Voigt, J.; Soltner, H.; Babcock, E.; Aldus, R.J.; Salhi, Z.; Gainov, R.R.; Brueckel, T.: Polarization analysis for the thermal chopper spectrometer TOPAS. EPJ Web of Conferences 83 (2015), p. 03016/1-5
Open Accesn Version

We report on the progress of the construction of the thermal time-of-flight spectrometer with polarization analysis TOPAS at the Mayer-Leibnitz Zentrum (MLZ). The instrument components approach the status to be ready for installation. The special feature of the instrument is its capability for wide-angle polarization analysis in the thermal spectral range. Here we describe a novel approach to rotate the neutron spin adiabatically into the X, Y or Z direction of the laboratory frame by combination of permanent magnets aligned as Halbach rings and electrically generated fields. Despite the severe spatial restrictions the design exhibits a very high adiabaticity and interacts only weakly with the coil layout for the analyzing 3He spin filter cell (SFC).