J. G. Saraiva

The RD52 calorimeter is an instrument intended to detect both electromagnetic and hadronic showers, as well as muons, using the dual-readout principle. Scintillation and Cherenkov light provide the two signals which, in combination, allow for superior hadronic performance. In this paper, we report on the electromagnetic performance of this instrument, and compare this performance with that of other calorimeters that were constructed with similar goals in mind.

The RD52 dual-readout calorimeter is a longitudinally unsegmented instrument intended for the detection of both electromagnetically and hadronically interacting particles with unprecedented precision.In this paper, the identification of the showering particles and, in particular, the identification of electrons and γs with this instrument are investigated.The techniques used for this purpose include differences in the shower development observed with scintillation light and Cherenkov radiation, the radial shower profile of the particles and the time structure (including the starting point) of the calorimeter signals.It turns out that, at 60 GeV, electrons can be correctly identified in 99.8% of the cases, by means of criteria that eliminate 99.8% of the hadrons.

The RD52 calorimeter uses the dual-readout principle to detect both electromagnetic and hadronic showers, as well as muons. Scintillation and Cherenkov light provide the two signals which, in combination, allow for superior hadronic performance. In this paper, we report on detailed, GEANT4 based Monte Carlo simulations of the performance of this instrument. The results of these simulations are compared in great detail to measurements that have been carried out and published by the DREAM Collaboration. This comparison makes it possible to understand subtle details of the shower development in this unusual particle detector. It also allows for predictions of the improvement in the performance that may be expected for larger detectors of this type. These studies also revealed some inadequacies in the GEANT4 simulation packages, especially for hadronic showers, but also for the Cherenkov signals from electromagnetic showers.

Abstract Fast light pulse sources became easily available with the development of ultra bright and fast LEDs in recent years, with emission spectra in the blue—of widespread use in high-energy physics experiments—and UV regions. Studies on their use as radiation sources for fibre characterization include stability, linearity of system components under their light pulses and the measurement of fibre parameters.

Natural and accelerated ageing studies for the different components of the TILECAL calorimeter, of the ATLAS experiment, play a central role in forecasting the evolution of the detector's performance throughout its operating life. It is possible that the operation of ATLAS will be extended by 5 years in an upgraded LHC scenario. Such prospect makes these studies even more important, in order to assess the contribution of the natural ageing in relation to the other processes inducing performance loss in the optical components. Among other activities in this LHC/CERN collaboration, the Lisbon calorimetry group is involved in studying the impact of radiation damage and natural ageing in optical characteristics of the TILECAL wavelength shifter (WLS) optical fibers and scintillators, and to reevaluate the light budget of the tile/fiber system. The light yield and the attenuation length of the WLS and scintillating optical fibers are measured using an X–Y table. Results are presented for several sets of WLS optical fibers (Kuraray Y11(200)MSJ) whose characteristics have been monitored since 1999. Most of those 338 fibers are from the mass production for the TILECAL detector: 208 non-aluminized 200 cm fibers, from several production batches, and 128 batch #6 aluminized fibers, with lengths ranging from 114 to 207 cm.

The ATLAS hadronic barrel calorimeter was tested using dedicated calibration systems, cosmic ray muons and single beam data prior to the start of collisions. Before collisions, in addition to the hardware maintenance, the verification of the electromagnetic energy scale set during test-beam and the read-out synchronization of the tile calorimeter were undertaken. The results obtained showed that the calorimeter was well calibrated and ready for the challenges of the LHC collisions.