# Timing calibration

## Run-2

During the physics data taking, the reconstructed time in Tile Calorimeter channels is monitored with jet collision data as sudden changes in the time settings (so-called timing jumps) might occur. During the run 325790 (pp data at √s=13 TeV, 2017), a timing jump of about 15 ns occurred for channels 30-35 of the EBC09 module, as demonstrated in the top plot (ES1 stream). These results are available during the calibration loop and allow for time constants correction before the data are processed for the physics analyses. The reconstructed time in physics events after the bulk physics data processing is shown in the bottom plot (BLK stream). White colour on the plots corresponds to uninstrumented/masked channels.

Contact: tomas.davidek@cern.ch, michaela.mlynarikova@cern.ch
Reference: ATLAS-COM-TILECAL-2020-028
Date: July 2020

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The mean cell time (left) and time resolution (right) in jet events (pp data at √s=13 TeV, 2017) as a function of the cell energy as determined in run 339500. All Tile Calorimeter cells belonging to reconstructed jets with pT > 20 GeV are considered, after applying the usual event and jet cleaning procedures. The mean cell time slowly decreases with deposited energy due to neutrons/slow hadronic component of the hadronic showers. The region close to 22 GeV corresponds to the high-/low-gain transition. Each symbol shows results for the given partition.

Contact: tomas.davidek@cern.ch, michaela.mlynarikova@cern.ch
Reference: ATLAS-COM-TILECAL-2020-028
Date: July 2020

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The mean cell time in jet events (pp data at √s=13 TeV, 2017) as a function of the cell energy as determined in high-statistics runs of individual years. In particular, we used all runs of the period 2015.J and 2016.L to determine the mean cell time in 2015 and 2016, respectively. Individual runs 339500 and 363710 were used to determine the mean cell time in 2017 and 2018, respectively. All Tile Calorimeter cells belonging to reconstructed jets with pT > 20 GeV are considered, after applying the usual event and jet cleaning procedures. The mean cell time slowly decreases with deposited energy due to neutrons/slow hadronic component of the hadronic showers. The region close to 22 GeV corresponds to the high-/low-gain transition. Results from all partitions are combined.

Contact: tomas.davidek@cern.ch, michaela.mlynarikova@cern.ch
Reference: ATLAS-COM-TILECAL-2020-028
Date: July 2020

eps

The cell time resolution in jet events (pp data at √s=13 TeV) as a function of the cell energy obtained in the run 339500 for 2017 (top) and run 363710 for 2018 (bottom). All Tile Calorimeter cells belonging to reconstructed jets with pT > 20 GeV are considered, after applying the usual event and jet cleaning procedures. The closed circles correspond to Gaussian σ the open squares indicate the RMS of the underlying time distributions. Results from all partitions are combined. The resolution is fitted with the displayed formula for high- and low-gain separately, as indicated with red and blue curves, respectively.

Contact: tomas.davidek@cern.ch, michaela.mlynarikova@cern.ch
Reference: ATLAS-COM-TILECAL-2020-028
Date: July 2020

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Fits of the cell time resolution in jet events (pp data at √s=13 TeV) as a function of the cell energy are shown for each year. The resolution is fitted with the formula separately for the high- and low-gain. In the high-gain, the differences among the years arise from different pile-up conditions. The improved low-gain calibration procedure was implemented in 2016 and it brings better time resolution even with higher pile-up. The bottom panel shows the fitted time resolution relative to that obtained in 2015 data.

Contact: tomas.davidek@cern.ch, michaela.mlynarikova@cern.ch
Reference: ATLAS-COM-TILECAL-2020-028
Date: July 2020

eps
Mean cell time in jet events (pp data at √s = 13 TeV, 25 ns bunch spacing, 2015) as a function of the energy deposited in cells. All Tile Calorimeter cells belonging to reconstructed jets with pT>20 GeV are considered, after the usual event and jet cleaning procedures are applied. The mean cell time slowly decreases with deposited energy due to neutrons/slow hadronic component of the hadronic showers.
Each colour corresponds to different run, the run-to-run differences up to ~0.5 ns are evident (left panel). These differences come from beam phases and they are also observed in other ATLAS subdetectors, in very good mutual correlation. The differences can be largely removed by adjusting the global time offset for each run in one specific bin E~21 GeV (all mean times are set equal in this bin), as shown in the right panel.

Contact: Tomas Davidek tomas.davidek@cernSPAMNOT.ch
Reference: ATLAS-COM-TILECAL-2016-008
Date: 3 May 2016

eps version of the figure
The cell time resolution in jet events (pp data at √s=13 TeV, 25 ns bunch spacing, 2015) as a function of the energy deposited in Long Barrel cells of the Tile Calorimeter, after accounting for run-to-run differences. All cells belonging to reconstructed jets with pT>20 GeV are considered, after the usual event and jet cleaning procedures are applied.
The closed circles correspond to Gaussian σ, the open squares indicate the RMS of the underlying time distributions. The resolution in Long Barrel is slightly better than in Extended Barrel cells (even if E-cells are excluded), due to physically smaller cells in Long Barrel compared to Extended Barrel.

