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Question Problem Matching Mulassis Energy Deposit with My Own Geant4 Slab Implementation 

Forum: Physics List
Date: 02 Jun, 2010
From: Bryan C. Callahan <Bryan C. Callahan>

I'm working on a shielding project where I'm trying to match results with Mulassis (http://reat.space.qinetiq.com/mulassis/). Basically, the idea is I have a 10 cm slab of lead that I'm shooting 3000 electrons at 550 keV at. With each collision, I'm summing up the energy deposits which should be less than 3000 * 550 keV due to conservation of energy. I set this up with Mulassis (see Mulassis test macro below) and I get agreement between my geant4 application for some energies but not others.

Both my application and Mulassis get an average energy deposit of about 360 keV. Furthermore, trying these results at different energies I get agreements at 50 keV, 100 keV, 250 keV, 350 keV, and 550 keV. The problem, however, is when I use energies higher than about 2 MeV. For instance, shooting 3000 particles at 4 MeV, Mulassis gets an average energy deposit of 3.247 MeV (as I would expect). With my geant4 application I get about 141 keV (way less average energy deposit than I would expect). Continuing this test at higher energies leaves my application with decreasing energy deposit (I tested up to 10 MeV with an average energy deposit of 135 keV).

This leads me to believe that something must be incorrect with my PhysicsList. I've tried several different lists provided with geant4 (geant4/source/physics_lists/lists) and I even tried the EXACT lists used by Mulassis (MLEMPhysics.hh, MLGeneralPhysics.hh, MLHEMPhysics.hh, MLIonPhysics.hh). With all of these lists I'm getting ~360 keV average energy deposit at 550 keV (expected match) and ~141 keV average energy deposit at 4 MeV (unexpected mismatch).

Below I have attached the macro file I'm using with Mulassis and the implementation of my Physics List.`

Any help would be /very/ much appreciated!! :)


---------- Mulassis Test Macro =>

/geometry/layer/delete 0
/geometry/material/add lead Pb 11.35
/geometry/layer/shape slab
/geometry/layer/add 0 lead 1 10.0 cm
/analysis/dose/add 1
/analysis/dose/unit MeV
/geometry/update
/phys/cuts/global/default 1.000E-03 mm
/phys/scenario em
/gps/particle e-
/gps/ene/type Mono
/analysis/file my_test_output
/analysis/normalise 1.000E+00 cm2
/gps/ang/type planar
/gps/direction 0.000E+00 0.000E+00 1.000E+00
/event/printModulo 1000
/gps/energy 4000 keV
/run/beamOn 3000


---------- My Physics List Configuration =>

#include "BccGdmlPartGunPhysicsList.hh"
#include "G4EmStandardPhysics.hh"

BccGdmlPartGunPhysicsList::BccGdmlPartGunPhysicsList(): G4VModularPhysicsList()
{
    defaultCutValue = 0.001 * mm;
    RegisterPhysics(new G4EmStandardPhysics());
}

BccGdmlPartGunPhysicsList::~BccGdmlPartGunPhysicsList()
{
}

void BccGdmlPartGunPhysicsList::SetCuts()
{
    // Sets the default cut value for all particle types...
    SetCutsWithDefault();

    // Dump table if verbose...
    if (verboseLevel > 0) DumpCutValuesTable();
}

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1 Idea: Re: Problem Matching Mulassis Energy Deposit with My Own Geant4 Slab Implementation   (Vladimir Ivanchenko - 11 Jun, 2010)
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