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File indexing completed on 2021-02-14 14:30:36

0001 #include "SiLinearChargeCollectionDrifter.h"
0002 #include "vdt/log.h"
0003 
0004 SiLinearChargeCollectionDrifter::SiLinearChargeCollectionDrifter(double dc, double cdr, double dv, double av)
0005     :  // Everything which does not depend on the specific det
0006       diffusionConstant(dc),
0007       chargeDistributionRMS(cdr),
0008       depletionVoltage(dv),
0009       appliedVoltage(av) {}
0010 
0011 SiChargeCollectionDrifter::collection_type SiLinearChargeCollectionDrifter::drift(
0012     const SiChargeCollectionDrifter::ionization_type& ion, const LocalVector& driftDir, double mt, double tn) {
0013   // prepare output
0014   collection_type _temp;
0015   _temp.resize(ion.size());
0016   // call the drift method for each deposit
0017   for (size_t i = 0; i < ion.size(); i++) {
0018     _temp[i] = drift(ion[i], driftDir, mt, tn);
0019   }
0020   return _temp;
0021 }
0022 
0023 SignalPoint SiLinearChargeCollectionDrifter::drift(const EnergyDepositUnit& edu,
0024                                                    const LocalVector& drift,
0025                                                    double moduleThickness,
0026                                                    double timeNormalisation) {
0027   // computes the fraction of the module the charge has to drift through,
0028   // ensuring it is bounded in [0,1]
0029   double depth = (moduleThickness / 2. - edu.z());
0030   double thicknessFraction = depth / moduleThickness;
0031   thicknessFraction = thicknessFraction > 0. ? thicknessFraction : 0.;
0032   thicknessFraction = thicknessFraction < 1. ? thicknessFraction : 1.;
0033 
0034   // computes the drift time in the sensor
0035   double driftTime = -timeNormalisation * vdt::fast_log(1. - 2 * depletionVoltage * thicknessFraction /
0036                                                                  (depletionVoltage + appliedVoltage)) +
0037                      chargeDistributionRMS;
0038 
0039   // returns the signal: an energy on the surface, with a size due to diffusion.
0040   return SignalPoint(edu.x() + depth * drift.x() / drift.z(),
0041                      edu.y() + depth * drift.y() / drift.z(),
0042                      sqrt(2. * diffusionConstant * driftTime),
0043                      edu.energy());
0044 }