Status and Developments of BL13-XALOC, the macromolecular crystallography beamline at Alba

Abstract

BL13-XALOC is a Macromolecular Crystallography beamline at the newly built 3-GeV synchrotron ALBA (Barcelona). The optics design is based on an in-vacuum undulator, a Si(111) channel-cut crystal monochromator, and a pair of KB mirrors. The optical design allows three main operation modes: an unfocused configuration, where one or both mirrors are removed from the photon beam path; a focused configuration, where both mirrors can focus the beam to 49×9 μm2 FWHM (H×V), and a defocused configuration that can match the size of the beam to the dimensions of the crystals or to focus it at the detector. To achieve a uniform defocused beam, the slope errors were reduced by using novel method together with our high-accuracy metrology laboratory. Thorough commissioning has also demonstrated that the X-ray beam has excellent energy and spatial stability. The End Station includes a high accuracy single axis diffractometer, a removable mini-kappa goniometer, an automated sample mounting robot and a Pilatus6M, photon-counting detector. This equipment, together with the operation flexibility, allows the beamline to tackle a large variety of crystals, from medium sized crystals with large unit cell parameters to microcrystals. Several examples of high-quality data collections measured during beamline commissioning are described. The beamline started user operation on 18th July 2012.