GEANT4 crash with logicDetector->SetSensitiveDetector

Good morning,

I’m using GEANT4 (10.07.p03) on an Ubuntu 20 (LTS) WSL. I’m following this youtube tutorial Geant4 Tutorial 7: Inserting Sensitive Detectors - YouTube
in order to get more familiar with this software.

I created the detector geometry as a matrix of pixels in this way:

#include "geometry.hh"

MyDetectorConstruction::MyDetectorConstruction()
{}

MyDetectorConstruction::~MyDetectorConstruction()
{}

G4VPhysicalVolume *MyDetectorConstruction::Construct()
{
	G4NistManager *nist = G4NistManager::Instance();

	//material definition for the particle detector
	//mixture arguments: name, density, number of components
	G4Material *SiO2 = new G4Material("SiO2", 2.201*g/cm3, 2);
	//add elements to the mixture with the molecula quantity
	SiO2->AddElement(nist->FindOrBuildElement("Si"), 1);
	SiO2->AddElement(nist->FindOrBuildElement("O"), 2);

	G4Material *H2O = new G4Material("H2O", 1.000*g/cm3, 2);
	H2O->AddElement(nist->FindOrBuildElement("H"), 2);
	H2O->AddElement(nist->FindOrBuildElement("O"), 1);

	G4Element *C = nist->FindOrBuildElement("C");

	G4Material *Aerogel = new G4Material("Aerogel",0.200*g/cm3,3);
	Aerogel->AddMaterial(SiO2, 62.5*perCent);
	Aerogel->AddMaterial(H2O, 37.4*perCent);
	Aerogel->AddElement(C, 0.1*perCent);
	
	//optical properties for two different wavelenght: 200 and 900 nm
	G4double energy[2] = {1.239841939*eV/0.2, 1.239841939*eV/0.9}; //momentum of cherenkov photons (but for photons momentum == energy)
	G4double rindexAerogel[2] = {1.1, 1.1}; //refrective index of Aerogel
	G4double rindexWorld[2] = {1.0, 1.0}; //refrective index of world
	
	//add optical property of detector
	G4MaterialPropertiesTable *mptAerogel = new G4MaterialPropertiesTable();
	mptAerogel->AddProperty("RINDEX", energy,  rindexAerogel, 2); //the last argument is the size of "energy[2]"
	//address the refrective index to the material (Aerogel)	
	Aerogel->SetMaterialPropertiesTable(mptAerogel);
	
	//material definition for the mother volume
	G4Material *worldMat = nist->FindOrBuildMaterial("G4_AIR");
	
	//in order to propagate the photons also outside of the detector I have to define the opt properties also for the world
	G4MaterialPropertiesTable *mptWorld = new G4MaterialPropertiesTable();
	mptWorld->AddProperty("RINDEX", energy,  rindexWorld, 2); //the last argument is the size of "energy[2]"
	//address the refrective index to the material (Aerogel)	
	worldMat->SetMaterialPropertiesTable(mptWorld);
	
	//each volume in GEANT4 is composed by 3 parts: solid (e.g. size, etc.), logical (e.g. material, etc.) and physical (e.g. rotation, translation, etc.) 
	//solid 
	//arguments: half size in x-y-z directions
	G4Box *solidWorld = new G4Box("solidWorld", 0.5*m, 0.5*m, 0.5*m);
	//logical
	//arguments: solid volume name, material, name
	G4LogicalVolume *logicWorld = new G4LogicalVolume(solidWorld, worldMat, "logicWorld");
	//physical
	//arguments: rotation, center of SR, logical volume, name, mother volume, (boolean?), index of volume, check the overlaps
	G4VPhysicalVolume *physWorld = new G4PVPlacement(0, G4ThreeVector(0.,0.,0.), logicWorld, "physWorld", 0, false, 0, true);

	//build the detector
	G4Box *solidRadiator = new G4Box("solidRadiator", 0.4*m, 0.4*m, 0.01*m);
	G4LogicalVolume *logicRadiator = new G4LogicalVolume(solidRadiator, Aerogel, "logicalRadiator");
	G4VPhysicalVolume *physRadiator = new G4PVPlacement(0, G4ThreeVector(0.,0.,0.25*m), logicRadiator, "physRadiator", logicWorld, false, 0, true); //it is a part of the mother world, thus: 0 --> logicWorld

