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Pharos Description

Pharos is a time-of-flight spectrometer for inelastic neutron scattering (INS) designed for studies of fundamental excitations in condensed-matter systems.

Pharos exploits the unique strengths of a pulsed neutron source, allowing for the simultaneous measurement of neutrons scattered over a wide scattering vector (Q) and energy transfer (E) range. The resulting scattering function S(Q,E) provides direct information on phonon, electronic, and magnetic excitations in a broad range of materials such as high-temperature superconductors, alloys, semiconductors, ferroelectrics, nano-materials, and biomolecules.

The name Pharos is not an acronym, but refers instead to the famous lighthouse of Alexandria, one of the seven wonders of the ancient world. This is in reference to the "lighthouse" effect for the Fermi chopper, the energy-selecting element of the instrument. The Fermi chopper rotates, along with an angular acceptance zone, quite like lighthouses and their beams of light.

Inelastic Neutron Scattering: Scattering in which exchange of energy and momentum between the incident neutron and the sample causes both the direction and the magnitude of the neutron's wave vector to change. (Image from "Neutron Scattering - A Primer")

An excellent tutorial on neutron scattering in general, and inelastic neutron scattering in particular, can be found here: "Neutron Scattering: A Primer" (PDF 2.2Mb) LAUR 95-3840