Papers by Leonello Servoli
Radiotherapy and Oncology, 2012
[1] Istituto Nazionale di Fisica Nucleare, Perugia [2] Universita degli Studi di Perugia [3] ASL ... more [1] Istituto Nazionale di Fisica Nucleare, Perugia [2] Universita degli Studi di Perugia [3] ASL 3 Umbria, Ospedale di Foligno, Foligno [4] Universita “Sapienza”, Roma [5] ASL 1 Umbria, Ospedale di Citta di Castello, Citta di Castello [*] Contact: [email protected] [a] Supported by a grant from Regione Umbria (Progetto POR Umbria FSE 2007-2013). Research Partially funded by Fondazione Cassa di Risparmio di Perugia, Bando Ricerca di Base 2010 code number: 2010.011.0421 and 2010.011.0474
2007 IEEE Nuclear Science Symposium Conference Record, 2007
A system allowing for deep investigation of charge collection properties of active pixel particle... more A system allowing for deep investigation of charge collection properties of active pixel particle detectors fabricated in standard 0.18 mum CMOS bulk technology (i.e. without epitaxial layer) has been devised and implemented. The system includes an advanced laser test bench featuring fast laser pulser (68 ps, 80 MHz) and different laser heads (UV 407 nm, VIS 783 nm, IR 1060 nm), as well as integrated movement and acquisition capabilities. In particular, the sub-micron focusing and positioning capabilities of the whole system enable efficient, fast and versatile sensor characterization. Extensive test have been carried out, with the aim of evaluating the sensitivity, the spatial resolution and the efficiency of APS CMOS sensors with different wavelength laser stimuli. The test system provides advanced capabilities for deep understanding of silicon particle detectors to be used in high energy physics experiments and/or medical imaging systems.
Physics Reports, 2013
Electroweak measurements performed with data taken at the electron-positron collider LEP at CERN ... more Electroweak measurements performed with data taken at the electron-positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb −1 collected by the four LEP experiments ALEPH, DELPHI, L3 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron-positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose-Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m W and Γ W , the branching fraction of W decays to hadrons, B(W → had), and the trilinear gauge-boson selfcouplings g Z 1 , κ γ and λ γ are determined to be: m W = 80.376 ± 0.033 GeV Γ W = 2.195 ± 0.083 GeV B(W → had) = 67.41 ± 0.27 % g Z 1 = 0.984 +0.018 −0.020 κ γ = 0.982 ± 0.042 λ γ = −0.022 ± 0.019 .
Nuclear Physics B - Proceedings Supplements, 1995
Collaboration members and their institutes are listed following the references.
2008 IEEE Nuclear Science Symposium Conference Record, 2008
In modern distributed computer systems for scientific computing (clusters and computing GRIDs) a ... more In modern distributed computer systems for scientific computing (clusters and computing GRIDs) a new class of problems, due to the increasing heterogeneity of users’ requests, have to be tackled by the administrators. One possible solution is to create on-demand virtual working environments tailored on the user’s requirements. Hence the need for an architecture to manage dynamically such environments. In this
IEEE Transactions on Nuclear Science, 1989
The basic design of the SLD data acquisition system and its present status are reviewed. Aspects ... more The basic design of the SLD data acquisition system and its present status are reviewed. Aspects of the design that take particular advantage of the relatively low e+e-cross section and the low beam crossing rate of a linear collider are explained.
Modern Physics Letters A, 1993
We present the first measurement of the left-right cross-section asymmetry (A LR ) in Z-boson pro... more We present the first measurement of the left-right cross-section asymmetry (A LR ) in Z-boson production observed at the SLAC Linear Collider. In 1992 the SLD detector recorded 10 224 Z events produced by the collision of longitudinally polarized electrons with an unpolarized positron beam at a center-of-mass energy of 91.55 GeV. The average electron beam polarization during the run was (22.4 ± 0.6)%. We measure A LR to be 0.100 ± 0.0440 (stat.) ±0.004 (syst.) , which determines the effective weak mixing angle to be [Formula: see text].
