High-Resolution Chopper Spectrometer | Pharos

Local Structure, Magnetism, and Nanomaterials

Pharos is designed for studies of fundamental excitations in condensed-matter systems. The instrument provides 2% to 4% incident energy resolution and uses a high-speed Fermi chopper to obtain monochromatic incident energies in the range from 10 meV to 2 eV. The sample is positioned 20 meters from a chilled-water moderator. The spectrometer consists of an evacuated, shielded flight path with 10 m2 of meter-long position-sensitive detectors located at a distance of 4 meters from the sample and covering scattering angles between -10° and 145°.

Pharos can accommodate the full range of inelastic scattering experiments on liquid, polycrystalline, and single-crystal samples. This includes phonon and spin-wave dispersions, phonon density-of-states, magnetic excitations, momentum distributions, spin-orbit and crystal-field levels, chemical spectroscopy, and measurements of S(Q, ω) in disordered systems. In addition, the low-angle detectors are available for use at distances between 4 and 10 meters with scattering angles down to 0.65°, thus making it suitable for high-resolution inelastic studies (< 1% resolution) at low Q.