Spatial resolution and detection efficiency of algorithms for charge sharing compensation in single photon counting hybrid pixel detectors

2018 ◽  
Vol 882 ◽  
pp. 91-95 ◽  
Author(s):  
Piotr Otfinowski
Keyword(s):  
Spatial Resolution ◽  
Detection Efficiency ◽  
Single Photon ◽  
Photon Counting ◽  
Charge Sharing ◽  
Single Photon Counting ◽  
Pixel Detectors ◽  
Efficiency Of Algorithms

Measurements of charge sharing in a hybrid pixel photon counting CdTe detector

2021 ◽  
Vol 16 (12) ◽  
pp. C12027
Author(s):  
A. Krzyzanowska
Keyword(s):  
Spatial Resolution ◽  
Single Photon ◽  
Spectral Response ◽  
Photon Counting ◽  
Radiation Detectors ◽  
Charge Sharing ◽  
Single Photon Counting ◽  
X Ray ◽  
Cdte Detector ◽  
Wide Range

Abstract Hybrid pixel radiation detectors working in a single-photon counting mode have gained increasing attention due to their noiseless imaging and high dynamic range. Due to the fact that sensors of different materials can be attached to the readout circuit, they allow operation with a wide range of photon energies. The performance of the single photon counting detectors is limited by pile-up. To allow a detector to work under high flux conditions, the pixel size is reduced, which minimizes detector dead time. However, with smaller pixel sizes the charge sharing effect, a phenomenon that deteriorates both detection efficiency and spatial resolution is more profound. The influence of charge sharing on the detector performance can be quantified using parameterization of the s-curve obtained in the spectral response measurements. The article presents the measurements of the response function of a hybrid pixelated photon counting detector for certain primary energy, which corresponds to the probability of detecting a photon as a function of its energy deposition. The measurements were carried out using an X-ray tube by performing a threshold scan during illumination with X-ray photons of a 1.5 mm and 0.75 mm thick CdTe detector with 100 µm pixel pitch. The charge size cloud depends on the sensor material, the bias voltage, and the sensor thickness. Therefore, the experimental data from a sensor biased with different bias voltages are compared to the theoretical results based on a cascaded model of a single-photon counting segmented silicon detector. The study of the charge sharing influence on the spatial resolution of the CdTe detector will serve for a further study of the possible implementations of the algorithms achieving subpixel resolution, in which the charge sharing becomes the desired effect since the charge division in the pixels is used to interpolate the photon interaction position.

Pixel readout IC for CdTe detectors operating in single photon counting mode with interpixel communication

2022 ◽  
Vol 17 (01) ◽  
pp. C01036
Author(s):  
P. Grybos ◽  
R. Kleczek ◽  
P. Kmon ◽  
A. Krzyzanowska ◽  
P. Otfinowski ◽  
...  
Keyword(s):  
Integrated Circuit ◽  
Single Photon ◽  
Photon Counting ◽  
Recognition Algorithm ◽  
Total Charge ◽  
Readout Integrated Circuit ◽  
Single Photon Counting ◽  
X Ray ◽  
Pixel Detectors ◽  
Photon Counting Mode

Abstract This paper presents a readout integrated circuit (IC) of pixel architecture called MPIX (Multithreshold PIXels), designed for CdTe pixel detectors used in X-ray imaging applications. The MPIX IC area is 9.6 mm × 20.3 mm and it is designed in a CMOS 130 nm process. The IC core is a matrix of 96 × 192 square-shaped pixels of 100 µm pitch. Each pixel contains a fast analog front-end followed by four independently working discriminators and four 12-bit ripple counters. Such pixel architecture allows photon processing one by one and selecting the X-ray photons according to their energy (X-ray colour imaging). To fit the different range of applications the MPIX IC has 8 possible different gain settings, and it can process the X-ray photons of energy up to 154 keV. The MPIX chip is bump-bonded to the CdTe 1.5 mm thick pixel sensor with a pixel pitch of 100 µm. To deal with the charge sharing effect coming from a thick semiconductor pixel sensor, multithreshold pattern recognition algorithm is implemented in the readout IC. The implemented algorithm operates both in the analog domain (to recover the total charge spread between neighboring pixels, when a single X-ray photon hits the border of the pixel) and in the digital domain (to allocate a hit position to a single pixel).

