908 research outputs found
Uniformity of the 2000 test beam module with the new optimal filtering coefficients
An original method to reconstruct electron and pion signals in the Liquid ARGon barrel calorimeter (LARG) is applied to test beam data collected at the H8 line of the CERN North Area in July and August 2000. The method is based on the use of optimal filtering coefficients and takes into account the electrical description of the read-out electronics in the reconstruction of the physics pulses. Results on improvements in the LARG response and in particular on the energy uniformity of the calorimeter are shown
Uniformity Of The 2000 Test Beam Module With The New Optimal Filtering Coefficients
An original method to reconstruct electron and pion signals in the Liquid ARGon barrel calorimeter (LARG) is applied to test beam data collected at the H8 line of the CERN North Area in July and August 2000. The method is based on the use of optimal filtering coefficients and takes into account the electrical description of the read-out electronics in the reconstruction of the physics pulses. Results on improvements in the LARG response and in particular on the energy uniformity of the calorimeter are shown
Test Bench Of The Barrel Calorimeter Modules
A systematic procedure to qualify the barrel calorimeter modules is an essential step to guarantee a 0.7% constant term, which is the collaboration objective. The procedure detailed in this note consists of quality monitoring during mechanical assembling and of a set of electrical tests such as electrical continuity, cell and cross-talk capacitance measurement, and high-voltage behaviour. For the whole test, it has been necessary to develop dedicated electronic boards, to develop measurement methods, and the whole operation software. Making the procedure automatic will guarantee the quality of each module during assembling, cabling, and test in liquid argon
Position resolution and particle identification with the ATLAS EM calorimeter
In the years between 2000 and 2002 several pre-series and series modules of
the ATLAS EM barrel and end-cap calorimeter were exposed to electron, photon
and pion beams. The performance of the calorimeter with respect to its finely
segmented first sampling has been studied. The polar angle resolution has been
found to be in the range 50-60 mrad/sqrt(E (GeV)). The neutral pion rejection
has been measured to be about 3.5 for 90% photon selection efficiency at pT=50
GeV/c. Electron-pion separation studies have indicated that a pion fake rate of
(0.07-0.5)% can be achieved while maintaining 90% electron identification
efficiency for energies up to 40 GeV.Comment: 32 pages, 22 figures, to be published in NIM
Energy Linearity and Resolution of the ATLAS Electromagnetic Barrel Calorimeter in an Electron Test-Beam
A module of the ATLAS electromagnetic barrel liquid argon calorimeter was
exposed to the CERN electron test-beam at the H8 beam line upgraded for
precision momentum measurement. The available energies of the electron beam
ranged from 10 to 245 GeV. The electron beam impinged at one point
corresponding to a pseudo-rapidity of eta=0.687 and an azimuthal angle of
phi=0.28 in the ATLAS coordinate system. A detailed study of several effects
biasing the electron energy measurement allowed an energy reconstruction
procedure to be developed that ensures a good linearity and a good resolution.
Use is made of detailed Monte Carlo simulations based on Geant which describe
the longitudinal and transverse shower profiles as well as the energy
distributions. For electron energies between 15 GeV and 180 GeV the deviation
of the measured incident electron energy over the beam energy is within 0.1%.
The systematic uncertainty of the measurement is about 0.1% at low energies and
negligible at high energies. The energy resolution is found to be about 10%
sqrt(E) for the sampling term and about 0.2% for the local constant term
Search for CP Violation in the Decay Z -> b (b bar) g
About three million hadronic decays of the Z collected by ALEPH in the years
1991-1994 are used to search for anomalous CP violation beyond the Standard
Model in the decay Z -> b \bar{b} g. The study is performed by analyzing
angular correlations between the two quarks and the gluon in three-jet events
and by measuring the differential two-jet rate. No signal of CP violation is
found. For the combinations of anomalous CP violating couplings, and , limits of \hat{h}_b < 0.59h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st
Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV
A search for pair-production of supersymmetric particles under the assumption
that R-parity is violated via a dominant LQDbar coupling has been performed
using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV.
The observed candidate events in the data are in agreement with the Standard
Model expectation. This result is translated into lower limits on the masses of
charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for
m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81
GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the
95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure
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