed for steady-state monochromatic instruments. We discuss alternative ways to shape the reflecting surfaces in order to obtain a maximum angular aperture at the sample position at the expense of beam cross-section reduction. An optimal piecewise solution is proposed and Monte Carlo simulations with the IDEAS package are presented. Simulations for General Purpose Powder Diffractometer (GPPD) at Argonne National Laboratory are presented and the impact of a vertically focusing multiple-stage tapered guide is discussed. The results obtained by simulating the guide system options of engineering diffractometer VULCAN at the Spallation Neutron Source (SNS) are also presented, including vertically and horizontally tapered guide sections. The optimal multi-stage tapered guide design is discussed in terms of instrument figure of merit corresponding to different experimental needs ranging from high Q resolution to high intensity and/or high spatial resolution.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Alexandru Dan Stoica, Xun-Li Wang, Wai-Tung Lee, and James W. Richardson "Multiple-stage tapered neutron guide as a broad band focusing system", Proc. SPIE 5536, Advances in Computational Methods for X-Ray and Neutron Optics, (21 October 2004); doi: 10.1117/12.560007; https://doi.org/10.1117/12.560007


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