3,557 research outputs found
Geologia del Nucleo Mesozoico della Val di Lima (Provincie di Pistoia e Lucca, Appennino Settentrionale) note illustrative della carta geologica (scala 1:25.000)
No full textA short outline of the geology of the Mesozoic inlier in the Lima Valley, Northern Apennines.
No full textThe CMS Si-strip Tracker
No full textThe Compact Muon Solenoid (CMS) experiment at LHC features the largest Silicon Strip Tracker (SST) ever build. This device is immersed in a 4T magnetic field and, in conjunction with a Pixel system, it allows the momentum of the charged particles to be measured and the heavy-flavour final states to be tagged despite the hostile radiation environment. The impact of operating conditions and physics requirements on the SST layout and design choices is discussed and the expected performances are reviewed. The SST collaboration is now facing the production of the ~15000 modules and their assembly into the SST substructures. A status is given.The Compact Muon Solenoid (CMS) experiment at LHC features the largest Silicon Strip Tracker (SST) ever build. This device is immersed in a 4T magnetic field and, in conjunction with a Pixel system, it allows the momentum of the charged particles to be measured and the heavy-flavour final states to be tagged despite the hostile radiation environment. The impact of operating conditions and physics requirements on the SST layout and design choices is discussed and the expected performances are reviewed. The SST collaboration is now facing the production of the ~15000 modules and their assembly into the SST substructures. A status is given.The CMS experiment at LHC features the largest Silicon Strip Tracker (SST) ever build. This device will be immersed in a 4T magnetic field in conjunction with a Pixel system allowing the momentum reconstruction of charged particles and the heavy-flavor tagging despite the hostile radiation environment. The impact of the operating conditions and the physics requirements on the SST layout and design choices is discussed and the expected performances are reviewed
SUSY Particles Searches at LEP and Interpretations within the MSSM
No full textSearches for R-parity conserving supersymmetric particles have been performed in e+e- data collected by LEP detectors, at centre-of-mass energies up to 209GeV, corresponding to an integrated luminosity of 3.1fb-1. The results and their interpretation in the context of MSSM frameworks are briefly reviewed
Scalar Quark searches with the ALEPH Experiment at LEP2
No full textThe description of the strong, weak and electromagnetic interactions within matter, the Standard Model theory, has been shown to be very consistent with experimental data up to explored energy scale even if the Higgs boson, the visible remnant of mechanism responsible of the gauge symmetry breaking and of the fermion mass hierarchy, is not yet discovered. Despite this success it is common opinion that Standard Model is a lower energy effective theory of a larger and more fundamental framework not suffering the several problems that occur as soon as one tries to extend the Standard Model to higher energies (typically the Planck scale). Supersymmetry (SUSY) is one of the most elegant theory that provides such a solid framework. Supersymmetry enlarges the elementary particle spectra predicting the existence of new particles. The supersymmetric particles have the same couplings as the Standard Model particles. Therefore the LEP e+e- collider is almost ideal to confirm or exclude their presence. In particular the supersymmetric scalar partners of top and bottom quarks could be enough light; thus they are a natural target of an experimental search of SUSY existence. In this report the extensive scalar quark ( squarks) search performed at LEP2 with the ALEPH experiment will be described. The obtainable results are complementary to the ones from similar searches performed at the TEVATRON collider since the LEP experiments have the possibility of testing for squarks domains left unexplored by the TEVATRON experiments. The results presented here are based on ALEPH data sample collected at energies up to 202GeV. The report is organised as follows: the chapter 1 is a short introduction to Supersymme- try and its motivations compared with weak aspects of the Standard Model. In chapter 2 some detail about the squark sector phenomenology is given. In chapter 3 the ALEPH experiment and the LEP collidcr arc described. Chapter 4 gives details about the Monte Carlo generation of signal samples that is critical in several aspects; the Monte Carlo simu- lation of backgrounds processes is described as well. Chapter 5 is dedicated to the detailed description of the selections used to search for squark signal, while in the chapter 7 the re- sults and their interpretation are discussed after the description of systematic uncertainties of chapter 6
Higgs and Beyond Standard Model Searches at LEP
No full textExtensive searches for Higgs bosons and other new phenomena predicted by extensions of the Standard Model have been performed at LEP. A summary is given reviewing the principal aspects and presenting a selection of results
An innovative seeding technique for photon conversion reconstruction at CMS
No full textThe conversion of photons into electron-positron pairs in the detector material is a nuisance in the event reconstruction of high energy physics experiments, since the measurement of the electromagnetic component of interaction products results degraded. Nonetheless this unavoidable detector effect can be also extremely useful. The reconstruction of photon conversions can be used to probe the detector material and to accurately measure soft photons that come from radiative decays in heavy flavor physics. In fact a converted photon can be measured with very high momentum resolution by exploiting the excellent reconstruction of charged tracks of a tracking detector as the one of CMS at LHC.
The main issue is that photon conversion tracks are difficult to reconstruct for standard reconstruction algorithms. They are typically soft and very displaced from primary interaction vertex.
An innovative seeding technique that exploits the peculiar photon conversion topology, successfully applied in the CMS track reconstruction sequence, is presented. The performances of this technique and the substantial enhancement of photon conversion reconstruction efficiency are discussed. Application examples are given
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