1,721,138 research outputs found
Diamond sensors for future high energy experiments
No full textWith the planned upgrade of the LHC to High-Luminosity-LHC [1], the general purpose experiments ATLAS and CMS are planning to upgrade their innermost tracking layers with more radiation tolerant technologies. Chemical Vapor Deposition CVD diamond is one such technology. CVD diamond sensors are an established technology as beam condition monitors in the highest radiation areas of all LHC experiments. The RD42-collaboration at CERN is leading the effort to use CVD diamond as a material for tracking detectors operating in extreme radiation environments. An overview of the latest developments from RD42 is presented including the present status of diamond sensor production, a study of pulse height dependencies on incident particle flux and the development of 3D diamond sensors
Modeling radiation damage in TCAD
No full textThe aim of this work is to develop a TCAD radiation damage model at a device level, enablinga predictive insight on the electrical behaviour of detectors and aiming at their ultimate perfor-mance optimization for the operation at HL-LHC expected fluences (e.g. greater than 2.0×10161 MeV equivalent neutrons/cm2). Our approach aims at keeping the number of fitting parame-ters as low as possible, at the same time accounting for new experimental evidences of relevanteffects at these very high fluences (e.g. charge multiplication and avalanche effects). A physi-cally grounded approach is being pursued, aiming at devising a not over-specific modelling whilekeeping predictive capabilities on the device behavior fabricated by different vendors (e.g. withdifferent technology flavors) and in different operating conditions, e.g. at different fluences, tem-peratures and biasing voltages. The model development follows a test campaign with a twofoldgoal: from one hand, the relevant technology parameters such as oxide charge and interface trapstates as a function of the irradiation dose have been measured. On the other hand, DC and ACmeasurements on gate-controlled diodes and MOS capacitors can be used as reference for TCADsimulation models validation purpose. The complete bulk and surface radiation damage modelcan be exploited for the analysis of the active behavior of different classes of new generationdetectors to be used in the future HEP experiments
Diamond Pixel Detectors and 3D Diamond Devices
No full textResults from detectors of poly-crystalline chemical vapour deposited (pCVD) diamond are presented. These include the first analysis of data of the ATLAS Diamond Beam Monitor (DBM). The DBM module consists of pCVD diamond sensors instrumented with pixellated FE-I4 front-end electronics. Six diamond telescopes, each with three modules, are placed symmetrically around the ATLAS interaction point. The DBM tracking capabilities allow it to discriminate between particles coming from the interaction point and background particles passing through the ATLAS detector. Also, analysis of test beam data of pCVD DBM modules are presented. A new low threshold tuning algorithm based on noise occupancy was developed which increases the DBM module signal to noise ratio significantly. Finally first results from prototypes of a novel detector using pCVD diamond and resistive electrodes in the bulk, forming a 3D diamond device, are discussed. 3D devices based on pCVD diamond were successfully tested with test beams at CERN. The measured charge is compared to that of a strip detector mounted on the same pCVD diamond showing that the 3D device collects significantly more charge than the planar device
Diamond particle detectors systems in high energy physics
No full textWith the first three years of the LHC running complete, ATLAS and CMS are planningto upgrade their innermost tracking layers with more radiation hard technologies. Chemical VaporDeposition (CVD) diamond is one such technology. CVD diamond has been used extensively inbeam condition monitors as the innermost detectors in the highest radiation areas of BaBar, Belle,CDF and all LHC experiments. The lessons learned in constructing the ATLAS Beam ConditionsMonitor (BCM), Diamond Beam Monitor (DBM) and the CMS Pixel Luminosity Telescope (PLT)all of which are based on CVD diamond with the goal of elucidating the issues that should beaddressed for future diamond based detector systems. The first beam test results of prototypediamond devices with 3D detector geometry should further enhance the radiation tolerance of thismaterial
TCAD Modeling of Surface Radiation Damage Effects: A State-Of-The-Art Review
No full textA comprehensive numerical model which accounts for surface damage effects induced by radiation on silicon particle detectors is presented with reference to the state-of-the-art Synopsys Sentaurus Technology CAD (TCAD) tool. The overall aim of this work is to present the “Perugia 2019 Surface” damage modeling scheme, fully implemented within the TCAD environment, which effectively describes the surface damage effects induced by radiation in silicon sensors relying on a limited number of parameters relevant for physics. To this end, extensive measurement campaigns have been recently performed on gated-diodes and MOS capacitors at Fondazione Bruno Kessler (FBK) in Italy, Hamamatsu Photonics (HPK) in Japan and Infineon Technologies (IFX) in Austria on both n-type and p-type substrates (with and without p-spray isolation implants), in order to extrapolate the relevant parameters which rule the surface damage effects. The integrated interface trap density and the oxide charge density, have been determined before and after X-ray irradiation with doses ranging from 0.05 to 100 Mrad(SiO2), for each specific foundry and technology flavor. The main guidelines of this study are the versatility and generality of the simulation approach
Beam test results of the dependence of signal size on incident particle flux in diamond pixel and pad detectors
No full textWe present results of beam tests of charged particle detectors based on single-crystal and poly-crystalline Chemical Vapor Deposition (CVD) diamond. We measured the signal pulse height dependence on the particle flux. The detectors were tested over a range of particle fluxes from 2 kHz/cm2 to 20 MHz/cm2. The pulse height of the sensors was measured with pad and pixel readout electronics. The pulse height of the non-irradiated single-crystal CVD diamond pad sensors was stable with respect to flux, while the pulse height of irradiated single-crystal CVD diamond pad sensors decreased with increasing particle flux. The pulse height of the non-irradiated single-crystal CVD diamond pixel detectors decreased slightly with increasing particle flux while the pulse height of the irradiated single-crystal CVD diamond pixel detectors decreased significantly with increasing particle flux. The observed sensitivity to flux is similar in both the diamond pad sensors constructed using diamonds from the Pixel Luminosity Telescope (PLT) irradiated during its pilot run in the Compact Muon Solenoid (CMS) detector and in neutron irradiated diamond pad sensors from the same manufacturer irradiated to the same fluence of neutrons. The pulse height for irradiated poly-crystalline CVD diamond pad sensors proved to be stable with respect to particle flux
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
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