AliRoot Core  aab2016 (aab2016)
MUON Tracking DA

The detector algorithms are implemented for the Muon Tracking in the AliRoot framework. We currently have 4 DAs for MCH :

  • MCHPEDda.cxx for PEDESTAL runs, running at the end of data taking on each LDC (seing only the LDC part of each event, but all events)
  • MCHOCCda.cxx for PHYSICS runs, running during data taking on a monitoring machine (seing full events, but only a sample of the full stat)
  • MCHBPEVOda.cxx for PHYSICS runs, running during data taking on a monitoring machine (seing full events, but only a sample of the full stat)

The Muon Tracking Calibration

The Muon tracking chambers needs two types of calibration in order to work properly : pedestals and occupancies. Actually to be more precise pedestals are absolutely required, and the occupancy is needed in order not to spend all the reconstruction time in hot-spots, and the bus patch evolution is needed to get an idea on long term stability.

Pedestals

The front-end electronics performs an online zero suppression using a threshold level. Those threshold levels for all channels (~ 1 million) have to be computed in a dedicated PEDESTALS runs. During this runs the zero suppression is OFF and the pedestal level and the noise is obtained for each channel. The threshold for the FEE is obtained adding the pedestal level to 3 sigmas of the noise.

The typical ECS sequence for pedestals is :

  • Switch ON the electronics LV
  • Boot the CROCUS
  • Configuration
  • Saving Configuration in an ascii file then transferring in the File eXchange Server (FXS)
  • Zero suppression OFF
  • Data taking (typically 400 events)
  • The DA computes the mean and sigma (it runs in each LDC)
  • The DA writes one ASCII file per LDC with the results in the File Exchange Server

Then the SHUTTLE process the ASCII files and store the result on the OCDB (Keyword=PEDESTALS) Only configuration files corresponding to a change of the Muon Tracker configuration are written in the FXS (Keyword=CONFIG).

Occupancy

For PHYSICS (or STANDALONE) runs, the MCHOCCda, which is a monitoring DA, keep track of how many times each channel has been hit during the run. The output is an ASCII file containing the needed information to compute the occupancy values. This file is written to the DAQ FXS so the SHUTTLE can transfer it to the OCDB.

Bus Patch Evolution

For PHYSICS (or STANDALONE) runs, the MCHBPEVOda, which is a monitoring DA, keep track of how many times each bus patch has been hit during the run. The output is a Root file containing the time evolution of the bus patch hit count, together with the time evolution of the number of events (used later on to compute the bus patch occupancy evolution). This file (mchbpevo.conf) is written to the DAQ FXS so the SHUTTLE can transfer it to the OCDB (MUON/Calib/BPEVO).

The MCHBPEVOda is using a configuration file (from the DAQ detector database),

See also
mchbpevo.conf, and the AliMUONBusPatchEvolution class. Output of the DA (either direct one, or the corresponding OCDB object) can be inspected with the help of the MUONBusPatchEvolution.C macro.

Using the DA Online

Pedestals

The syntax is: MCHPEDda.exe "raw data file"

Two input files located in the DAQ Detector database (DetDB) are needed:

  • muontrkpedvalues is built in flight in CONFIGURATION_PED.sh (ECS script) and contains one parameter "config" : config = 1 if configuration file has to be used (OnLine case) config = 0 if not (OffLine case for the time being)
  • config_ldc-MTRK-S3-0 : configuration file name corresponding to MuonTracker Station 3 if (for example) DA is running on ldc-MTRK-S3-0
  • DA validation: see Header of MCHPEDda.cxx for reference run, and corresponding input mutrkpedvalues and configuration files are located in path=/afs/cern.ch/user/j/jcharvet/public/DA_validation

Electonics gain

The syntax is: MCHGAINda.exe "raw data file"

Two input files located in the DAQ Detector database (DetDB) are needed:

  • muontrkcalibvalues: which attributes to each run index (1->11) its corrresponding DAC value. The other parameters are used to tune the fit procedure (for expert). The last parameter indicates the number of events to be read: if "0" all events in the run are read, if not the parameter indicates the maximum number of events to be read. Default values are listed below
1 0     
2 200
3 400
4 800
5 1200
6 1600
7 2000
8 2500
9 3000
10 3500
11 4000
1           
6
0
1
1
0
  • config_ldc-MTRK-S3-0 : configuration file name corresponding to MuonTracker station 3 if (for example) DA is running on ldc-MTRK-S3-0

DA validation: Header of MCHGAINda.cxx shows the list of the 11 reference runs, and corresponding input mutrkcalibvalues and configuration files are located in path=/afs/cern.ch/user/j/jcharvet/public/DA_validation

Using the DA Offline

The DAs normally runs with a RAW data DATE format as input The development of an Offline version is under way.

Nevertheless, Pedestal runs can be analysed locally, but without detector configuration file. If you get a file in root format (e.g. from alien), you can de-rootify it using the "deroot" program which is part of aliroot. Note that PED and GAIN DAs work with ROOT input files as well.

You have a line command help. To have it just type :

> MCHPEDda.exe -h

******************* ./MCHPEDda.exe usage **********************
Online (called from ECS) : ./MCHPEDda.exe <raw data file> (no inline options)

./MCHPEDda.exe can be used locally only with options (without DiMuon configuration file)
./MCHPEDda.exe -options, the available options are :
-h help                    (this screen)

 Input
-f <raw data file>         (default = )

 Output
-a <Flat ASCII file>       (default = MCHPEDda.ped)

 Options
-m <max date events>       (default = 1000000)
-s <skip events>           (default = 0)
-n <max events>            (default = 1000000)

In case of trouble

Please contact :

Jean-Luc Charvet : jean-.nosp@m.luc..nosp@m.charv.nosp@m.et@c.nosp@m.ern.c.nosp@m.h or Alberto Baldisseri : a.bal.nosp@m.diss.nosp@m.eri@c.nosp@m.ea.f.nosp@m.r or Laurent Aphecetche : laure.nosp@m.nt.a.nosp@m.phece.nosp@m.tche.nosp@m.@suba.nosp@m.tech.nosp@m..in2p.nosp@m.3.fr (for OCC DA)

This chapter is defined in the READMEmchda.txt file.