	//build a matrix of sensors detector
	G4Box *solidDetector = new G4Box("solidDetector", 0.005*m, 0.005*m, 0.01*m);
	logicDetector = new G4LogicalVolume(solidDetector, worldMat, "logicDetector");
	for(G4int i = 0; i<100; i++){
		for(G4int j = 0; j<100; j++){
			G4VPhysicalVolume *physDetector = new G4PVPlacement(0, G4ThreeVector(-0.5*m+(i+0.5)*m/100,-0.5*m+(j+0.5)*m/100,0.49*m), logicDetector, "physDetector", logicWorld, false, j+i*100, true);
		}
	}

	return physWorld;
	

}


//function to implement the detector sensitivity and (in case) electric/magnetic fields
void MyDetectorConstruction::ConstructSDandField()
{
    MySensitiveDetector *sensDet = new MySensitiveDetector("SensitiveDetector");

    if(logicDetector != NULL){
    	logicDetector->SetSensitiveDetector(sensDet);
    }
}

The last function of the code above defines "MySensitiveDetector *sensDet " which is defined in the following class:

#include "detector.hh"

MySensitiveDetector::MySensitiveDetector(G4String name) : G4VSensitiveDetector(name)
{}

MySensitiveDetector::~MySensitiveDetector()
{}

//function to access to particle information (like position, momentum, etc.)
G4bool MySensitiveDetector::ProcessHits(G4Step *aStep, G4TouchableHistory *ROhist)
{

	//we need to track the photons
	G4Track *track = aStep->GetTrack();

	track->SetTrackStatus(fStopAndKill);

	//access to information of photons that enter in the detector
    G4StepPoint *preStepPoint = aStep->GetPreStepPoint();
	//access to information of photons that leave in the detector
    G4StepPoint *postStepPoint = aStep->GetPostStepPoint();

    G4ThreeVector posPhoton = preStepPoint->GetPosition();
    G4ThreeVector momPhoton = preStepPoint->GetMomentum();

	G4cout << "Photon position: " << posPhoton << G4endl;

	//to know the number (index) of the detector hit
	const G4VTouchable *touchable = aStep->GetPreStepPoint()->GetTouchable();

    G4int copyNo = touchable->GetCopyNumber();

}

I can compile and build the geometry without problems but if I run the simulation it will crash if the last line of the file geometry.cc:

logicDetector->SetSensitiveDetector(sensDet);

is uncommented. If I comment that line the simulation works. Does someone has some ideas of this bug?

I’m also available to send the entire project, but unfortunately I can’t share here because it contains more than 5 files and I can’t upload a .zip file.

Thank you in advance,
Lorenzo

1 Like

Hi Lorenzo

I have not looked into this…but I want to discourage users from relying on unauthorised YouTube videos. I principle, videos are a great resource, but they are not trivial to produce (I admire those who try) and even less easy to keep up to date. So the only reliable place to look is the official documentation at https://geant4.web.cern.ch.

I hope you get some more positive feedback nevertheless.

John

It crashes, but with what error message, if any?

I would guess, despite the check for NULL (but it is better to use the C++11 nullptr keyword there is a null pointer somewhere. That can be checked by G4couting the values, or better in a debugging tool such as gdb. Its documentation is verbose but complete, but there are a ton of tutorials online about using it from simple to advanced.

Thank a lot for you replay. This is the output of the simulation:

### Birks coefficients used in run time
Available UI session types: [ Qt, GAG, tcsh, csh ]
qt.qpa.xcb: X server does not support XInput 2
failed to get the current screen resources
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-lscavarda'
Visualization Manager instantiating with verbosity "warnings (3)"...
Visualization Manager initialising...
Registering graphics systems...

You have successfully registered the following graphics systems.
Registered graphics systems are:
  ASCIITree (ATree)
  DAWNFILE (DAWNFILE)
  G4HepRep (HepRepXML)
  G4HepRepFile (HepRepFile)
  RayTracer (RayTracer)
  VRML1FILE (VRML1FILE)
  VRML2FILE (VRML2FILE)
  gMocrenFile (gMocrenFile)
  OpenGLImmediateQt (OGLIQt, OGLI)
  OpenGLStoredQt (OGLSQt, OGL, OGLS)
  OpenGLImmediateX (OGLIX, OGLIQt_FALLBACK)
  OpenGLStoredX (OGLSX, OGLSQt_FALLBACK)
  RayTracerX (RayTracerX)

Registering model factories...

