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

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).

Timepix4, a large area pixel detector readout chip which can be tiled on 4 sides providing sub-200 ps timestamp binning

Timepix4 is a 24.7 × 30.0 mm2 hybrid pixel detector readout ASIC which has been designed to permit detector tiling on 4 sides. It consists of 448 × 512 pixels which can be bump bonded to a sensor with square pixels at a pitch of 55 µm. Like its predecessor, Timepix3, it can operate in data driven mode sending out information (Time of Arrival, ToA and Time over Threshold, ToT) only when a pixel has a hit above a pre-defined and programmable threshold. In this mode hits can be tagged to a time bin of <200 ps and Timepix4 can record hits correctly at incoming rates of ∼3.6 MHz/mm2/s. In photon counting (or frame-based) mode it can count incoming hits at rates of up to 5 GHz/mm2/s. In both modes data is output via between 2 and 16 serializers each running at a programmable data bandwidth of between 40 Mbps and 10 Gbps. The specifications, architecture and circuit implementation are described along with first electrical measurements and measurements with radioactive sources. In photon counting mode X-ray images have been taken at a threshold of 650 e− (with <10 masked pixels). In data driven mode images were taken of ToA/ToT data using a 90Sr source at a threshold of 800 e− (with ∼120 masked pixels).

Лидарная система комбинационного рассеяния света для зондирования молекул водорода в атмосфере

Computer simulation of the Raman lidar equation for measurement of the hydrogen molecules at the concentration level of 1013 cm-3 and higher in atmosphere at the ranging distances up to 100 m in the synchronous photon counting mode and selection of such a lidar optimal parameters have been fulfilled. It is shown that for hydrogen molecules concentration of N(z)=1013 cm-3 measurement at the distances from 5 to 100 m the measurement time t is in the range from 3.83 s to 26.5 min, for measurement of concentration N(z) = 1015 cm-3 - from 38 ms to 15.9 s and for the concentration measurement of N(z) = 1017 cm-3 - already from 0.4 ms to 160 ms, respectively.

Investigation of the characteristics of matrix multi-element avalanche photodetectors operating in the photon counting mode

At present, matrix multi-element avalanche photodetectors operating in the photon counting mode are widely used for detecting optical radiation. However, the char-acteristics of matrix multi-element avalanche photodetectors operating in this mode are currently insufficiently studied. Prototypes of Si-photomultiplier tubes (Si-PMTs) with a p+–p–n+ structure produced by JSC Integral (Republic of Belarus), as well as serially produced silicon photomultipliers Ketek PM 3325 and ON Semi FC 30035 have been used as objects of research. This article presents the research results of characteristics in the photon counting mode of the specified photodetec-tors. The dependences of the specific amplitude sensitivity ratio on the wavelength of optical radiation, the temperature, the supply voltage of the matrix multi-element avalanche photodetector are determined.

A digital technology for scanning the luminescent characteristics of alkali halide crystals

A digital technology for scanning the X-ray luminescence, tunnel luminescence, and thermostimulated luminescence spectra in the spectral range from 200 nm to 850 nm is experimentally demonstrated using the example of a NaCl crystal, which is part of the group of alkali halide crystals. This is done with the specified spectrum intervals and scanning speed using a high-aperture monochromator MSD-2 and a photoelectronic multiplier type H 8259 of the company “Hamamatsu”, operating in the photon counting mode, controlled by special programs SpectraScan and ThermoScan. The obtained experimental data are digitally converted for further processing of the graphical representation of the results using the OriginPro software package, which allows you to draw up graphical dependencies of the spectra and perform their mathematical processing.