The first polarised neutron beam at OPAL has been observed using our Platypus time-of-flight neutron reflectometer. The polarised neutron beam is prepared using a (m=4) Fe/Si supermirror in transmission mode installed in the collimation system of Platypus.
Neutrons reflected from this supermirror are captured within the collimation system and do not strike the sample under study.
The figure shows a comparison between the (spin-down) polarised and the standard non-polarised neutron spectra for Platypus in the absence of a magnetic guide field.
The effective bandwidth available for use in future polarized neutron reflectivity experiments is 2.5 Ǻ to 13 Ǻ.
The main application for this method is for the study of thin magnetic films and multilayers, like those found in magnetic recording applications, for instance in computer hard drives and the associated read-heads.
Published: 22/07/2009