scholarly journals CdTe Based Energy Resolving, X-ray Photon Counting Detector Performance Assessment: The Effects of Charge Sharing Correction Algorithm Choice

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6093
Author(s):  
Oliver L. P. Pickford Scienti ◽  
Jeffrey C. Bamber ◽  
Dimitra G. Darambara
Keyword(s):  
Detection Efficiency ◽  
Photon Counting ◽  
Charge Sharing ◽  
Correction Algorithm ◽  
Detector Performance ◽  
Photon Counting Detector ◽  
Photon Counting Detectors ◽  
The Difference ◽  
Pixel Pitch ◽  
Made In

Most modern energy resolving, photon counting detectors employ small (sub 1 mm) pixels for high spatial resolution and low per pixel count rate requirements. These small pixels can suffer from a range of charge sharing effects (CSEs) that degrade both spectral analysis and imaging metrics. A range of charge sharing correction algorithms (CSCAs) have been proposed and validated by different groups to reduce CSEs, however their performance is often compared solely to the same system when no such corrections are made. In this paper, a combination of Monte Carlo and finite element methods are used to compare six different CSCAs with the case where no CSCA is employed, with respect to four different metrics: absolute detection efficiency, photopeak detection efficiency, relative coincidence counts, and binned spectral efficiency. The performance of the various CSCAs is explored when running on systems with pixel pitches ranging from 100 µm to 600µm, in 50 µm increments, and fluxes from 106 to 108 photons mm−2 s−1 are considered. Novel mechanistic explanations for the difference in performance of the various CSCAs are proposed and supported. This work represents a subset of a larger project in which pixel pitch, thickness, flux, and CSCA are all varied systematically.

scholarly journals Dual energy X-ray beam ptycho-fluorescence imaging

2021 ◽  
Vol 28 (6) ◽  
Author(s):  
Silvia Cipiccia ◽  
Francesco Brun ◽  
Vittorio Di Trapani ◽  
Christoph Rau ◽  
Darren J. Batey
Keyword(s):  
Fresnel Zone ◽  
Imaging Techniques ◽  
Photon Counting ◽  
Field Of View ◽  
Step Size ◽  
X Ray ◽  
Single Beam ◽  
Photon Counting Detector ◽  
Nanoscale Imaging ◽  
The Difference

X-ray ptychography and X-ray fluorescence are complementary nanoscale imaging techniques, providing structural and elemental information, respectively. Both methods acquire data by scanning a localized beam across the sample. X-ray ptychography processes the transmission signal of a coherent illumination interacting with the sample, to produce images with a resolution finer than the illumination spot and step size. By enlarging both the spot and the step size, the technique can cover extended regions efficiently. X-ray fluorescence records the emitted spectra as the sample is scanned through the localized beam and its spatial resolution is limited by the spot and step size. The requisites for fast ptychography and high-resolution fluorescence appear incompatible. Here, a novel scheme that mitigates the difference in requirements is proposed. The method makes use of two probes of different sizes at the sample, generated by using two different energies for the probes and chromatic focusing optics. The different probe sizes allow to reduce the number of acquisition steps for the joint fluorescence–ptychography scan compared with a standard single beam scan, while imaging the same field of view. The new method is demonstrated experimentally using two undulator harmonics, a Fresnel zone plate and an energy discriminating photon counting detector.

scholarly journals Effect of Deep-Level Defects on the Performance of CdZnTe Photon Counting Detectors

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 2032
Author(s):  
Yingrui Li ◽  
Gangqiang Zha ◽  
Dengke Wei ◽  
Fan Yang ◽  
Jiangpeng Dong ◽  
...  
Keyword(s):  
Deep Level ◽  
Energy Levels ◽  
Photon Counting ◽  
Optical Microscope ◽  
Deep Level Defect ◽  
X Ray ◽  
Photon Counting Detector ◽  
Related Defect ◽  
The Difference ◽  
Cdznte Detectors

