Inelastic rotor spectrometer at the Harwell Linac

The spectrometer is designed to measure energy transfer from 50 MeV to 400 MeV covering a range of Q values from 1 to 15 A-1. Particular emphasis has been placed on the low Q counter banks where measurements at low Q reduce multiphonon contributions in vibrational spectra, diffusional broadening in liquids and allow measurements to be made on magnetic excitations. All indications are that the energy resolution is as predicted and is certainly twice as good as that of any other spectrometer presently available to the UK users at these energy transfers. Backgrounds on the high angle banks 240 to 940 are excellent but at the low angles are too high at present for anything but hydrogenous samples. Tests have shown that much of this background comes from the main beam in the area of the collimation between the chopper and the sample, and steps are being taken to improve this area