Magnetic systems for wide-aperture neutron polarizers and analyzers

Abstract

Requirements on the field uniformity in neutron polarizers are analyzed in view of the fact that neutron polarizing coatings have been improved during the past decade. The design of magnetic systems that meet new requirements is optimized by numerical simulations. Magnetic systems for wide-aperture multichannel polarizers and analyzers are represented, including (a) the polarizer to be built at channel 4-4′ of the reactor PIK (Gatchina, Russia) for high-flux experiments with a 100×150mm2 beam of polarized cold neutrons; (b) the fan analyzer covering a 150×100mm2 window of the detector at the Magnetism Reflectometer (SNS, ORNL, USA); (c) the polarizer and (d) the fan analyzer covering a 220×110mm2 window of the detector at the reflectometer NERO, which is transferred to PNPI (Russia) from HZG (Germany). Deviations of the field from the vertical did not exceed 2°. The polarizing efficiency of the analyzer at the Magnetism Reflectometer reached 99%, a record level for wide-aperture supermirror analyzers.