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TY - UNPB AU - Liu, F. AU - Blanchet, Blanchet, C. AU - Bourenkov, G. AU - Fiedler, S. AU - Gehrmann, T. AU - Jahn, D. AU - Marshall, G. AU - Meyer, Meyer, J. AU - Pompidor, G. AU - Ristau, U. ED - Schaa, Volker RW ED - Tavakoli, Keihan ED - Tilmont, Manuel TI - Upgrade of Double Crystal Monochromators for EMBL Beamlines at PETRAIII 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 - Double crystal monochromators (DCM) are very important instruments in hard X-ray beamlines. Publications have indicated that the mechanical stability of the DCM would affect the whole beam quality very much. To upgrade the performance of the DCMs of the EMBL beamlines, the vibrational stability, thermal stability and mechanical repeatability were improved. To improve the vibrational stability, an off-line vibration measurement for the pitch and roll, as well as the perp, were designed with a set of in-vacuum interferometers was developed for measuring the vibrations without X-ray beam. Then several attempts were tried to reduce the vibration caused by the cooling system, in the end, the pitch vibration was improved from 390nrad to 50nrad. To improve the thermal stability, the cooling blocks and thermal braids were optimized with the FEA methods, the steady time of the 2nd crystal were improved from 2.5 hours to less than 45 minutes after each energy change. To improve the repeatability of the orientation, the wedge jacks were replaced by worm gear boxes, repeatability was reached to less than 3 um. PB - JACoW Publishing CP - Geneva, Switzerland ER -