Gamma interaction with electron leads to half energy loss

Hi All,

I am currently attempting to simulate a O(keV) gamma interacting with a scintillator, YAP (density = 5.37 g/cm3, Y 54%, Al 17%, O 29%). I find that the secondary electron which is produced takes on only rough half of the energy of the gamma, and deposits the other half.
I have tried changing the defaultCutValue, from 1mm, to 1cm and also 1*nm, with no drastic change. I am using the ConstructEMLivermore process for the interaction.
Please let me know if y’all need any other information to understand what is happening. Thanks.


you may want fully enable atomic de-excitation module to see all transitions: “/process/em/deexcitationIgnoreCuts true” on top Option4 EM physics. With this command you do not need defining extremely low cuts.


Hi VI,

Thanks for your suggestion I will implement this and let you know if it fixes the issue. Also, it has come to my attention that there is a possibility that Geant4’s photoelectric effect may also have something to do with what I am observing. Do you think it is possible that in some cases I am generating photoelectrons from the K shell (17 keV pe) and in others from the L shell (30 keV pe)?