The high energy X-rays coming from the central portion of the wiggler radiation fan are reflected inboard by a Si (111), (422), or (533) single crystal monochromator in Laue mode.  The monochromator also provides excellent vetical focusing and some horizontal focusing.

Flux ranges from about 5x10⁹ to 2x10¹³ depending on the energy.  Vertical focal size is about 50 μm whle horizontal focus is a about 2 mm but is usually slitted down to be close to 200-300 μm.

The high energy beamline generally operates with a Perkin Elmer area detector mounted on a translation table which moves to follow the Bragg angle of the monochromator as the energy is changed.  This flexible setup allows essentially any energy within the beamlines range to be easily accessed.  The ability to choose the energy and to collect and integrate the entire diffraction rings enables the following abilities.

Pair Distribution Functions:  The PDF gives the distribution of inter-atomic distances in a material and is an excellent probe of the local and medium range structure.  The use of high energy X-rays allows high resolution PDFs to be generated by collecting data up to high Qmax values. Typical usable Qmax values can range anywhere from 22 - 32 A^-1 depending on the energy chosen.  Even higher values can be obtained by raising and tilting the detector.  The ablity to choose the wavelength allows one to optimize between photon flux, Qmax, and instrumental dampening to suit the needs of a particular problem.

Rapid Powder Diffraction Data Collection:  The use of an area detector allows rapid collection of powder diffraction data with very high counting statisitics.  Patterns can ususally be collected in under a minute and often in just a few seconds.  This can be very useful for making measurements as a function of temperature, in-situ reactions, studying large numbers of samples, and many other purposes.

Sample loading for loose powders at WHE

Measurements of loose powders are generally done using Kapton capillaries. In general, the largest capillary for which the absorption is not problematic is preferred. The absorption can be estimated using this website. For the WHE beamline, flux is lower and absorption is usually negligable so capillaries between 0.5 and 0.9 mm inner diameter are used. Generally sizes of 0.63 or 0.8 are preferred. Tubes of 0.5 mm can be used if there is limited sample and 0.9 mm or even larger can be used for weakly scattering samples. For a capillary to fit in the WHE sample changer it should be at least 30 mm in total length and it is best if the sample fills at least 12 mm of the capillary. When loading capillaries it is best to seal the ends with wax or putty. Glue can be used to seal air sensitive samples but be careful not to form a bead at the end which is wider than the capillary or it may not be possible to fit it in the holder. Be sure to grind your samples well before loading! Having samples with large grains will reduce the quality of the data.

Users are encouraged to purchase their own capillaries and load the samples prior to arrivial. We also have capillaries on-site which users can use. Those mailing samples should load them prior to shipping. If you do not have any we can mail capillaries on request. Capillaries can be ordered here as well as from other vendors. For high temperature experiments quartz capillaries of various sizes are available.Air sensitive samples can be loaded in a glove box at the home institution or at the CLS. If you wish to use a CLS glove box please contact the instrument scientist well before your arrival so we can make sure one will be available.  Users also have access to our chemistry lab for sample preparation.

We can also measure solid pieces in transmission mode in the high energy beamline. This is useful for measurements of samples such as pieces of steel or in-situ battery experiments. 

Penetration of Samples:  By using high energy X-rays powder diffraction data can be collected on thick samples, such as  batteries and other devices that benefit from being examined in-operando. We can also penetrate pieces of metal while heating to high temperature.

High Pressure Studies:  This beamline has the ideal energy range for high pressure expeirments using a diamond anvil cell (DAC).  Users usually bring their own but with special arrangement Diamond Anvil Cells( Pmax 38 GPa and 20 GPa) can be provided to users.

The Bragg-LT(G) Plus diaphragm diamond anvil cell fit with diamond anvil, type IIas, Boehler-Almax design, 16-sided, diameter 3.30 - 85° (X-ray aperture 4θ), culet of 0.5 mm (Pmax 38 GPa) and 1.20 mm (Pmax 20 GPa),  (100)-oriented, ultra-low birefringence, Raman ultra-low fluorescence.

Gas loading system for Diamond Anvil cell: A stand-alone instrument for loading gasses into diaphragm or mechanical diamond anvil cells (DACs) under high pressure.

Training is required to use the gas loading system.