ATLAS Detector Performance in 2012 : Calorimeters

Nikolina Ilic and Ki Lie, for the ATLAS Collaboration

12Detector Status in 2012-2013 Data Stability of the Calibration Systems

Tile operated with good data quality efficiency of 99.6% in 2012 data taking.

At the end of 2013 run, 2.9% of the cells were flagged as bad in Tile. The improvement of detector stability with respect to 2011 data-taking was largely attributed to the installation of the new LVPS in 45 of the 256 phi-wedges during the end of 2011 maintenance.

The observed drifts in Cesium decay is attributed mostly to a variation of the photomultiplier response and not to the scintillator degradation from irradiation, except for the gap & crack cells.

Down-drift is observed when beam is on, up-drift when beam is off and during heavy ion run.

Cells re-calibration is done periodically to keep electromagnetic scale to a level of <1% precision.

Install new LVPSDrawer consolidation (connectors, flex

foils,...)Standard maintenance (repair a few %

of channels)Install 16 missing crack scintillators

(after disconnecting MBTS)Consolidate cesium calibration (new

hydraulic system)Install new laser calibration systemImprove DAQ, DCS, monitoring, DQ,

calibration, & software toolsInstall first demonstrator in spring 2014,

full replacement of electronics planned ~ 2022.

The response of TileCal cells is monitored periodically with a 137-Cesium radioactive source and a Laser calibration systems that monitors respectively the scintillator and photomultiplier chain.

The similar response behavior in both systems indicates that the scintillators irradiation was negligible in 2012.

Keep LAr in operation with the high voltage off and do regular calibrations with high voltage at 50V to check for shorts

Extract, repair and re‐install 10‐20 front end boards

Improve calibration speed Update software for online, HV, DCS Study LAr performance in 4 sample

mode Installation of demonstrator

for the Phase-I upgrade of the L1 calo trigger for higher granularity readout in LAr

On the front end crates, install 46 new low voltage power supplies (12 already installed)

LAr is ready for 100KHz as shown by September 2012 tests. LAr ran in 4 sample mode with 0% busy

Data Quality and Physics 2013-2014 Shutdown Plans

Tile Calorimeter Operations, Performance and Plans

Only 0.06% unusable channels (42 dead/disconnected channels: 23 channels with dead electronics readout, 55 high noise)

Factor of 3 reduction in high voltage trips from 2011

New HV modules (with independent HV generators) installed in inner radius of electromagnetic endcaps

High voltage modules with improved current reading installed in forward calorimeters for luminosity monitoring

Cooling leak in part of endcap C front-end cooling developed during November 2012: 4 front end boards were turned off, affecting 4.5% of the hadronic endcap C channels and 1.2% of the electromagnetic endcap C channels, fixed end of November

Front end board timing is stable

Online software and monitoring is very stable

Improvements were made in trigger monitoring

Overall Status and Performance

0.46% Loss from HV trips (data is recoverable when HV is ramping, but data during trip is lost)

Time evolution of data rejection due to high voltage trips is shown below

Proportion of channels above 3σ

(electronic noise) improves after vetos

LAr has demonstrated good energy response stability with increasing pileup in the 2012 data as show below

0.3% Loss from noise bursts (flagged at the trigger level)

Example of typical noise burst in electromagnetic endcap shown below

LAr operated with good data quality efficiency of 99.1% in 2012 data taking

Liquid Argon Calorimeter Operations, Performance and Plans

2012 ATLAS DQ Efficiency

Calorimeters

LAr Tile

99.1 99.6

ATLAS operated with an excellent efficiency during 2012 data taking period, recording an integrated luminosity of 21.6 fb-1 at √s = 8 TeV. The Liquid Argon and Tile Calorimeter contributed to this effort by operating with a good data quality efficiency of 99.1% and 99.6% respectively, as shown by the table on the left. This poster presents the overall status, operations, performance and shutdown plans for the calorimeters.

Performance of New Low Voltage Power Supplies (LVPS)

During the winter 2011-2012 maintenance, 40 new LVPS were installed in the detector. These LVPS were mostly in the long barrels where most of the LVPS trips occur.

Only one of the 40 new LVPS tripped in 2012.

2013-2014 Shutdown Plans

The new production also benefits from a lower electronic noise. The average cell noise is decreased by 13% and the noise distribution is more Gaussian.

Full production of the new LVPS will be installed during 2013-2014 long shutdown (LS1).