atlas liquid argon calorimeter monitoring & data quality

17
ATLAS Liquid Argon Calorimeter Monitoring & Data Quality Jessica Levêque Centre de Physique des Particules de Marseille ATLAS Liquid Argon Calorimeter Group NEC, Varna, Bulgaria 7-11 th September 2009

Upload: amaya-contreras

Post on 03-Jan-2016

42 views

Category:

Documents


1 download

DESCRIPTION

ATLAS Liquid Argon Calorimeter Monitoring & Data Quality. Jessica Lev ê que Centre de Physique des Particules de Marseille ATLAS Liquid Argon Calorimeter Group NEC, Varna, Bulgaria 7-11 th September 2009. Introduction: about ATLAS data. Raw data in ATLAS: 1.6 MByte per event - PowerPoint PPT Presentation

TRANSCRIPT

Page 1: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

ATLAS Liquid Argon Calorimeter

Monitoring &

Data Quality

Jessica LevêqueCentre de Physique des Particules de Marseille

ATLAS Liquid Argon Calorimeter Group

NEC, Varna, Bulgaria7-11th September 2009

Page 2: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 2Jessica Levêque

Introduction: about ATLAS dataRaw data in ATLAS:

1.6 MByte per eventAcquisition rate: 200 Hz1 day = 2 runs = 2*10 hours of data

~23 TBytes per day

Disk Buffer at Tier 0: 610 TBytesAfter migration of data on tape: 200 Hz readout rate

Consequences: Delay between data acquisition and data reconstruction should be less than 5 days Very efficient monitoring and Data Quality feedback loops are required

Page 3: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 3Jessica Levêque

ATLAS Data Processing Model

Page 4: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 4Jessica Levêque

The Liquid Argon Calorimeters

~ 182 000 readout channels

- Sampling Calorimeter- Active Medium : LAr- Absorber: lead in EM, copper in HEC, copper & tungsten in FCAL

Page 5: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 5Jessica Levêque

LAr Calorimeter Electronic

Page 6: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 6Jessica Levêque

LAr Calorimeter MonitoringDetector Control System:

To monitor variations of liquid argon purity, temperature High voltage, cooling plant, power supplies

Data Integrity: To monitor the electronic front-end boards, and the integrity of the readout data

Signal Peak positionTo monitor the detector timing

Misbehaving channels: to spot hot channels that might affect the physics objects reconstruction.

Physics objects (electrons, photons, jets…) not a “detector task”, therefore not presented here.

Page 7: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 7Jessica Levêque

Validation of monitoring tools Extensive use of cosmics data:

Experience daily detector operations Validation of the full data chain reconstructionTest and optimization of automatic data quality and monitoring tools

In the following: a few examples of calorimeter monitoring during ATLAS cosmics runs

Page 8: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 8Jessica Levêque

Detector Control SystemDetector fully operational during last cosmic campaign

Requirement for physics: detector coverage and behavior should be stable during a run (oa a luminosity block)

Data Quality Flag assessment: warning when the detector states changes during the run.

Page 9: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 9Jessica Levêque

Online Computation MonitoringFor all cells, the energy is computed online and sent to the central acquisition system.

For high energy cells (typically above few GeV) the individual digits in ADC counts are also readout

For these energetic cells, we recompute the energy offline from the digits and compare the result with the energy computed online

The plot illustrates the perfect reliability over ~ 40 000 events. The 1 MeV tails are within the expected accuracy.

Page 10: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 10Jessica Levêque

Signal Timing MonitoringThe digits are readout for each cell above a given threshold (typically above a few GeV)

For these very energetic cells,we average the pulse shapes per detector region

This allows to compare the timing between the different LAr detector parts

This check is also very important for ATLAS, as the LAr calorimeter is the subdetector with the largest time window (32 time samples, i.e 800ns). The plot above is used to align the timing between different trigger sources.

Page 11: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 11Jessica Levêque

Noise monitoringFor each calorimeter cell, the electronic noise is measured in random triggered events, and stored in a database

The electronic noise is used as a reference to spot channels with deviant behavior during physics runs

Monitoring individual noisy cells: number of events per cell, where the cell energy is above 3 times the expected noiseMonitoring global detector noise: number of cells per event, with energy above 3 times the expected noise With perfectly gaussian noise, we expect 0.27% of events/cells passing the cut.

Page 12: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 12Jessica Levêque

Global Detector Noise example

December 2007: O(10) events out of 3 000 in non-gaussian tailsFor these events, a large number of cells are fluctuating outside 3 at the same time

Expected Value: 0.27%

Page 13: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 13Jessica Levêque

insulation

HV cable 110m long

Origin of the Global Noise

Counting Room Detector Cryostat

1-2 volts difference

between cryostat ground

and HV module ground

degrading the filter box

performances

Page 14: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 14Jessica Levêque

CAPACITOR one per cable

HV cable 110m long

Fixing the Problem

Counting Room Detector Cryostat

improve the grounding

between HV filter box and

the cryostat by adding

capacitive link.

Page 15: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 15Jessica Levêque

Global Detector Noise: current status

Page 16: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 16Jessica Levêque

Individual cell noise example

October 2008 (blue line): large tails above 0.7%. This tail is populated by channels with unstable and noisy shapers, creating large noise pulses that triggered the event data taking.

April 2009 (red line): the tails vanished after a major campaign of FEB refurbishment, replacing the faulty preamplifiers.

Cosmic data triggered by a signal in LAr calorimeter Given the very low muon rate, physics signal does not bias the expected event rate (we still expect 0.27% of cells)

Page 17: ATLAS Liquid Argon Calorimeter  Monitoring  &  Data Quality

Varna - September 2009 17Jessica Levêque

Summary & Conclusions

Conclusion: we are ready and waiting for beam !

Liquid Argon Monitoring and Data Quality developed and tested with cosmics data since 2006

Monitoring extensively used to commission the detector and provide meaningful information to others ATLAS subdetectors

Liquid Argon detector fully operational and in a very good shape (99.8% channels active and calibrated)