Developments in optics and performance at BL13-XALOC, the macromolecular crystallography beamline at the Alba Synchrotron

Jordi Juanhuix, Fernando Gil-Ortiz, Guifre Cuni, Carles Colldelram, Josep Nicolas, Julio Lidon-Simon, Eva Boter, Claude Ruget, Salvador Ferrer, Jordi Benach

Research output: Contribution to journalArticlepeer-review

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 mu m x 5.5 mu m FWHM(H x 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.
Original languageEnglish
Pages (from-to)679-689
JournalJournal of Synchrotron Radiation
Volume21
DOIs
Publication statusPublished - 2014

Subject classification (UKÄ)

  • Accelerator Physics and Instrumentation

Free keywords

  • macromolecular crystallography
  • beamline
  • Alba
  • mirror slope errors

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