XFM Detectors
Maia detector
The Maia detector has been a workhorse at XFM for over a decade. It consists of 384 individual silicon detector channels in an array as shown below. The incident beam passes through an aperture in the centre of the detector array an onto the sample. The X-ray fluorescence from the sample is collected in the so-called backscatter geometry. The energy resolution of the Maia (Mn K_a) is approximately 275 eV. With our current scanning stages, the maximum size of a scan with the Maia is approximately 130mm x 98mm ( H x V).
Below: a sample platen with a LOT of seeds getting positioned for scanning with the Maia detector.
Vortex ME3
The Vortex ME3 is a silicon drift detector arranged in a 3-element vertical array. It is placed at a 90 degree angle to the incident beam with the sample scanned at a 45 degree angle. In this geometry the scatter collected is much less than in the Maia geometry. The energy resolution of the Vortex is about 135 eV. The maximum scan size with the Vortex detector is approximately 70mm x 98mm (H x V).
The incident beam onto the sample is shown as the green arrow below. The Vortex ME3 is close to the sample platen for optimal detection sensitivity.
Below is a view from the rear of the samples with the collimator snout of the Vortex ME3 clearly shown. The green arrow denotes the incident beam.
EIGER2 X 1M
A 1 Mpixel-array detector for scanning X-ray diffraction microscopy (SXDM) measurements. Essentially an X-ray camera, the Eiger detector records images of the transmitted beam downstream of the sample. The Eiger detector is necessary for ptychography, SXDM, scanning SAXS/WAXS and differential phase contrast (DPC) measurements. See the XFM beamline paper for more details.
Photos to come.
Mirion 4-element Germanium detector (coming mid-2024)
The Ge detector has much better detection efficiency over a silicon-based detector at high energies (>20 keV). It may be advantageous to use a Ge detector over a Si detector in cases where so-called ‘escape peaks’ interfere with elements of interest. A classic case occurs in calcium-rich samples such as calcite, or bone where the high calcium signal creates a detector artifact, with a peak approximately 1.8 keV (the Si fluorescence energy) below the calcium fluorescence peak. This escape peak can mask elements of interest such as phosphorus and sulfur.
Photos to come.