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1989
The iron flux-return structure for the SLC Large Detector (SLD) has' been instrumented with plast... more The iron flux-return structure for the SLC Large Detector (SLD) has' been instrumented with plastic streamer tubes covering an area of about 4500 square meters, to provide muon identification plus energy measurement of hadron showers. A description is given of the production techniques used to construct this large detector system, with an emphasis on the methods by which high reliability and a small number of defects in the completed assembly were ensured.
IEEE Symposium Conference Record Nuclear Science 2004.
Abstract-- This work aims at exploring and validating the adoption of standard fabrication proces... more Abstract-- This work aims at exploring and validating the adoption of standard fabrication processes for the realization of CMOS active pixel sensor, for particle detection purposes. The goal is to implement a single-chip, complete radiation sensor system, including on a CMOS IC the ...
Journal of High Energy Physics
A measurement of the angular correlations between beauty and anti-beauty hadrons ( \textB[`(\text... more A measurement of the angular correlations between beauty and anti-beauty hadrons ( \textB[`(\textB)] {\text{B}}\overline {\text{B}} ) produced in pp collisions at a centre-of-mass energy of 7 TeV at the CERN LHC is presented, probing for the first time the region of small angular separation. The B hadrons are identified by the presence of displaced secondary vertices from their decays. The B hadron angular separation is reconstructed from the decay vertices and the primary-interaction vertex. The differential \textB[`(\textB)] {\text{B}}\overline {\text{B}} production cross section, measured from a data sample collected by CMS and corresponding to an integrated luminosity of 3.1 pb−1, shows that a sizable fraction of the \textB[`(\textB)] {\text{B}}\overline {\text{B}} pairs are produced with small opening angles. These studies provide a test of QCD and further insight into the dynamics of \textb[`(\textb)] {\text{b}}\overline {\text{b}} production. KeywordsHadron-Hadron Scattering
Journal of High Energy Physics
A measurement of the angular correlations between beauty and anti-beauty hadrons (B B-bar) produc... more A measurement of the angular correlations between beauty and anti-beauty hadrons (B B-bar) produced in pp collisions at a centre-of-mass energy of 7 TeV at the CERN LHC is presented, probing for the first time the region of small angular separation. The B hadrons are identified by the presence of displaced secondary vertices from their decays. The B hadron angular separation is reconstructed from the decay vertices and the primary-interaction vertex. The differential B B-bar production cross section, measured from a data sample collected by CMS and corresponding to an integrated luminosity of 3.1 inverse picobarns, shows that a sizable fraction of the B B-bar pairs are produced with small opening angles. These studies provide a test of QCD and further insight into the dynamics of b b-bar production.
Journal of Instrumentation, 2010
Recent developments in the domain of the standard CMOS imagers for visible light, mainly in the r... more Recent developments in the domain of the standard CMOS imagers for visible light, mainly in the reduction of the pixel size, has led us to investigate the suitability of some of these devices as ionizing radiation detectors. A standard 640x480 imager with 5.6x5.6 micrometer pixel size (Aptina product MT9SH06) has been characterized with X-ray (55Fe and 8 keV X-ray tube) and charged particles sources (500 MeV electrons). The main results obtained are: a small average pixel multiplicity (4-5), for the detection of either X-ray or charged particles; a good linearity of the response; a S/N ratio of 29 for a Minimum Ionizing Particle and an estimated sensitivity to X-rays down to 1 keV.
IEEE Nuclear Science Symposium Conference Record, 2005
A set of innovative active pixel architectures has been conceived and implemented in standard CMO... more A set of innovative active pixel architectures has been conceived and implemented in standard CMOS technology. Active circuits are introduced into the pixel, to increase S/N ratio and to perform basic signal processing. Testing of such devices, however, becomes critical, due to the circuit relative complexity and to the need of accurately evaluating timing and position of the impinging radiation. A test strategy has thus been devised, exploiting a NIR laser source, which has been carefully characterized and tuned. The NIR laser allows for emulating, in a much more controllable fashion, a MIP event. This allow for validation of novel pixel architectures proposed and, more generally, of the whole design flow.
