Photon Energy deposition in a pure Ge crystal
Perform a fit to the 2nd hit distribution using an exponential fitting function. Do this for 100keV, 500keV, 1MeV, 3Mev and for this test, please run some 10 MeV gammas. —the result of the fit should be equal to the mass attenuation coefficient multiplied by the density of Ge. Therefore, dividing the fit result by 5.323 yields the mass attenuation coefficient at each energy and we can compare them directly with the NIST database values for validation of the GEANT4 total cross sections and sampling.
I got for 3MeV constant: -1.88934 and slope: -1.84926e-02 +/- 1.63709e-02. 1MeV: -2.852121 slope: -3.04127e-02 +/- 4.63910e-02 500k: -3.66350 slope: -4.25739e-02 +/- 1.10890e-01 Research shows this says these values are on a "log scale", not sure how exactly to read this.
Simulation Set Up - Detector Construction
A pure block of 50x50x50cm Germanium is placed in front of a lead cylinder, inner radius 0.75cm, outer radius 50cm of height 55cm. There is a 1mmx1cm hole (made of Argon) from the center of the lead cask to the outside, pointed toward the middle of the Germanium crystal.
Photons are fired from a cylindrical gps from within the inner radius of the lead cask. This cylinder has a height of 40.25 cm and a radius of 0.5 cm. The goal of this gun is to simulate decay from a fuel rod on the inside of the lead cylinder. Angular cuts are made on the gun to limit wasteful gammas from being calculated. There is a phi (x direction) cut of 22 degrees, centered on the hole leading to the Germanium block, and a theta cut of about 45 degrees. The phi coincides with the 1mm side of the hole, and the theta coincides with the 1cm side of the hole.
Send photons from inside an infinite crystal at 100, 500, 1000, 3000 keV energy. Add up all the energy loss and see if you get delta functions or a delta + tail because GEANT4 stopped taking the photon and thus the energy is not accounted for.
Start with= 100 keV
Initial verification - first hit position distribution is consistent with published attenuation coefficient.
Start with= 500 keV
Change units on Y-axis to Energy (eV?)
"No Backscattering" Do another plot with momentum cut Pz>0
Initial verification - The first gamma interaction distribution is consistent with the published Ge mass attenuation coefficient at 500keV (0.08212) and a Ge density of 5.323.
Are the 2-D plots energy weights (normalized)? Set the Z-axis color range by hand in cold.
Start with= 1 MeV
Initial verification - first interaction is consistent with published attenuation coefficient.
Start with= 3 MeV
Initial verification - first interaction distribution is consistent with published attenuation coefficient.
This is looking at total energy deposition from the child particles in Germanium, from a incident gamma shot from within the crystal.
Confirmed, GEANT keeps track of all energy deposited in the crystal, with little error that scales with initial photon energy. Could be minor leakage of secondary photons.
To submit batch job to minerve:
nohup ../exampleN02 run1.mac > /dev/null &
For parallel processing on plexi:
Run module load geant/geant4-10.2.0 when you first log in to set up the environment for Geant4 Use the command G4make when you configure your application (instead of 'cmake') to provide the necessary default options for Plexi. To run: salloc -n <number_of_processes> mpirun /absolute/path/to/your/application