XALOC - BL13

XALOC aims to provide the present and future Structural Biology groups with a flexible and reliable tool to help in solving structures of macromolecules and complexes. The beamline shall cope with a broad variety of crystal sizes and unit cell parameters, and will allow both wavelength dependent and independent experiments.

Status

The beamline is under COMMISSIONING with BEAM, to be open to users mid 2012.

Proposal submissions open until 17 January 2012.

Beamline infrastructure was mostly installed in first half 2009. The main optical elements, namely the Si(111) monochromator and the Horizontal and Vertical Focusing Mirrors (HFM and VFM), were set up in June 2009. Rest of the optics is now completed (Slits and XBPMs: October 2009; Photon Shutter: May 2010; Fluo screens and white beam attenuator: fall 2010). The Experimental Station started assembly in Summer 2010, and was completed in July 2011. The detector was received in integrated into the beamline in May 2011. In-vacuum Undulator has been installed in Summer 2011.

The process of building the beamline is shown here.

FIRST BEAM at sample position taken in 15 December 2011.

	First beam in XALOC - BL13 18 October 2011 View of white beam at the first Fluorescence screen. Inhomogeneities are due to the granularity of the CVD diamond screen, and are not related to the quality of the beam.
	First beam at the Pilatus Detector 15 December 2011 First image of the beam at detector. It shows a power diffraction pattern produced by the-2mm thick granulated aluminum detector cover.

Staff

Jordi Juanhuix & Jordi Benach: Beamline Scientists

Carles Colldelram : Mechanical Engineer
Roger Martín : Mechanical Engineer
Julio Lidón : Electronics Engineer
Guifré Cuní: Controls Engineer

Alejandro Enrique: Beamline Technician

Beamline characteristics

The beam size will be fitted to the crystal dimensions by (a) adjusting the focus of the mirrors along the beam path, and (b) having two operation modes of the beamline: focused and unfocused.

In unfocused configuration, one or both mirrors are removed from the photon beam path, resulting in a very small beam divergence of less than 0.03 mrad vertically. This mode can be especially useful for large macromolecular complexes with large unit cell parameters. In focused configuration both mirrors can focus the beam to 50×7 um² FWHM (H×V) on small or microcrystals, while at the same time keeping a small and useful vertical divergence (0.1 mrad). In addition, the mirrors allow variable focusing (defocusing) if matching the size of the x-ray beam to the dimensions of the crystals or if focusing at the detector (which can be placed at any distance between 80 mm to 1300 mm from sample) are required. In this case, the beam size at sample position can range from 50×7 um² to 300×300 um² (H×V). In order to avoid x-ray beam deformations caused by the optics when defocusing, slope errors of the mounted mirrors have been reduced to 70 nrad rms and the monochromator crystal can work near the zero expansion temperature of Silicon (124 K).

Technical Description

• Photon source
• Optics
• End Station

Documentation

• Original Proposal of the beamline (2005)
• Conceptual Design (2006)
• Minutes 1a Reunión de Usuarios de Líneas de Luz de Cristalografía Macromolecular de España (22 Octubre 2007)
• Poster XALOC in 4th Annual Meeting BioXHit (16-18 April 2008)
• Poster XALOC in Spanish Synchrotron Users Meeting (AUSE4, 15-18 September 2009) 

• Poster XALOC in 2011 IUCr General Congress (Madrid, 22-29 August 2011)