1,720,966 research outputs found
Excess noise and spectra distortion in pulsed-reset charge sensitive amplifiers due to non-stationary gain: analytical model and Monte Carlo simulations
No full textDynamic range enhancement circuit and characterization of non-stationary gain effects in pulsed-reset charge sensitive amplifiers
No full textAnalytical Model of the Discharge Transient in Pulsed-Reset Charge-Sensitive Amplifiers
No full textA study of the reset transient of charge-sensitive amplifiers operating with a pulsed switch in parallel to the feedback capacitance is presented. Analytical models have been developed for amplifiers in both linear and slew rate regimes during the reset phase. The models predict the time interval required to reset the amplifier that, in most cases, significantly differs by the simple discharge of the feedback capacitance through the switch resistance and strongly depends on the open-loop gain and bandwidth of the core amplifier and on the input capacitance. The models also quantitatively predict spurious voltage transients at the preamplifier's input and possible ringings at the output, as a function of the main general parameters of the circuit. A case application study of the presented model is proposed for low-capacitance detectors, such as semiconductor drift detectors or small pixel detectors
Transimpedance amplifier for LGAD noise measurements: design and characterization
No full textA wideband low-noise transimpedance amplifier (TIA) is designed for the measurement of the noise power spectral density (NPSD) of the current of low-gain avalanche diodes (LGADs). The design focuses on minimization of system background noise and maximization of operating bandwidth. The diffusive line effect of the high value resistor used in the feedback network has been analyzed, and a compensation of its effect has been implemented. With a transimpedance of 200 MΩ, a background white noise of 9.5 fA/√(Hz) and an input current dynamic range up to 20 nA are achieved. The useful bandwidth ranges from 1 kHz up to 3 MHz depending on the noise level to be measured. An effective method for calibrating the system and measuring its transfer function with high accuracy over the full bandwidth is described. The designed TIA enables an accurate characterization of LGADs noise, which is a crucial step for the technology qualification and for the prediction of the performance of these devices as radiation and particle detectors
An Open-Source Monte Carlo Simulator for High-Z Semiconductor Detectors with a Charge Cloud Discretization Method
Full text linkA Monte Carlo simulator is presented to evaluate the spectroscopic response of high-Z semiconductor pixel radiation detectors starting from the first principles of physical laws. It performs simulation in three different domains: electrostatic fields, photon-matter interaction, and photo-generated charge-carriers transport. A sampling algorithm is proposed to address the issue of fast and accurate computations of charge cloud dynamics in the presence of both diffusion and electrostatic repulsion effects, avoiding direct numerical integration of the induced current equation stated by the Shockley-Ramo theorem under a constant electric field hypothesis. The simulator is written as an object-oriented programming (OOP) source code repository, relying on the integration between MATLAB and COMSOL Multiphysics, and can be run with one executable script. The simulator architecture is presented, followed by a detailed explanation of all the physical models and implemented simulation strategies. The simulator is validated with experimental energy spectra acquired with a radiation detection system based on cadmium zinc telluride (CdZnTe) pixel detectors and ultralow-noise front-end electronics with state-of-the-art energy resolution
A spectroscopic Monte Carlo simulator for high-Z semiconductor detectors with a charge cloud discretization approach
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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