Adding Photomultiplier SD

CMakeLists.txt

@@ -32,6 +32,7 @@ endif()
 # ---------------------------------------------------------------------------
 # load additional OS dependent settings
 include(cmake/os.cmake)
+include(cmake/root.cmake)
 
 #----------------------------------------------------------------------------
 # Find Libraries

src/GenericDetectors/CMakeLists.txt

@@ -5,12 +5,14 @@ cmake_minimum_required(VERSION 3.3 FATAL_ERROR)
 # locations on all platforms.
 include(GNUInstallDirs)
 include ( ${DD4hep_DIR}/cmake/DD4hep.cmake )
+dd4hep_configure_output()
 
 #-----------------------------------------------------------------------------------
 
 find_package(Acts REQUIRED COMPONENTS Core IdentificationPlugin TGeoPlugin DD4hepPlugin )
 
-dd4hep_configure_output()
+add_subdirectory(pid/sdet)
+
 #dd4hep_package (GenDetectors MAJOR ${NPDet_VERSION_MAJOR} MINOR ${NPDet_VERSION_MINOR} PATCH ${NPDet_VERSION_PATCH}
 #    USES            [ROOT   REQUIRED COMPONENTS Geom GenVector] 
 #                    [DD4hep REQUIRED COMPONENTS DDCore DDRec]

src/GenericDetectors/pid/compact/sim_test.py

@@ -31,6 +31,7 @@ def run():
 
   geant4 = DDG4.Geant4(kernel, tracker='Geant4TrackerCombineAction')
   geant4.printDetectors()
+
   logger.info("#  Configure UI")
   geant4.setupUI('qt',vis=True,macro='vis.mac')
 
@@ -150,7 +151,9 @@ def run():
   #kernel.registerGlobalFilter(f3)
   #kernel.registerGlobalFilter(f4)
 
-  logger.info("#  First the tracking detectors")
+  logger.info("#  First the PID detectors")
+  seq, act = geant4.setupDetector('ForwardRICH','PhotoMultiplierSDAction')
+
   #seq, act = geant4.setupTracker('SiVertexBarrel')
   #seq.adopt(f1)
   ## seq.adopt(f4)

src/GenericDetectors/pid/sdet/CMakeLists.txt

+cmake_minimum_required(VERSION 3.12 FATAL_ERROR)
+
+#find_package ( DD4hep REQUIRED )
+#include ( ${DD4hep_DIR}/cmake/DD4hep.cmake )
+include ( ${DD4hep_DIR}/cmake/DD4hepBuild.cmake )
+dd4hep_configure_output()
+dd4hep_set_compiler_flags()
+
+set( sdet_headers
+  include/PhotoMultiplierHit.h
+  )
+
+
+root_generate_dictionary(G__DDG4_PIDsdet
+  #$<BUILD_INTERFACE:-I${SPDLOG_INCLUDE_DIR}>
+  #$<BUILD_INTERFACE:-I${FMT_INCLUDE_DIR}>
+  -I${CMAKE_CURRENT_SOURCE_DIR} 
+  -I${CMAKE_CURRENT_SOURCE_DIR}/include 
+  ${sdet_headers}
+  LINKDEF LinkDef.h 
+  )
+add_custom_target(G__DDG4_PIDsdet_ROOTDICT DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/G__DDG4_PIDsdet.cxx)
+
+#dd4hep_add_dictionary(G__DDG4_PIDsdet
+#  SOURCES ${DD4hep_DIR}/include/ROOT/Warnings.h src/PhotoMultiplierHit.h
+#  LINKDEF ${DD4hep_DIR}/include/ROOT/LinkDef.h
+#  OUTPUT  ${LIBRARY_OUTPUT_PATH}
+#  USES    DD4hep::DDCore DD4hep::DDG4 Geant4::Interface
+#  )
+#
+#----  Example of a client library with user defined plugins  --------------------
+dd4hep_add_plugin( DDG4_PIDsdet
+  GENERATED G__DDG4_PIDsdet.cxx
+  SOURCES   
+    src/PhotoMultiplierHit.cpp 
+    src/PhotoMultiplierSDAction.cpp
+  USES DD4hep::DDCore DD4hep::DDG4 Geant4::Interface ROOT::Core ROOT::Geom ROOT::GenVector ROOT::RIO
+  )
+add_dependencies(DDG4_PIDsdet G__DDG4_PIDsdet_ROOTDICT)
+target_include_directories(DDG4_PIDsdet 
+  PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+  PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+  PUBLIC $<INSTALL_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+  )
+install(TARGETS DDG4_PIDsdet DESTINATION lib)
+
+  # # Geant4 material scan. From position=0,0,0 to end-of-world 
+  # dd4hep_add_test_reg( DDG4_PIDsdet_g4material_scan_SiliconBlock_LONGTEST
+  #   COMMAND    "${CMAKE_INSTALL_PREFIX}/bin/run_test_DDG4_PIDsdet.sh"
+  #   EXEC_ARGS  python ${DD4hep_ROOT}/bin/g4MaterialScan --compact=file:${CMAKE_INSTALL_PREFIX}/examples/ClientTests/compact/SiliconBlock.xml
+  #              "--position=0,0,0" "--direction=0,1,0"
+  #   REGEX_PASS " Terminate Geant4 and delete associated actions."
+  # )
+  #            
+  # dd4hep_add_test_reg( DDG4_PIDsdet_sim_SiliconBlock_LONGTEST
+  #   COMMAND    "${CMAKE_INSTALL_PREFIX}/bin/run_test_DDG4_PIDsdet.sh"
+  #   EXEC_ARGS  python ${DDG4_PIDsdet_INSTALL}/scripts/PhotoMultiplierSD_sim.py 
+  #              --compact=file:${CMAKE_INSTALL_PREFIX}/examples/ClientTests/compact/SiliconBlock.xml
+  #   REGEX_PASS NONE
+  #   REGEX_FAIL "Exception;EXCEPTION;ERROR;Error" )
+
+  #endif()

