The TileCal Energy Reconstruction for LHC Run2 and Future Perspectives

The TileCal is the main hadronic calorimeter of ATLAS and it covers the central part of the detector ($|\eta|$ < 1.6). The energy deposited by the particles in TileCal is read out by approximately 10,000 channels. The signal provided by the readout electronics for each channel is digitized at 40 MHz and its amplitude is estimated by an optimal filtering algorithm. The increase of LHC luminosity leads to signal pile-up that deforms the signal of interest and compromises the amplitude estimation performance. This work presents the proposed algorithm for energy estimation during LHC Run 2. The method is based on the same approach used during LHC Run 1, namely the Optimal Filter. The only difference is that the signal baseline (pedestal) will be subtracted from the received digitized samples, while in Run 1 this quantity was estimated on an event-by-event basis. The pedestal value is estimated through special calibration runs and it is stored in a data base for online and offline usage. Additionally, the background covariance matrix will also be used for the computation of the Optimal Filter weights for high occupancy channels. The use of such information reduces the bias and uncertainties introduced by signal pile-up. The performance of the Optimal Filter version used in Run 1 and Run 2 is compared using Monte Carlo data. The efficiency achieved by the methods is shown in terms of error estimation, when different conditions of luminosity and occupancy are considered. Concerning future work, a new method based on linear signal deconvolution has been recently proposed and it is under validation. It could be used for Run 2 offline energy reconstruction and future upgrades.Comment: 5 pages, 7 figures, LISHEP 2015, 2-9 August 2015, Manau

Calibration Systems of the ATLAS Tile Calorimeter

TileCal is the hadronic calorimeter covering the most central region of the ATLAS experiment at the LHC. This sampling calorimeter uses iron plates as absorber and plastic scintillating tiles as the active material. A multi-faceted calibration system allows to monitor and equalize the calorimeter response at each stage of the signal production, from scintillation light to digitization. This calibration system is based on signal generation from different sources: a Cs radioactive source, laser light, charge injection and minimum bias events produced in proton-proton collisions. A brief description of the different TileCal calibration systems is given and the latest results on their performance in terms of calibration factors, linearity and stability are presented.Comment: 4 pages, 2 figures. For the 32nd Symposium on Physics in Collision, Strbske Pleso 12th - 15th September 201

ATLAS Tile Calorimeter Readout Electronics Upgrade Program for the High Luminosity LHC

The Tile Calorimeter (TileCal) is the hadronic calorimeter covering the most central region of the ATLAS experiment at LHC. The TileCal readout consists of about 10000 channels. The ATLAS upgrade program is divided in three phases: The Phase~0 occurs during 2013-2014, Phase~1 during 2018-1019 and finally Phase~2, which is foreseen for 2022-2023, whereafter the peak luminosity will reach 5-7 x 10$^{34}$ cm$^2$s$^{-1}$ (HL-LHC). The main TileCal upgrade is focused on the Phase~2 period. The upgrade aims at replacing the majority of the on- and off-detector electronics so that all calorimeter signals are directly digitized and sent to the off-detector electronics in the counting room. All new electronics must be able to cope with the increased radiation levels. An ambitious upgrade development program is pursued to study different electronics options. Three options are presently being investigated for the front-end electronic upgrade. The first option is an improved version of the present system built using commercial components, the second alternative is based on the development of a dedicated ASIC (Application Specific Integrated Circuit) and the third is the development of a new version of the QIE (Charge Integrator and Encoder) based on the one developed for Fermilab. All three options will use the same readout and control system using high speed (up to 40 Gb/s) links for communication and clock synchronization. For the off-detector electronics a new back-end architecture is being developed. A demonstrator prototype read-out for a slice of the calorimeter with most of the new electronics, but still compatible with the present system, is planned to be inserted in ATLAS already in mid 2014 (at the end of the Phase~0 upgrade).Comment: 6 pages, 6 figures, LISHEP 201

A mobile data acquisition system

A mobile data aquisition (MobiDAQ) was developed for the ATLAS central hadronic calorimeter (TileCal). MobiDAQ has been designed in order to test the functionalities of the TileCal front-end electronics and to acquire calibration data before the final back-end electronics were built and tested. MobiDAQ was also used to record the first cosmic ray events acquired by an ATLAS subdetector in the underground experimental area

