A helium mini-cryostat for the nanoprobe beamline ID16B at ESRF: characteristics and performance.

A helium mini-cryostat has been developed for the hard X-ray nanoprobe ID16B of the European Synchrotron to collect X-ray excited optical luminescence and X-ray fluorescence at low temperature (<10 K). The mini-cryostat has been specifically designed to fit within the strong space restrictions and high-demanding mechanical constraints imposed by the beamline to provide vibration-free operation and maximal thermal stability. This paper reports the detailed design, architecture and technical requirements of the mini-cryostat, and presents the first experimental data measured using the cryogenic equipment. The resulting cryo-system features ultimate thermal stability, fast cool-down and ultra-low vibrations. The simultaneous X-ray fluorescence and X-ray excited optical luminescence data acquired from bulk GaN and core/shell InGaN/GaN multi-quantum wells validated the excellent performance of the cryostat with ultimate resolution, stability and sensitivity.