Add common mode per pad saturation

Author: tubagundem

Detectors/TPC/base/include/TPCBase/ParameterElectronics.h

@@ -48,6 +48,7 @@ struct ParameterElectronics : public o2::conf::ConfigurableParamHelper<Parameter
   bool doIonTail = false;                                                       ///< add ion tail in simulation
   bool doIonTailPerPad = false;                                                 ///< add ion tail in simulation using pad-by-pad values
   bool doCommonModePerPad = true;                                               ///< add common mode in simulation using pad-by-pad values
+  bool doCommonModePerPadSaturation = true;                                     ///< Saturate the common mode seen by each pad at its pedestal value
   bool doSaturationTail = false;                                                ///< add saturation tail in simulation
   bool doNoiseEmptyPads = false;                                                ///< add noise in pads without signal in simulation
   bool applyDeadMap = true;                                                     ///< apply dead channel map

Detectors/TPC/simulation/include/TPCSimulation/DigitContainer.h

@@ -96,19 +96,19 @@ class DigitContainer
   void updateCalibrations();
 
  private:
-  TimeBin mFirstTimeBin = 0;                                  ///< First time bin to consider
-  TimeBin mEffectiveTimeBin = 0;                              ///< Effective time bin of that digit
-  TimeBin mTmaxTriggered = 0;                                 ///< Maximum time bin in case of triggered mode (hard cut at average drift speed with additional margin)
-  TimeBin mOffset;                                            ///< Size of the container for one event
-  std::deque<DigitTime*> mTimeBins;                           ///< Time bin Container for the ADC value
-  std::unique_ptr<DigitTime::PrevDigitInfoArray> mPrevDigArr; ///< Keep track of ToT and ion tail cumul from last time bin
-  o2::utils::DebugStreamer mStreamer;                         ///< Debug streamer
-  const CalPad* mPadParams[3] = {nullptr, nullptr, nullptr};  //!< Ion tail fraction, ion tail slope and common mode k-values per pad
-  const CalDet<bool>* mDeadMap = nullptr;                     //!< Dead channel map
-  bool mCMCEnabled = false;                                   //!< Common mode correction enabled in the FEE config (DigiMode Auto)
-  bool mCalibrationsUpdated = false;                          //!< Whether updateCalibrations was called
-  SAMPAProcessing* mSAMPAProcessing = nullptr;                //!< SAMPAProcessing used for the output, the singleton if not set
-  std::vector<std::pair<MCCompLabel, int>> mLabelCollector;   //!< Workspace to sort the MC labels of a digit
+  TimeBin mFirstTimeBin = 0;                                          ///< First time bin to consider
+  TimeBin mEffectiveTimeBin = 0;                                      ///< Effective time bin of that digit
+  TimeBin mTmaxTriggered = 0;                                         ///< Maximum time bin in case of triggered mode (hard cut at average drift speed with additional margin)
+  TimeBin mOffset;                                                    ///< Size of the container for one event
+  std::deque<DigitTime*> mTimeBins;                                   ///< Time bin Container for the ADC value
+  std::unique_ptr<DigitTime::PrevDigitInfoArray> mPrevDigArr;         ///< Keep track of ToT and ion tail cumul from last time bin
+  o2::utils::DebugStreamer mStreamer;                                 ///< Debug streamer
+  const CalPad* mPadParams[4] = {nullptr, nullptr, nullptr, nullptr}; //!< Ion tail fraction, ion tail slope, common mode k-values and pedestals per pad
+  const CalDet<bool>* mDeadMap = nullptr;                             //!< Dead channel map
+  bool mCMCEnabled = false;                                           //!< Common mode correction enabled in the FEE config (DigiMode Auto)
+  bool mCalibrationsUpdated = false;                                  //!< Whether updateCalibrations was called
+  SAMPAProcessing* mSAMPAProcessing = nullptr;                        //!< SAMPAProcessing used for the output, the singleton if not set
+  std::vector<std::pair<MCCompLabel, int>> mLabelCollector;           //!< Workspace to sort the MC labels of a digit
 
   void reportSettings();
 };

