1,721,825 research outputs found
Comunicazione di crisi e pratiche digitali di engagement: il caso della mappa condivisa SARDSOS
No full textIl capitolo affronta il tema dell'uso delle piattaforme digitali per la comunicazione di crisi e per le emergenze, mettendo in luce sia la prospettiva delle amministrazioni pubbliche, che quella dei cittadini e dei volontari digitali. In particolare, attraverso una survey online, esplora anche l'uso delle mappe condivise nell'occasione dell'alluvione dell'autunno del 2014 avvenuta in Sardegna
Timepix3 detector for measuring radon decay products
Full text linkThe present work is focused on the characterization of a
Timepix3 (TPX3) based test system for the identification of
particles produced by the complex decay chain of Rn. The
detector used is composed of a pixelated Cadmium Telluride (CdTe)
semiconductor (500 μm thick) bump-bonded on an ASIC TPX3
chip. Measurements were carried out at the NIXT Laboratory (ENEA
Frascati) using radioactive sources and exploiting the presence of
natural radon gas by collecting its decay products on the sensor
surface. Estimation of the radon gas risk is one of the most
important problems in radiation protection and has stimulated
further development of new advanced methods suitable for detecting
this gas in confined environments. A study of the spatial uniformity
and high energy calibration is also presented and an improved
cluster analysis is introduced. The performance highlighted in this
study will allow a detailed and faster analysis of the radon
products and may have an important impact on the environmental
radioprotection applications. This paper describes the application
and use of this test system to identify the different decay
signatures and follow the temporal evolution of the Radon decay
chain
RaDoM: A lung dosimeter for radon progeny
Full text linkThis paper discusses a novel Timepix-based on-line radon dose monitor called RaDoM. The detector provides a direct estimate of the effective dose to the lung via a system of filters having the same absorption characteristics as this organ and a measurement of the PAEC (the potential alpha energy concentration). Measurements performed in a reference radon chamber and in normal environmental conditions showed that RaDoM well follows changes in the radon concentration and is accurate in both long- and short-term measurements. The paper describes the detector and associated software for data acquisition and analysis, and compares the measurement of the lung dose with the value derived from a measurement of the radon concentration
An hybrid detector GEM-ASIC for 2-D soft X-ray imaging for laser produced plasma and pulsed sources
No full textThe following paper presents a new 2-D detector ('GEMpix') in the soft X-ray range, having a wide dynamic range thanks to its intrisic gain, working in charge integration mode to be used for diagnosing laser produced plasma (LPP) or X-ray pulsed sources. It is a gas detector based on the Gas Electron Multiplier (GEM) technology with a quad-medipix chip as read-out electronics. In our prototype, the substitution of semiconductor material with a gas triple-GEM allows several advantages with respect to the detectors commonly used in LPP, as X-ray CCDs and Micro Channel Plates or Image Plates. In these experiments the configuration Time-over-Threshold (ToT) has been used, to measure the total charge released to the gas and collected by each pixel, integrated over the X-ray burst duration. Intensity response and spatial resolution has been measured first in laboratory for calibration, as function of the voltage applied to the GEMs, in single photon regime with energies between 3.7 and 17 keV. Subsequently it has been tested at the ABC laser facility (ENEA, Frascati). In this case, we measured the X-rays produced when the ABC neodymium laser, with pulse of 50 J and 3 ns time width, hits plane targets of aluminum. 2-D images have been acquired by means of a pinhole configuration with magnification 1.5 and 50 μm of spatial resolution. The results are encouraging regarding the capability of this imaging detector to work in experiments where soft X-ray emissivity varies over many orders of magnitude. © 2016 IOP Publishing Ltd and Sissa Medialab srl
Timepix3 detector for measuring radon decay products
No full textThe present work is focused on the characterization of a Timepix3 (TPX3) based test
system for the identification of particles produced by the complex decay chain of 222Rn. The
detector used is composed of a pixelated Cadmium Telluride (CdTe) semiconductor (500 μm thick)
bump-bonded on an ASIC TPX3 chip. Measurements were carried out at the NIXT Laboratory
(ENEA Frascati) using radioactive sources and exploiting the presence of natural radon gas by
collecting its decay products on the sensor surface. Estimation of the radon gas risk is one of the most
important problems in radiation protection and has stimulated further development of new advanced
methods suitable for detecting this gas in confined environments. A study of the spatial uniformity
and high energy calibration is also presented and an improved cluster analysis is introduced. The
performance highlighted in this study will allow a detailed and faster analysis of the radon products
and may have an important impact on the environmental radioprotection applications. This paper
describes the application and use of this test system to identify the different decay signatures and
follow the temporal evolution of the Radon decay chain
Timepix3 detector and Geant4-based simulations for gamma energy detection in Laser Produced Plasmas
No full textThe particular physics of Laser Produced Plasmas (LPP) needs some diagnostic requirements. Specifically, the X-ray monitoring of the plasma is known to be difficult since typically X-ray emissions are concentrated in bursts from a few tens of ps to few ns, based on the power and pulse time width of the laser. Therefore, the energy measurement of the radiation coming from a single experimental run is basically unfeasible using conventional techniques. Additional particles can be produced from LPP experiments, especially high energy gamma photons and electrons. As a case study in recent experiments, carried out on VEGA-2 laser facility (CLPU, Salamanca, Spain), the aim was to produce neutrons through photonuclear reactions on different types of solid targets. We have used the Timepix3 chip, in a "side-on" configuration, in order to produce a quick estimate of the gamma photons energy involved in the reactions. This detector, based on silicon, is realized with a single chip of 256 × 256 pixels bump-bonded with a 14 mm × 14 mm × 300 μm silicon layer. Interaction of gammas with the detector in this configuration produces some characteristic clusters of pixels and, for each cluster, a variety of physical and morphological parameters can be defined. Based on some of these parameters, we have characterized the detector response using some known laboratory gamma sources and the related Geant4 simulations. This allows quick energy discrimination for the gamma photons coming from different experimental runs
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
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