Fly-scan-oriented motion analyses and upgraded beamline integration architecture for the High-Dynamic Double-Crystal Monochromator at Sirius/LNLS

Abstract

The High-Dynamic Double-Crystal Monochromator (HD-DCM) is a mechatronic system with unique control-based architecture and deep paradigm changes as compared with traditional beamline monochromators. Aiming at unprecedented inter-crystal positioning stability in vertical-bounce double-crystal monochromators (DCMs) of the order of 10 nrad RMS (1 Hz to 2.5 kHz), and not only in fixed-energy but also in fly-scan operation, it has been developed according to a 'first-time right' predictive design approach for hard X-ray beamlines at Sirius, the fourth-generation light source at the Brazilian Synchrotron Light Laboratory (LNLS/CNPEM). This work explores some of the challenges that emerge with this new technology and presents the latest commissioning results that demonstrate the unparallel performances of the HD-DCM at the undulator-based EMA (Extreme Methods of Analysis) beamline at Sirius. With the enabled fast spectroscopy fly-scan possibilities, a new energy-tuning evaluation method, based on wave-propagation simulations, becomes part of a motion-oriented analysis that is carried out to derive the multi-axis non-linear positioning problem, covering not only energy selection and fixed exit in the HD-DCM but also the emission spectrum of an adjustable-phase undulator (APU). The HD-DCM control scheme and its flexible operation modes are described in detail as well. Furthermore, a new integration topology between the HD-DCM and EMA's APU, coming already close to ultimate motion levels, is described and validated.