title: Developments in optics and performance at BL13-XALOC, the macromolecular crystallography beamline at the ALBA synchrotron.
abstract: BL13-XALOC is currently the only macromolecular crystallography beamline at the 3 GeV ALBA synchrotron near Barcelona, Spain. The optics design is based on an in-vacuum undulator, a Si(111) channel-cut crystal monochromator and a pair of KB mirrors. It allows three main operation modes: a focused configuration, where both mirrors can focus the beam at the sample position to 52 µm × 5.5 µm FWHM (H × V); a defocused configuration that can match the size of the beam to the dimensions of the crystals or to focus the beam at the detector; and an unfocused configuration, where one or both mirrors are removed from the photon beam path. To achieve a uniform defocused beam, the slope errors of the mirrors were reduced down to 55 nrad RMS by employing a novel method that has been developed at the ALBA high-accuracy metrology laboratory. Thorough commissioning with X-ray beam and user operation has demonstrated an excellent energy and spatial stability of the beamline. The end-station includes a high-accuracy single-axis diffractometer, a removable mini-kappa stage, an automated sample-mounting robot and a photon-counting detector that allows shutterless operation. The positioning tables of the diffractometer and the detector are based on a novel and highly stable design. This equipment, together with the operation flexibility of the beamline, allows a large variety of types of crystals to be tackled, from medium-sized crystals with large unit-cell parameters to microcrystals. Several examples of data collections measured during beamline commissioning are described. The beamline started user operation on 18 July 2012.
authors: ALBA Synchrotron, BP 1413, km 3.3, Cerdanyola del Vallès, Spain.
authors: Jordi
authors: J
authors: Juanhuix
authors: ALBA Synchrotron, BP 1413, km 3.3, Cerdanyola del Vallès, Spain.
authors: Fernando
authors: F
authors: Gil-Ortiz
authors: ALBA Synchrotron, BP 1413, km 3.3, Cerdanyola del Vallès, Spain.
authors: Guifré
authors: G
authors: Cuní
authors: ALBA Synchrotron, BP 1413, km 3.3, Cerdanyola del Vallès, Spain.
authors: Carles
authors: C
authors: Colldelram
authors: ALBA Synchrotron, BP 1413, km 3.3, Cerdanyola del Vallès, Spain.
authors: Josep
authors: J
authors: Nicolás
authors: ALBA Synchrotron, BP 1413, km 3.3, Cerdanyola del Vallès, Spain.
authors: Julio
authors: J
authors: Lidón
authors: ALBA Synchrotron, BP 1413, km 3.3, Cerdanyola del Vallès, Spain.
authors: Eva
authors: E
authors: Boter
authors: ALBA Synchrotron, BP 1413, km 3.3, Cerdanyola del Vallès, Spain.
authors: Claude
authors: C
authors: Ruget
authors: ALBA Synchrotron, BP 1413, km 3.3, Cerdanyola del Vallès, Spain.
authors: Salvador
authors: S
authors: Ferrer
authors: ALBA Synchrotron, BP 1413, km 3.3, Cerdanyola del Vallès, Spain.
authors: Jordi
authors: J
authors: Benach
keywords: Alba; beamline; macromolecular crystallography; mirror slope errors