src/GenericDetectors/pid/sdet/LinkDef.h

+#if defined(__CINT__) || defined(__MAKECINT__) || defined(__CLING__) || defined(__ROOTCLING__)
+#pragma link off all globals;
+#pragma link off all classes;
+#pragma link off all functions;
+
+#pragma link C++ nestedclass;
+#pragma link C++ nestedtypedef;
+
+/// Define namespaces
+#pragma link C++ namespace dd4hep;
+#pragma link C++ namespace dd4hep::sim;
+#pragma link C++ namespace npdet;
+
+#pragma link C++ class     npdet::PhotoMultiplierHit+;
+#endif
+

src/GenericDetectors/pid/sdet/include/MyTrackerHit.h

+//==========================================================================
+//  AIDA Detector description implementation 
+//--------------------------------------------------------------------------
+// Copyright (C) Organisation europeenne pour la Recherche nucleaire (CERN)
+// All rights reserved.
+//
+// For the licensing terms see $DD4hepINSTALL/LICENSE.
+// For the list of contributors see $DD4hepINSTALL/doc/CREDITS.
+//
+// Author     : M.Frank
+//
+//==========================================================================
+#ifndef SOMEEXPERIMENT_MYTRACKERHIT_H
+#define SOMEEXPERIMENT_MYTRACKERHIT_H
+
+/// Framework include files
+#include "DDG4/Geant4Data.h"
+
+namespace SomeExperiment {
+
+  /// This is the hit definition.
+  /** I took here the same definition of the default Geant4Tracker class,
+   *  (see DDG4/Geant4Data.h)  but it could be anything else as well.
+   *
+   *  Please note:
+   *  ============
+   *  The MC truth handling as implemented in the Geant4ParticleHandler
+   *  will not work with this class if the object(s) are saved with 
+   *  the standard Geant4Output2ROOT event action. If the hit is 
+   *  specialized, the output writing also must be specialized if
+   *  MC truth handling should be supported.
+   *  Otherwise it is sufficient to provide a ROOT dictionary as long as the
+   *  base class dd4hep::sim::Geant4HitData is kept.
+   *
+   *  \author  M.Frank
+   *  \version 1.0
+   *  \ingroup DD4HEP_SIMULATION
+   */
+  class MyTrackerHit /* : public dd4hep::sim::Geant4HitData  */ {
+
+  public:
+    /// dd4hep::sim::Geant4HitData: cellID
+    long long int cellID = 0;
+    /// dd4hep::sim::Geant4HitData: User flag to classify hits
+    long flag = 0;
+    /// dd4hep::sim::Geant4HitData: Original Geant 4 track identifier of the creating track (debugging)
+    long g4ID = -1;
+
+    
+    /// Hit position
+    dd4hep::Position      position;
+    /// Hit direction
+    dd4hep::Direction     momentum;
+    /// Length of the track segment contributing to this hit
+    double        length = 0;
+    /// Monte Carlo / Geant4 information
+    dd4hep::sim::Geant4HitData::MonteCarloContrib truth;
+    /// Energy deposit in the tracker hit
+    double        energyDeposit = 0;
+
+  public:
+    /// Default constructor
+    MyTrackerHit() = default;
+    /// Initializing constructor
+    MyTrackerHit(int track_id, int pdg_id, double deposit, double time_stamp)
+      : length(0.0), truth(track_id, pdg_id, deposit, time_stamp, 0.), energyDeposit(deposit) {}
+    /// Default destructor
+    virtual ~MyTrackerHit() = default;
+    /// Assignment operator
+    MyTrackerHit& operator=(const MyTrackerHit& c);
+    /// Clear hit content
+    MyTrackerHit& clear();
+    /// Store Geant4 point and step information into tracker hit structure.
+    MyTrackerHit& storePoint(const G4Step* step, const G4StepPoint* pnt);
+  };
+}
+
+// CINT configuration
+#if defined(__CINT__) || defined(__MAKECINT__) || defined(__CLING__) || defined(__ROOTCLING__)
+#pragma link off all globals;
+#pragma link off all classes;
+#pragma link off all functions;
+
+/// Define namespaces
+#pragma link C++ namespace dd4hep;
+#pragma link C++ namespace dd4hep::sim;
+#pragma link C++ namespace SomeExperiment;
+#pragma link C++ class     SomeExperiment::MyTrackerHit+;
+#endif
+
+#endif /* SOMEEXPERIMENT_MYTRACKERHIT_H */

