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TY - CONF AU - Fisher, M.V. AU - Assoufid, L. AU - McChesney, J.L. AU - Qian, J. AU - Reininger, R. AU - Rodolakis, F.M. ED - Casas, Joan ED - Schaa, Volker RW ED - Costa, Isidre ED - López, David ED - Prieto, Montserrat TI - Minimizing Grating Slope Errors in the IEX Monochromator at the Advanced Photon Source J2 - Proc. of MEDSI2016, Barcelona, Spain, 11-16 September 2016 CY - Barcelona, Spain T2 - Mechanical Engineering Design of Synchrotron Radiation Equipment and Instrumentation Conference T3 - 9 LA - english AB - The IEX beamline at the APS is currently in the commissioning phase. The energy resolution of the beamline was not meeting original specifications by several orders of magnitude. The monochromator, an in-focus VLS-PGM, is currently configured with a high and a medium-line-density grating. Experimental results indicated that both gratings were contributing to the poor energy resolution and this led to venting the monochromator to investigate. The initial suspicion was that a systematic error had occurred in the ruling process on the VLS gratings, but that proved to not be the case. Instead the problem was isolated to mechanical constraints used to mount the gratings into their respective side-cooled holders. Modifications were made to the holders to eliminate problematic constraints without compromising the rest of the design. Metrology performed on the gratings in the original and modified holders demonstrated a 20-fold improvement in the surface profile error which was consistent with finite element analysis performed in support of the modifications. Two gratings were successfully reinstalled and subsequent measurements with beam show a dramatic improvement in energy resolution. PB - JACoW Publishing CP - Geneva, Switzerland SP - 336 EP - 338 KW - ion KW - photon KW - experiment KW - ISOL KW - optics DA - 2017/06 PY - 2017 SN - 978-3-95450-188-5 DO - doi:10.18429/JACoW-MEDSI2016-WEPE14 UR - http://jacow.org/medsi2016/papers/wepe14.pdf ER -