N1D2  High Energy and Nuclear Physics Instrumentation: Calorimeters

Monday, Nov. 2  16:30-18:10  San Diego

Session Chair:  Imad laktineh, IPNL-UCBL-IN2P3, France; Ren-Yuan Zhu, California Institute of Technology, United States

Show/Hide All Abstracts

(16:30) N1D2-1, Performance of the ATLAS Tile laser_II Calibration System

F. Scuri

Sezione di Pisa, INFN, Pisa, Italy

On behalf of the ATLAS Tile Calorimeter Group
The Atlas Tilecal hadronic calorimeter is equipped with a 3-level calibration system; it is used to monitor and to calibrate the response of the active devices (plastic scintillation tiles) in the projective towers of the detector, the response of the PMTs receiving the light from clusters of tiles (cells), and the response of the Front End and digitization electronics of the individual readout channels. The global detector calibration is performed by measuring the individual cell response to a reference excitation produced by calibrated Cesium sources which float inside the detector through a suitable pipe network. Calibrations of the PMTs and of the readout chain are performed between two subsequent Cesium scans; laser pulses are distributed to each individual PMT cathode (approximatively 10,000 channels) by a suitable optical distribution line having a power laser (several ?J per pulse) as a source. The linearity of the readout electronics response is controlled with fast calibrations using a Charge Injection System (CIS) . During the Long Shutdown I (LSI) of the operations of the LHC accelerator, the Tilecal laser calibration system has been almost completely re-designed, tested, and installed for the LHC Run II operations with the aim of achieving an accuracy on the global calibration constants at the sub-percent level; this is required to keep the uncertainty from the global calibration below the irreducible systematics in determining the detector performances in terms of Jet Energy Resolution and Jet Energy Scale. Details are given here on the new optical line up-stream the unchanged distribution from the control room to the PMTs and on the multi-monitor system of the optical line stability. A summary of the performances of new laser system during the commission period between installation and first collisions and after resuming stable LHC conditions will be presented for the operation stability and on the accuracy in extracting the laser calibration constants.

(16:50) N1D2-2, Testing Hadronic Interaction Models Using a Highly Granular Silicon-Tungsten Calorimeter

N. van der Kolk

Max-Planck-Institute for Physics, Munich, Germany

On behalf of the CALICE collaboration
The CALICE collaboration has published a detailed study of hadronic interactions using data recorded with the highly granular CALICE silicon-tungsten electromagnetic calorimeter (Si-W ECAL). Approximately 350,000 selected p- events at energies between 2 and 10 GeV have been studied. The predictions of several physics models available within the Geant4 simulation tool kit are compared to this data. A reasonable overall description of the data is observed; the Monte Carlo predictions are within 20 % of the data, and for many observables much closer. The largest quantitative discrepancies are found in the longitudinal and transverse distributions of reconstructed energy. Based on the good control of the data set and general observables, the next step is to achieve a deeper understanding of hadronic interactions by studying the interaction zone and by reconstructing secondaries that emerge from the hadronic interaction in the Si-W ECAL.

(17:30) N1D2-4, High-Energy Electron Test Results of a Calorimeter Prototype Based on CeF3 for HL-LHC Applications

F. Micheli1, L. Bianchini1, G. Dissertori1, M. Donegà1, W. Lustermann1, A. Marini1, F. Nessi-Tedaldi1, F. Pandolfi1, M. Peruzzi1, M. Schönenberger1, L. Brianza2, A. Ghezzi2, P. Govoni2, A. Martelli2, T. Tabarelli de Fatis2, F. Cavallari3, I. Dafinei3, M. Diemoz3, P. Meridiani3, R. Paramatti3, C. Rovelli3, D. Del Re4, G. D'Imperio4, S. Gelli4, C. Jorda Lope4, G. Organtini4, L. Pernié4, S. Rahatlou4, F. Santanastasio4, L. Soffi4, P. Traczyk4, N. Pastrone5, V. Candelise6, G. Della Ricca6

1Institute for Particle Physics, ETH, Zurich, Switzerland
2INFN - Sezione di Milano-Bicocca, Milano, Italy
3INFN - Sezione di Roma, Roma, Italy
4Dipartimento di Fisica, Sapienza, Università di Roma e INFN-Sezione di Roma, Roma, Italy
5INFN - Sezione di Torino, Torino, Italy
6Università degli studi di trieste e INFN, Trieste, Italy
The High-Luminosity phase of the Large Hadron Collider at CERN (HL-LHC) poses stringent requirements on calorimeter performance in terms of resolution, pileup resilience and radiation hardness. A tungsten-CeF3 sampling calorimeter is a possible option for the upgrade of current detectors. A prototype, read out with different types of wavelength-shifting fibers, has been built and exposed to high energy electrons, representative for the particle energy spectrum at HL-LHC, at the CERN SPS H4 beam line. This paper shows the performance of the prototype, mainly focussing on energy resolution and uniformity. A detailed simulation has been also developed in order to compare with data and to extrapolate to different configurations to be tested in future beam tests. Additional studies on the calorimeter and the R&D projects ongoing on the various components of the experimental setup will be also discussed.

(17:50) N1D2-5, Electromagnetic Calorimetry at the Highest Energy and Intensity Proton-Proton Collider : CMS ECAL Performance at LHC Run II and Prospects for High Luminosity LHC.

A. Massironi

CERN, Geneva, Switzerland

On behalf of the CMS Collaboration
The electromagnetic calorimeter (ECAL) of the Compact Muon Solenoid Experiment (CMS) started operating at the Large Hadron Collider (LHC) in Spring 2015 with proton-proton collisions at 13 TeV center-of-mass energy and at a reduced bunch spacing of 25 ns. The instantaneous luminosity during this LHC Run II is expected to exceed the levels achieved in the LHC Run I in the years 2010 to 2012 very significantly. In this talk we present new reconstruction algorithms and calibration strategies to maintain the excellent performance of the CMS ECAL under these challenging conditions. We will show first performance results from the 2015 data taking period and give an outlook on the expected Run II performance. The current Run II of LHC is expected to accumulate a few hundred inverse femtobarn of proton-proton collisions before LHC will be upgraded to provide an even higher instantaneous luminosity, referred to as HL-LHC. HL-LHC is expected to provide a few inverse attobarn of integrated luminosity. This will result in even higher rates of simultaneous proton-proton collisions, called pile-up (PU), up to and exceeding 140 PU collisions. Likewise the physics event rates will increase further which requires upgrades to the readout and trigger electronics of of the existing ECAL. We will briefly discuss the upgrade plans and present in detail the plans to suppress the effects of the pile-up under these conditions. One promising technique is based on the very good time resolution the CMS ECAL provides. We present the current status of timing performance of the CMS ECAL, plans to improve this for the future and examples how this can be used for pile-up mitigation.