1,721,116 research outputs found
GaAs X-ray detector characterization through a 3D finite element model
No full textIn this paper the characterization of a GaAs X-ray pixel detector is presented. The performance is obtained experimentally by a detector using a Schottky diode on a semi-insulating, Vertical Gradient Freeze, (100) oriented single crystal GaAs substrate. Moreover, a new 3D Model based on the Finite Element Method is shown which takes into account the carrier trapping and emission phenomena. The model analyzes the single event upset for a photon hitting the pixel surface in any direction. The main advantage of the model used is its ability to determine the influence of both the position of the impact point and of the slope of the particle trajectory with respect to the pixel surface on the detector performance. The numerical simulations obtained confirm the experimental values and permit the indirect evaluation of the charge collection efficiency through a preliminary determination of the real trap distribution and transport parameters depending on the electric field
Fast Parallelized Algorithm for ECG Analysis
No full textA new approach based on the adoption of wavelet transforms is presented for the R point localization in ECG signals. The conceived real time signal processing technique, which uses a fast parallelized algorithm, has been evaluated adopting the standard MIT-BIH Arrhythmia database which includes specially selected holter recordings with anomalous but clinically important phenomena. In the procedure a soft thresholding technique is applied to dyadic scales in which the ECG signal is decomposed. Therefore, noise contribution is reduced and then signal is easily reconstructed in the time domain for further processing. Moreover, the tool analyzes the signal on different level wavelet representation at the same time showing a great parallelism degree and an enhancement in processing time. To evaluate the algorithm noise immunity, the MIT-BIH Noise Stress Test Database has been adopted containing baseline wander, muscle artifacts and electrode motion artifacts as noise sources. The obtained performance shows the method validity in terms of algorithm speed up and characteristic parameter values. In fact, sensitivity and positive predictivity values of about 99.8% are obtained with a detection error rate of about 0.4%. Moreover, the conceived procedure gives satisfactory results also for ECG signals heavily corrupted by nois
Semiconductor detectors and principles of radiation-matter interaction
No full textSemiconductor devices are widely used as radiation detectors in a large variety of fields such as nuclear physics, elementary particle physics, optical, x-ray astronomy, medicine, material testing and so on. As the detector working mode is dependent not only on the adopted material and the chosen architecture, but also on the detection method, the paper reviews the various radiation types, the principles of physics in detection, the semiconductor detector operational characteristics and the semiconductor device structures
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