LNLS, Campinas, Brazil
CNPEM, Campinas, SP, Brazil
Beamlines of new 4th-generation machines present high-performance requirements in terms of preserving beam quality, in particular wavefront integrity and position stability at micro and nanoprobe stations. It brings about numerous efforts to cope with engineering challenges comprehending high thermal load, cooling strategy, crystal manufacturing, vibration sources, alignment and coupled motion control. This contribution presents the design and performance of a four-bounce silicon-crystal monochromator for the Sirius beamlines at the Brazilian Synchrotron Light Source (LNLS), which is basically composed of two channel-cut crystals mounted on two goniometers that counter-rotate synchronously. The mechanical design ascertained the demands for the nanoprobe and coherent scattering beamlines - namely, CARNAÚBA and CATERETÊ - focusing on solutions to minimize misalignments among the parts, to grant high stiffness and to ensure that the thermal performance would not impair beam characteristics. Hence, all parts were carefully simulated, machined, and measured before assembling. This work details mechanical, thermal, diagnostics, and dynamic aspects of the instruments, from the design phase to their installation and initial commissioning at the beamlines.