You have successfully registered the following model factories.
Registered model factories:
  generic
  drawByAttribute
  drawByCharge
  drawByOriginVolume
  drawByParticleID
  drawByEncounteredVolume

Registered models:
  None

Registered filter factories:
  attributeFilter
  chargeFilter
  originVolumeFilter
  particleFilter
  encounteredVolumeFilter

Registered filters:
  None

You have successfully registered the following user vis actions.
Run Duration User Vis Actions: none
End of Event User Vis Actions: none
End of Run User Vis Actions: none

Some /vis commands (optionally) take a string to specify colour.
"/vis/list" to see available colours.
/tracking/storeTrajectory 2
Attributes available for modeling and filtering with
  "/vis/modeling/trajectories/create/drawByAttribute" and
  "/vis/filtering/trajectories/create/attributeFilter" commands:
G4TrajectoriesModel:
  Event ID (EventID): G4int
  Run ID (RunID): G4int
G4SmoothTrajectory:
  Charge (Ch): unit: e+ (G4double)
  Track ID (ID): G4int
  Initial kinetic energy (IKE): G4BestUnit (G4double)
  Initial momentum magnitude (IMag): G4BestUnit (G4double)
  Initial momentum (IMom): G4BestUnit (G4ThreeVector)
  No. of points (NTP): G4int
  PDG Encoding (PDG): G4int
  Parent ID (PID): G4int
  Particle Name (PN): G4String
G4SmoothTrajectoryPoint:
  Auxiliary Point Position (Aux): G4BestUnit (G4ThreeVector)
  Step Position (Pos): G4BestUnit (G4ThreeVector)
WARNING: Trajectory storing has been requested.  This action may be
  reversed with "/tracking/storeTrajectory 0".
WARNING: The vis manager will keep up to 100 events.
  This may use a lot of memory.
  It may be changed with, e.g., "/vis/scene/endOfEventAction accumulate 10".
qt.qpa.xcb: QXcbConnection: XCB error: 1 (BadRequest), sequence: 164, resource id: 90, major code: 130 (Unknown), minor code: 47
qt.qpa.xcb: QXcbConnection: XCB error: 170 (Unknown), sequence: 177, resource id: 90, major code: 146 (Unknown), minor code: 20

phot:  for gamma SubType=12 BuildTable=0
      LambdaPrime table from 200 keV to 100 TeV in 61 bins
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
 LivermorePhElectric : Emin=    0 eV  Emax=  100 TeV  SauterGavrila Fluo

compt:  for gamma SubType=13 BuildTable=1
      Lambda table from 100 eV  to 1 MeV, 7 bins/decade, spline: 1
      LambdaPrime table from 1 MeV to 100 TeV in 56 bins
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
       Klein-Nishina : Emin=    0 eV  Emax=  100 TeV

conv:  for gamma SubType=14 BuildTable=1
      Lambda table from 1.022 MeV to 100 TeV, 18 bins/decade, spline: 1
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
     BetheHeitlerLPM : Emin=    0 eV  Emax=  100 TeV  ModifiedTsai

Rayl:  for gamma SubType=11 BuildTable=1
      Lambda table from 100 eV  to 100 keV, 7 bins/decade, spline: 0
      LambdaPrime table from 100 keV to 100 TeV in 63 bins
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
   LivermoreRayleigh : Emin=    0 eV  Emax=  100 TeV  CullenGenerator

msc:  for e-  SubType= 10
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
            UrbanMsc : Emin=    0 eV  Emax=  100 MeV Nbins=42 100 eV  - 100 MeV
              StepLim=UseSafety Rfact=0.04 Gfact=2.5 Sfact=0.6 DispFlag:1 Skin=1 Llimit=1
        WentzelVIUni : Emin=  100 MeV Emax=  100 TeV Nbins=42 100 MeV - 100 TeV
              StepLim=UseSafety Rfact=0.04 Gfact=2.5 Sfact=0.6 DispFlag:1 Skin=1 Llimit=1

eIoni:  for e-  SubType=2
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      StepFunction=(0.2, 1 mm), integ: 1, fluct: 1, linLossLim= 0.01
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
        MollerBhabha : Emin=    0 eV  Emax=  100 TeV

eBrem:  for e-  SubType=3
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      LPM flag: 1 for E > 1 GeV,  VertexHighEnergyTh(GeV)= 100000
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
             eBremSB : Emin=    0 eV  Emax=    1 GeV  ModifiedTsai
            eBremLPM : Emin=    1 GeV Emax=  100 TeV  ModifiedTsai