Tile Calorimeter Upgrade Program for the Luminosity Increasing at the LHC

The Tile Calorimeter (TileCal) is the central hadronic calorimeter of the ATLAS experiment at the Large Hadron Collider (LHC). The LHC is scheduled to undergo a major upgrade, in 2022, for the High Luminosity LHC (HL-LHC). The ATLAS upgrade program for high luminosity is split into three phases: Phase-0 occurred during $2013-2014$ and prepared the LHC for Run 2; Phase-I, foreseen for 2019, will prepare the LHC for Run 3, whereafter the peak luminosity reaches $2-3 \times 10^{34}$ cm$^{2}s^{-1}$; finally, Phase-II, which is foreseen for 2024, will prepare the collider for the HL-LHC operation ($5-7 \times 10^{34}$ cm$^{2}s^{-1}$). The TileCal main activities for Phase-0 were the installation of the new low voltage power supplies and the activation of the TileCal third layer signal for assisting the muon trigger at $1.0<|\eta|<1.3$ (TileMuon Project). In Phase-II, a major upgrade in the TileCal readout electronics is planned. Except for the photomultipliers tubes (PMTs), most of the on- and off-detector electronics will be replaced, with the aim of digitizing all PMT pulses at the front-end level. This work describes the TileCal upgrade activities, focusing on the TileMuon Project and the new on-detector electronics.Comment: arXiv admin note: substantial text overlap with arXiv:1305.085

Optics robustness of the ATLAS Tile Calorimeter

TileCal, the central hadronic calorimeter of the ATLAS detector is composed of plastic scintillators interleaved by steel plates, and wavelength shifting optical fibres. The optical properties of these components are known to suffer from natural ageing and degrade due to exposure to radiation. The calorimeter was designed for 10 years of LHC operating at the design luminosity of $10^{34}$cm$^{-2}$s$^{-1}$. Irradiation tests of scintillators and fibres have shown that their light yield decrease by about 10% for the maximum dose expected after 10 years of LHC operation. The robustness of the TileCal optics components is evaluated using the calibration systems of the calorimeter: Cs-137 gamma source, laser light, and integrated photomultiplier signals of particles from proton-proton collisions. It is observed that the loss of light yield increases with exposure to radiation as expected. The decrease in the light yield during the years 2015-2017 corresponding to the LHC Run 2 will be reported. The current LHC operation plan foresees a second high luminosity LHC (HL-LHC) phase extending the experiment lifetime for 10 years more. The results obtained in Run 2 indicate that following the light yield response of TileCal is an essential step for predicting the calorimeter performance in future runs. Preliminary studies attempt to extrapolate these measurements to the HL-LHC running conditions.Comment: 8 pages, 9 figures, proceedings of CALOR 2018, Eugene, OR, USA, May 201

The ATLAS Tile Calorimeter Test Beam Monitoring Program

During 2003 test beam session for ATLAS Tile Calorimeter a monitoring program has been developed to ease the setup of correct running condition and the assessment of data quality. The program has been built using the Online Software services provided by the ATLAS Online Software group. The first part of this note contains a brief overview of these services followed by the full description of Tile Calorimeter monitoring program architecture and features. Performances and future upgrades are discussed in the final part of this note.Comment: 11 pages, 8 figures, ATLAS TILECAL Not

Non-compensation of an Electromagnetic Compartment of a Combined Calorimeter

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 $1.74\pm0.04$ 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.Comment: LATEX, 17 pages, 7 figure

On the e/h Ratio of the Electromagnetic Calorimeter

The method of extraction of the e/h ratio for an electromagnetic compartment of a combined calorimeter is suggested and the non-compensation was determined. The results agree with the Monte Carlo prediction and results of the weighting method for electromagnetic compartment of combined calorimeter. The new easy method of a hadronic energy reconstruction for a combined calorimeter is also suggested. The proposed methods can be used for a combined calorimeter, which is being designed to perform energy measurement in a next-generation high energy collider experiment like ATLAS at LHC.Comment: Latex, 9 pages, 1 figur