Contact: Tomas Davidek tomas.davidek@cernSPAMNOT.ch
Reference: ATLAS-COM-TILECAL-2016-008
Date: 3 May 2016

eps version of the figure
The cell time resolution in jet events (pp data at √s=13 TeV, 50 ns bunch spacing, 2015) as a function of the energy deposited in Long Barrel cells of the Tile Calorimeter, after accounting for run-to-run differences. All cells belonging to reconstructed jets with pT>20 GeV are considered, after the usual event and jet cleaning procedures are applied.
The closed circles correspond to Gaussian σ, the open squares indicate the RMS of the underlying time distributions. The Gaussian widths are basically the same as with 25 ns data, while the RMS is better with 50 ns data due to lower contribution from the out-ouf-time pile-up.

Contact: Tomas Davidek tomas.davidek@cernSPAMNOT.ch
Reference: ATLAS-COM-TILECAL-2016-008
Date: 3 May 2016

eps version of the figure
The reconstructed time in Tile Calorimeter channels is monitored during the physics runs with jet collision data (top) as well as with the laser calibration system (bottom). The sudden shifts (so-called timing jumps) are simultaneously detected by both monitoring systems, the plots show an example of a timing shift by ~10 ns in a group of six channels of the LBC42 module. These results are available during the so-called calibration loop and allow for time constants correction before the data are processed for the physics analyses.

Contact: Tomas Davidek tomas.davidek@cernSPAMNOT.ch
Reference: ATLAS-COM-TILECAL-2016-008
Date: 3 May 2016

eps version of the figure

eps version of the figure

## Run-1

The reconstructed time in all Tile calorimeter channels is monitored in physics runs with laser calibration events shot during empty bunch crossings. In Run-1, TileCal suffered from frequent sudden changes in time settings (typically in a group of six channels), mostly associated with the module configuration after power restart due to LVPS trips. As the time changes are also seen in laser events (left plot), they were used for correcting the physics reconstructed time during the calibration loop, still before physics data are processed. The reconstructed time in physics events after the bulk physics data processing is shown in the right plot.

Contact: Tomas Davidek tomas.davidek@cernSPAMNOT.ch
Reference: ATLAS-COM-TILECAL-2015-015
Date: 9 Mar 2015

In Run-1, TileCal suffered from frequent sudden changes in time settings (typically in a group of six channels), mostly associated with the module configuration after power restart due to LVPS trips. The changes were monitored and corrected using the laser events shot in the empty bunch crossings. The plot demonstrates the impact of these corrections in physics data of period 2012.G. Displayed is the reconstructed time in Tile calorimeter channels (E_{channel} > 4 GeV) belonging to cells that are part of reconstructed AntiKtTopo jets (R=0.4). The timing corrections significantly reduce tails in the physics data reconstructed time, the corresponding RMS improves from 0.90 ns to 0.82 ns.

Contact: Tomas Davidek tomas.davidek@cernSPAMNOT.ch
Reference: ATLAS-COM-TILECAL-2015-015
Date: 9 Mar 2015

The Tilecal cell time distribution (Ecell > 20 GeV) observed with 2010 collision data (October 2010 high-statistics runs, representing ~15 pb-1).

In every event, only cells belonging topoclusters of the reconstructed jets with pT>20 GeV are selected. Jets are required to have at least one reconstructed track and point to the primary vertex. Background is removed using the standard jet cleaning requirements except the jet time, which is calculated only from non-TileCal cells. Gaussian fit to the distribution results in mean/sigma compatible with Mean/RMS indicated in the plot. Excluded from the analysis are cells with unstable/incorrect timing (1% of cells) as well as scintillator cells.
Contact: Tomas Davidek Tomas.Davidek@cernNOSPAMPLEASE.ch
Reference: ATLAS-PLOT-TILECAL-2011-001
Date: 24 Mar 2011

eps version of the figure
Mean cell reconstructed time as a function of cell energy in the 2011 collision data at $\sqrt{s}=7$ TeV and 50 ns bunch spacing. Left plot is obtained with isolated muons, right plot with jets (pT>20 GeV). The mean muon time response is very close to zero and essentially independent of the energy deposited for muons as expected. The mean time for jets decreases with energy deposited in the cell, probably due to neutron/slow hadronic component of the hadronic showers.

Contact: Tomas Davidek tomas.davidek@cernNOSPAMPLEASE.ch and Javier Montejo jmontejo@ifaeNOSPAMPLEASE.es
Reference: ATLAS-PLOT-TILECAL-2011-012
Date: 18 Oct 2011

eps version of the figure
Cell time resolution as a function of cell energy in the 2011 collision data at $\sqrt{s}=7$ TeV and 50 ns bunch spacing. The time of the cell has been corrected for its mean time. The resolution was parametrized with the function % $\sigma=\sqrt{{p_0}^2+\left(\frac{p_1}{\sqrt{E}}\right)^2+\left(\frac{p_2}{E}\right)^2}$ %, describing well the data. Muons deposit only a small fraction of their energy, so only high-gain region is explored, which reaches up to 20 GeV. The time resolution is 0.5-0.6ns for E~20 GeV and 1.3-1.15 ns at ~2 GeV for jets and muons respectively.

Contact: Tomas Davidek tomas.davidek@cernNOSPAMPLEASE.ch and Javier Montejo jmontejo@ifaeNOSPAMPLEASE.es
Reference: ATLAS-PLOT-TILECAL-2011-012
Date: 18 Oct 2011

eps version of the figure
Time distribution of the TileCal cells. Cells were selected with an energy cut of 300 MeV and difference between the energies of the two readout channels of the cell < 0.2 Ecell.
Contact:
Reference:
Date:

eps version of the figure

-- PawelKlimek - 2016-08-23

Responsible: PawelKlimek
Subject: public

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Topic revision: r5 - 2020-07-15 - MichaelaMlynarikova

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