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The Polaris system is an array of 18 position-sensitive detectors, using 6 cm3 pixelated CdZnTe crystals from Redlen Technologies and readout electronics from Gamma-Medica Ideas (GMI). Many detectors received from Redlen Technologies are capable of achieving 1% energy resolution or better at 662 keV for all single-pixel events during room temperature operation. Furthermore, 3D position reconstruction...
An experiment to measure the performance of 3-D position-sensitive pixellated HgI2 crystals cooled below room temperature was carried out using a new ASIC from GammaMedica-Ideas. This ASIC is capable of reading out the digitized pre-amplifier signal waveforms of 121 pixels and the cathode. A significant improvement in energy resolution from 1.48% FWHM at 662keV for the whole detector to 1.09% FWHM...
This work investigate the full energy and total efficiencies of large volume CdZnTe detectors. The efficiencies of three 20 mm × 20 mm × 15 mm pixelated CdZnTPe detectors were measured using the H3Dv2 Application Specific Integrated Circuit (ASIC) readout system developed by Brookhaven National Laboratory with un-collimated 241Am, 137Cs, and 60Co sources. One detector was made by eV-Products while...
Semi-Supervised Classification (SSC), which makes use of both labeled and unlabeled data to determine classification borders in feature space, has great advantages in extracting classification information from mass data. In this paper, a novel SSC method is proposed based on Remote Sensing Image character, which utilizes both spacial and spectrum feature relationship between labeled and unlabeled...
The contemporary digital society is filled with the image world. Image digitization not only standardizes the image storage but also benefits the image recognition based on the computational methods. By the nature of Hopfield neural network, associative memory based on this mechanism can be effectively adopted for the image recognition application. This paper proposes the design and the prototype...
We report on the development of an application specific integrated circuit (ASIC) for 3D position sensitive detectors (3D PSD). The ASIC is designed to operate with pixelated wide bandgap sensors like Cadmium-Zinc-Telluride (CZT), Mercuric Iodide (Hgl2) and Thallium Bromide (TIBr). It measures the amplitudes and timings associated with an ionizing event on 128 anodes, the anode grid, and the cathode...
Due to the steering grid that aids the collection of electrons by the anode pixels, the common-grid pixelated CdZnTe (CZT) detectors have demonstrated better performance than simple pixel detectors. For a detailed analysis of charge sharing and weighting potential cross-talk that occurs near and underneath the gap and energy resolution degradation in common-grid CZT detectors, a detailed detector...
A 3-dimensional position-sensitive CdZnTe gamma-ray detector employs a pixellated anode (11 ?? 11 pixels) and a planar cathode on a 15 ?? 15 ?? 10 mm3 or 20 ?? 20 ?? 15 mm3 CdZnTe single crystal. The signals from the 121 pixels and the cathode read out by Application Specific Integrated Circuits (ASIC) are used to reconstruct the energy depositions and 3-D coordinates of multiple gamma-ray interactions...
The depth of interaction in pixelated CdZnTe and HgI2 detectors is determined using either the cathode-to-anode signal ratio (CAR) or drift time information. The CAR can be used if a ??-ray interacts only once in the detector. The drift time must be used if the ??-ray interacts over multiple pixels. The accuracy of these reconstruction techniques is evaluated using a collimated fan beam of ??-rays...
A new natural image denoising method using Sparse Independent Component Analysis (SICA) based on Gabor wavelet is discussed in this paper. In order to maximize the sparsity, SICA algorithm utilizes linfin norm as the sparse penalty function. At the same time, to insure the speed of SICA, 2-D Gabor wavelet bases are used as the initialization feature bases of SICA. This SICA algorithm does not need...
The observed energy resolution of pixellated wide band-gap semiconductor detectors degrades as the number of triggered pixels increases. For multiple pixel events, one of the biggest barriers to overcome during the energy reconstruction is the effects of weighting potential cross-talk. The current calibration method determines a set of correction coefficients to convert each measured signal to an...
The signals from 3-D position-sensitive pixellated CdZnTe (CZT) detectors have been modeled for the VAS_UM/TAT4 ASIC readout electronics. Each detector has dimensions of 20 mm × 20 mm × 15 mm, with an 11 × 11 square pixel anodes fabricated on the anode surface having a pixel pitch of 1.72 mm. Gamma-ray interactions with detector material, charge drift, charge trapping and diffusion, signal induction,...
How to find an efficient method to solve the problems of object auto-recognition has been a research hot point. For the application of remote sensing image processing, this paper analyses features and inner relations of traffic objects. Handling with multi-agent system (MAS) technology, by using prior knowledge, we design a whole auto-recognition pattern. That is based-on the thought of dynamic plan...
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