CoulombScat:  for e-, integral:1  SubType=1 BuildTable=1
      Lambda table from 100 MeV to 100 TeV, 7 bins/decade, spline: 1
      ThetaMin(p) < Theta(degree) < 180; pLimit(GeV^1)= 0.139531
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
  eCoulombScattering : Emin=  100 MeV Emax=  100 TeV

msc:  for e+  SubType= 10
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
            UrbanMsc : Emin=    0 eV  Emax=  100 MeV Nbins=42 100 eV  - 100 MeV
              StepLim=UseSafety Rfact=0.04 Gfact=2.5 Sfact=0.6 DispFlag:1 Skin=1 Llimit=1
        WentzelVIUni : Emin=  100 MeV Emax=  100 TeV Nbins=42 100 MeV - 100 TeV
              StepLim=UseSafety Rfact=0.04 Gfact=2.5 Sfact=0.6 DispFlag:1 Skin=1 Llimit=1

eIoni:  for e+  SubType=2
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      StepFunction=(0.2, 1 mm), integ: 1, fluct: 1, linLossLim= 0.01
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
        MollerBhabha : Emin=    0 eV  Emax=  100 TeV

eBrem:  for e+  SubType=3
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      LPM flag: 1 for E > 1 GeV,  VertexHighEnergyTh(GeV)= 100000
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
             eBremSB : Emin=    0 eV  Emax=    1 GeV  ModifiedTsai
            eBremLPM : Emin=    1 GeV Emax=  100 TeV  ModifiedTsai

annihil:  for e+, integral:1  SubType=5 BuildTable=0
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
            eplus2gg : Emin=    0 eV  Emax=  100 TeV

CoulombScat:  for e+, integral:1  SubType=1 BuildTable=1
      Lambda table from 100 MeV to 100 TeV, 7 bins/decade, spline: 1
      ThetaMin(p) < Theta(degree) < 180; pLimit(GeV^1)= 0.139531
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
  eCoulombScattering : Emin=  100 MeV Emax=  100 TeV

msc:  for proton  SubType= 10
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
        WentzelVIUni : Emin=    0 eV  Emax=  100 TeV Nbins=84 100 eV  - 100 TeV
              StepLim=Minimal Rfact=0.2 Gfact=2.5 Sfact=0.6 DispFlag:0 Skin=1 Llimit=1

hIoni:  for proton  SubType=2
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      StepFunction=(0.2, 0.1 mm), integ: 1, fluct: 1, linLossLim= 0.01
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
               Bragg : Emin=    0 eV  Emax=    2 MeV
          BetheBloch : Emin=    2 MeV Emax=  100 TeV

hBrems:  for proton  SubType=3
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
               hBrem : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

hPairProd:  for proton  SubType=4
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      Sampling table 17x1001; from 7.50618 GeV to 100 TeV
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
           hPairProd : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

CoulombScat:  for proton, integral:1  SubType=1 BuildTable=1
      Lambda table from threshold  to 100 TeV, 7 bins/decade, spline: 1
      ThetaMin(p) < Theta(degree) < 180; pLimit(GeV^1)= 0.139531
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
  eCoulombScattering : Emin=    0 eV  Emax=  100 TeV

msc:  for GenericIon  SubType= 10
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
            UrbanMsc : Emin=    0 eV  Emax=  100 TeV
              StepLim=Minimal Rfact=0.2 Gfact=2.5 Sfact=0.6 DispFlag:0 Skin=1 Llimit=1

ionIoni:  for GenericIon  SubType=2
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      StepFunction=(0.2, 0.1 mm), integ: 1, fluct: 1, linLossLim= 0.02
      Stopping Power data for 17 ion/material pairs
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
            BraggIon : Emin=    0 eV  Emax=    2 MeV
          BetheBloch : Emin=    2 MeV Emax=  100 TeV

msc:  for alpha  SubType= 10
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
            UrbanMsc : Emin=    0 eV  Emax=  100 TeV Nbins=84 100 eV  - 100 TeV
              StepLim=Minimal Rfact=0.2 Gfact=2.5 Sfact=0.6 DispFlag:0 Skin=1 Llimit=1

