Development of new readout electronics for the ATLAS LAr Calorimeter at the sLHC

The readout of the ATLAS Liquid Argon (LAr) calorimeter is a complex multi-channel system to amplify, shape, digitize and process signals of the detector cells. The current on-detector electronics is not designed to sustain the ten times higher radiation levels expected at sLHC in the years beyond 2019/2020, and will be replaced by new electronics with a completely different readout scheme. The future on-detector electronics is planned to send out all data continuously at each bunch crossing, as opposed to the current system which only transfers data at a trigger-accept signal. Multiple high-speed and radiation-resistant optical links will transmit 100 Gb/s per front-end board. The off-detector processing units will not only process the data in real-time and provide digital data buffering, but will also implement trigger algorithms. An overview about the various components necessary to develop such a complex system is given. The current R&D activities and architectural studies of the LAr Calorimeter group are presented, in particular the on-going design of the mixed-signal and radiation hard front-end ASICs, the Silicon-on-Saphire based optical-link, the high-speed off-detector FPGA based processing units, and the power distribution scheme

Development of new readout electronics for the ATLAS LAr calorimeter at the sLHC

The ATLAS Liquid Argon (LAr) calorimeter consists of 182,486 detector cells whose signals need to be read out, digitized and processed, in order to provide signal timing and the energy deposited in each detector element. The current readout electronics is not designed to sustain the ten times higher radiation levels expected at sLHC in the years beyond 2017, and will be replaced by new electronics with a completely different readout scheme. The future on-detector electronics is planned to send out all data continuously at each bunch crossing, as opposed to the current system which only transfers data at a trigger-accept signal. Multiple high-speed and radiation-resistant optical links will transmit 100 Gbps per front-end board, each covering 128 readout channels. The off-detector processing units will not only process the data in real-time and provide digital data buffering, but will also implement trigger algorithms. An overview about the various components necessary to develop such a complex system will be given. The current R&D activities and architectural studies of the LAr Calorimeter group will be presented, in particular the on-going design of the mixed-signal and radiation hard front-end ASICs, the Silicon-on-Saphire (SOS) based optical-link, the high-speed off-detector FPGA based processing units and the power supply distribution scheme

Measurement of the mass of the W boson at LEP and determination of electroweak parameters

Precise measurements of the W mass and width performed at LEP are presented, which yield M/sub W/=80.427+or-0.046 GeV and Gamma /sub W /=2.12+or-0.11 GeV. A comparison is made between this direct determination and the W mass value obtained indirectly in an analysis of other electroweak measurements. Good agreement is observed. All electroweak data are very consistent with the standard model predictions. In a combined fit an upper limit on the mass of the Higgs boson is put to M/sub H/<203 GeV at 95% confidence level. (20 refs)

Study of Spin and Decay-Plane Correlations of W Bosons in the e+e- -> W+W- Process at LEP

Data collected at LEP at centre-of-mass energies \sqrt(s) = 189 - 209 GeV are used to study correlations of the spin of W bosons using e+e- -> W+W- -> lnqq~ events. Spin correlations are favoured by data, and found to agree with the Standard Model predictions. In addition, correlations between the W-boson decay planes are studied in e+e- -> W+W- -> lnqq~ and e+e- -> W+W- -> qq~qq~ events. Decay-plane correlations, consistent with zero and with the Standard Model predictions, are measured

Measurement of the Cross Section for Open-Beauty Production in Photon-Photon Collisions at LEP

The cross section for open-beauty production in photon-photon collisions is measured using the whole high-energy and high-luminosity data sample collected by the L3 detector at LEP. This corresponds to 627/pb of integrated luminosity for electron-positron centre-of-mass energies from 189GeV to 209GeV. Events containing b quarks are identified through their semi-leptonic decay into electrons or muons. The e+e- -> e+e-b b~X cross section is measured within our fiducial volume and then extrapolated to the full phase space. These results are found to be in significant excess with respect to Monte Carlo predictions and next-to-leading order QCD calculations

Ultrarelativistic sources in nonlinear electrodynamics

The fields of rapidly moving sources are studied within nonlinear electrodynamics by boosting the fields of sources at rest. As a consequence of the ultrarelativistic limit the delta-like electromagnetic shock waves are found. The character of the field within the shock depends on the theory of nonlinear electrodynamics considered. In particular, we obtain the field of an ultrarelativistic charge in the Born-Infeld theory.Comment: 10 pages, 3 figure

ATLAS liquid argon calorimeter back end electronics

The Liquid Argon calorimeters play a central role in the ATLAS (A Toroidal LHC Apparatus) experiment. The environment at the Large Hadron Collider (LHC) imposes strong constraints on the detectors readout systems. In order to achieve very high precision measurements, the detector signals are processed at various stages before reaching the Data Acquisition system (DAQ). Signals from the calorimeter cells are received by on-detector Front End Boards (FEB), which sample the incoming pulse every 25ns and digitize it at a trigger rate of up to 75~kHz. Off-detector Read Out Driver (ROD) boards further process the data and send reconstructed quantities to the DAQ while also monitoring the data quality. In this paper, the ATLAS Liquid Argon electronics chain is described first, followed by a detailed description of the off-detector readout system. Finally, the tests performed on the system are summarized

A Combination of Preliminary Electroweak Measurements and Constraints on the Standard Model, 2006

This note presents a combination of published and preliminary electroweak results from the four LEP collaborations ALEPH, DELPHI, L3 and OPAL based on electron-positron collision data taken at centre-of-mass energies above the Z-pole, 130 GeV to 209 GeV (LEP-II), as prepared for the 2006 summer conferences. Averages are derived for di-fermion cross sections and forward-backward asymmetries, photon-pair, W-pair, Z-pair, single-W and single-Z cross sections, electroweak gauge boson couplings, W mass and width and W decay branching ratios. An investigation of the interference of photon and Z-boson exchange is presented, and colour reconnection and Bose-Einstein correlation analyses in W-pair production are combined. The main changes with respect to the experimental results presented in 2005 are new preliminary combinations of final LEP-II results on the mass and width of the W boson. Including the precision electroweak measurements performed at the Z pole published recently, the results are compared with precise electroweak measurements from other experiments, notably CDF and DØ at the Tevatron. Constraints on the input parameters of the Standard Model are derived from the results obtained in high-Q^2 interactions, and used to predict results in low-Q^2 experiments, such as atomic parity violation, Möller scattering, and neutrino-nucleon scattering

Precision Electroweak Measurements and Constraints on the Standard Model

This note presents constraints on Standard Model parameters using published and preliminary precision electroweak results measured at the electron-positron colliders LEP and SLC. The results are compared with precise electroweak measurements from other experiments, notably CDF and D{\O}at the Tevatron. Constraints on the input parameters of the Standard Model are derived from the results obtained in high-$Q^2$ interactions, and used to predict results in low-$Q^2$ experiments, such as atomic parity violation, M{\o}ller scattering, and neutrino-nucleon scattering