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Geant4 Version: 10.7.4
Operating System: RHEL9
Compiler/Version: 11.4.1
CMake Version: 3.20.2
I’ve simulated a Cs137 point source sitting next to a NaI crystal and recorded the energy deposited in the crystal to form an energy spectra. I’ve uploaded the results of the simulated energy spectra along with one collected from a NaI detector I have in my lab. The big noticable difference is in the Compton back scatter peak around 200keV which is absent from the simulation. Can someone help pin point how to figure out if I’m using the right physics libraries to properly simulate an energy spectra of a gamma less than 2MeV?
The simulation was done using the topasmc.org geant4 framework.
Here is a cut and paste of the simulation output at the initialization stage listing all the physics processes.
Registered Physics Processes:
Transportation, StepLimiter, UserSpecialCut, phot
compt, conv, Rayl, msc
eIoni, eBrem, CoulombScat, msc
eIoni, eBrem, annihil, CoulombScat
msc, ionIoni, msc, muIoni
CoulombScat, muIoni, msc, hIoni
CoulombScat, hIoni, msc, hIoni
CoulombScat, hIoni, msc, hIoni
CoulombScat, msc, hIoni, CoulombScat
hIoni, hIoni, msc, ionIoni
msc, ionIoni,RadioactiveDecayBase
Visualization verbosity changed to quiet (0)
My Begin Run has been called edited
### === Deexcitation model UAtomDeexcitation is activated for 1 region:
DefaultRegionForTheWorld 1 1 0
### === Auger cascade flag: 1
### === Ignore cuts flag: 1
phot: for gamma SubType=12 BuildTable=0
LambdaPrime table from 200 keV to 500 MeV in 25 bins
===== EM models for the G4Region DefaultRegionForTheWorld ======
LivermorePhElectric : Emin= 0 eV Emax= 500 MeV 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 500 MeV in 20 bins
===== EM models for the G4Region DefaultRegionForTheWorld ======
Klein-Nishina : Emin= 0 eV Emax= 500 MeV
conv: for gamma SubType=14 BuildTable=1
Lambda table from 1.022 MeV to 500 MeV, 33 bins/decade, spline: 1
===== EM models for the G4Region DefaultRegionForTheWorld ======
BetheHeitlerLPM : Emin= 0 eV Emax= 500 MeV 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 500 MeV in 27 bins
===== EM models for the G4Region DefaultRegionForTheWorld ======
LivermoreRayleigh : Emin= 0 eV Emax= 500 MeV 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= 500 MeV Nbins=7 100 MeV - 500 MeV
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 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 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= 500 MeV
eBrem: for e- SubType=3
dE/dx and range tables from 100 eV to 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 7 bins/decade, spline: 1
LPM flag: 1 for E > 0.5 GeV, VertexHighEnergyTh(GeV)= 100000
===== EM models for the G4Region DefaultRegionForTheWorld ======
eBremSB : Emin= 0 eV Emax= 500 MeV ModifiedTsai
CoulombScat: for e-, integral:1 SubType=1 BuildTable=1
Lambda table from 100 MeV to 500 MeV, 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= 500 MeV
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= 500 MeV Nbins=7 100 MeV - 500 MeV
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 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 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= 500 MeV
eBrem: for e+ SubType=3
dE/dx and range tables from 100 eV to 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 7 bins/decade, spline: 1
LPM flag: 1 for E > 0.5 GeV, VertexHighEnergyTh(GeV)= 100000
===== EM models for the G4Region DefaultRegionForTheWorld ======
eBremSB : Emin= 0 eV Emax= 500 MeV ModifiedTsai
annihil: for e+, integral:1 SubType=5 BuildTable=0
===== EM models for the G4Region DefaultRegionForTheWorld ======
eplus2gg : Emin= 0 eV Emax= 500 MeV
CoulombScat: for e+, integral:1 SubType=1 BuildTable=1
Lambda table from 100 MeV to 500 MeV, 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= 500 MeV
msc: for proton SubType= 10
===== EM models for the G4Region DefaultRegionForTheWorld ======
WentzelVIUni : Emin= 0 eV Emax= 500 MeV Nbins=49 100 eV - 500 MeV
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 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 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= 500 MeV
CoulombScat: for proton, integral:1 SubType=1 BuildTable=1
Lambda table from threshold to 500 MeV, 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= 500 MeV
msc: for GenericIon SubType= 10
===== EM models for the G4Region DefaultRegionForTheWorld ======
UrbanMsc : Emin= 0 eV Emax= 500 MeV
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 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 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= 500 MeV
======================================================================
