Understanding the output of Histogram (.root) for throwing neutron beam inside a hollow concrete box

Hello everyone,
In my project I am simulating the energy deposition in a concrete bunker for neutron. I have modified the B1 example and created histogram. I got a histogram output but not understood the output properly. This is my geometry:


And here is my code for runaction:

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/// \file B1RunAction.cc
/// \brief Implementation of the B1RunAction class

#include “B1RunAction.hh”
#include “B1PrimaryGeneratorAction.hh”
#include “B1DetectorConstruction.hh”
// #include “B1Run.hh”
#include “B1Analysis.hh”
#include “G4RunManager.hh”
#include “G4Run.hh”
#include “G4AccumulableManager.hh”
#include “G4LogicalVolumeStore.hh”
#include “G4LogicalVolume.hh”
#include “G4UnitsTable.hh”
#include “G4SystemOfUnits.hh”

//…oooOO0OOooo…oooOO0OOooo…oooOO0OOooo…oooOO0OOooo…

B1RunAction::B1RunAction()
: G4UserRunAction(),
fEdep(0.),
fEdep2(0.)
{

//edit start
// set printing event number per each event
G4RunManager::GetRunManager()->SetPrintProgress(1);

// Create analysis manager
// The choice of analysis technology is done via selectin of a namespace
// in B4Analysis.hh
auto analysisManager = G4AnalysisManager::Instance();
// G4cout << "Using " << analysisManager->GetType() << G4endl;

// Create directories
//analysisManager->SetHistoDirectoryName(“histograms”);
//analysisManager->SetNtupleDirectoryName(“ntuple”);
analysisManager->SetVerboseLevel(1);
analysisManager->SetNtupleMerging(true);
// Note: merging ntuples is available only with Root output

// Book histograms, ntuple
//
// Creating histograms
analysisManager->CreateH1(“Energy”,“Edep in Concrete”, 1000, 0., 16.5MeV);
analysisManager->CreateH1(“Tlen”,“Track length”, 100, 0., 1
mm);
//edit end

// add new units for dose
//
const G4double milligray = 1.e-3gray;
const G4double microgray = 1.e-6
gray;
const G4double nanogray = 1.e-9gray;
const G4double picogray = 1.e-12
gray;

new G4UnitDefinition(“milligray”, “milliGy” , “Dose”, milligray);
new G4UnitDefinition(“microgray”, “microGy” , “Dose”, microgray);
new G4UnitDefinition(“nanogray” , “nanoGy” , “Dose”, nanogray);
new G4UnitDefinition(“picogray” , “picoGy” , “Dose”, picogray);

// Register accumulable to the accumulable manager
G4AccumulableManager* accumulableManager = G4AccumulableManager::Instance();
accumulableManager->RegisterAccumulable(fEdep);
accumulableManager->RegisterAccumulable(fEdep2);
}

//…oooOO0OOooo…oooOO0OOooo…oooOO0OOooo…oooOO0OOooo…

B1RunAction::~B1RunAction()
{
delete G4AnalysisManager::Instance(); //edit
}

//…oooOO0OOooo…oooOO0OOooo…oooOO0OOooo…oooOO0OOooo…

void B1RunAction::BeginOfRunAction(const G4Run*)
{
// inform the runManager to save random number seed
G4RunManager::GetRunManager()->SetRandomNumberStore(false);

//edit start
// Create/get analysis manager
G4AnalysisManager* analysisManager = G4AnalysisManager::Instance();
// analysisManager->SetVerboseLevel(1);
// Open an output file
//
G4String fileName = “B1root”;
analysisManager->OpenFile(fileName);
// Create histograms
//analysisManager->CreateH1(“Edep”,“Energy deposit”, 100, 0., 800MeV);
//analysisManager!CreateH1(“Tlen”,“Track length”, 100, 0., 100
mm);
//edit end

// reset accumulables to their initial values
G4AccumulableManager* accumulableManager = G4AccumulableManager::Instance();
accumulableManager->Reset();

}

//…oooOO0OOooo…oooOO0OOooo…oooOO0OOooo…oooOO0OOooo…

void B1RunAction::EndOfRunAction(const G4Run* run)
{

// Get analysis manager
G4AnalysisManager* analysisManager = G4AnalysisManager::Instance(); //edit
G4int nofEvents = run->GetNumberOfEvent();
if (nofEvents == 0) return;

// Merge accumulables
G4AccumulableManager* accumulableManager = G4AccumulableManager::Instance();
accumulableManager->Merge();

// Compute dose = total energy deposit in a run and its variance
//
G4double edep = fEdep.GetValue();
G4double edep2 = fEdep2.GetValue();

G4double rms = edep2 - edep*edep/nofEvents;
if (rms > 0.) rms = std::sqrt(rms); else rms = 0.;

const B1DetectorConstruction* detectorConstruction
= static_cast<const B1DetectorConstruction*>
(G4RunManager::GetRunManager()->GetUserDetectorConstruction());
G4double mass = detectorConstruction->GetScoringVolume()->GetMass();
G4double dose = edep/mass;
G4double rmsDose = rms/mass;

// Run conditions
// note: There is no primary generator action object for “master”
// run manager for multi-threaded mode.
const B1PrimaryGeneratorAction* generatorAction
= static_cast<const B1PrimaryGeneratorAction*>
(G4RunManager::GetRunManager()->GetUserPrimaryGeneratorAction());
G4String runCondition;
if (generatorAction)
{
const G4ParticleGun* particleGun = generatorAction->GetParticleGun();
runCondition += particleGun->GetParticleDefinition()->GetParticleName();
runCondition += " of ";
G4double particleEnergy = particleGun->GetParticleEnergy();
runCondition += G4BestUnit(particleEnergy,“Energy”);
}
// Write and close the output file
analysisManager->Write();
analysisManager->CloseFile();
// Print
//
if (IsMaster()) {
G4cout
<< G4endl
<< “--------------------End of Global Run-----------------------”;
}
else {
G4cout
<< G4endl
<< “--------------------End of Local Run------------------------”;
}

G4cout
        << G4endl
        << " The run consists of " << nofEvents << " "<< runCondition
        << G4endl
 << " Cumulated dose per run, in scoring volume : " 
 << G4BestUnit(dose,"Dose") << " rms = " << G4BestUnit(rmsDose,"Dose")
 << G4endl
 << "------------------------------------------------------------"
 << G4endl
 << G4endl;

}

//…oooOO0OOooo…oooOO0OOooo…oooOO0OOooo…oooOO0OOooo…

void B1RunAction::AddEdep(G4double edep)
{
fEdep += edep;
fEdep2 += edep*edep;
}

//…oooOO0OOooo…oooOO0OOooo…oooOO0OOooo…oooOO0OOooo…

Blockquote

And this is my .root plot.


My code for creating histogram is " analysisManager->CreateH1(“Energy”,“Edep in Concrete”, 1000, 0., 16.5*MeV);"
I applied 16.5 MeV energy’s 100 neutron beam. I can’t get it why there is a peak at arount 9.5 Mev. And what does the y axis parameter mean actually here?

Please help.
Regards,
Arnab