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LHCb Data Quality


This page summarises the activities of the LHCb data quality group (DQG). It is coordinated by MarcoAdinolfi

The group is in charge of ensuring the best quality of the LHCb data for physics. Its starting point is the data flowing out of the detector, assuming that the LHCb shift crew and the subdetectors are monitoring the data in real time and that problems affecting data taking are fixed as quickly as possible. The DQ team then covers data quality during the data processing phase up to DST production.

Mailing list

A mailing list has been set up: lhcb-data-quality@cern.ch.Subdetector specific mailing lists are also available (only some of which are used so far).

Data Quality Infrastructure


See DQProcedures page.


See DQShifts page.


Below are listed the various issues that need to be sorted out for data taking. Some features listed here are crucial as soon as we have data, some don't need to be fully operational before 2009. In any case we'll use 2008 as a learning phase and will revise all procedures for 2009.

Problems database External link mark
The problems database External link mark stores and follows up all DQ related problems.
Monitoring farm (MF)
The various taks run in the MF are used by shifters to look after data taking. The histograms are also inputs to DQ.
Online Reconstruction Farm
Most of the DQ after data taking will be based on Brunel histograms. This will run as a task in the monitoring farm, and offline. All histograms from offline processing will be collected and analysed.
Calibration jobs
In case of a problem which can be solved in software, calibration jobs will be submitted and then test jobs to check that the problems was actually solved.
  • A proposal is described here External link mark
Bookkeeping External link mark
The bookkeeping database will contain a data quality flag. Each file will be flagged as OK, Bad, Maybe, Unchecked. The single flag implies there's a single decision made for every file (practically, for every run). The subdetector and working group experts will have to meet regularly (initially daily on week days) and decide for each run. An expert will the flag the runs in the bookkeeping, which will trigger the reconstruction. Ideally there should be a very limited number of people allow to do this. Typically the DQ responsible and a deputy.
DQ will vary with time. The result of a query on OK files might not be reproducible at a later date. We will have to "lock" some samples as the ones to be used for conferences. This would be done by running a query at a given moment in time and storing the result. The bookkeeping database would not have to know about this. If something needs to be changed later, one would have to reproduce this data list and advertise it.
  • [3/3/09]: The bookkeeping flag is released. See here External link mark for instructions.
Data Quality Monitor
The web-based Data Quality Monitor twiki page.
Data Quality e-log External link mark
As for any shifts there is an e-log set up.
AFS space
There is a scratch space at /afs/cern.ch/lhcb/group/dataquality/, with write permission to everyone in the group z5:dataquality. To become a member contact PK or Joel.

Subsystem Contact Persons

The monitoring and calibration of each subcomponent is a responsibility of the relevant projects and described on the web pages linked below.

Marco Gersabeck, Eduardo Rodrigues, David Hutchcroft, Kurt Rinnert. Mailing list: lhcb-velo-dataquality@cern.ch.

Silicon Trackers
Helge Voss. Mailing list: lhcb-st-dataquality@cern.ch.

Outer Tracker
Francesco Dettori. Mailing list: lhcb-ot-dataquality@cern.ch.

Please first contact the RICH DQ shifter via lhcb-rich-dataquality@cern.ch - Backups are Chris Jones, Antonis Papanestis.

Marie-Noëlle Minard, Olivier Deschamps. Mailing list: lhcb-calo-dataquality@cern.ch.

Muon Detector
Giacomo Graziani, Gaia Lanfranchi (PID). Mailing list: lhcb-muon-dataquality@cern.ch.

L0 Trigger
Julien Cogan, Renaud Le Gac. Mailing list: lhcb-l0-dataquality@cern.ch.

Tomasz Skwarnicki, Miriam Gandelman. Mailing list: lhcb-hlt-dataquality@cern.ch.

Johan Blouw, Stephanie Hansmann-Menzemer. Mailing list: lhcb-reconstruction@cern.ch.

Magnetic Field
Manuel Schiller.

Global PID
Chris Jones.

Jaap Panman.

Notes and presentations

Victor Egorychev and Dmitry Golubkov:Calorimeter PID Quality Monitoring Algorithm Implementation in Calo/CaloMoniDst v3r6 (REC v7r0) LHCb-INT-2009-022 External link mark

More Links

-- PatrickKoppenburg - 02 May 2008 - 28 May 2008 - 19 Jun 2008 - 30 Jun 2008 - 22 Aug 2008
Topic revision: r76 - 2015-10-26 - MarcoAdinolfi

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