ionIoni:  for alpha  SubType=2
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      StepFunction=(0.2, 0.1 mm), integ: 1, fluct: 1, linLossLim= 0.02
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
            BraggIon : Emin=    0 eV  Emax=7.9452 MeV
          BetheBloch : Emin=7.9452 MeV Emax=  100 TeV

msc:  for anti_proton  SubType= 10
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
        WentzelVIUni : Emin=    0 eV  Emax=  100 TeV Nbins=84 100 eV  - 100 TeV
              StepLim=Minimal Rfact=0.2 Gfact=2.5 Sfact=0.6 DispFlag:0 Skin=1 Llimit=1

hIoni:  for anti_proton  SubType=2
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      StepFunction=(0.2, 0.1 mm), integ: 1, fluct: 1, linLossLim= 0.01
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
            ICRU73QO : Emin=    0 eV  Emax=    2 MeV
          BetheBloch : Emin=    2 MeV Emax=  100 TeV

hBrems:  for anti_proton  SubType=3
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
               hBrem : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

hPairProd:  for anti_proton  SubType=4
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      Sampling table 17x1001; from 7.50618 GeV to 100 TeV
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
           hPairProd : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

CoulombScat:  for anti_proton, integral:1  SubType=1 BuildTable=1
      Lambda table from threshold  to 100 TeV, 7 bins/decade, spline: 1
      ThetaMin(p) < Theta(degree) < 180; pLimit(GeV^1)= 0.139531
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
  eCoulombScattering : Emin=    0 eV  Emax=  100 TeV

msc:  for kaon+  SubType= 10
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
        WentzelVIUni : Emin=    0 eV  Emax=  100 TeV Nbins=84 100 eV  - 100 TeV
              StepLim=Minimal Rfact=0.2 Gfact=2.5 Sfact=0.6 DispFlag:0 Skin=1 Llimit=1

hIoni:  for kaon+  SubType=2
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      StepFunction=(0.2, 0.1 mm), integ: 1, fluct: 1, linLossLim= 0.01
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
               Bragg : Emin=    0 eV  Emax=1.05231 MeV
          BetheBloch : Emin=1.05231 MeV Emax=  100 TeV

hBrems:  for kaon+  SubType=3
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
               hBrem : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

hPairProd:  for kaon+  SubType=4
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      Sampling table 18x1001; from 3.94942 GeV to 100 TeV
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
           hPairProd : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

CoulombScat:  for kaon+, integral:1  SubType=1 BuildTable=1
      Lambda table from threshold  to 100 TeV, 7 bins/decade, spline: 1
      ThetaMin(p) < Theta(degree) < 180; pLimit(GeV^1)= 0.139531
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
  eCoulombScattering : Emin=    0 eV  Emax=  100 TeV

msc:  for kaon-  SubType= 10
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
        WentzelVIUni : Emin=    0 eV  Emax=  100 TeV Nbins=84 100 eV  - 100 TeV
              StepLim=Minimal Rfact=0.2 Gfact=2.5 Sfact=0.6 DispFlag:0 Skin=1 Llimit=1

hIoni:  for kaon-  SubType=2
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      StepFunction=(0.2, 0.1 mm), integ: 1, fluct: 1, linLossLim= 0.01
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
            ICRU73QO : Emin=    0 eV  Emax=1.05231 MeV
          BetheBloch : Emin=1.05231 MeV Emax=  100 TeV

hBrems:  for kaon-  SubType=3
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
               hBrem : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

hPairProd:  for kaon-  SubType=4
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      Sampling table 18x1001; from 3.94942 GeV to 100 TeV
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
           hPairProd : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

CoulombScat:  for kaon-, integral:1  SubType=1 BuildTable=1
      Used Lambda table of kaon+
      ThetaMin(p) < Theta(degree) < 180; pLimit(GeV^1)= 0.139531
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
  eCoulombScattering : Emin=    0 eV  Emax=  100 TeV

msc:  for mu+  SubType= 10
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
        WentzelVIUni : Emin=    0 eV  Emax=  100 TeV Nbins=84 100 eV  - 100 TeV
              StepLim=Minimal Rfact=0.2 Gfact=2.5 Sfact=0.6 DispFlag:0 Skin=1 Llimit=1

muIoni:  for mu+  SubType=2
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      StepFunction=(0.2, 0.1 mm), integ: 1, fluct: 1, linLossLim= 0.01
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
               Bragg : Emin=    0 eV  Emax=  200 keV
          BetheBloch : Emin=  200 keV Emax=    1 GeV
        MuBetheBloch : Emin=    1 GeV Emax=  100 TeV

muBrems:  for mu+  SubType=3
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
              MuBrem : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

muPairProd:  for mu+  SubType=4
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      Sampling table 21x1001; from 1 GeV to 100 TeV
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
          muPairProd : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