====== Radioactive Decay Physics Parameters =======
======================================================================
Max life time 1.4427e+06 ps
Internal e- conversion flag 1
Stored internal conversion coefficients 1
Enable correlated gamma emission 0
Max 2J for sampling of angular correlations 10
Atomic de-excitation enabled 1
Auger electron emission enabled 1
Auger cascade enabled 1
Check EM cuts disabled for atomic de-excitation 1
Use Bearden atomic level energies 0
======================================================================
msc: for alpha SubType= 10
===== EM models for the G4Region DefaultRegionForTheWorld ======
UrbanMsc : Emin= 0 eV Emax= 500 MeV Nbins=49 100 eV - 500 MeV
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 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 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= 500 MeV
msc: for anti_proton SubType= 10
===== EM models for the G4Region DefaultRegionForTheWorld ======
WentzelVIUni : Emin= 0 eV Emax= 500 MeV Nbins=49 100 eV - 500 MeV
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 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 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= 500 MeV
CoulombScat: for anti_proton, integral:1 SubType=1 BuildTable=1
Lambda table from threshold to 500 MeV, 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= 500 MeV
msc: for kaon+ SubType= 10
===== EM models for the G4Region DefaultRegionForTheWorld ======
WentzelVIUni : Emin= 0 eV Emax= 500 MeV Nbins=49 100 eV - 500 MeV
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 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 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= 500 MeV
CoulombScat: for kaon+, integral:1 SubType=1 BuildTable=1
Lambda table from threshold to 500 MeV, 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= 500 MeV
msc: for kaon- SubType= 10
===== EM models for the G4Region DefaultRegionForTheWorld ======
WentzelVIUni : Emin= 0 eV Emax= 500 MeV Nbins=49 100 eV - 500 MeV
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 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 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= 500 MeV
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= 500 MeV
msc: for mu+ SubType= 10
===== EM models for the G4Region DefaultRegionForTheWorld ======
WentzelVIUni : Emin= 0 eV Emax= 500 MeV Nbins=49 100 eV - 500 MeV
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 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 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= 500 MeV
CoulombScat: for mu+, integral:1 SubType=1 BuildTable=1
Lambda table from threshold to 500 MeV, 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= 500 MeV
msc: for mu- SubType= 10
===== EM models for the G4Region DefaultRegionForTheWorld ======
WentzelVIUni : Emin= 0 eV Emax= 500 MeV Nbins=49 100 eV - 500 MeV
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 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 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= 500 MeV
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= 500 MeV
msc: for pi+ SubType= 10
===== EM models for the G4Region DefaultRegionForTheWorld ======
WentzelVIUni : Emin= 0 eV Emax= 500 MeV Nbins=49 100 eV - 500 MeV
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 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 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= 500 MeV
CoulombScat: for pi+, integral:1 SubType=1 BuildTable=1
Lambda table from threshold to 500 MeV, 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= 500 MeV
msc: for pi- SubType= 10
===== EM models for the G4Region DefaultRegionForTheWorld ======
WentzelVIUni : Emin= 0 eV Emax= 500 MeV Nbins=49 100 eV - 500 MeV
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 500 MeV in 49 bins
Lambda tables from threshold to 500 MeV, 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= 500 MeV
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= 500 MeV
=======================================================================
--> G4MTRunManager::CreateAndStartWorkers() --> Initializing workers...
=======================================================================
G4WT0 > Transportation, StepLimiter, UserSpecialCut, phot
G4WT0 > compt, conv, Rayl, msc
G4WT0 > eIoni, eBrem, CoulombScat, msc
G4WT0 > eIoni, eBrem, annihil, CoulombScat
G4WT0 > msc, ionIoni, msc, muIoni
G4WT0 > CoulombScat, muIoni, msc, hIoni
G4WT0 > CoulombScat, hIoni, msc, hIoni
G4WT0 > CoulombScat, hIoni, msc, hIoni
G4WT0 > CoulombScat, msc, hIoni, CoulombScat
G4WT0 > hIoni, hIoni, msc, ionIoni
G4WT0 > msc, ionIoni,RadioactiveDecayBase
G4WT0 > Begin processing for Run: 0, History: 0