src/GenericDetectors/pid/sdet/include/PhotoMultiplierHit.h

+//==========================================================================
+//  AIDA Detector description implementation 
+//--------------------------------------------------------------------------
+// Copyright (C) Organisation europeenne pour la Recherche nucleaire (CERN)
+// All rights reserved.
+//
+// For the licensing terms see $DD4hepINSTALL/LICENSE.
+// For the list of contributors see $DD4hepINSTALL/doc/CREDITS.
+//
+// Author     : Whitney Armstrong
+//
+//==========================================================================
+#ifndef NPDet_PhotoMultiplierHIT_H
+#define NPDet_PhotoMultiplierHIT_H
+
+/// Framework include files
+#include "DDG4/Geant4Data.h"
+
+namespace npdet {
+
+  /// PhotoMultiplier Hit definition.
+  /** Nearly the same as a tracker hit but stores energy (convertable to wavelength). 
+   *
+   *  Please note:
+   *  ============
+   *  The MC truth handling as implemented in the Geant4ParticleHandler
+   *  will not work with this class if the object(s) are saved with 
+   *  the standard Geant4Output2ROOT event action. If the hit is 
+   *  specialized, the output writing also must be specialized if
+   *  MC truth handling should be supported.
+   *  Otherwise it is sufficient to provide a ROOT dictionary as long as the
+   *  base class dd4hep::sim::Geant4HitData is kept.
+   *
+   *  \author  Whitney Armstrong
+   *  \version 1.0
+   *  \ingroup DD4HEP_SIMULATION
+   */
+  class PhotoMultiplierHit /* : public dd4hep::sim::Geant4HitData  */ {
+
+  public:
+    /// dd4hep::sim::Geant4HitData: cellID
+    int64_t cellID = 0;
+    /// dd4hep::sim::Geant4HitData: User flag to classify hits
+    long flag = 0;
+    /// dd4hep::sim::Geant4HitData: Original Geant 4 track identifier of the creating track (debugging)
+    long g4ID = -1;
+
+    
+    /// Hit position
+    dd4hep::Position      position;
+    /// Hit direction
+    dd4hep::Direction     momentum;
+    /// Length of the track segment contributing to this hit
+    double        length = 0;
+    /// Monte Carlo / Geant4 information
+    dd4hep::sim::Geant4HitData::MonteCarloContrib truth;
+    /// Energy of photon
+    double        energy = 0;
+
+  public:
+    /// Default constructor
+    PhotoMultiplierHit() = default;
+    /// Initializing constructor
+    PhotoMultiplierHit(int track_id, int pdg_id, double en, double time_stamp)
+      : length(0.0), truth(track_id, pdg_id, en, time_stamp, 0.), energy(en) {}
+    /// Default destructor
+    virtual ~PhotoMultiplierHit() = default;
+    /// Assignment operator
+    PhotoMultiplierHit& operator=(const PhotoMultiplierHit& c);
+    /// Clear hit content
+    PhotoMultiplierHit& clear();
+    /// Store Geant4 point and step information into tracker hit structure.
+    PhotoMultiplierHit& storePoint(const G4Step* step, const G4StepPoint* pnt);
+  };
+}
+
+#endif

