1) XIDyn: A Charge Cancellation Detector for High Timing and Flux Measurements at 4th Generation Synchrotrons
Speaker: Matt Wilson, Science and Technology Facilities Council, United Kingdom
Primary author: WILSON, Matt (Science & Technology Facilities Council)
XIDyn is a hard X-ray detector that will measure fluxes up to 1012 photons/mm2
/s with >100 kHz continuous frame rate
and capture bursts of frames at up to 5.7 MHz. The detector will have 144 x 192 pixels on a 110 µm designed to operate
with CdZnTe detector material and operate at energies of 10 - 100 keV.
The XIDyn ASIC is a two-stage charge cancellation and digitisation design. The first “coarse” stage integrates, cancels and
counts integer numbers of photons at a time. The second “fine” stage is operated in a pipeline with the coarse stage and
resolves single or fractions of a photon using the same charge cancellation method. The “sub-frames” measured on coarse
and fine stage counters are merged and stored in the pixel RAM. The pixel RAM can be flexibly programmed so that the
sub-frames can be summed, averaged, stored in a sequence, and vetoed before readout. The data is readout as 66b64b
aurora encoded packets by serialisers operating at 14.1 Gbps. There are 6 serialisers along one edge of the chip and there is
an option to operate all serialiser or one, depending on required frame rate.
The chip has two main modes of operation but retains functionality for other modes. In continuous mode the sub-frames are
summed or averaged in the pixel RAM and readout a regular intervals. For example, with a sub-frame rate of 533 kHz
to match the orbit of Diamond, and a pixel count of 16 bits, the ASIC could operate with a frame rate of 133.5 kHz. In
burst mode, the RAM can be used to capture sequences of sub-frames at rates higher than the output rate of the chip. For
example, a sub-frame rate of 5.7 MHz to match the 16-bunch mode of ESRF could be used with an 8 bit value per pixel.
The RAM could capture a sequence of 256 sub-frames that are readout at the end of the collection.
In addition to progress in the design of the XIDyn ASIC, results will be presented from a 16x32 pixel MPW ASIC. The
electrical performance and measurements made with HF-CdZnTe detectors will be discussed and how these findings may
impact the design of the full-scale detector.
Presentation
2) Spectroscopic Hard X-Ray Imaging at MHz Frame Rates
Speaker: Matthew Veale, Ukri Science and Technology Facilities Council, United Kingdom
Primary author: VEALE, Matthew (STFC Rutherford Appleton Laboratory)
Co-authors: Mr DAVIES, Adam (STFC Rutherford Appleton Laboratory); Mr CLINE, Ben (STFC Rutherford Appleton
Laboratory); Mr BANKS, Dominic (STFC Rutherford Appleton Laboratory); Mr NOBES, Joseph (STFC Rutherford Appleton
Laboratory); JONES, Lawrence (UKRI STFC Rutherford Appleton Laboratory); Mr HART, Matt (STFC Rutherford Appleton
Laboratory); Mr ROBERTS, Matt (STFC Rutherford Appleton Laboratory); WILSON, Matt (Science & Technology Facilities
Council); Mr PRADEEP, Sooraj (STFC Rutherford Appleton Laboratory); Mr BELL, Stephen (STFC Rutherford Appleton
Laboratory); Dr NICHOLLS, Tim (STFC Rutherford Appleton Laboratory); GARDINER, Thomas (STFC)
The High Energy X-ray Imaging Technology (HEXITEC) camera system was developed by the Science & Technology Facilities
Council (STFC) in the late 2000’s with the aim of delivering fully spectroscopic (colour) X-ray imaging at energies 2 – 200
keV. The original system has a pixel pitch of 250µm, 80×80 pixels, each with an energy resolution of ~ 800eV running at
10kHz. To correct for sensor effects such as charge sharing, the system is run at <10% occupancy which limits it’s use
to photon fluxes of ~ 104
ph s−1 mm−2
. The original camera has been used in a broad range or fields, from battery[1]
and materials science[2] at synchrotrons to medical imaging[3], these flux restrictions have limited its applications in some
areas, like colour CT. Prompted by a new generation of diffraction limited storage rings, STFC have developed a new
generation of the technology that can operate at fluxes in excess of 106
ph s−1 mm−2 without compromising spectroscopic
performance.
The HEXITEC-MHz ASIC runs at a continuous 1 million frames per second which, when coupled to high-flux-capable
CdZnTe material, delivers per pixel spectroscopy for hard X-rays in the range 2 – 300 keV with a resolution of < 1keV for
polychromatic sources up to fluxes of 2×106
ph s−1 mm−2 [4]. The capabilities of the camera system enable the use of
techniques such as full colour X-ray CT for dynamic systems on time scales of <1s at synchrotron facilities and beyond. The
integrating architecture also means that, where a monochromatic source is in use, the system can be used up to fluxes of
2×108
ph s−1 mm−2
(assuming 30keV X-rays).
A summary of recent testing using lab-based sources and the Diamond Light Source will be presented. These include
measurements with monochromatic 20keV X-rays that have confirmed the excellent per-pixel energy resolution of the system
of 0.8keV for HF-CdZnTe sensors and 0.6keV for p-type Si sensors at a flux of 106
ph s−1 mm−2 [5]
.
[1] C. Leung et al., https://doi.org/10.1016/j.mtener.2022.101224
[2] S. Feng et al., https://doi.org/10.1557/mrs.2020.270
[3] S. Mandot et al., https://doi.org/10.1109/TMI.2023.3348791
[4] M. Veale et al., https://doi.org/10.1088/1748-0221/18/07/P07048
[5] B. Cline et al., https://doi.org/10.1016/j.nima.2023.168718
Presentation
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