I am looking at thermal neutron absorption (and subsequent energy deposition) in a GS20 scintillator containing Si, Al, O, Mg, Li6, Li7, and Ce. My surrounding World is G4Galactic. However, I am seeing N15 as a particle, and I do not know its source. I would like to output the isotope that my particle interacts with so I can get a better picture of the reaction producing this N15.
More detail:
I am expecting to see a spectrum with maximum energy deposited of ~4.7 MeV (Q value of Li6 + n reaction) with some values lower than this due to energy loss of particles leaving the scintillator before depositing energy. However, I have found values above 4.7 MeV
Spectrum.pdf (14.4 KB)
I am trying to hunt down the cause of these high energy depositions to make sure there is not an error in my logic. I am not using a sensitive detector; instead I am tracking each step and accumulating the energy deposited in my scintillator. I have found that there is no overlap between events (multiple neutron interactions counting as one). If I output some step information during the run using the following code:
auto particle = track->GetParticleDefinition()->GetParticleName();
auto run = static_cast<Run*>(G4RunManager::GetRunManager()->GetNonConstCurrentRun());
auto writer = DetectorConstruction::GetWriter();
G4double calcX = 0;
G4double calcY = 0;
auto status = track->GetTrackStatus();
auto posLi = postStep->GetPosition();
auto stepProcess = (G4VProcess*)postStep->GetProcessDefinedStep();
auto preproc = (G4VProcess*)preStep->GetProcessDefinedStep();
auto procName = stepProcess->GetProcessName();
auto name = postPv->GetName();
if (preproc){
std::cout << "Creating Process " << preproc->GetProcessName() << std::endl;}
std::cout << "particle " << particle << std::endl;
std::cout << "process " << procName << std::endl;
std::cout << "kinetic " << track->GetDynamicParticle()->GetKineticEnergy() << std::endl;
std::cout << "edep " << edep << std::endl;
std::cout << "start body " << preStep->GetPhysicalVolume()->GetName() <<std::endl;
std::cout << "end body " << postPv->GetName() << std::endl;
I sometimes see this for a single thermal neutron. I can see the Li6 reaction and creation of alpha and tritum with kinetic energies of 2.05 MeV and 2.72 MeV, respectively. But it looks like the tritum creates a 6 MeV gamma as well as an N15 (maybe coming from the gamma). I am not sure of the reaction that is creating this N15, as there should be no N at all in my system, so it must be a daughter product or a decay of someking.
Creating Neutron
particle neutron
process Transportation
kinetic 2.5e-08
edep 0
start body World
end body Scint1
Creating Process Transportation
particle neutron
process neutronInelastic
kinetic 0
edep 0
start body Scint1
end body Scint1
e1 : 0
e3 : 0
particle alpha
process ionIoni
kinetic 0
edep 2.05532
start body Scint1
end body Scint1
e1 : 2.05532
e3 : 0
Creating Process ionIoni
particle alpha
process NoProcess
kinetic 0
edep 0
start body Scint1
end body Scint1
e1 : 2.05532
e3 : 0
particle triton
process tInelastic
kinetic 1.70061
edep 1.02522
start body Scint1
end body Scint1
e1 : 3.08054
e3 : 0
Creating Process tInelastic
particle triton
process tInelastic
kinetic 0
edep 5.12828e-16
start body Scint1
end body Scint1
e1 : 3.08054
e3 : 0
particle gamma
process Transportation
kinetic 6.01269
edep 0
start body Scint1
end body World
particle alpha
process ionIoni
kinetic 0
edep 1.92203
start body Scint1
end body Scint1
e1 : 5.00257
e3 : 0
Value too high
Creating Process ionIoni
particle alpha
process NoProcess
kinetic 0
edep 0
start body Scint1
end body Scint1
e1 : 5.00257
e3 : 0
Value too high
particle N15
process ionIoni
kinetic 0
edep 1.45305
start body Scint1
end body Scint1
e1 : 6.45562
e3 : 0
Value too high
Creating Process ionIoni
particle N15
process NoProcess
kinetic 0
edep 0
start body Scint1
end body Scint1
e1 : 6.45562
e3 : 0
Value too high