Bad Channels Map

1. General Description

Bad Channels Map is a list of strips flagged as bad (see below), stored as a ROOT file containing AliITSBadChannelsSSDv2 object. There are two types of the map:

• Static Bad Channels Map is generated manually (offline) and passed to SSD DA through daqDetDB and configuration file.
• Dynamic Bad Channels Map is generated by the SSD DA during a pedestal run and merged on top of the static bad channels map.

The main difference is that Static Bad Channels Map contains (besides the list of empty/excluded modules that are found also by the DA i.e. contained in Dynamic Map) a list of open channels. These are strips for which the connection between the sensor and the electronics is interrupted somewhere. These channels are not found by the checks that are implemented in the Pedestal DA. The introduction of these checks in the DA would make the DA itself too slow. Anyhow, these channels influence the calculation of the common mode and therefore are needed to be masked. It is not expected that the list of open channels changes with time too frequently therefore a static map can be used.

Bad Flag	Value (dec)	Set in Static Map	Set in Dynamic Map	Description
ZS/Excluded	3	No	Yes	ZS threshold > ZS bits or Ladder excluded
Pedestal	4+3	Yes	Yes	Strip with pedestal problems
Noise	8+3	Yes	Yes	Strip with high noise
Dead	16+3	Yes	Yes	Strip with noise < 1 or Ladder excluded
Open	32+3	Yes	No	Open channels / empiric criteria

2. How to create a Static Bad Channels Map

Perform a long pedestal run with mStream Recording

From ACR SSD station perform a standalone PEDESTAL run with following parameters:

• GDC: mStream recording
• LDC: Set Max. number of subevents to 1000 (runControl > RunParameters > Define...)

After the run is completed start data migration to CASTOR (DCA > File > Start migration...).

You can access the data either with alien or directly on CASTOR via lxplus. The second option is described in following:

• Using command nsls you can browse CASTOR. The pedestal run you've shoulde be in directory /castor/cern.ch/alice/raw/ssd/<year>/<month>/<day>/<hour>/
• Format of files in directory is <year_last_2_digits>000<run_number>0<gdc>.<part>.root e.g. 15000219043008.19.root
• Command rfcp allows you to copy files from CASTOR. Copy all the files corresponding to the run you've performed previously somewhere locally.

Create Static Bad Channels Map using provided macros

BadChannelsMapStatic.tar.gz contains macros needed to produce Static Bad Channels Map from the raw data acquired in the previous step. To run them you will need a system with LSF batch service and AliRoot installed. Tar package contains following files and directories:

• Compile_Ladder_Noise_Open.C - for compilation of ROOTLadderNoiseForListOpen.C
• Launch_Ladder_Noise_Open.C - for launching ROOTLadderNoiseForListOpen.C
• readbad_v2.C - creates static map from ROOTLadderNoiseForListOpen.C output
• ROOTLadderNoiseForListOpen.C - main macro which reads raw files and creates text file of bad channels
• visualizeSSDMap.C - macro for visualising created bad channels map
• bin/ - containing:
  • catFinalFrom_DDL_AD.sh - explained below
  • Compile_Ladder_Noise_Open.sh - run by Launch_Ladder_Noise_Loop_Open.sh
  • Launch_Ladder_Noise_Loop_Open.sh - main script for launching all jobs
  • Launch_Ladder_Noise_Open.sh - run by Launch_Ladder_Noise_Loop_Open.sh
• examples/ - contains examples of output the macros should produce
• data/, logs/ and output/ - empty directories for input/output

First you will need to adjust macros for your environment:

• In macro ROOTLadderNoiseForListOpen.C at least the following variables should be edited:
  
  • rawfile_prefix - path to data directory containing raw files, edit the string describing a part of rawfile name (see previous section)
  • rawfile_first - first raw data file (see previous section)
  • rawfile_last - last raw data file (see previous section)
• In Launch_Ladder_Noise_Loop_Open.sh change:
  • M_WORK_DIR - set correct path to work directory (BadChannelsMapStatic)
  • M_RUN - set correct run number
• In macros Compile_Ladder_Noise_Open.sh and Launch_Ladder_Noise_Open.sh setup correct path and arguments for sourcing alice-env.sh
• If you changed only these variables all other scripts should work without modifications

To obtain the Static Bad Channels Map the following procedure should be followed:

• Execute bin/Launch_Ladder_Noise_Loop_Open.sh <queue>, where <queue> is the batch queue to which you want submit jobs. This will launch 144 jobs (16 DDL x 9 ADs) and will create a .txt file for each AD in the directory output/. Logs will be written in logs/<submit_date>. Execution takes up to 4 hours for each job. Wait for all jobs to finish.
• Run bin/catFinalFrom_DDL_AD.sh - it will concatenate all the outputs of different DDLs and ADs and create a single file output/BadChannelsListwithOpen_final.txt
• Run aliroot -l -b -q readbad_v2.C - it will create Static Bad Channels Map in the correct format (badchannels_v2.root) from output/BadChannelsListwithOpen_final.txt
• If you want to visualize the newly created map run aliroot -l visualizeSSDMap.C
• In the examples/ directory there are sample output files with which you can compare your output

Upload the static map to the LDCs and change the configuration file

...todo...

3. Static Bad Channels Map uplodad to LDCs in April 2015

The two images show Static Bad Channels Map uploaded in April 2015 and DCS Main panel as reference for the excluded ladders.

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-- MiljenkoSuljic - 2015-04-11