LNLS, Campinas, Brazil
The High-Dynamic Double-Crystal Monochromator (HD-DCM)*,** is an opto-mechatronic system with unique architecture, and deep paradigm changes as compared to traditional beamline monochromators. Aiming at unmatching scanning possibilities and positioning stability in vertical-bounce DCMs, it has been developed since 2015 for hard X-ray beamlines at Sirius Light Source at the Brazilian Synchrotron Light Laboratory (LNLS). Two units are currently operational at the MANACA (macromolecular crystallography) and the EMA (extreme conditions) undulator beamlines, whereas a model for extended scanning capabilities in the energy range between 3.1 to 43 keV, the so-called HD-DCM-Lite, is in advanced development stage for two new beamlines, namely: QUATI (quick absorption spectroscopy), with a bending-magnet source; and SAPUCAIA (small-angle scattering), with an undulator source. In this work, online commissioning and operating results of the HD-DCMs are presented with emphasis on: the 10 nrad RMS (1 Hz - 2.5 kHz) pitch-parallelism performance; energy calibration; energy-dependent beam motion at sample; and flyscan with monochromator-undulator synchronization, which is a well-known control challenge at beamlines. To conclude, the Sirius HD-DCM family prospects, including the HD-DCM-Lite, are discussed.
*Geraldes, R. R., et al. "The New High-dynamics DCM for Sirius." Proc. of MEDSI 2016.
**Geraldes, R. R., et al. "The Status of the New High-Dynamic DCM for Sirius." Proc. of MEDSI 2018.
LNLS, Campinas, Brazil
After successfully designing, installing, and commissioning two units of the High-Dynamic Double-Crystal Monochromator (HD-DCM) at the Brazilian Synchrotron Light Laboratory (LNLS) - Sirius, two more units are now required. Since they demand only a smaller energy range (5 to 35 keV), the total gap stroke of the new instruments can be significantly reduced, creating an opportunity to adapt the existing design towards the so-called HD-DCM-Lite. Removing the large gap adjustment mechanism allows a reduction of the main inertia by a factor of 5, enabling the HD-DCM-Lite to deliver energy flyscans of hundreds of eV reaching 20 cycles per second while keeping fixed exit and the pitch stability in the range of 10 nrad RMS (1 Hz - 2.5 kHz). Hence, an unparallel bridge between slow step-scan DCMs and fast channel-cut monochromators is created. This work presents the in-house development of the HD-DCM-Lite, focusing on its mechanical design, discussions on the ultimate scanning constraints (rotary stage torque, voice-coil forces, interferometers and encoders readout speed limits and subdivisional errors), and thermal management.
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