src/GenericDetectors/pid/sdet/src/MyTrackerHit.cpp

+//==========================================================================
+//  AIDA Detector description implementation 
+//--------------------------------------------------------------------------
+// Copyright (C) Organisation europeenne pour la Recherche nucleaire (CERN)
+// All rights reserved.
+//
+// For the licensing terms see $DD4hepINSTALL/LICENSE.
+// For the list of contributors see $DD4hepINSTALL/doc/CREDITS.
+//
+// Author     : M.Frank
+//
+//==========================================================================
+
+/// Framework include files
+#include "MyTrackerHit.h"
+#include "G4Track.hh"
+
+using namespace SomeExperiment;
+
+/// Assignment operator
+MyTrackerHit& MyTrackerHit::operator=(const MyTrackerHit& c)  {
+  if ( &c != this )  {
+    position = c.position;
+    momentum = c.momentum;
+    length = c.length;
+    truth = c.truth;
+  }
+  return *this;
+}
+
+/// Clear hit content
+MyTrackerHit& MyTrackerHit::clear() {
+  position.SetXYZ(0, 0, 0);
+  momentum.SetXYZ(0, 0, 0);
+  length = 0.0;
+  truth.clear();
+  return *this;
+}
+
+/// Store Geant4 point and step information into tracker hit structure.
+MyTrackerHit& MyTrackerHit::storePoint(const G4Step* step, const G4StepPoint* pnt) {
+  G4Track* trk = step->GetTrack();
+  G4ThreeVector pos = pnt->GetPosition();
+  G4ThreeVector mom = pnt->GetMomentum();
+
+  truth.trackID = trk->GetTrackID();
+  truth.pdgID   = trk->GetDefinition()->GetPDGEncoding();
+  truth.deposit = step->GetTotalEnergyDeposit();
+  truth.time    = trk->GetGlobalTime();
+  position.SetXYZ(pos.x(), pos.y(), pos.z());
+  momentum.SetXYZ(mom.x(), mom.y(), mom.z());
+  length = 0;
+  return *this;
+}

