These GEANT4 simulations were built on top of work by Dr. Ryan Fitzgerald at NIST.
As part of a measurement of the 12C(n,2n)11C cross section, the efficiency of NaI(Tl) scintillation detectors was calculated. Following a measurment of the cross section at Ohio University, the same detectors were set up in a lab at Houghton College and measurements were taken of 511 keV coincidence gamma from several positron emitting sources in varied geometries. These experimental set ups were modeled in GEANT4 along with the original measurement. When the model accurately calculated the measurements made in the Houghton lab, the code was used to model the Ohio University experiment and accurately measure the 12C(n,2n)11C cross section.