TRANSMISSION POLARIZER FOR NEUTRON DIFFRACTION. V.Nunez, Department of Physics, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK and C.F.Majkrzak, Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA

The performance of a transmission polarizer for neutron diffraction applications is described. The polarizer consists of multiple plates of single crystalline Si on which are deposited Fe/Si supermirrors having a critical angle of reflection for one neutron spin state that is approximately three times that of an ordinary Ni film. A stack of 100 Si wafers, alternating plates having supermirror coating on both sides and uncoated plates, is then curved mechanically to a radius of about 2.5 meters. The resulting assembly is 2.5 cm wide x 7.5 cm high and 5.0 cm in length along the incident beam direction. At the proper angle of inclination, one spin state is effectively reflected out of the incident beam direction and subsequently absorbed in a downstream Soller collimator. The other, desired, spin state passes through undeviated. For neutron diffraction measurements performed on single crystals, at 4.15 Å wavelength with 40 min. collimation and 25 min. mosaic monochromator and analyser, transmissions of the desired spin state greater than 0.80 and polarization efficiencies greater than 0.90 have been obtained using these devices.