scholarly journals Single photon counting X-ray imaging with Si and CdTe single chip pixel detectors and multichip pixel modules

2004 ◽  
Vol 51 (4) ◽  
pp. 1717-1723 ◽  
Author(s):  
M. Locker ◽  
P. Fischer ◽  
S. Krimmel ◽  
H. Kruger ◽  
M. Lindner ◽  
...  
Keyword(s):  
Single Photon ◽  
Photon Counting ◽  
Single Chip ◽  
Single Photon Counting ◽  
X Ray ◽  
Pixel Detectors ◽  
X Ray Imaging

scholarly journals Design and Implementation of a Compact Single-Photon Counting Module

Electronics ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1131
Author(s):  
Ming Chen ◽  
Chenghao Li ◽  
Alan P. Morrison ◽  
Shijie Deng ◽  
Chuanxin Teng ◽  
...  
Keyword(s):  
Bias Voltage ◽  
Dead Time ◽  
Detection Efficiency ◽  
Single Photon ◽  
Photon Counting ◽  
Reverse Bias Voltage ◽  
Single Photon Counting ◽  
Avalanche Diode ◽  
Silicon Based ◽  
Off Time

A compact single-photon counting module that can accurately control the bias voltage and hold-off time is developed in this work. The module is a microcontroller-based system which mainly consists of a microcontroller, a programmable negative voltage generator, a silicon-based single-photon avalanche diode, and an integrated active quench and reset circuit. The module is 3.8 cm × 3.6 cm × 2 cm in size and can communicate with the end user and be powered through a USB cable (5 V). In this module, the bias voltage of the single-photon avalanche diode (SPAD) is precisely controllable from −14 V ~ −38 V and the hold-off time (consequently the dead time) of the SPAD can be adjusted from a few nanoseconds to around 1.6 μs with a setting resolution of ∼6.5 ns. Experimental results show that the module achieves a minimum dead time of around 28.5 ns, giving a saturation counting rate of around 35 Mcounts/s. Results also show that at a controlled reverse bias voltage of 26.8 V, the dark count rate measured is about 300 counts/s and the timing jitter measured is about 158 ps. Photodetection probability measurements show that the module is suited for detection of visible light from 450 nm to 800 nm with a 40% peak photon detection efficiency achieved at around 600 nm.

Proton Irradiation of 4H-SiC Ultraviolet Single Photon Avalanche Diodes

2011 ◽  
Vol 679-680 ◽  
pp. 551-554
Author(s):  
D. Kurt Gaskill ◽  
Jun Hu ◽  
X. Xin ◽  
Jian Hui Zhao ◽  
Brenda L. VanMil ◽  
...  
Keyword(s):  
Proton Irradiation ◽  
Detection Efficiency ◽  
Single Photon ◽  
Photon Counting ◽  
Chemical Vapor ◽  
Single Photon Detection ◽  
Proton Radiation ◽  
Space Applications ◽  
Single Photon Counting ◽  
Avalanche Diodes

The effects of proton irradiation on uv 4H-SiC single photon avalanche photodiodes (SPADs) are reported. The SPADs, grown by chemical vapor deposition, were designed for uv operation with dark count rates (DCR) of about 30 kHz and single photon detection efficiency (SPDE) of 4.89%. The SPADs were irradiated with 2 MeV protons to a fluence of 1012 cm-2. After irradiation, the I-V characteristics show forward voltage (<1.9 V) generation-recombination currents 2 to 3 times higher than before irradiation. Single photon counting measurements imply generation-recombination centers created in the band gap after irradiation. For threshold voltage ranging from 23 to 26 mV, the 4H-SiC SPAD showed low DCR (<54 kHz) and high SPDE (>1%) after irradiation. The SPADs demonstrated proton radiation tolerance for geosynchronous space applications.

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