I built an electromagnetic calorimeter with LYSO crystals in Geant4.
When I simulated my detector with 100 keV photon, I encountered an issue: the different response functions for 10.5.p01 and 10.6.p02 showed up for the same photon energy.
I want to know what changed in EM physics or other things in 10.6.
First off, I made a 5 * 5 * 55 mm^3 LYSO crystal and then wrap with aluminum foil.
I attached SiPM’s to both ends of the crystal.
I formed a 30 x 30 matrix with these crystals.
The thickness of SiPM is 0.3mm, and the area is 5 x 5 mm^2 which is the same as the area of the LYSO.
And I set the photon detection efficiency of the SiPM with Hamamatsu S13615-1025N MPPC array as the figure (a).
I sent 0.1 MeV photons to the center of the crystal. The photon beam direction was perpendicular to the 55 mm side.
My simulations were done with two geant4 versions & two physics lists.
Geant4 versions: 10.5.p01, 10.6.p02
Physics lists: FTFP_BERT, FTFP_BERT_HP
I draw the distributions for # of photoelectrons.
We got four distributions for four simulation cases:
- 10.5 - FTFP_BERT : figure (b)
- 10.5 - FTFP_BERT_HP : figure (c)
- 10.6 - FTFP_BERT : figure (d)
- 10.6 - FTFP_BERT_HP : figure (e)
In 10.5.p01, the results of FTFP_BERT & FTFP_BERT_HP are the same.
However, for 10.6.p02, FTFP_BERT & FTFP_BERT_HP resulted in the different response functions.
In addition, we can see the different distributions for 10.5.p01 and 10.6.p02.
I am very curious and want to figure out why we obtained different distributions between 10.5 and 10.6, and between FTFP_BERT and FTFP_BERT_HP in 10.6.
Which version and physics list describe the real world better than the others?
Thank you for reading my question.