BioCARS: A synchrotron resource for time-resolved X-ray science

T. Graber*, S. Anderson, H. Brewer, Y. S. Chen, H. S. Cho, N. Dashdorj, R. W. Henning, I. Kosheleva, G. MacHa, M. Meron, R. Pahl, Z. Ren, S. Ruan, F. Schotte, V. Šrajer, P. J. Viccaro, F. Westferro, P. Anfinrud, K. Moffat

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

96 Scopus citations


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 m horizontal by 20 m 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 × 1010 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.

Original languageEnglish (US)
Pages (from-to)658-670
Number of pages13
JournalJournal of Synchrotron Radiation
Issue number4
StatePublished - Jul 2011


  • Laue crystallography
  • X-ray optics
  • synchrotron beamline
  • time-resolved crystallography

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation
  • Radiation


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