AliRoot Core  c8915ff (c8915ff)
MUON Calibration

The Offline Condition DataBase is described extensively on ALICE Offline pages.

Here you'll find mainly information relevant to the MUON objects in the OCDB, and to the AliMUONCDB class (formerly MUONCDB.C macro), which defines a set of functions to read/write MUON information to this CDB. Those functions are not meant to be used as black boxes.

Please have a closer look before using (especially the ones writing to the CDB...)

# MUON objects in OCDB

 OCDB path Subsystem Run Type FileID DAQsource Update frequency Appox. Size MUON/Calib/RecoParam both N/A N/A N/A Few per year ? 5 KB MUON/Calib/MappingData both N/A N/A N/A Once for all once debugged 1 MB MUON/Calib/MappingRunData both N/A N/A N/A Between zero and few per year 100 KB MUON/Calib/HV MCH PHYSICS N/A N/A Once per physics run Depends on the number of trips, 10-20 KB normally MUON/Calib/LV MCH PHYSICS N/A N/A Once per physics run Depends on the number of LV trips, XX-YY KB normally MUON/Calib/Neighbours MCH N/A N/A N/A As MappingData 10 MB MUON/Calib/OccupancyMap MCH PHYSICS OCCUPANCY MON Once per physics run Depends on the number of bad manus, normally 100-200 KB MUON/Calib/OccupancyMap MCH PHYSICS OCCUPANCY MON Once per physics run Depends on the number of run duration and the time resolution used MUON/Calib/Pedestals MCH PEDESTAL PEDESTALS LDC Once per pedestal run 7 MB MUON/Calib/RejectList MCH N/A N/A N/A Few per year Depends on the number of bad elements MUON/Calib/GlobalTriggerCrateConfig MTR ? ? ? ? ? MUON/Calib/LocalTriggerBoardMasks MTR ? ? ? ? ? MUON/Calib/RegionalTriggerConfig MTR ? ? ? ? ? MUON/Calib/TriggerDCS MTR ? ? ? ? ? MUON/Calib/TriggerEfficiency MTR ? ? ? ? ? MUON/Calib/TriggerLut MTR ? ? ? ? ?

In addition, the following ones were used in the past, but have been discontinued (but are still present in the OCDB, as object removal is not allowed).

# Calibration data object classes

We've designed generic data containers to store calibration information, tailored to the way we usually access MUON tracker data, that is, indexed by the pair (detElemId,manuId). This container is called AliMUONVStore. You can attach a TObject to every and each pair (detElemId,manuId).

For the moment, that TObject is generally of AliMUONVCalibParam type, which handles a given number of channels (64 typically) as a group. There's also 1D versions of AliMUONVStore for data types which only requires indexing by 1 value (like trigger masks for instance).

As the class names suggest (V...), those classes are only interfaces. Concrete ones are AliMUON2DMap (used instead of a vector as detElemId are not contiguous), AliMUON1DArray (for things where indices are contiguous) and AliMUON1DMap, and CalibParamNI (VCalibParam storing n integer per channel), CalibParamNF (VCalibParam storing n floats per channel), and CalibParamND (VCalibParam storing n doubles per channel).

One exception are the HV and LV values from DCS, which are stored "as they come" from the shuttle-dcs interface, as a TMap, where the key is the aliasname (TString), and the value a TObjArray of AliDCSValue.

# CDB location

One very important notion is that of the DefaultStorage (which you might set with AliCDBManager::Instance()->SetDefaultStorage(path)), which tells the CDB library where the CDB is sitting (either locally on disk, or on the grid).

For local tests, path will be most likely =  "local://$ALICE_ROOT/OCDB" (i.e. there is, in svn a slim version of the calibration objects needed for running the MUON code), or  "local://$ALICE_ROOT/OCDB/SHUTTLE/TestShuttle/TestCDB  for Shuttle testing.

When using alien, the path definition can be eg.  "alien://folder=/alice/data/2009/OCDB" .

# Writing to CDB

AliMUONCDB class is used to populate the CDB with fake calibration objects for testing purposes. Real calibration data will normally be handled by the Shuttle (see READMEshuttle).