No Arabic abstract
This work is devoted to the experimental study of the longitudinal hadronic shower development in the ATLAS barrel combined prototype calorimeter consisting of the lead-liquid argon electromagnetic part and the iron-scintillator hadronic part. The results have been obtained on the basis of the 1996 combined test beam data which have been taken on the H8 beam of the CERN SPS, with the pion beams of 10, 20, 40, 50, 80, 100, 150 and 300 GeV/c. The degree of description of generally accepted Bock parameterization of the longitudinal shower development has been investigated. It is shown that this parameterization does not give satisfactory description for this combined calorimeter. Some modification of this parameterization, in which the e/h ratios of the compartments of the combined calorimeter are used, is suggested and compared with the experimental data. The agreement between such parameterization and the experimental data is demonstrated.
The extension of the longitudinal hadronic shower profile parameterization which takes into account non-compensations of calorimeters and the algorithm of the longitudinal hadronic shower profile curve making for a combined calorimeter are suggested. The proposed algorithms can be used for data analysis from modern combined calorimeters like in the ATLAS detector at the LHC.
Hadrons have finite interaction size with dense material, a basic feature common to known forms of hadronic calorimeters (HCAL). We argue that substructure variables cannot use HCAL information to access the microscopic nature of jets much narrower than the hadronic shower size, which we call superboosted massive jets. It implies that roughly 15% of their transverse energy profile remains inaccessible due to the presence of long-lived neutral hadrons. This part of the jet substructure is also subject to order-one fluctuations. We demonstrate that the effects of the fluctuations are not reduced when a global correction to jet variables is applied. The above leads to fundamental limitations in the ability to extract intrinsic information from jets in the superboosted regime. The neutral fraction of a jet is correlated with its flavor. This leads to an interesting and possibly useful difference between superboosted W/Z/h/t jets and their corresponding backgrounds. The QCD jets that form the background to the signal superboosted jets might also be qualitatively different in their substructure as their mass might lie at or below the Sudakov mass peak. Finally, we introduce a set of zero-cone longitudinal jet substructure variables and show that while they carry information that might be useful in certain situations, they are not in general sensitive to the jet substructure.
We present a study of showers initiated by electrons, pions, kaons, and protons with momenta from 15 GeV to 150 GeV in the highly granular CALICE scintillator-tungsten analogue hadronic calorimeter. The data were recorded at the CERN Super Proton Synchrotron in 2011. The analysis includes measurements of the calorimeter response to each particle type as well as measurements of the energy resolution and studies of the longitudinal and radial shower development for selected particles. The results are compared to Geant4 simulations (version 9.6.p02). In the study of the energy resolution we include previously published data with beam momenta from 1 GeV to 10 GeV recorded at the CERN Proton Synchrotron in 2010.
This paper presents results obtained with the combined CALICE Scintillator Electromagnetic Calorimeter, Analogue Hadronic Calorimeter and Tail Catcher & Muon Tracker, three high granularity scintillator-SiPM calorimeter prototypes. The response of the system to pions with momenta between 4 GeV/c and 32 GeV/c is analysed, including the energy response, resolution, and longitudinal shower profiles. The results of a software compensation technique based on weighting according to hit energy are compared to those of a standard linear energy reconstruction. The results are compared to predictions of the GEANT4 physics lists QGSP_BERT_HP and FTFP_BERT_HP.
The method of extraction of the $e/h$ ratio, the degree of non-compensation, of the electromagnetic compartment of the combined calorimeter is suggested. The $e/h$ ratio of $1.74pm0.04$ has been determined on the basis of the 1996 combined calorimeter test beam data. This value agrees with the prediction that $e/h > 1.7$ for this electromagnetic calorimeter.