Journal of High Energy Physics, 2011
The result of a search at the LHC for heavy stable charged particles produced in pp collisions at... more The result of a search at the LHC for heavy stable charged particles produced in pp collisions at √ s = 7 TeV is described. The data sample was collected with the CMS detector and corresponds to an integrated luminosity of 3.1 pb −1. Momentum and ionization-energy-loss measurements in the inner tracker detector are used to identify tracks compatible with heavy slow-moving particles. Additionally, tracks passing muon identification requirements are also analyzed for the same signature. In each case, no candidate passes the selection, with an expected background of less than 0.1 events. A lower limit at the 95% confidence level on the mass of a stable gluino is set at 398 GeV/c 2 , using a conventional model of nuclear interactions that allows charged hadrons containing this particle to reach the muon detectors. A lower limit of 311 GeV/c 2 is also set for a stable gluino in a conservative scenario of complete charge suppression, where any hadron containing this particle becomes neutral before reaching the muon detectors.
Journal of Instrumentation, 2010
Performance study of the CMS barrel resistive plate chambers with cosmic rays The MIT Faculty has... more Performance study of the CMS barrel resistive plate chambers with cosmic rays The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters.
2012 IEEE International Instrumentation and Measurement Technology Conference Proceedings, 2012
ABSTRACT Interventional radiologists and staff members, during all their professional activities,... more ABSTRACT Interventional radiologists and staff members, during all their professional activities, are frequently exposed to protracted and fractionated low doses of ionizing radiation. Due to of skin tissues and peripheral blood irradiation, these exposures can result in deterministic effects (radiodermatitis, aged skin, hands depilation) or stochastic ones (skin and nonsolid cancers incidence). The authors present a novel approach to perform on line monitoring of the staff during their interventions by using a device based on an Active Pixel Sensor. A good linearity with passive dosimeters (TLD) dose measurements has been demonstrated and the response difference between pulsed and continuous operational modes is reduced to less than 10%, marking a distinct improvement with respect to commercial active pixel dosimeters (APDs).
Journal of Instrumentation, 2012
Interventional radiologists and staff members are frequently exposed to protracted and fractionat... more Interventional radiologists and staff members are frequently exposed to protracted and fractionated low doses of ionizing radiation due to diffused X-ray radiation. The authors propose a novel approach to monitor on line staff during their interventions by using a device based on an Active Pixel Sensor developed for tracking applications. Two different photodiode configurations have been tested in standard Interventional
Physics Letters B, 2011
The first measurement of the cross section for top-quark pair production in pp collisions at the ... more The first measurement of the cross section for top-quark pair production in pp collisions at the LHC at center-of-mass energy √ s = 7 TeV has been performed using 3.1 ± 0.3 pb −1 of data recorded by the CMS detector. This result utilizes the final state with two isolated, highly energetic charged leptons, large missing transverse energy, and two or more jets. Backgrounds from Drell-Yan and non-W/Z boson production are estimated from data. Eleven events are observed in the data with 2.1 ± 1.0 events expected from background. The measured cross section is 194 ± 72(stat.) ± 24(syst.) ± 21(lumi.) pb, consistent with next-to-leading order predictions.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007
ABSTRACT An active pixel sensor has been developed using standard CMOS technology, UMC with no ep... more ABSTRACT An active pixel sensor has been developed using standard CMOS technology, UMC with no epitaxial layer, with pixel size , in the framework of the INFN RAPS project. In this work we will report on the results obtained using several types of ionizing radiation sources (laser, X-ray tubes, β and γ) to test extensively the device. Some of the main results obtained are: a signal/noise value for minimum ionizing particles of about 20, a very good linearity of the response, a good spatial confinement of the signal (cluster size of the order of few pixels).
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Papers by Leonello Servoli