Can I use QE as EFFICIENCY in surface property of PMTs

Dear expert,

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 [1]). 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?

Thanks!

[1] https://www.hamamatsu.com/resources/pdf/etd/R8900(U)-00-C12_TPMH1299E.pdf

EFFICIENCY is detected/absorbed.

Please try to convince yourself of this with examples/extended/optical/OpNovice2. Modify unified.mac to specify dielectric_metal (as below). The printout will show the number of detected photons, etc.

/control/verbose 2
/tracking/verbose 0

/opnovice2/boxProperty RINDEX 0.000002 1.3 0.000008 1.4
/opnovice2/boxProperty ABSLENGTH 0.000002 1000000 0.000005 2000000 0.000008 3000000

/opnovice2/worldProperty RINDEX 0.000002 1.01 0.000008 1.01
/opnovice2/worldProperty ABSLENGTH 0.000002 1000000 0.000005 2000000 0.000008 3000000

/opnovice2/surfaceModel unified
/opnovice2/surfaceType dielectric_metal

############################# ground ################################
/opnovice2/surfaceFinish ground

#/opnovice2/surfaceProperty TRANSMITTANCE 0.000002 0.1 0.000008 0.1
/opnovice2/surfaceProperty REFLECTIVITY 0.000002 0.8 0.000008 0.8
/opnovice2/surfaceProperty EFFICIENCY 0.000002 0.1 0.000008 0.1

/run/initialize

/gun/particle opticalphoton
/gun/energy 3 eV
/gun/position 0 0 0 cm
/gun/direction 1 0 0
/opnovice2/gun/optPhotonPolar
/run/beamOn 100000

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