People speak of a beamline in three ways. It’s a physical space within the experimental hall. It’s also a set of equipment that brings the X-ray beam to the material being studied and records what happens. And most importantly, it’s a dynamic meeting place, where multidisciplinary teams of local and visiting scientists and staff collaborate to answer leading-edge research questions.

Location

Within the experimental hall, a beamline consists of an optics cabin, a experimental cabin, and a control cabin, aligned in a row.

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A set of equipment

X-ray optics (in optics cabin)

Scientists in the optics cabin of beamline ID26, March 2009 (Credit: ESRF/Molyneux Associates).The first job of the beamline is to modify the raw X-ray beam provided by the accelerator. Specialised mirrors and crystal optics may be used to focus the beam and to select the wavelength, or energy, desired. Because the beam carries a lot of energy in a very small area, these optics are designed to handle a lot of heat.

Sample environment and detectors (in experimental cabin)

Next, the beamline provides a way to put a sample of material in the X-ray beam. Depending on the experiment, the sample might be in the open air, or cooled by a jet of liquid nitrogen or helium, or contained within a custom-designed chamber that controls the experimental conditions (e.g. atmosphere, reactants, pressure, etc.). The sample workspace may include motors that position the sample very precisely with respect to the beam.

Preparation of an experiment in a vacuum tank on ESRF beamline ID01 for anomalous scattering studies, January 2005 (Credit: ESRF/P. Ginter).Around the sample are detectors that capture and record the X-rays that pass through or reflect from the sample. The simplest X-ray detector is photographic film, but at a synchrotron the detectors are made of material that turns the X-ray photon into either a visible-light photon or an electrical signal. Scintillation detectors pick up the visible-light photons and semiconductor or charge-coupled detectors pick up the electrical signals.

 

Beamline controls and data analysis (in control cabin)

Researchers use custom software to control devices that position samples, adjust the beam, and capture data. Sometimes data are analysed “on the fly” during the experiment, but usually researchers leave with vast quantities of data that they analyse later at their home institutions.

A dynamic meeting place

Outside an experimental hutch. Credit: ESRF/Molyneux Associates.Every experiment at the ESRF is the result of an extended collaboration among many people that culminates in an intense period at a specific beamline. A typical experiment involves quite a team:

  • several visiting scientists (called “users”), often from different countries and different disciplines, who spend several days at the ESRF
  • resident engineers and technical support staff, when specialised capabilities must be built
  • resident scientists and technicians who are expert users of the particular beamline
  • other resident scientific and adminstrative staff, who may perform analyses or arrange shipping of samples and equipment, for example.

An experiment may run night and day for several days, making a synchrotron collaboration a particularly dynamic research experience.