G. Susinno

Dual-Readout Calorimetry with Lead Tungstate Crystals

Abstract Results are presented of beam tests in which a small electromagnetic calorimeter consisting of lead tungstate crystals was exposed to 50xa0GeV electrons and pions. This calorimeter was backed up by the DREAM Dual-Readout calorimeter, which measures the scintillation and Cherenkov light produced in the shower development, using two different media. The signals from the crystal calorimeter were analyzed in great detail in an attempt to determine the contributions from these two types of light to the signals, event by event. This information makes it possible to eliminate the dominating source of fluctuations and thus achieve an important improvement in hadronic calorimeter performance.

Contributions of Cherenkov light to the signals from lead tungstate crystals

Results are presented of detailed measurements of the signals generated by high-energy electrons and muons in lead tungstate crystals. A significant fraction of the light produced in these crystals and detected by photomultiplier tubes is the result of the Cherenkov mechanism. This is concluded from the angular dependence of the signals and from their time structure. Depending on the orientation of the crystals and on the particle type, Cherenkov light may account for up to 15% of the total signals. r 2007 Elsevier B.V. All rights reserved. PACS: 29.40.Ka; 29.40.Mc; 29.40.Vj

Measurement of the contribution of neutrons to hadron calorimeter signals

The contributions of neutrons to hadronic signals from the DREAM calorimeter are measured by analyzing the time structure of these signals. The neutrons, which mainly originate from the evaporation stage of nuclear breakup in the hadronic shower development process, contribute through elastic scattering off protons in the plastic scintillating fibers which provide the dE=dx information in this calorimeter. This contribution is characterized by an exponential tail in the pulse shape, with a time constant of � 25 ns. The relative contribution of neutrons to the signals increases with the distance from the shower axis. As expected, the neutrons do not contribute to the DREAM Cherenkov signals. r 2007 Elsevier B.V. All rights reserved. PACS: 29.40.Ka; 29.40.Mc; 29.40.Vj

Production and test of monitored drift tubes for the muon spectrometer of the ATLAS experiment

ATLAS is one of the two general-purpose experiments being built for the Large Hadron Collider at CERN. Its muon spectrometer consists of very high-precision chambers made of drift tubes. Up to now, more than 5000 monitored drift tubes (MDTs) have been constructed and tested at the University of Calabria, Italy, for ATLAS barrel system chambers of the muon detector. This paper reports the critical MDT assembly techniques in detail, including the automatic electronics system and data acquisition system. The extensive tests performed on individual drift tubes and the first results and experience are also reported.

Čerenkov light contribution in lead tungstate crystals

Results of detailed measurements of the Cerenkov light yield from lead tungstate (PbWO4) crystals are presented. A single crystal as well as a small homogeneous calorimeter (ECAL), consisting of 19 PbWO4 crystals, were exposed to electrons, muons and pions at the H4 beam line at CERN. It turns out that a significant fraction of the detected light is not the result of scintillation processes, but rather of the Cerenkov mechanism. This can be assessed from the analysis of both the angular dependence of the signals and their time structure. Detailed studies of the ECAL signals, corroborated by the measurements taken with the Dual-Readout calorimeter (DREAM), backing up the ECAL during beam tests, show that it is possible to estimate the independent contributions of scintillation and Cerenkov light. This information makes it possible to account for one of the dominant sources of fluctuations in hadronic showers and thus to achieve a significant improvement in hadronic calorimetry performance.

Construction and test of monitored drift tube for the muon spectrometer of ATLAS experiment

ATLAS is one of the two general purpose experiments being built for the Large Hadron Collider at CERN. Its muon spectrometer consists of very high precision chambers made of drift tubes (MDT: monitored drift tubes). Up to now more than 5000 MDTs have been constructed and tested at the University of Calabria for ATLAS BIL chambers of the muon detector. This work reports the critical MDT assembly techniques in detail, including the automatic electronics system and DAQ system. The extensive tests performed on individual drift tubes and the first results and experience are also reported.

Measurement of the neutron fraction event-by-event in DREAM

We have measured the neutron fraction event-by-event in beam test data taken at CERN by the DREAM collaboration. I will review these measurements in the context of the importance of neutrons to future high-precision calorimetry, and bring together the data from SPACAL, the GLD compensating calorimeter, and DREAM to estimate the impact neutron fraction measurements will make on hadronic energy resolution in dual-readout calorimeters.