Polarisation analysis on the LET time-of-flight spectrometer

International Conference on Polarised Neutrons for Condensed Matter Investigations

Nilsen, G.J.^1 ; Koata, J.^1 ; Devonport, M.^1 ; Galsworthy, P.^1 ; Bewley, R.I.^1 ; Voneshen, D.J.^1 ; Dalgliesh, R.^1 ; Stewart, J.R.^1

ISIS Neutron and Muon Facility, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot

OX11 0QX, United Kingdom^1

关键词: Conducting materials;    Homogenous magnetic field;    Polarisation analysis;    Polarised neutrons;    Quasielastic neutron scattering;    Sample position;    Spatial requirements;    Time-of-flight spectrometer;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/862/1/012019/pdf
DOI  :  10.1088/1742-6596/862/1/012019

来源: IOP

【 摘 要 】

We present a design for implementing uniaxial polarisation analysis on the LET cold neutron time-of-flight spectrometer, installed on the second target station at ISIS. The polarised neutron beam is to be produced by a transmission-based supermirror polariser with the polarising mirrors arranged in a "double-V" formation. This will be followed by a Mezei-type precession coil spin flipper, selected for its small spatial requirements, as well as a permanent magnet guide field to transport the beam polarisation to the sample position. The sample area will contain a set of holding field coils, whose purpose is to produce a highly homogenous magnetic field for the wide-angle3He analyser cell. To facilitate fast cell changes and reduce the risk of cell failure, we intend to separate the cell and cryostat from the vacuum of the sample tank by installing both in a vessel at atmospheric pressure. When the instrument upgrade is complete, the performance of LET is expected to be commensurate with existing and planned polarised cold neutron spectrometers at other sources. Finally, we discuss the implications of performing uniaxial polarisation analysis only, and identify quasi-elastic neutron scattering (QENS) on ionic conducting materials as an interesting area to apply the technique.