Detectors/TPC/simulation/include/TPCSimulation/DigitGlobalPad.h

@@ -80,7 +80,7 @@ class DigitGlobalPad
                 o2::dataformats::LabelContainer<std::pair<MCCompLabel, int>, false>&);
 
   /// Fold signal with previous pad signal add ion tail and ToT for sigmal saturation
-  void foldSignal(PrevDigitInfo& prevDigit, const int sector, const int pad, const TimeBin time, Streamer* debugStream = nullptr, const CalPad* padParams[3] = nullptr);
+  void foldSignal(PrevDigitInfo& prevDigit, const int sector, const int pad, const TimeBin time, Streamer* debugStream = nullptr, const CalPad* padParams[4] = nullptr);
 
   void setID(int id) { mID = id; }
   int getID() const { return mID; }
@@ -132,7 +132,7 @@ inline void DigitGlobalPad::addDigit(const MCCompLabel& label, float signal,
   mChargePad += signal;
 }
 
-inline void DigitGlobalPad::foldSignal(PrevDigitInfo& prevDigit, const int sector, const int pad, const TimeBin time, Streamer* debugStream, const CalPad* padParams[3])
+inline void DigitGlobalPad::foldSignal(PrevDigitInfo& prevDigit, const int sector, const int pad, const TimeBin time, Streamer* debugStream, const CalPad* padParams[4])
 {
   const auto& eleParam = ParameterElectronics::Instance();
   const auto& itSettings = IonTailSettings::Instance();

Detectors/TPC/simulation/include/TPCSimulation/DigitTime.h

@@ -80,7 +80,7 @@ class DigitTime
                            std::vector<CommonMode>& commonModeOutput, const Sector& sector, TimeBin timeBin,
                            SAMPAProcessing& sampaProcessing, std::vector<std::pair<MCCompLabel, int>>& labelCollector,
                            PrevDigitInfoArray* prevTime = nullptr, Streamer* debugStream = nullptr,
-                           const CalPad* padParams[3] = nullptr, const CalDet<bool>* deadMap = nullptr);
+                           const CalPad* padParams[4] = nullptr, const CalDet<bool>* deadMap = nullptr);
 
  private:
   std::array<float, GEMSTACKSPERSECTOR> mCommonMode;                 ///< Common mode container - 4 GEM ROCs per sector
@@ -131,7 +131,7 @@ template <DigitzationMode MODE>
 inline void DigitTime::fillOutputContainer(std::vector<Digit>& output, dataformats::MCTruthContainer<MCCompLabel>& mcTruth,
                                            std::vector<CommonMode>& commonModeOutput, const Sector& sector, TimeBin timeBin,
                                            SAMPAProcessing& sampaProcessing, std::vector<std::pair<MCCompLabel, int>>& labelCollector,
-                                           PrevDigitInfoArray* prevTime, Streamer* debugStream, const CalPad* padParams[3],
+                                           PrevDigitInfoArray* prevTime, Streamer* debugStream, const CalPad* padParams[4],
                                            const CalDet<bool>* deadMap)
 {
   const auto& mapper = Mapper::instance();
@@ -153,23 +153,33 @@ inline void DigitTime::fillOutputContainer(std::vector<Digit>& output, dataforma
     mCommonMode[cru.gemStack()] += digit.getChargePad() * eleParam.commonModeCoupling * cmKValue; // TODO: Add stack-by-stack variation?
   }
 