CoulombScat:  for mu+, integral:1  SubType=1 BuildTable=1
      Lambda table from threshold  to 100 TeV, 7 bins/decade, spline: 1
      ThetaMin(p) < Theta(degree) < 180; pLimit(GeV^1)= 0.139531
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
  eCoulombScattering : Emin=    0 eV  Emax=  100 TeV

msc:  for mu-  SubType= 10
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
        WentzelVIUni : Emin=    0 eV  Emax=  100 TeV Nbins=84 100 eV  - 100 TeV
              StepLim=Minimal Rfact=0.2 Gfact=2.5 Sfact=0.6 DispFlag:0 Skin=1 Llimit=1

muIoni:  for mu-  SubType=2
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      StepFunction=(0.2, 0.1 mm), integ: 1, fluct: 1, linLossLim= 0.01
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
            ICRU73QO : Emin=    0 eV  Emax=  200 keV
          BetheBloch : Emin=  200 keV Emax=    1 GeV
        MuBetheBloch : Emin=    1 GeV Emax=  100 TeV

muBrems:  for mu-  SubType=3
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
              MuBrem : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

muPairProd:  for mu-  SubType=4
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      Sampling table 21x1001; from 1 GeV to 100 TeV
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
          muPairProd : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

CoulombScat:  for mu-, integral:1  SubType=1 BuildTable=1
      Used Lambda table of mu+
      ThetaMin(p) < Theta(degree) < 180; pLimit(GeV^1)= 0.139531
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
  eCoulombScattering : Emin=    0 eV  Emax=  100 TeV

msc:  for pi+  SubType= 10
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
        WentzelVIUni : Emin=    0 eV  Emax=  100 TeV Nbins=84 100 eV  - 100 TeV
              StepLim=Minimal Rfact=0.2 Gfact=2.5 Sfact=0.6 DispFlag:0 Skin=1 Llimit=1

hIoni:  for pi+  SubType=2
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      StepFunction=(0.2, 0.1 mm), integ: 1, fluct: 1, linLossLim= 0.01
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
               Bragg : Emin=    0 eV  Emax=297.505 keV
          BetheBloch : Emin=297.505 keV Emax=  100 TeV

hBrems:  for pi+  SubType=3
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
               hBrem : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

hPairProd:  for pi+  SubType=4
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      Sampling table 20x1001; from 1.11656 GeV to 100 TeV
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
           hPairProd : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

CoulombScat:  for pi+, integral:1  SubType=1 BuildTable=1
      Lambda table from threshold  to 100 TeV, 7 bins/decade, spline: 1
      ThetaMin(p) < Theta(degree) < 180; pLimit(GeV^1)= 0.139531
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
  eCoulombScattering : Emin=    0 eV  Emax=  100 TeV

msc:  for pi-  SubType= 10
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
        WentzelVIUni : Emin=    0 eV  Emax=  100 TeV Nbins=84 100 eV  - 100 TeV
              StepLim=Minimal Rfact=0.2 Gfact=2.5 Sfact=0.6 DispFlag:0 Skin=1 Llimit=1

hIoni:  for pi-  SubType=2
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      StepFunction=(0.2, 0.1 mm), integ: 1, fluct: 1, linLossLim= 0.01
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
            ICRU73QO : Emin=    0 eV  Emax=297.505 keV
          BetheBloch : Emin=297.505 keV Emax=  100 TeV

hBrems:  for pi-  SubType=3
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
               hBrem : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

hPairProd:  for pi-  SubType=4
      dE/dx and range tables from 100 eV  to 100 TeV in 84 bins
      Lambda tables from threshold to 100 TeV, 7 bins/decade, spline: 1
      Sampling table 20x1001; from 1.11656 GeV to 100 TeV
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
           hPairProd : Emin=    0 eV  Emax=  100 TeV  ModifiedMephi

CoulombScat:  for pi-, integral:1  SubType=1 BuildTable=1
      Used Lambda table of pi+
      ThetaMin(p) < Theta(degree) < 180; pLimit(GeV^1)= 0.139531
      ===== EM models for the G4Region  DefaultRegionForTheWorld ======
  eCoulombScattering : Emin=    0 eV  Emax=  100 TeV
G4VisManager: Using G4TrajectoryDrawByCharge as fallback trajectory model.
See commands in /vis/modeling/trajectories/ for other options.
G4ParticleGun::geantino
 was defined in terms of KineticEnergy: 1GeV
 is now defined in terms Momentum: 100GeV/c
Segmentation fault (core dumped) 

Do you see something strange?

