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BioCARS: a synchrotron resource for time-resolved X-ray science.

BioCARS, a NIH-supported national user facility for macromolecular time-resolved X-ray crystallography at the Advanced Photon Source (APS), has recently completed commissioning of an upgraded undulator-based beamline optimized for single-shot laser-pump X-ray-probe measurements with time resolution as short as 100 ps. The source consists of two in-line undulators with periods of 23 and 27 mm that together provide high-flux pink-beam capability at 12 keV as well as first-harmonic coverage from 6.8 to 19 keV. A high-heat-load chopper reduces the average power load on downstream components, thereby preserving the surface figure of a Kirkpatrick-Baez mirror system capable of focusing the X-ray beam to a spot size of 90 µm horizontal by 20 µm vertical. A high-speed chopper isolates single X-ray pulses at 1 kHz in both hybrid and 24-bunch modes of the APS storage ring. In hybrid mode each isolated X-ray pulse delivers up to ~4 × 10(10) photons to the sample, thereby achieving a time-averaged flux approaching that of fourth-generation X-FEL sources. A new high-power picosecond laser system delivers pulses tunable over the wavelength range 450-2000 nm. These pulses are synchronized to the storage-ring RF clock with long-term stability better than 10 ps RMS. Monochromatic experimental capability with Biosafety Level 3 certification has been retained.

Pubmed ID: 21685684


  • Graber T
  • Anderson S
  • Brewer H
  • Chen YS
  • Cho HS
  • Dashdorj N
  • Henning RW
  • Kosheleva I
  • Macha G
  • Meron M
  • Pahl R
  • Ren Z
  • Ruan S
  • Schotte F
  • Srajer V
  • Viccaro PJ
  • Westferro F
  • Anfinrud P
  • Moffat K


Journal of synchrotron radiation

Publication Data

July 20, 2011

Associated Grants

  • Agency: NCRR NIH HHS, Id: RR007707

Mesh Terms

  • Crystallography, X-Ray
  • Synchrotrons