G. Parrour

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.

Performance of a liquid argon Accordion calorimeter with fast readout

Abstract A prototype lead-liquid-argon electromagnetic calorimeter with parallel plates and Accordion geometry has been equipped with high speed readout electronics and tested with electron and muon beams at the CERN SPS. For a response peaking time of about 35 ns, fast enough for operation at the future hadron colliders, the energy resolution for electrons is 9.6%/√E[GeV] with a local constant term of 0.3% and a noise contribution of 0.33 E[ GeV ] . The spatial accuracy achieved with a detector granularity of 2.7 cm is 3.7 mm E[ GeV ] and the angular resolution 12 mrad at 60 GeV.

Performance of a liquid argon preshower detector integrated with an Accordion calorimeter

Abstract A prototype liquid argon preshower detector with a strip granularity of 2.5 mm has been tested at the CERN SPS in front of a liquid argon Accordion calorimeter. For charged tracks a signal-to-noise ratio of 9.4 and a space resolution of 340 μm were measured; the rejection power against overlapping photons produced in the decay of 50 GeV π 0 s is larger than 3; the precision on

Performance of a liquid argon electromagnetic calorimeter with a cylindrical accordion geometry

Abstract A prototype of a lead liquid argon accordion calorimeter with two types of cylindrical geometry was constructed and equipped with high speed readout electronics. The energy resolution for electrons is 10%/√E (GeV) with a local constant term of 0.65%. The resolutions obtained for position and angular measurements are given.

Electronic chain for the readout of a fast liquid argon prototype calorimeter

Summary form only given. A research and development program is being conducted in view of realizing an electromagnetic and hadronic calorimeter for the Large Hadron Collider (LHC). The authors report on tests on fast electronics, coupled to an electromagnetic prototype calorimeter built with an accordion structure. Three different types of preamplifiers have been used. In two (Si and GaAs hybrids), the preamplifier is operated in liquid argon. In the third one, a common based (Si JFET or GaAs) transistor is in the liquid, the charge preamplifier being outside the cryostat, after about 6 m of 50- Omega cable. The shaping amplifier uses RC-CR filtering. The response to a short current pulse peaks after about 20 ns. When the system is connected to the calorimeter, the liquid argon signals peak, as expected, after 30 ns. Noise, linearity, and cross-talk between channels were investigated. First results from an exposure of the calorimeter to electrons of energy 30 to 175 GeV were obtained.<<ETX>>