SiHitDigitizer.cc

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#include "SiHitDigitizer.h"
#include "SimDataFormats/TrackingHit/interface/PSimHit.h"
#include "SiLinearChargeCollectionDrifter.h"
#include "SiLinearChargeDivider.h"

#include "DataFormats/GeometryVector/interface/LocalPoint.h"
#include "SiTrivialInduceChargeOnStrips.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"

//#define CBOLTZ (1.38E-23)
//#define e_SI (1.6E-19)
static const double CBOLTZ_over_e_SI = 1.38E-23 / 1.6E-19;
static const double noDiffusionMultiplier = 1.0e-3;

SiHitDigitizer::SiHitDigitizer(const edm::ParameterSet& conf)
    : depletionVoltage(conf.getParameter<double>("DepletionVoltage")),
      chargeMobility(conf.getParameter<double>("ChargeMobility")),
      theSiChargeDivider(new SiLinearChargeDivider(conf)),
      theSiChargeCollectionDrifter(new SiLinearChargeCollectionDrifter(
          CBOLTZ_over_e_SI * chargeMobility * conf.getParameter<double>("Temperature") *
              (conf.getParameter<bool>("noDiffusion") ? noDiffusionMultiplier : 1.0),
          conf.getParameter<double>("ChargeDistributionRMS"),
          depletionVoltage,
          conf.getParameter<double>("AppliedVoltage"))),
      theSiInduceChargeOnStrips(new SiTrivialInduceChargeOnStrips(conf, conf.getParameter<double>("GevPerElectron"))) {}

SiHitDigitizer::~SiHitDigitizer() {}

void SiHitDigitizer::processHit(const PSimHit* hit,
                                const StripGeomDetUnit& det,
                                GlobalVector bfield,
                                float langle,
                                std::vector<float>& locAmpl,
                                size_t& firstChannelWithSignal,
                                size_t& lastChannelWithSignal,
                                const TrackerTopology* tTopo,
                                CLHEP::HepRandomEngine* engine) {
  // Compute the drift direction for this det
  double moduleThickness = det.specificSurface().bounds().thickness();  // active detector thicness
  double timeNormalisation = (moduleThickness * moduleThickness) / (2. * depletionVoltage * chargeMobility);
  LocalVector driftDir = DriftDirection(&det, bfield, langle);

  // Fully process one SimHit
  theSiInduceChargeOnStrips->induce(
      theSiChargeCollectionDrifter->drift(theSiChargeDivider->divide(hit, driftDir, moduleThickness, det, engine),
                                          driftDir,
                                          moduleThickness,
                                          timeNormalisation),
      det,
      locAmpl,
      firstChannelWithSignal,
      lastChannelWithSignal,
      tTopo);
}