src/GenericDetectors/pid/sdet/src/MyTrackerSDAction.cpp

+//==========================================================================
+//  AIDA Detector description implementation 
+//--------------------------------------------------------------------------
+// Copyright (C) Organisation europeenne pour la Recherche nucleaire (CERN)
+// All rights reserved.
+//
+// For the licensing terms see $DD4hepINSTALL/LICENSE.
+// For the list of contributors see $DD4hepINSTALL/doc/CREDITS.
+//
+// Author     : M.Frank
+//
+//==========================================================================
+
+// Framework include files
+#include "MyTrackerHit.h"
+#include "DDG4/Geant4SensDetAction.inl"
+#include "DDG4/Factories.h"
+
+//using namespace CLHEP;
+
+namespace SomeExperiment {
+
+  class MyTrackerSD {
+  public:
+    typedef MyTrackerHit Hit;
+    // If we need special data to personalize the action, be put it here
+    int mumDeposits = 0;
+    double integratedDeposit = 0;
+  };
+}
+
+/// Namespace for the AIDA detector description toolkit
+namespace dd4hep {
+
+  /// Namespace for the Geant4 based simulation part of the AIDA detector description toolkit
+  namespace sim   {
+
+    using namespace SomeExperiment;
+    
+    // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+    //               Geant4SensitiveAction<MyTrackerSD>
+    // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+    /** \addtogroup Geant4SDActionPlugin
+     *
+     * @{
+     * \package MyTrackerSDAction
+     * \brief Sensitive detector meant for tracking detectors, will produce one hit per step
+     *
+     * @}
+     */
+
+    /// Define collections created by this sensitivie action object
+    template <> void Geant4SensitiveAction<MyTrackerSD>::defineCollections()    {
+      m_collectionID = declareReadoutFilteredCollection<MyTrackerSD::Hit>();
+    }
+
+    /// Method for generating hit(s) using the information of G4Step object.
+    template <> bool Geant4SensitiveAction<MyTrackerSD>::process(G4Step* step,G4TouchableHistory* /*hist*/ ) {
+      Geant4StepHandler h(step);
+      Position prePos    = h.prePos();
+      Position postPos   = h.postPos();
+      Position direction = postPos - prePos;
+      Position position  = mean_direction(prePos,postPos);
+      double   hit_len   = direction.R();
+
+      // Somehow extract here the physics you want
+      MyTrackerSD::Hit* hit = new MyTrackerSD::Hit(h.trkID(), h.trkPdgID(), h.deposit(), h.track->GetGlobalTime());
+      Geant4HitData::MonteCarloContrib contrib = Geant4HitData::extractContribution(step);
+      hit->cellID        = cellID(step);
+      hit->energyDeposit = contrib.deposit;
+      hit->position      = position;
+      hit->momentum      = 0.5*(h. preMom() + h.postMom());
+      hit->length        = hit_len;
+      collection(m_collectionID)->add(hit);
+      mark(h.track);
+      if ( 0 == hit->cellID )  {
+        hit->cellID        = volumeID(step);
+        except("+++ Invalid CELL ID for hit!");
+      }
+      printP1("Hit with deposit:%f  Pos:%f %f %f ID=%016X",
+            step->GetTotalEnergyDeposit(),position.X(),position.Y(),position.Z(),
+            (void*)hit->cellID);
+      Geant4TouchableHandler handler(step);
+      print("    Geant4 path:%s",handler.path().c_str());
+
+      // Do something with my personal data (can be also something more clever ;-):
+      m_userData.integratedDeposit += contrib.deposit;
+      ++m_userData.mumDeposits;
+      return true;
+    }
+
+  }
+}
+
+//--- Factory declaration
+namespace dd4hep { namespace sim {
+    typedef Geant4SensitiveAction<MyTrackerSD> MyTrackerSDAction;
+  }}
+DECLARE_GEANT4SENSITIVE(MyTrackerSDAction)

src/GenericDetectors/pid/sdet/src/PhotoMultiplierHit.cpp

+//==========================================================================
+//  AIDA Detector description implementation 
+//--------------------------------------------------------------------------
+// Copyright (C) Organisation europeenne pour la Recherche nucleaire (CERN)
+// All rights reserved.
+//
+// For the licensing terms see $DD4hepINSTALL/LICENSE.
+// For the list of contributors see $DD4hepINSTALL/doc/CREDITS.
+//
+// Author     : Whitney Armstrong
+//
+//==========================================================================
+
+#include "PhotoMultiplierHit.h"
+#include "G4Track.hh"
+
+using namespace npdet;
+
+/// Assignment operator
+PhotoMultiplierHit& PhotoMultiplierHit::operator=(const PhotoMultiplierHit& c)  {
+  if ( &c != this )  {
+    position = c.position;
+    momentum = c.momentum;
+    length = c.length;
+    truth = c.truth;
+    energy = c.energy;
+  }
+  return *this;
+}
+
+/// Clear hit content
+PhotoMultiplierHit& PhotoMultiplierHit::clear() {
+  position.SetXYZ(0, 0, 0);
+  momentum.SetXYZ(0, 0, 0);
+  energy = 0.0;
+  length = 0.0;
+  truth.clear();
+  return *this;
+}
+
+/// Store Geant4 point and step information into tracker hit structure.
+PhotoMultiplierHit& PhotoMultiplierHit::storePoint(const G4Step* step, const G4StepPoint* pnt) {
+  G4Track* trk = step->GetTrack();
+  G4ThreeVector pos = pnt->GetPosition();
+  G4ThreeVector mom = pnt->GetMomentum();
+
+  truth.trackID = trk->GetTrackID();
+  truth.pdgID   = trk->GetDefinition()->GetPDGEncoding();
+  truth.deposit = step->GetTotalEnergyDeposit();
+  truth.time    = trk->GetGlobalTime();
+  position.SetXYZ(pos.x(), pos.y(), pos.z());
+  momentum.SetXYZ(mom.x(), mom.y(), mom.z());
+  length = 0;
+  energy = pnt->GetTotalEnergy();
+  return *this;
+}

