I am simulating the number of photons detected by PMTs in calorimeter.
In the case of an interface between a dielectric (scintillator) and a metal (detector), I have two related properties could be set: REFLECTIVITY ® and EFFICIENCY (a).
The photon can be absorbed by the metal or reflected back into the dielectric. If the photon is absorbed it can be detected according to the photoelectron efficiency of the metal.
So the total collection effciency = (1 - r)*a
However, when searching for the properties of certain detector (PMTs or SiPMs), we are usually given the quantum efficiency (QE) directly (for example, this one ). QE = the number of photoelectrons emitted from the photocathode / the number of incident photons.
I am not clear about the definition of EFFICIENCY in GEANT. If it is detected photons / absorbed photons, then QE = (1-r)*a, I shouldn’t set QE directly as EFFICIENCY. Instead, the EFFICIENCY should be QE/(1-r).
If it is detected photons / incident photons, then QE = a, so I should set REFLECTIVITY = 0 and EFFICIENCY = QE?