FARO: A new type of neutron spectrometer with flux and resolution optimized

A new type of high intensity and high resolution time-of-flight near backscattering neutron spectrometer is presented which is capable of an energy resolution of 4.0 mu eV with a data collection rate an order of magnitude larger than current near backscattering spectrometers capable of this resolution. This design challenges two accepted norms of high resolution indirect neutron spectrometers: it uses large mosaic pyrolytic graphite (002) crystals instead of nearly perfect silicon (111) crystals to select the final neutron energy, and it operates well away from the normal backscattering condition 2 phi approximate to 180 degrees instead using 2 phi = 160 degrees. This paper describes the methodology behind this spectrometer along with ray-tracing simulations of the instrument using the McStas program.