Simulation: define PSimHit track Id offset and propagate to MTD hit categories

SimDataFormats/TrackingHit/interface/PSimHit.h

@@ -14,6 +14,8 @@ class TrackingSlaveSD;  // for friend declaration only
 
 class PSimHit {
 public:
+  static constexpr unsigned int k_tidOffset = 200000000;
+
   PSimHit() : theDetUnitId(0) {}
 
   PSimHit(const Local3DPoint& entry,
@@ -105,6 +107,15 @@ class PSimHit {
    */
   unsigned int trackId() const { return theTrackId; }
 
+  /** In case te SimTrack ID is incremented by the k_tidOffset for hit category definition, this
+   * methods returns the original theTrackId value directly.
+   */
+  unsigned int originalTrackId() const { return theTrackId % k_tidOffset; }
+
+  unsigned int offsetTrackId() const { return theTrackId / k_tidOffset; }
+
+  static unsigned int addTrackIdOffset(unsigned int tId, unsigned int offset) { return offset * k_tidOffset + tId; }
+
   EncodedEventId eventId() const { return theEventId; }
 
   void setEventId(EncodedEventId e) { theEventId = e; }

SimG4CMS/Forward/BuildFile.xml

@@ -8,6 +8,7 @@
 <use name="DataFormats/ForwardDetId"/>
 <use name="DataFormats/Math"/>
 <use name="SimDataFormats/SimHitMaker"/>
+<use name="SimDataFormats/TrackingHit"/>
 <use name="SimDataFormats/CaloHit"/>
 <use name="Geometry/MTDCommonData"/>
 <use name="boost"/>

SimG4CMS/Forward/interface/MtdSD.h

@@ -28,9 +28,9 @@ class MtdSD : public TimingSD {
   int getTrackID(const G4Track *) override;
 
 private:
-  static constexpr unsigned int k_idsecOffset = 100000000;
-  static constexpr unsigned int k_idloopOffset = 200000000;
-  static constexpr unsigned int k_idFromCaloOffset = 300000000;
+  static constexpr unsigned int k_idsecOffset = 1;
+  static constexpr unsigned int k_idloopOffset = 2;
+  static constexpr unsigned int k_idFromCaloOffset = 3;
 
   double energyCut;
   double energyHistoryCut;

SimG4CMS/Forward/src/MtdSD.cc

@@ -8,6 +8,7 @@
 #include "Geometry/MTDCommonData/interface/BTLNumberingScheme.h"
 #include "Geometry/MTDCommonData/interface/ETLNumberingScheme.h"
 #include "DataFormats/ForwardDetId/interface/MTDDetId.h"
+#include "SimDataFormats/TrackingHit/interface/PSimHit.h"
 
 #include "G4Track.hh"
 #include "G4Step.hh"
@@ -108,11 +109,11 @@ int MtdSD::getTrackID(const G4Track* aTrack) {
     if (rname == "FastTimerRegionSensBTL") {
       theID = trkInfo->mcTruthID();
       if (trkInfo->isExtSecondary() && !trkInfo->isInTrkFromBackscattering()) {
-        theID += k_idsecOffset;
+        theID = PSimHit::addTrackIdOffset(theID, k_idsecOffset);
       } else if (trkInfo->isInTrkFromBackscattering()) {
-        theID += k_idFromCaloOffset;
+        theID = PSimHit::addTrackIdOffset(theID, k_idFromCaloOffset);
       } else if (trkInfo->isBTLlooper()) {
-        theID += k_idloopOffset;
+        theID = PSimHit::addTrackIdOffset(theID, k_idloopOffset);
       }
 #ifdef EDM_ML_DEBUG
       edm::LogVerbatim("MtdSim") << "MtdSD: Track ID: " << aTrack->GetTrackID()

SimG4Core/Application/test/SimHitCaloHitDumper.cc

@@ -371,7 +371,10 @@ void SimHitCaloHitDumper::analyze(const edm::Event& iEvent, const edm::EventSetu
     edm::LogPrint("SimHitCaloHitDumper") << (*icoll).second << " hits in the event = " << (*icoll).first;
     edm::LogPrint("SimHitCaloHitDumper") << "\n";
     for (int ihit = 0; ihit < (*icoll).first; ++ihit) {
-      edm::LogPrint("SimHitCaloHitDumper") << theMTDHits[nhit] << " Track Id = " << theMTDHits[nhit].trackId();
+      edm::LogPrint("SimHitCaloHitDumper")
+          << theMTDHits[nhit] << " Energy = " << theMTDHits[nhit].energyLoss()
+          << " tid orig/offset= " << theMTDHits[nhit].originalTrackId() << " " << theMTDHits[nhit].offsetTrackId()
+          << " Track Id = " << theMTDHits[nhit].trackId();
       nhit++;
     }
   }

SimG4Core/Notification/BuildFile.xml

@@ -2,6 +2,7 @@
   <lib name="1"/>
 </export>
 <use name="SimDataFormats/Forward"/>
+<use name="SimDataFormats/TrackingHit"/>
 <use name="SimDataFormats/Track"/>
 <use name="SimDataFormats/Vertex"/>
 <use name="DataFormats/Math"/>

SimG4Core/Notification/src/SimTrackManager.cc

@@ -19,6 +19,7 @@
 #include "SimG4Core/Notification/interface/TmpSimVertex.h"
 #include "SimG4Core/Notification/interface/TmpSimEvent.h"
 #include "SimG4Core/Notification/interface/TrackInformation.h"
+#include "SimDataFormats/TrackingHit/interface/PSimHit.h"
 
 #include "FWCore/MessageLogger/interface/MessageLogger.h"
 #include "FWCore/Utilities/interface/Exception.h"
@@ -162,6 +163,10 @@ void SimTrackManager::reallyStoreTracks() {
       }
     }
 
+    if (id >= static_cast<int>(PSimHit::k_tidOffset)) {
+      throw cms::Exception("SimTrackManager::reallyStoreTracks")
+          << " SimTrack ID " << id << " exceeds maximum allowed by PSimHit identifier" << PSimHit::k_tidOffset;
+    }
     TmpSimTrack* g4simtrack =
         new TmpSimTrack(id, trkH->particleID(), trkH->momentum(), trkH->totalEnergy(), ivertex, ig, pm, spos, smom);
     g4simtrack->copyCrossedBoundaryVars(trkH);