Multi-channel neutron guides of PNPI: results of neutron and X-ray reflectometry tests

Both polarizing and non-polarizing multichannel neutron guides produced in PNPI (Gatchina) have been considered in the present work. Neutron data for supermirrors on glass, with a critical angle theta(c) in two times exceedin g that of Ni, have been represented: polarizing FeCoV/TiZr supermirrors with theta(c) = 3.4 mrad/Angstrom and th e reflectivity 0.75 at this angle, non-polarizing NiC/Ti, NiMo/Ti supermirrors with theta(c) = 3.3 mrad/Angstr om and the reflectivity at this angle approaching 0.9. A method of testing multichannel neutron guides by means of neutron and X-r ay reflectometry has been developed. which is based on testing single mirro rs and then neutron optical systems assembled from them. The results of cal culation of the neutron transmittance of single channels have been given. I t has been shown that the numerical method developed enables to reliably pr edict the resultant neutron fluxes at the exit of neutron guides. Moreover, the experimental transmittances of the multi-channel neutron guides have b een found to be close to those calculated on assumption of their perfect ge ometry. (C) 1999 Elsevier Science B.V. All rights reserved.