Photon-beam stabilization systems for the MX2 beamline at LNLS

The MX2, a wiggler beamline dedicated to macromolecular crystallography, started routinely operating for users in 2007. Late in the commissioning phase, several experiments started to be conducted in order to characterize photon-beam stability. At that time, position movements of typically 150 μm per shift and severe energy drifts reaching 0.8 eV/h were observed at sample position, which would certainly spoil the MAD experiments. The severity of this scenario for a recently delivered beamline led us to install temperature sensors and inclinometers along the optical hutch, besides performing exhaustive tests to clarify the disturbance paths. To elucidate the main instability mechanisms, three control systems for beam stabilization were considered—position stabilization, ground motion canceling and, the most important of all, temperature control for the optical hutch. Results and perspectives are presented hereafter.