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TY - UNPB AU - Waterstradt, T. AU - Diete, W. AU - Engblom, C. AU - Schacht, A. AU - Scheel, M. AU - Weitkamp, T. ED - Schaa, Volker RW ED - Tavakoli, Keihan ED - Tilmont, Manuel TI - Sub-20-nrad Stability of an LN2-Cooled Vertical-Offset Double-Crystal Monochromator J2 - Proc. of MEDSI2018, Paris, France, 25-29 June 2018 C1 - Paris, France T2 - Mechanical Engineering Design of Synchrotron Radiation Equipment and Instrumentation T3 - 10 LA - english AB - We have developed a compact and rigid mechanical design for a liquid-nitrogen-cooled vertically-deflecting double-crystal monochromator (DCM) for the ANATOMIX beamline at Synchrotron SOLEIL. An in-situ differential interferometer setup directly measures the pitch and roll parallelism between the 1st and the 2nd crystal under operating conditions with liquid-nitrogen flow and at pressures below 10⁻⁸ mbar. Factory measurements at moderate LN2 flow rates show a stability of the relative pitch of 25 nrad RMS (0.1 to 10 kHz) and a first relevant resonant frequency of 175 Hz. At lower flow rates, still sufficient to dissipate several hundred watts of heat load, an angular stability of 15 nrad RMS is achieved. PB - JACoW Publishing CP - Geneva, Switzerland ER -