-  // fill common mode output container
-  for (size_t i = 0; i < mCommonMode.size(); ++i) {
-    const float cm = getCommonMode(GEMstack(i));
-    if (cm > 0.) {
-      commonModeOutput.push_back({cm, timeBin, static_cast<unsigned char>(i)});
-    }
-  }
+  // the common mode is induced on all pads of the GEM stack, but the baseline of a pad can at most drop to 0 ADC,
+  // so the common mode seen by a pad saturates at its pedestal value
+  const CalPad* pedestals = eleParam.doCommonModePerPadSaturation ? padParams[3] : nullptr;
+  std::array<double, GEMSTACKSPERSECTOR> commonModeSeen{}; // double: sum of ~3000 values per stack
 
   for (size_t iPad = 0; iPad < mGlobalPads.size(); ++iPad) {
     auto& digit = mGlobalPads[iPad];
+    const CRU cru = mapper.getCRU(sector, iPad);
+    float commonMode = getCommonMode(cru);
+    if (pedestals) {
+      commonMode = std::min(commonMode, pedestals->getValue(sector.getSector(), iPad));
+      commonModeSeen[cru.gemStack()] += commonMode;
+    }
     if (eleParam.doNoiseEmptyPads || (digit.getChargePad() > 0.f)) {
       PrevDigitInfo prevDigit;
       if (prevTime) {
         prevDigit = (*prevTime)[iPad];
       }
-      const CRU cru = mapper.getCRU(sector, iPad);
-      digit.fillOutputContainer<MODE>(output, mcTruth, cru, timeBin, iPad, mLabels, sampaProcessing, labelCollector, getCommonMode(cru), prevDigit, debugStream, deadMap);
+      digit.fillOutputContainer<MODE>(output, mcTruth, cru, timeBin, iPad, mLabels, sampaProcessing, labelCollector, commonMode, prevDigit, debugStream, deadMap);
+    }
+  }
+
+  // fill common mode output container, with saturation the average common mode seen by the pads of the GEM stack
+  for (size_t i = 0; i < mCommonMode.size(); ++i) {
+    const float cm = pedestals ? static_cast<float>(commonModeSeen[i] / mapper.getNumberOfPads(GEMstack(i))) : getCommonMode(GEMstack(i));
+    if (cm > 0.) {
+      commonModeOutput.push_back({cm, timeBin, static_cast<unsigned char>(i)});
     }
   }
 }

Detectors/TPC/simulation/src/DigitContainer.cxx

@@ -160,6 +160,9 @@ void DigitContainer::updateCalibrations()
     mPadParams[2] = &cdb.getCMkValues();
   }
 
+  // pedestals for the common mode saturation per pad
+  mPadParams[3] = eleParam.doCommonModePerPadSaturation ? &cdb.getPedestals() : nullptr;
+
   // dead channel map
   mDeadMap = eleParam.applyDeadMap ? &cdb.getDeadChannelMap() : nullptr;
 
@@ -174,7 +177,7 @@ void DigitContainer::reportSettings()
   auto& cdb = CDBInterface::instance();
   const auto& eleParam = ParameterElectronics::Instance();
   const auto& feeConfig = cdb.getFEEConfig();
-  LOGP(info, "ParameterElectronics:  doIonTail={}, doIonTailPerPad={}, doCommonModePerPad={}, doSaturationTail={}, doNoiseEmptyPads={}, applyDeadMap={}, commonModeCoupling={}, DigiMode={}",
-       eleParam.doIonTail, eleParam.doIonTailPerPad, eleParam.doCommonModePerPad, eleParam.doSaturationTail, eleParam.doNoiseEmptyPads, eleParam.applyDeadMap, eleParam.commonModeCoupling, (int)eleParam.DigiMode);
+  LOGP(info, "ParameterElectronics:  doIonTail={}, doIonTailPerPad={}, doCommonModePerPad={}, doCommonModePerPadSaturation={}, doSaturationTail={}, doNoiseEmptyPads={}, applyDeadMap={}, commonModeCoupling={}, DigiMode={}",
+       eleParam.doIonTail, eleParam.doIonTailPerPad, eleParam.doCommonModePerPad, eleParam.doCommonModePerPadSaturation, eleParam.doSaturationTail, eleParam.doNoiseEmptyPads, eleParam.applyDeadMap, eleParam.commonModeCoupling, (int)eleParam.DigiMode);
   feeConfig.printShort();
 }