1,720,977 research outputs found
Versatile multi-channel CMOS frontend with selectable full-scale dynamics from 100 MeV up to 2.2 GeV for the readout of detector's signals in nuclear physics experiments
Full text linkWe developed a versatile multichannel CMOS frontend with selectable full-scale energy range from 100 MeV up to 2.2 GeV for the readout of detector's signals in nuclear physics experiments. The core of the frontend electronics is a custom designed CMOS charge preamplifier able to guarantee an energy resolution of the order of 10 keV FWHM with a power budget of about 10 mW/channel (ASIC only). 16-channel charge preamplifiers are integrated in a single chip in ams 0.35 μm C35B4C3 technology together with the CsI(Tl) frontend and few additional slow control services. A dedicated 8 layer frontend motherboard houses 2 ASICs and the line-drivers needed to provide a differential output and to drive the several-meter long connections. High-density right-angle open-pin-field connectors interconnect the motherboards and a patch-panel responsible of the slow-control and the interconnections to the meters-long cables. The designed frontend is extremely versatile, being suitable to be coupled to different detector topologies and signal polarities with capacitances ranging from about 10 pF up to about 200 pF. The first application of the developed frontend is to instrument the FARCOS (Fem-toscope ARray for Correlation and Spectroscopy) detection system, a novel detector featuring high angular and energy resolution able to reconstruct the particle's momentum at high precision and capable of performing correlation measurements of LCPs and of LCPs and IMFs. A thorough experimental qualification allowed verifying the frontend performance. The measured energy resolution with the frontend coupled with a 300 μm thick Double Sided Silicon Strip Detector (DSSSD) of the FARCOS telescope illuminated with a mixed-nuclei α source shows a resolution below 10 keV FWHM. The paper focuses on the designed frontend system and on the results of its qualification
A CMOS Frontend for Scintillators Readout by Photodiodes for Nuclear Physics Experiments
No full textWe designed a CMOS frontend for the readout of scintillators coupled with silicon photodiodes for nuclear physics experiments. The preamplifier features a continuous-reset feedback and an input pMOS transistor. The designed input dynamic range is 90-MeV silicon equivalent. The frontend has been integrated in single channel and multichannel versions up to 16-channel application specific integrated circuits (ASICs) in the C35B4C3 AMS technology. The measured integral-non-linearity over the whole dynamic range is below 0.5%. The intrinsic rise time (10%-90%) of the preamplifier is of the order of 3 ns over the entire dynamic range and is below 50 ns when coupled with a 130-pF photodiode. We qualified the spectroscopic performance by acquiring spectra of a mixed nuclei α source and of different Î3 sources (137Cs and60Co) with a CsI(Tl) scintillator crystal 3.2 à 3.2 à 6 coupled with a 18mm à 18mm silicon p-i-n diode 300-Î1⁄4m -thick readout by the developed ASIC
Experimental qualification of an 8-channel selectable-gain CMOS frontend for Double-Sided Silicon Strip Detectors
No full textWe are developing a multi-channel double-polarity selectable-gain frontend to be coupled to the Double-Sided Silicon Strip Detectors (DSSSD) of a novel versatile and modular Femtoscope ARray for Correlation and Spectroscopy, named FARCOS, featuring high angular and energy resolution and able to address several open cases in nuclear physics (nuclear dynamics and asy-EOS). The key feature of FARCOS, not present in similar existing correlator systems as MUST2 and HiRA, is the capability to perform pulse-shape analysis in order to fully identify the particles stopping even in the first detection layer. Therefore the frontend electronics to be coupled to the DSSSDs layers has to amplify the whole signal waveform without shape distortion. We developed an AC coupled frontend circuit in 0.35 μm CMOS AMS technology. To face different experimental scenarios we implemented 4 selectable gain configuration corresponding to different full scale ranges. A single design amplifies the signals coming from both junction-side and ohmic-side strips and for the two different detector thicknesses. In this work we present the design and the experimental qualification of the multichannel frontend
From noise to information. Analysing macro-XRF mapping of strontium impurities in Raphael's Baglioni Entombment in the Galleria Borghese, Rome
No full textIn the paintings of the Old Masters, strontium is present only as an impurity of the materials, that is the gypsum used for the preparation of the panels, and for this reason its presence is generally considered – at best – accidental information. However, an in-depth study of the distribution of strontium beneath the surface of Raphael's Entombment in the Borghese Gallery in Rome by means of MA-XRF provided detailed information regarding a reapplication of the preparatory gypsum ground layers on an area probably damaged before the painter began the execution of the painting. Furthermore, the comparison of MA-XRF distribution maps for lead and strontium with radiographic images, aimed to establish at what point the painter decided to eliminate a female figure in the centre of the painting, and the state of completion of the figure when this occurred
Going 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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