Polarization analysis on the LET cold neutron spectrometer using a 3He spin-filter: First results

We report on the design and construction of a neutron polarization analyzer based on a 3He spin filter for the LET spectrometer at the ISIS facility. Its commissioning completes the uniaxial polarized mode of the instrument. Besides the 3He spin filter cell, the analyzer consists of a set of electromagnetic coils to provide a uniform magnetic field, and a collimator to eliminate background from the sample environment and analyzer infrastructure. The 3He cell is separated from the LET main tank vacuum by means of a gas tank, which permits rapid cell changeovers and guarantees safe operation. In addition to the analyzer hardware, software has been written to reduce and correct polarized data. The successful operation of the polarized mode was realized for the separation of coherent and incoherent dynamics in an organic solar cell polymer blend