Auxiliary Optics For meV-IXS at SPring-8: KB, Analyzer Masks, Soller Slit & Screen, BPM

TL;DR

This paper details the design and implementation of advanced optical components at the RIKEN SPring-8 beamline, enhancing high-resolution inelastic x-ray scattering experiments with improved focusing, background reduction, and beam monitoring.

Contribution

It introduces specific optical elements like multilayer KB mirrors, Soller slits, analyzer masks, and a diamond BPM tailored for high-resolution meV-IXS at SPring-8, improving experimental capabilities.

Findings

Achieved a focused beam spot of 4.4 x 4.1 μm² with 60% throughput.

Implemented Soller slits and masks to reduce background and enhance resolution.

Demonstrated successful experiments under extreme conditions using these optics.

Abstract

This paper discusses several optical elements now in use at BL43LXU, the RIKEN Quantum NanoDynamics Beamline, of the RIKEN SPring-8 Center. BL43LXU is dedicated to meV-resolved inelastic x-rays scattering using spherical analyzers operating between 15.8 and 25.7 keV. The work described here is relevant for setups on the high-resolution spectrometer (10m two-theta arm) with resolution between 2.8 and 0.8 meV. Specific optics discussed include a multilayer Kirkpatrick-Baez (KB) mirror pair that focuses the full (~1x3mm2) beam at 17.79 keV to a 4.4 X 4.1 {\mu}m2 spot with ~60% throughput, two different types of Soller slits that help reduce backgrounds, masks for the analyzers that allow increased solid angle to be collected while preserving momentum resolution, and a diamond quadrant beam position monitor (BPM). These elements have been used and facilitate experiments in extreme conditions with diamond anvil cells, and liquid measurements at low momentum transfers, among other work.