International
Tables for
Crystallography
Volume F
Crystallography of biological molecules
Edited by M. G. Rossmann and E. Arnold

International Tables for Crystallography (2006). Vol. F, ch. 8.1, pp. 156-158   | 1 | 2 |

Section 8.1.4. Beam characteristics delivered at the crystal sample

J. R. Helliwella*

aDepartment of Chemistry, University of Manchester, M13 9PL, England
Correspondence e-mail: john.helliwell@man.ac.uk

8.1.4. Beam characteristics delivered at the crystal sample

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The sample acceptance, α [equation (8.1.4.1)[link]], is a quantity to which the synchrotron machine emittance [equation (8.1.2.2)[link]] should be matched, i.e., [\alpha = x \eta, \eqno(8.1.4.1)] where x is the sample size and η the mosaic spread. For example, if [x = 0.1\;\hbox{mm}] and [\eta = 1\;\hbox{mrad}] (0.057°), then [\alpha = 10^{-7}\;\hbox{m rad}] or 100 nm rad.

At the sample position, the intensity of the beam, usually focused, is a useful parameter: [\hbox{Intensity} = \hbox{photons per s per focal spot area}. \eqno(8.1.4.2)] Moreover, the horizontal and vertical convergence angles are ideally kept smaller than the mosaic spread, e.g. ~1 mrad, so as to measure reflection intensities with optimal peak-to-background ratio.

To produce a focal spot area that is approximately the size of a typical crystal (~0.3 mm) and with a convergence angle ~1 mrad sets a sample acceptance requirement to be met by the X-ray beam and machine emittance. A machine with an emittance that matches the acceptance of the sample greatly assists the simplicity and performance of the beamline optics (mirror and/or monochromator) design. The common beamline optics schemes are shown in Fig. 8.1.4.1[link].

[Figure 8.1.4.1]

Figure 8.1.4.1 | top | pdf |

Common beamline optics modes. (a) Horizontally focusing cylindrical monochromator and vertical focusing mirror [shown here for station 9.6 at the SRS (adapted from Helliwell et al., 1986[link])]. (b) Rapidly tunable double-crystal monochromator and point-focusing toroid mirror [shown here for station 9.5 at the SRS (adapted from Brammer et al., 1988[link])].

In addition to the focal spot area and convergence angles, it is necessary to provide the appropriate spectral characteristics. In monochromatic applications, involving the rotating-crystal diffraction geometry, for example, a particular wavelength, λ, and narrow spectral bandwidth, [{\delta\lambda /\lambda}], are used. Fig. 8.1.4.2(a)[link] shows an example of a monochromatic oscillation diffraction photograph from a rhinovirus crystal as an example recorded at CHESS, Cornell. Fig. 8.1.4.2(b)[link] shows the prediction of a white-beam broad-band Laue diffraction pattern from a protein crystal recorded at the SRS wiggler, Daresbury, colour-coded for multiplicity.

[Figure 8.1.4.2]

Figure 8.1.4.2 | top | pdf |

Single-crystal SR diffraction patterns. (a) Rhinovirus monochromatic oscillation photograph recorded at CHESS (Arnold et al. 1987[link]; see also Rossmann & Erickson, 1983[link]). (b) Prediction of a protein crystal Laue diffraction pattern (for an illuminating bandpass, without monochromator, [\sim \!0.4 \lt \lambda \lt 2.6 \;\hbox{\AA}]). The colour coding is according to the multiplicity of each spot: turquoise for singlet reflections, yellow for doublets, orange for triplets and blue for quartet or higher-multiplicity Laue spots. Reproduced with permission from Cruickshank et al. (1991[link]).

Table 8.1.4.1[link] lists the internet addresses of the SR facilities worldwide that currently have macromolecular beamlines.

Table 8.1.4.1| top | pdf |
Internet addresses of SR facilities with macromolecular crystallography beamlines

Synchrotron-radiation sourceLocationAddress
ALS, Advanced Light Source Lawrence Berkeley Lab., Berkeley, California, USA http://www-als.lbl.gov/als/
APS, Advanced Photon Source Argonne National Lab., Chicago, Illinois, USA http://epics.aps.anl.gov/
BESSY Berlin, Germany http://www.bessy.de/
BSRF, Beijing Synchrotron Radiation Facility Beijing, China http://www.ihep.ac.cn/bsrf/english/main/main.htm
CAMD, Center for Advanced Microstructures and Devices Baton Rouge, Louisiana, USA http://www.camd.lsu.edu/
CHESS, Cornell High Energy Synchrotron Source Ithaca, New York, USA http://www.chess.cornell.edu/
Daresbury Laboratory CLRC Daresbury, England http://www.cclrc.ac.uk
Elettra Trieste, Italy http://www.elettra.trieste.it
ESRF, European Synchrotron Radiation Facility Grenoble, France http://www.esrf.fr/
HASYLAB DESY, Deutsches Elektronen-Synchrotron Hamburg, Germany http://www.desy.de/
LNLS, National Synchrotron Light Laboratory Campinas, Brazil http://www.lnls.br/
LURE Orsay, France http://www.lure.u-psud.fr/
MAXLab Lund, Sweden http://www.maxlab.lu.se/
NSLS, National Synchrotron Light Source Brookhaven National Lab., New York, USA http://www.nsls.bnl.gov/
The Photon Factory, KEK Tsukuba, Japan http://www.kek.jp/kek/IMG/PF.html
PLS, Pohang Light Source Pohang, Korea http://pal.postech.ac.kr/
SLS, Swiss Light Source Paul Scherrer Institut, Villigen, Switzerland http://sls.web.psi.ch/view.php/about/index.html
SPring-8, Super Photon Ring Riken Go, Japan http://www.spring8.or.jp/
SRRC, Synchrotron Radiation Research Center Hsinchu City, Taiwan http://www.nsrrc.org.tw/
SSRL, Stanford Synchrotron Radiation Laboratory SLAC, California, USA http://www-ssrl.slac.stanford.edu/
VEPP-3 Novosibirsk, Russia http://ssrc.inp.nsk.su/








































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