src/GenericDetectors/pid/sdet/src/PhotoMultiplierSDAction.cpp

+//==========================================================================
+//  AIDA Detector description implementation 
+//--------------------------------------------------------------------------
+// Copyright (C) Organisation europeenne pour la Recherche nucleaire (CERN)
+// All rights reserved.
+//
+// For the licensing terms see $DD4hepINSTALL/LICENSE.
+// For the list of contributors see $DD4hepINSTALL/doc/CREDITS.
+//
+// Author     : M.Frank
+//
+//==========================================================================
+
+// Framework include files
+#include "PhotoMultiplierHit.h"
+#include "DDG4/Geant4SensDetAction.inl"
+#include "DDG4/Factories.h"
+
+//using namespace CLHEP;
+
+namespace npdet {
+
+  class PhotoMultiplierSD {
+  public:
+    using Hit            = PhotoMultiplierHit;
+    int    nPhotons      = 0;
+    double averageEnergy = 0;
+  };
+}
+
+/// Namespace for the AIDA detector description toolkit
+namespace dd4hep {
+
+  /// Namespace for the Geant4 based simulation part of the AIDA detector description toolkit
+  namespace sim   {
+
+    using namespace npdet;
+    
+    // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+    //               Geant4SensitiveAction<PhotoMultiplierSD>
+    // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+    /** \addtogroup Geant4SDActionPlugin
+     *
+     * @{
+     * \package PhotoMultiplierSDAction
+     * \brief Sensitive detector meant for photon counting detectors, will produce one hit per step
+     *
+     * @}
+     */
+
+    /// Define collections created by this sensitivie action object
+    template <> void Geant4SensitiveAction<PhotoMultiplierSD>::defineCollections()    {
+      m_collectionID = declareReadoutFilteredCollection<PhotoMultiplierSD::Hit>();
+    }
+
+    /// Method for generating hit(s) using the information of G4Step object.
+    template <> bool Geant4SensitiveAction<PhotoMultiplierSD>::process(G4Step* step,G4TouchableHistory* /*hist*/ ) {
+      Geant4StepHandler h(step);
+      Position prePos    = h.prePos();
+      Position postPos   = h.postPos();
+      Position direction = postPos - prePos;
+      Position position  = mean_direction(prePos,postPos);
+      double   hit_len   = direction.R();
+
+      // Somehow extract here the physics you want
+      PhotoMultiplierSD::Hit* hit = new PhotoMultiplierSD::Hit(h.trkID(), h.trkPdgID(), h.deposit(), h.track->GetGlobalTime());
+      Geant4HitData::MonteCarloContrib contrib = Geant4HitData::extractContribution(step);
+      hit->cellID        = cellID(step);
+      hit->energy        = contrib.deposit;
+      hit->position      = position;
+      hit->momentum      = 0.5*(h. preMom() + h.postMom());
+      hit->length        = hit_len;
+      collection(m_collectionID)->add(hit);
+      mark(h.track);
+      if ( 0 == hit->cellID )  {
+        hit->cellID        = volumeID(step);
+        except("+++ Invalid CELL ID for hit!");
+      }
+      printP1("Hit with deposit:%f  Pos:%f %f %f ID=%016X",
+            step->GetTotalEnergyDeposit(),position.X(),position.Y(),position.Z(),
+            (void*)hit->cellID);
+      Geant4TouchableHandler handler(step);
+      print("    Geant4 path:%s",handler.path().c_str());
+
+      // Do something with my personal data (can be also something more clever ;-):
+      m_userData.averageEnergy += contrib.deposit;
+      ++m_userData.nPhotons;
+      return true;
+    }
+
+  }
+}
+
+//--- Factory declaration
+namespace dd4hep { namespace sim {
+    //typedef Geant4SensitiveAction<PhotoMultiplierSD> PhotoMultiplierSDAction;
+    using PhotoMultiplierSDAction = Geant4SensitiveAction<PhotoMultiplierSD>;
+  }}
+DECLARE_GEANT4SENSITIVE(PhotoMultiplierSDAction)