This paper discusses hadron energy reconstruction for the ATLAS barrel prototype combined calorimeter (consisting of a lead-liquid argon electromagnetic part and an iron-scintillator hadronic part) in the framework of the non-parametrical method. The non-parametrical method utilizes only the known e/h ratios and the electron calibration constants and does not require the determination of any parameters by a minimization technique. Thus, this technique lends itself to an easy use in a first level trigger. The reconstructed mean values of the hadron energies are within ±1% of the true values and the fractional energy resolution is [(58±3)%/E+(2.5±0.3)%]⊕(1.7±0.2)/E. The value of the e/h ratio obtained for the electromagnetic compartment of the combined calorimeter is 1.74±0.04 and agrees with the prediction that e/h>1.66 for this electromagnetic calorimeter. Results of a study of the longitudinal hadronic shower development are also presented. The data have been taken in the H8 beam line of the CERN SPS using pions of energies from 10 to 300GeV.

One strong constraint in ATLAS is the easy and fast access to the Tile calorimeter readout without any destructive interference with the rest of the detector. Therefore the drawer system has been designed to place all PMTs and associated electronics on a movable system inside the TILECAL girders which provide both, the structural support to the individual modules and the solenoid return ux. In case of faulty readout elements, these elements can be replaced because of the motion of the endcaps. In this note, the complete system from the manufacturing technique up to the readout components, is described. Each drawer is considered as an autonomous subsystem which requires a dedicated test bench.

Prototypes of the FERMI system have been used to read out a prototype of the ATLAS hadron calorimeter in a beam test at the CERN SPS. The FERMI read-out system, using a compressor and a sampling ADC, is compared to a standard charge integrating read-out by measuring the energy resolution of the calorimeter separately with the two systems on the same events.Signal processing techniques have been designed to optimize the treatment of FERMI data. The resulting energy resolution is better than the one obtained with the standard read-out. (C) 1998 Elsevier Science B.V. All rights reserved.

A study of high energy muons traversing the ATLAS hadron the calorimeter in the barrel region in the energy range between 10 and 300 GeV is presented. Both test beam experimental data and Monte Carlo simulations are given and show good agreement. The Tile calorimeter capability of detecting isolated muons over the above energy range is demonstrated. A signal to background ratio of about 10 is expected for the nominal LHC luminosity (10(34) l/cm(2) s). The photoelectron statistics effect in the muon shape response is shown. The e/mip ratio is found to be 0.81 +/- 0.03; the e/mu ratio is in the range 0.91-0.97.The energy loss of a muon in the calorimeter, dominated by the energy lost in the absorber, can be correlated to the energy loss in the active material. This correlation allows one to correct on an event by event basis the muon energy loss in the calorimeter and therefore reduce the low energy tails in the muon momentum distribution.

We report on an experimental study of the properties of a modular lead/scintillating-fiber calorimeter with a fully projective tower geometry. Although the calorimeter structure is monolythic, an effective segmentation into an electromagnetic and an hadronic section is achieved by separating the readout of the fibers running throughout the calorimeter from those starting beyond a depth of ∼ 25 radiation lengths. This feature is used for e/π separation. Discontinuities in the sampling fraction near the boundaries of the modules cause a signal nonuniformity for electrons, which can be corrected. Similar effects observed for high energy hadrons are discussed. Results are given on the energy and position resolution for electrons, on the signal linearity and on the absolute light yield. Pion showers were only partially contained in this detector. The information from a backing calorimeter, consisting of fast thin-gap wire chambers interleaved by iron slabs, significantly improves the energy resolution of the incompletely contained pion showers.

The first prototype of a scintillator tile hadron calorimeter with longitudinal tile orientation and wavelength shifting fiber readout has been built and tested with pion, electron and muon beams at the CERN SPS. This innovative geometry combines good performance and a simple and cost effective assembly procedure. Calibration and monitoring of this detector have also been investigated.

We report on an experimental study of the performance of an electromagnetic calorimeter consisting of thin (0.5 mm diameter) scintillating plastic fibers embedded in lead. Because of the small sampling fraction (3.5% for minimum ionizing particles), this detector is quite compact, with an effective radiation length of 7.2 mm and a Molière radius of 20 mm. Because of the very frequent shower sampling provided by the fibers, the energy resolution is nevertheless good: 9.2%/√E(GeV) for electromagnetic (e.m.) showers, with a small, angle dependent constant term. A non-uniformity in the response is observed at the 2% level across the calorimeter. In spite of the small sampling fraction the light yield is not a limiting factor in this calorimeter: we measured ∼ 500 photoelectrons per GeV shower energy. The position resolution for electrons and two e.m. showers separation have been studied. The fibers sticking out of the back of the detector do not appear to affect the measurements of hadronic showers.