Dead and noisy channels masking

General description

There are some channels that don't work properly. Generally we can divide this channels into two groups:

  • dead channels (do not answer)
  • noisy channels (answer to much)

The purpose of dead and noisy channels masking is to exclude both groups of channels from simulation and reconstruction.

Steps that have to be taken

Out of software:
  • retrieve list of dead and noisy channels
  • convert this list to XML file
In Software:
  • parse XML file and create AnalysisMask
  • use AnalysisMask in order to exclude channels from simulation and reconstruction

The software part of dead and noisy channels masking takes place during digitalization.

Common part for every detectors

parse XML file and create AnalysisMask

This step of masking takes part directly in software. In order to parse XML and create AnalysisMask(TotemCondFormats/DAQInformation/interface/AnalysisMask.h) we should use DAQMappingSourceXML class (TotemCondFormats/DAQInformation/plugins/ To use this class we have to include in our configuration file a special module. We have to also provide mapping files and XML files containing dead & noisy channels. Sample configuration files will be later presented in this document.

XML file

The XML files which contain dead and noisy channels have very similar format for every detector. The differences are induced by different construction of each detector. Bellow I present sample files.

Roman Pots

   <arm id="0">
      <station id="2">
         <rp_detector_set id="5">
            <rp_plane id="0">
               <vfat iid="1" fullmask="yes"/>
               <vfat iid="3" fullmask="no">
                  <channel id="51"/>
                  <channel id="94"/>


    <t1_detector_set id="100">
        <t1_arm id="0">
            <t1_plane id="1">
                <t1_csc id="2">
                    <t1_channel_type id="1" full_mask="no">
                        <channel id="44"/>
                        <channel id="55"/>
                    <t1_channel_type id="2" full_mask="yes"/>                                  
                    <t1_channel_type id="3" full_mask="no">
                        <channel id="220"/>
                        <channel id="129"/>

Configuration file

In reconstruction dead and noisy channels are always excluded. However in simulation it is not necessary, hence a special flag indicating whether we want to simulate dead channels or not was introduced. To simulate dead channels it is necessary to add to a configuration file following part:


# mapping files
process.DAQMappingSourceXML.mappingFileNames.append('TotemCondFormats/DAQInformation/data/rp_220.xml') #load all mapping files

# mask files
process.DAQMappingSourceXML.maskFileNames.append('TotemCondFormats/DAQInformation/data/deadChannels_220.xml') #load configuration files
process.DAQMappingSourceXML.maskFileNames.append('TotemCondFormats/DAQInformation/data/deadChannels_147.xml') #for both RP stations
process.DAQMappingSourceXML.maskFileNames.append('PATH_TO_T1_DEAD_CHANNEL_LIST')  #load configuration file for T1

process.T1Digis.simulateDeadChannels = cms.bool(True) #this flag (set to true) indicates that we want to take dead channels into account for T1
process.RPSiDetDigitizer.simulateDeadChannels = cms.bool(True) #this flag (set to true) indicates that we want to take 
                                                               #into account dead channels for RP

Sections for each detector

* Roman Pots

T1 detector

retrieve raw list of dead and noisy channels

The list of dead and noisy channels can be obtained by using T1DeadChannelAnalyzer that is similar to T1XMLDataDigiProducer. T1DeadChannelAnalyzer count hits per channel and saves it in the map: encoded_channel_number -> number_of_hits. where:
encoded_channel_number  = 1000000 * arm + 100000 * plane + 10000 * chamber + 1000 * channelType + channelNumber; 

You can run T1DeadChannelAnalyzer using sample configuration file:

import FWCore.ParameterSet.Config as cms
process = cms.Process("T1ChannelsHitRate")
process.maxEvents = cms.untracked.PSet(
    input = cms.untracked.int32(NUMBER_OF_EVENTS)
# raw data source
process.source = cms.Source("RawDataSource",
    verbosity = cms.untracked.uint32(0),
    eventsToCheck = cms.uint32(10),
    skipCorruptedEvents = cms.bool(False),
    performChecks = cms.bool(True), 
    fileNames = cms.untracked.vstring('PATH_TO_RAW_DATA')
process.DAQInformationSourceXML = cms.ESSource("DAQInformationSourceXML",
    xmlFileName = cms.string('TotemRawData/RawToDigi/python/T1_all_0.xml')
process.t1raw2digi = cms.EDAnalyzer("T1DeadChannelDataAnalyzer",
                                    verbosity = cms.untracked.uint32(0),
                                    deadCutValue= cms.untracked.uint32(150),
                                    noiseCutValue= cms.untracked.uint32(10),
process.o1 = cms.OutputModule("PoolOutputModule",
    fileName = cms.untracked.string('./recoT1_091101_mux.root'),
    outputCommands=cms.untracked.vstring('drop totemRawEvent_*_*_*')
process.p1 = cms.Path(process.t1raw2digi)
process.outpath = cms.EndPath(process.o1)

it is advised to set NUMBER_OF_EVENTS > 10 000.

deadCutValue and noiseCutValue is used when checking if channel is dead or noisy. By default deadCutValue = 200 and noiseCutValue = 9.

it means that channel is considered dead if it's hits number is less or equal than average_number_of_hits_per_channel_in_plane / deadCutValue

channel is considered as noisy when it's hits number is greater or equal then average_number_of_hits_per_channel_in_plane * noiseCutValue

At the end of processing all channels that are considered dead or noisy are printed.

The output has format:



$ cmsRun > rawDeadChannelsList.txt

Create XML file with dead and noisy channels

rawDeadChannelsList.txt has to be changed to XML file. To do that i wrote that parse rawDeadChannelsList.txt file and prints xml format file - T1DeadChannelsList.xml

to run it:

$ python    rawDeadChannelsList.txt     >    T1DeadChannelsList.xml 

Chart presenting number of hits per channel in T1 detector

use AnalysisMask in order to exclude channels from simulation and reconstruction

To exclude channels from simulation or reconstruction we have to simply check whether an AnalysisMask contains this channels and then (if it is true) skip operation. For T1 it is done in:


In class (TotemRawData/RawToDigi/plugins/ in method T1DataProduce


In classes:

T1DigiProducer (SimTotem/T1DigiProducer/src/

T1Digitizer (SimTotem/T1DigiProducer/src/

T1WireElectronicsSim (SimTotem/T1DigiProducer/src/

T1StripElectronicsSimStandard (SimTotem/T1DigiProducer/src/

T1StripElectronicsSimVfat (SimTotem/T1DigiProducer/src/

In method beginJob of T1DigiProducer (after software migration it is very likely that this method will change to beginRun)

  • removing dead and noisy channels
In method produce, using T1DeadChannelsManager (SimTotem/T1DigiProducer/src/

-- MarcinBorratynski - 08-Sep-2011

-- JakubSmajek - 02-Sep-2011

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Topic revision: r6 - 2011-09-09 - JakubSmajek
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