The abnormal energy deposit in the target

Physics Processes, Models and Cross Sections
1

The 10 MeV neutron was used to boom lithium 6 target with 3 inch height and 3 inch diameter, the energy deposit by the proton event by event is shown below:

Pulse Amplitude Spectrum
Pulse Amplitude Spectrum896×572 5.45 KB

the key codes are:

if (aStep->GetPreStepPoint()->GetTouchable()->GetVolume() == fTargetVolume)
 { 
     if(aStep->GetTrack()->GetDefinition()==G4Proton::ProtonDefinition()
        )
     {
         G4double energy_deposit = aStep->GetTotalEnergyDeposit();
         G4double step_length = aStep->GetStepLength() / 10.;
         // 发光效率系数为：1.903MeVee/MeV
         // Birks系数为：26.03g/cm2/MeV
         // ej-309的密度为：0.96g/cm3
         G4double fluorescence_energy = 1.903 * energy_deposit / (1 + 26.03 * 1.e-3 / 0.96 * energy_deposit / step_length);
         event_action_->Add_Energy(fluorescence_energy);
     }           
 }
Maybe the cross section of Li6(n,p) is wrong?

Geant4 Version:11.4.1
Operating System:Ubuntu 24.04
Compiler/Version:13.3.0
CMake Version:3.28.3

2

Here, a run of example Hadr03.

According to the printout, the cross section of Li6(n,p) is ~1.6% of 664 mbarn = 10.6 mbarn.

the proton spectrum is shown.

siyuan.mac.txt (386 Bytes)

siyuan.out.txt (4.7 KB)

siyuan
siyuan698×475 19.7 KB

3

The proton energy from Li6(n,p) reaction is too high, it disagrees the energy conservation.

4

What is your electromagnetic physics module? It seems option3 and option4 have some problems, have you tried default option G4EmStandardPhysics()?

5

The physics list “FTFP_BERT_HP” is used.