THE NEUTRON TRANSMISSION OF SINGLE-CRYSTAL SAPPHIRE FILTERS

The wavelength dependence of the transmission probability of a beam of neutrons through super optical quality single-crystal sapphire at roo m temperature has been measured. The measurements extend over the neut ron wavelength range 0.05-1.2 nm. Sharp dips in the transmission cause d by Bragg reflection are not found. The data below the dip around 0.2 nm in the cross section have been fitted to a function that accounts for multiphonon scattering. Measurements performed on single crystals with increased lattice distortion (or mosaic spread) show an increase in the cross section at long wavelengths. The attenuation of room-temp erature Al2O3 is not significantly different from that for liquid-nitr ogen-cooled MgO.