Fix #228: force parent ID to zero if particle was not created in current sensor volume

    // Get Transportaion Matrix

    G4TouchableHandle theTouchable = step->GetPreStepPoint()->GetTouchableHandle();

    auto* track = step->GetTrack();

    // Put the charge deposit in the middle of the step unless it is a photon:

    auto is_photon = (step->GetTrack()->GetDynamicParticle()->GetPDGcode() == 22);

    auto is_photon = (track->GetDynamicParticle()->GetPDGcode() == 22);

    LOG(DEBUG) << "Placing energy deposit "

               << (is_photon ? "at the end of step, photon detected" : "in the middle of the step");

    G4ThreeVector step_pos = is_photon ? postStep->GetPosition() : (preStep->GetPosition() + postStep->GetPosition()) / 2;

                             deposit_position_g4.y() + detector_->getModel()->getSensorCenter().y(),

                             deposit_position_g4.z() + detector_->getModel()->getSensorCenter().z());

    const auto* userTrackInfo = dynamic_cast<TrackInfoG4*>(step->GetTrack()->GetUserInformation());

    const auto* userTrackInfo = dynamic_cast<TrackInfoG4*>(track->GetUserInformation());

    if(userTrackInfo == nullptr) {

        throw ModuleError("No track information attached to track.");

    }

    auto trackID = userTrackInfo->getID();

    auto parentTrackID = userTrackInfo->getParentID();

    // If this track originates in the sensor add parent ID. Otherwise set the ID to zero (primary particle) since it might

    // have a parent connected from a previous crossing of the sensor, i.e. backscattering from an interaction in non-sensor

    // material. While these particles are connected via MCTracks, we treat them as primaries to the sensor since they

    // entered from the outside and were not created in the sensor volume.

    auto parentTrackID =

        (track->GetVolume()->GetLogicalVolume() == track->GetLogicalVolumeAtVertex() ? userTrackInfo->getParentID() : 0);

    // Save begin point when track is seen for the first time

    if(track_begin_.find(trackID) == track_begin_.end()) {

        track_begin_.emplace(trackID, start_position);

        track_parents_.emplace(trackID, parentTrackID);

        track_time_.emplace(trackID, step_time);

        track_pdg_.emplace(trackID, step->GetTrack()->GetDynamicParticle()->GetPDGcode());

        track_pdg_.emplace(trackID, track->GetDynamicParticle()->GetPDGcode());

    }

    // Update current end point with the current last step