Spectrometer for Inelastic X-ray Measurements at Spring-8

This spectrometer is operating at the Spring-8 synchrotron in Japan as part of a dedicated inelastic beamline (BL12XU). The system is used for investigating electronic excitations with milli-electron volt resolution; therefore many of the specifications require high precision, and accuracy on the micron level. The 3-meter analyzer arm on the spectrometer needs to have an angular stability measured in arc seconds over a long range of travel, under vacuum conditions.

The spectrometer is designed for several types of inelastic X-ray measurements, such as performing non-resonant inelastic X-ray scattering, which directly measures the dynamical structure factor, S(q,w), of the sample. The scientific focus is to study the single-particle and collective electronic excitations in many-body systems. The incident table allows for diagnostics, attenuation of the highly monochromatic beam, and reduction of parasitic scattering. In addition to the standard capability of orienting the sample, the spectrometer will be used with large magnets, furnaces, or a specially designed cryostat with a fine-positioning carrier, for measurement of samples in extreme environments.

In the initial phase, the spectrometer will have a one-, two-, or three- meter radius spherically bent silicon analyzing crystal, allowing for a range of energy resolutions of around 100 meV to 1 eV. The spectrometer has the custom designed versatile capability of positioning a shielded detector in the backscattering geometry for use with various sample chambers, which will allow optimizing the energy resolution.

The second purpose of the spectrometer is for Resonant Raman scattering, to capitalize on the large resonant enhancement of the inelastic scattering cross sections. The incident X-ray energy will be widely tunable to excite core electron absorption edges of samples ranging from the copper to vanadium. For large-q scattering, the instrument can also be used to do high- resolution Compton scattering.

Final Acceptance Tests of the Phase I IXS Spectrometer at BL12XU, SPring-8 (15-30 Apr. 2002)

Publication: 2nd Internat’l Workshop on Mechanical Engineering Design of Synchrotron Radiation Equipment and Instrumentation (MEDSI02) September 5-6, 2002 – Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois U.S.A. Development of a Spectrometer for Inelastic X-ray Measurements 8th International Conference on Synchrotron Radiation Instrumentation (SRI) meeting in SanFransisco, California, August 25th 2003, Optical design and performance of the Taiwan Inelastic X-Ray scattering beamline (BL12XU) at Spring-8