Anyway I agree with you about the null pointer. However, since commenting that line the code works, I guess that the problem should be either with *sensDet or logicDetector . But I’m not spotting out the bug. The very strange thing is that I tried to run the same file on a centOS 7 machine with a GEANT4 version of 10.05.p01 and it works. So, I’m thinking that there is something trickier…

There is an alternative way to define a sensitive detector, with an extra argument for “multi”… you could try this and see if it helps:

    auto sdm = G4SDManager::GetSDMpointer();

    // sensorchip
    MySensitiveDetector *sensDet = new MySensitiveDetector("SensitiveDetector");
    sdm->AddNewDetector(sensDet);
    SetSensitiveDetector("logicDetector", sensDet , true);

besides that, either use gdb to see where the nullpointer dereferencing happens, or go line by line in your ProcessHits: comment out all lines, and add them one by one and see when the crash comes.

This line activates a complete block of code in your application. you do not consider this in your conclusion :wink:

Hi Weller, thanks a lot for your replay.

I tried to comment all the lines in

G4bool MySensitiveDetector::ProcessHits(G4Step *aStep, G4TouchableHistory *ROhist)

but it crashes anyway. For this reason I said that probably is something related with the line

logicDetector->SetSensitiveDetector(sensDet);

I tought also to look for the bug inside the GEANT4 function:

// ********************************************************************
// SetSensitiveDetector
// ********************************************************************
//
void G4LogicalVolume::SetSensitiveDetector(G4VSensitiveDetector* pSDetector)
{
  G4MT_sdetector = pSDetector;
  if (G4Threading::IsMasterThread())  { fSensitiveDetector = pSDetector; }
}

but if I add simple print outs there I should recompile all GEANT4. I don’t think is the best solution.

Anyway, I could try with your code. I’m just wondering, should I replace my function:

void MyDetectorConstruction::ConstructSDandField()
{
    MySensitiveDetector *sensDet = new MySensitiveDetector("SensitiveDetector");

    if(logicDetector != NULL){
    	logicDetector->SetSensitiveDetector(sensDet);
    }
}

with your lines?
Thanks again,
Lorenzo

thats the idea. fingers crossed :slight_smile:

Nope! Again, same crash :frowning:
In particular is at line:

SetSensitiveDetector("logicDetector", sensDet , true);

I tried to comment all the lines in

G4bool MySensitiveDetector::ProcessHits(G4Step *aStep, G4TouchableHistory *ROhist)

and add a cout in the function:

G4bool MySensitiveDetector::ProcessHits(G4Step *aStep, G4TouchableHistory *ROhist)
{

	G4cout << "MySensitiveDetector::I'M HERE!! " << G4endl;
	// //we need to track the photons
	// G4Track *track = aStep->GetTrack();

	// track->SetTrackStatus(fStopAndKill);

	//access to information of photons that enter in the detector
    // G4StepPoint *preStepPoint = aStep->GetPreStepPoint();
	//access to information of photons that leave in the detector
    // G4StepPoint *postStepPoint = aStep->GetPostStepPoint();

    // G4ThreeVector posPhoton = preStepPoint->GetPosition();
    // G4ThreeVector momPhoton = preStepPoint->GetMomentum();

	// G4cout << "Photon position: " << posPhoton << G4endl;

	//to know the number (index) of the detector hit
	// const G4VTouchable *touchable = aStep->GetPreStepPoint()->GetTouchable();

    // G4int copyNo = touchable->GetCopyNumber();

}

and I noticed that the code doesn’t crash anymore but it goes in an infinite loop and I have to kill it by myself. Could there be a bug inside this function as you proposed? Do you have some ideas?

Sorry for all these questions,
Thanks again,
Lorenzo

I spotted the bug!!! It was a really stupid mistake. I forgot to put the

return true;

because it was a G4bool function. Sorry for this but you helped a lot anyway.
Cheers,
Lorenzo

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