Top quark measurements at ATLAS Grancagnolo, S
Journal of physics. Conference series,
12/2017, Letnik:
934, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The top quark is the heaviest known fundamental particle. As it is the only quark that decays before it hadronizes, it allows us to probe the properties of bare quarks at the Large Hadron Collider. ...Highlights of a few recent precision measurements by the ATLAS Collaboration of the top quark using 13 TeV and 8 TeV collision data will be presented: top-quark pair and single top production cross sections including differential distributions will be presented alongside measurements of top-quark properties, including results using boosted top quarks, probe our understanding of top-quark production in the TeV regime. Measurements of the top-quark mass and searches for rare top quark decays are also presented.
The ATLAS Muon Trigger "Slice" Sidoti, A.; Bellomo, M.; Biglietti, M. ...
IEEE transactions on nuclear science,
02/2008, Letnik:
55, Številka:
1
Journal Article
Recenzirano
The ATLAS experiment at the Large Hadron Collider (LHC) will face the challenge of selecting interesting candidate events in proton-proton collisions at 14 TeV center of mass energy, while rejecting ...the enormous number of background events. The trigger system architecture is organized in three levels. From a bunch crossing rate of 40 MHz, the First Level trigger, hardware implemented, will reduce this rate to around ~75 kHz. Then the software based High Level Trigger (HLT), composed by the Second Level Trigger and the Event Filter reduces the rate to 200 Hz. In this paper, we will present the implementation of the muon trigger ldquoslice,rdquo signal efficiencies, background rejection rates, and system performances (execution time, memory consumption, etc.) for online muon selection based on Monte Carlo simulations and results obtained on real events collected during cosmic data taking runs.
Status and prospects of the BaBar SVT Re, V.; Bruinsma, M.; Curry, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2006, Letnik:
560, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The
BaBaR Silicon Vertex Tracker (SVT) has been efficiently operated for five years since the start of data taking in 1999. It has met design requirements and no degradation in its performance has ...been observed thus far. However, because of higher than expected background levels, and anticipated further increases in luminosity and dose rates, we have done a thorough study to assess the viability of operating the SVT until the end of the decade.
The Silicon Vertex Tracker (SVT) of the BABAR experiment at SLAC is a crucial tool to measure with precision the decay position of B mesons produced in the PEP-II electron–positron collisions. It is ...structured in five layers made of double-sided, AC coupled silicon microstrip sensors. In this paper, a review of some of the technical solutions chosen in the detector design phase is presented. In particular, we focus here on those elements which turned out to be sources of problems during the installation and the first few years of operation; the solutions adopted to solve the problems are presented together with recommendations and proposals for alternate future designs.
The silicon vertex tracker (SVT) of the BaBar experiment at PEP-II is described. This is the crucial device for the measurement of the B meson decay vertices to extract charge-conjugation parity (CP) ...asymmetries. It consists of five layers of double-sided ac-coupled silicon strip detectors, read out by a full-custom integrated circuit, capable of simultaneous acquisition, digitization, and transmission of data. It represents the core of the BaBar tracking system, providing position measurements with a precision of 10 /spl mu/m (inner layers) and 30 /spl mu/m (outer layers). The relevant performances of the SVT are presented, and the experience acquired during the construction, installation, and the first five years of data-taking is described. Innovative solutions are highlighted, like the sophisticated alignment procedure, imposed by the design of the silicon tracker, integrated in the beamline elements and mechanically separated from the other parts of BaBar. The harshness of the background conditions in the interaction region required several studies on the radiation damage of the sensors and the front-end chips, whose results are presented. Over the next five years the luminosity is predicted to increase by a factor three, leading to radiation and occupancy levels significantly exceeding the detector design. Extrapolation of future radiation doses and occupancies is shown together with the expected detector performance and lifetime. Upgrade scenarios to deal with the increased luminosity and backgrounds are discussed.
The ATLAS Muon Trigger Slice Biglietti, M.; Carlino, G.; Conventi, F. ...
2006 IEEE Nuclear Science Symposium Conference Record,
2006-Oct., Letnik:
2
Conference Proceeding
At LHC the 40 MHz bunch crossing rate dictates a high selectivity of the ATLAS trigger, which has to keep the full physics potential of the experiment with a limited DAQ and storage capability. A ...three-level trigger has been designed to reduce the input rate to about 100 Hz. The capability to select events with muons at an early stage of the trigger system is crucial to cope with the expected rates. In this paper we will describe the trigger of the muon system (muon vertical slice). The first level of trigger, implemented in a custom hardware, will use measurements from the trigger chambers of the muon spectrometer to reduce the initial rate to 100 kHz. It selects muons with transverse momentum above programmable thresholds with a coarse evaluation of the muon position (regions of interest, RoIs). The RoIs are passed to the second trigger level in which fast algorithms reconstruct muons with high transverse momentum combining full granularity information from trigger and precision chambers of the muon spectrometer. A third trigger level, the event filter will access the full event to further reduce the rate to about 100 Hz. To accomplish this, components of physics analysis traditionally deferred to offline physics analysis, are embedded within the on-line trigger system. Along with the muon vertical slice implementation and description we will also present the expected performance relative to signal efficiencies, background rejection and execution time.
The silicon vertex tracker (SVT) of the BaBar experiment at PEP-II is described. This is the crucial device for the measurement of the B meson decay vertices to extract CP-asymmetries. It consists of ...five layers of double-sided AC-coupled silicon strip detectors, read out by a full-custom integrated circuit, capable of simultaneous acquisition, digitization and transmission of data. It represents the core of the BaBar tracking system, providing position measurements with a precision of 10 /spl mu/m (inner layers) and 30/spl mu/m (outer layers). The relevant performances of the SVT are presented, and the experience acquired during the construction, installation and the first five years of data-taking is described. Innovative solutions are highlighted, like the sophisticated alignment procedure, imposed by the design of the silicon tracker, integrated in the beam-line elements and mechanically separated from the other parts of BaBar. The harshness of the background conditions in the interaction region required several studies on the radiation damage of the sensors and the front-end chips, whose results are presented. Over the next five years the luminosity is predicted to increase by a factor three, leading to radiation and occupancy levels significantly exceeding the detector design. Extrapolation of future radiation doses and occupancies is shown together with the expected detector performance and lifetime. Upgrade scenarios to deal with the increased luminosity and backgrounds are discussed.
The ATLAS Muon Trigger "Slice" Sidoti, A.; Bellomo, M.; Biglietti, M. ...
2007 15th IEEE-NPSS Real-Time Conference,
2007-April
Conference Proceeding
Odprti dostop
The ATLAS experiment at the LHC will face the challenge of selecting interesting candidate events in proton-proton collisions at 14 TeV center of mass energy, while rejecting the enormous number of ...background events. The trigger system architecture is organized in three levels. From a bunch crossing rate of 40 MHz the First level trigger, hardware implemented, will reduce this rate to around ~ 75 kHz. Then the software based high level trigger (HLT), composed by the second level trigger and the event filter reduces the rate to ~ 200 Hz. HLT is implemented on commercial CPUs using a framework built on the common ATLAS object oriented software architecture. Inclusive trigger selections are used to collect events for the ATLAS physics program; final states with muons are crucial for electroweak precision measurements as well as Higgs and SUSY searches. In this paper we will present the implementation of the muon slice, signal efficiencies, background rejection rates and system performances (execution time,...) for online muon selection based on Monte Carlo simulations and results obtained on real events collected during cosmic data taking runs.
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