Design of a Magnet for the Spin-Rotator Device for the High Magnetic Field <formula formulatype="inline"><tex Notation="TeX">$\mu{\rm SR}$</tex></formula> Instrument at Paul Scherrer Institute

Abstract

In this work we present the design, the construction and the measurements of the magnet for a so-called spin-rotator (Wien filter), a beam line device used to rotate the spin direction (and the associated magnetic moment) of muons in a beam used for condensed matter research at the Swiss Muon Source at the Paul Scherrer Institute. The design parameters-originating both from the properties of the preferred particle beam as well as the technological constraints for the high-voltage components generating the necessary electric field-were optimized for device compactness, cost and high beam transmission.Index Terms-Beam ray-tracing, beam transmission, ExB crossfield device, hall probe magnetic measurements, magnet design, muon beam line, muon spin rotation, optimization, spin-rotator, split-pole magnet, Swiss Muon source, Wien filter.