Dear Geant4 Experts,
I am currently simulating the Pulse Height Spectra for the light output of a BC501A organic scintillator detector and have encountered a significant discrepancy between the results from old Geant4 version 10.5.1 and the newer version 11.3.2.
With Geant4 10.5.1, the simulated pulse height spectrum aligns perfectly with my experimental data. However, when I run the same simulation with Geant4 11.3.2, I observe a “spike and edge-like” behavior near the maximum pulse height region, which deviates from the experimental results.
I have been meticulous in ensuring that the simulation parameters are identical across both versions. Specifically, I have used the same:
Detector Construction: The geometry and materials of the BC501A detector are defined identically.
Light Output Function: The function to convert deposited energy to scintillation photons remains unchanged.
Resolution Function: The energy resolution smearing function is the same.
I am attaching a comparison plot that clearly illustrates the difference between the spectra from the two Geant4 versions. I am also attaching the macro file and relevant C++ code used to run the simulation in Geant4 11.3.2.
Could anyone shed some light on what might be causing this difference in the newer version of Geant4? Are there any known changes in the physics lists or optical physics processes between these versions that could lead to such an effect in organic scintillators? Any suggestions on how to modify my simulation to obtain a more accurate result with Geant4 11.3.2 would be greatly appreciated.
Thank you for your time and assistance.
Best regards,
Pankaj
DetectorConstruction.cc (5.1 KB)
c1.pdf (21.3 KB)