J. Phys. IV France 03 (1993) C8-435-C8-438
Low-resolution small-angle scattering using neutron focusing opticsD.F.R. MILDNER, H. CHEN, R.G. DOWNING, R.E. BENENSON and C.J. GLINKA
National Institute of Standards and Technology, Gaithersburg, MD 20899, U.S.A.
Experiments at low values of scattering vector require tight collimation in the primary beam, as well as the ability to make measurements with good spatial resolution on the detector. Because neutron sources are not as intense as X-ray sources, large source and sample areas are used, and long instruments are necessary for adequate resolution. Increased count rates may be obtained using collimated beams which converge to a point on the detector. Further increases may be obtained with converging guides in the form of a focusing lens to increase the effective flux. Narrow guides enable the spectrometer dimensions to collapse for the same resolution. The critical angle of the fibers forming the focusing lens dominates the resolution, and such an instrument is useful only for low resolution measurements. However the greatly reduced length is only valuable if there is a high resolution detector to match the dimensions of the guide.
© EDP Sciences 1993