Synchrotron characterisation of non-uniformities in a small pixel cadmium zinc telluride imaging detector

Veale, Matthew C.; Bell, S.; Duarte, Diana D.; Schneider, Andreas; Seller, P.; Wilson, Matthew D.; Kachkanov, V.; Sawhney, Kawal

doi:10.1016/j.nima.2013.07.054

Cited by 11 publications

(11 citation statements)

References 32 publications

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“…The spectroscopic performance of the HF-CdZnTe detector compares favourably to the performance achieved using spectroscopic-grade CdZnTe from Redlen technologies [ 47 ], also coupled with the HEXITEC ASIC in a detector of 2 mm thickness and 250

pixel pitch. Using the spectroscopic-grade CdZnTe, the average FWHM of the 59.5 keV photopeak for the entire detector was 1.74 ± 0.39 keV for isolated events only, compared with 0.95 ± 0.07 keV achieved with the HF-CdZnTe detector here.…”

Section: Discussionmentioning

confidence: 99%

“…Using the spectroscopic-grade CdZnTe, the average FWHM of the 59.5 keV photopeak for the entire detector was 1.74 ± 0.39 keV for isolated events only, compared with 0.95 ± 0.07 keV achieved with the HF-CdZnTe detector here. Veale et al [ 47 ] showed evidence of local variations in the electric field, linked to the build up of space charge due to carrier trapping and the use of blocking contacts [ 48 ], which would damage spectroscopic performance. The agreement between the experimentally determined charge sharing rates and simulation set to the applied external bias of −750 V ( Figure 9 ), suggests that the electric field strength within the HF-CdZnTe does not significantly suffer from local distortions and is uniform.…”

Section: Discussionmentioning

confidence: 99%

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Charge Sharing and Charge Loss in High-Flux Capable Pixelated CdZnTe Detectors

Koch-Mehrin

Bugby

Lees

et al. 2021

Sensors

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Cadmium zinc telluride (CdZnTe) detectors are known to suffer from polarization effects under high photon flux due to poor hole transport in the crystal material. This has led to the development of a high-flux capable CdZnTe material (HF-CdZnTe). Detectors with the HF-CdZnTe material have shown promising results at mitigating the onset of the polarization phenomenon, likely linked to improved crystal quality and hole carrier transport. Better hole transport will have an impact on charge collection, particularly in pixelated detector designs and thick sensors (>1 mm). In this paper, the presence of charge sharing and the magnitude of charge loss were calculated for a 2 mm thick pixelated HF-CdZnTe detector with 250 μm pixel pitch and 25 μm pixel gaps, bonded to the STFC HEXITEC ASIC. Results are compared with a CdTe detector as a reference point and supported with simulations from a Monte-Carlo detector model. Charge sharing events showed minimal charge loss in the HF-CdZnTe, resulting in a spectral resolution of 1.63 ± 0.08 keV Full Width at Half Maximum (FWHM) for bipixel charge sharing events at 59.5 keV. Depth of interaction effects were shown to influence charge loss in shared events. The performance is discussed in relation to the improved hole transport of HF-CdZnTe and comparison with simulated results provided evidence of a uniform electric field.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Charge Sharing and Charge Loss in High-Flux Capable Pixelated CdZnTe Detectors

Koch-Mehrin

Bugby

Lees

et al. 2021

Sensors

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“…While the current iteration of the detector system is now in use at beam lines, a roadmap for STFC's continued development of this technology is in place. In the short term, the aim is to improve the efficiency of the system at energies > 150 keV through the use of thick cadmium zinc telluride sensor material [18] without compromising on the spectroscopic performance of the system. In the longer term, a new generation of the technology will be developed that delivers spectroscopic imaging at frame rates of up to 1 MHz which will meet the needs of future diffraction limited storage ring synchrotrons.…”

Section: Discussionmentioning

confidence: 99%

HEXITEC: A High-Energy X-ray Spectroscopic Imaging Detector for Synchrotron Applications

Veale

Seller

Wilson

et al. 2018

Synchrotron Radiation News

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HEXITEC is a compact high energy X-ray spectroscopic imaging detector system developed by the STFC Rutherford Appleton Laboratory (UK). The system is based on the high density compound semiconductor cadmium telluride and consists of an 80 × 80 array of pixels on a 250 m pitch with each channel capable of measuring X-ray spectra in the energy range 2 -200 keV with an energy resolution of 800 eV. The system operates at room temperature and removes the need for large cryogenic cooling systems used by other systems covering similar energy ranges. The system has applications at synchrotrons in experiments where mechanical, structural or chemical information is required from thick samples or to determine the chemical composition of samples containing multiple high Z materials. In this article the operation of the system is described, the sensor performance characterised and a simple example of spectroscopic imaging at a synchrotron beamline demonstrated.

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“…It is also worth noting that there is very little spatial variation in the charge sharing percentage across the entire detector, see Figure 5a, with only major variations observed at the physical edge of the sensor. The spatial uniformity of the charge sharing suggests that the electric field across the detector is also very uniform and does not contain the electric field variations that have been observed previously in spectroscopic-grade CdZnTe material from Redlen [23]. As the HEXITEC system records each frame of data, any charge sharing corrections are applied during data processing, allowing different algorithms to be used.…”

Section: Charge Sharingmentioning

confidence: 99%

Characterization of the Uniformity of High-Flux CdZnTe Material

Veale

Booker

Cross

et al. 2020

Sensors

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Since the late 2000s, the availability of high-quality cadmium zinc telluride (CdZnTe) has greatly increased. The excellent spectroscopic performance of this material has enabled the development of detectors with volumes exceeding 1 cm3 for use in the detection of nuclear materials. CdZnTe is also of great interest to the photon science community for applications in X-ray imaging cameras at synchrotron light sources and free electron lasers. Historically, spatial variations in the crystal properties and temporal instabilities under high-intensity irradiation has limited the use of CdZnTe detectors in these applications. Recently, Redlen Technologies have developed high-flux-capable CdZnTe material (HF-CdZnTe), which promises improved spatial and temporal stability. In this paper, the results of the characterization of 10 HF-CdZnTe detectors with dimensions of 20.35 mm × 20.45 mm × 2.00 mm are presented. Each sensor has 80 × 80 pixels on a 250-μm pitch and were flip-chip-bonded to the STFC HEXITEC ASIC. These devices show excellent spectroscopic performance at room temperature, with an average Full Width at Half Maximum (FWHM) of 0.83 keV measured at 59.54 keV. The effect of tellurium inclusions in these devices was found to be negligible; however, some detectors did show significant concentrations of scratches and dislocation walls. An investigation of the detector stability over 12 h of continuous operation showed negligible changes in performance.

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Synchrotron characterisation of non-uniformities in a small pixel cadmium zinc telluride imaging detector

Cited by 11 publications

References 32 publications

Charge Sharing and Charge Loss in High-Flux Capable Pixelated CdZnTe Detectors

Charge Sharing and Charge Loss in High-Flux Capable Pixelated CdZnTe Detectors

HEXITEC: A High-Energy X-ray Spectroscopic Imaging Detector for Synchrotron Applications

Characterization of the Uniformity of High-Flux CdZnTe Material

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