The effect of deep-level defects is a key issue for the applications of CdZnTe high-flux photon counting devices of X-ray irradiations. However, the major trap energy levels and their quantitive relationship with the device’s performance are not yet clearly understood. In this study, a 16-pixel CdZnTe X-ray photon counting detector with a non-uniform counting performance is investigated. The deep-level defect characteristics of each pixel region are analyzed by the current–voltage curves (I–V), infrared (IR) optical microscope photography, photoluminescence (PL) and thermally stimulated current (TSC) measurements, which indicate that the difference in counting performance is caused by the non-uniformly distributed deep-level defects in the CdZnTe crystals. Based on these results, we conclude that the CdZnTe detectors with a good photon counting performance should have a larger Te cd 2 + and Cd vacancy-related defect concentration and a lower A-center and Tei concentration. We consider the deep hole trap Tei, with the activation energy of 0.638–0.642 eV, to be the key deep-level trap affecting the photon counting performance. In addition, a theoretical model of the native defect reaction is proposed to understand the underlying relationships of resistivity, deep-level defect characteristics and photon counting performance.

Optimization of a CZT photon counting detector for contaminant detection

2021 ◽  
Vol 16 (11) ◽  
pp. P11015
Author(s):  
J. Nguyen ◽  
P.-A. Rodesch ◽  
D. Richtsmeier ◽  
K. Iniewski ◽  
M. Bazalova-Carter
Keyword(s):  
Food Industry ◽  
Photon Counting ◽  
Conveyor Belt ◽  
Weighting Scheme ◽  
X Ray ◽  
Photon Counting Detector ◽  
Inspection Systems ◽  
Photon Counting Detectors ◽  
High Level ◽  
Packaged Food

Abstract In the food industry, X-ray inspection systems are utilized to ensure packaged food is free from physical contaminants to maintain a high level of food safety for consumers. However, one of the challenges in the food industry is detecting small, low-density contaminants from packaged food. Cadmium zinc telluride (CZT) photon counting detectors (PCDs) can potentially alleviate this problem given its multi-energy bin capabilities, high spatial resolution and ability to eliminate electronic noise, which is superior to the conventional energy integrating detector (EID). However, the image quality from a CZT PCD can be further improved by applying an optimized energy bin weighting scheme that maximizes energy bin images that provide the largest image contrast and lowest image noise. Therefore, in this work, five contaminant materials embedded in an acrylic phantom were imaged using a CZT PCD while the phantom was in constant motion to mimic food products moving on a conveyor belt. Energy bin optimization was performed by applying an image-based weighting scheme and these results showed contrast-to-noise ratio (CNR) improvements ranging between 1.02–1.91 relative to an equivalent EID acquisition.

scholarly journals Binary Complementary Filters for Compressive Raman Spectroscopy

2017 ◽  
Vol 72 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Owen G. Rehrauer ◽  
Vu C. Dinh ◽  
Bharat R. Mankani ◽  
Gregery T. Buzzard ◽  
Bradley J. Lucier ◽  
...  
Keyword(s):  
Spectroscopic Analysis ◽  
Photon Counting ◽  
Optical Filters ◽  
Chemical Components ◽  
Digital Micromirror Device ◽  
Direct Photons ◽  
Powder Mixtures ◽  
Photon Counting Detector ◽  
Two Photon ◽  
Photon Counting Detectors

The previously described optimized binary compressive detection (OB-CD) strategy enables fast hyperspectral Raman (and fluorescence) spectroscopic analysis of systems containing two or more chemical components. However, each OB-CD filter collects only a fraction of the scattered photons and the remainder of the photons are lost. Here, we present a refinement of OB-CD, the OB-CD2 strategy, in which all of the collected Raman photons are detected using a pair of complementary binary optical filters that direct photons of different colors to two photon counting detectors. The OB-CD2 filters are generated using a new optimization algorithm described in this work and implemented using a holographic volume diffraction grating and a digital micromirror device (DMD) whose mirrors are programed to selectively direct photons of different colors either to one or the other photon-counting detector. When applied to pairs of pure liquids or two-component solid powder mixtures, the resulting OB-CD2 strategy is shown to more accurately estimate Raman scattering rates of each chemical component, when compared to the original OB-CD, thus facilitating chemical classification at speeds as fast as 3 μs per measurement and the collection of Raman images in under a second.

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