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Question Differences between G4PVPlacement and G4VPVParameterisation 

Forum: Geometry
Date: 10 Oct, 2014
From: Jelena Ilic <Jelena Ilic>

Hi,

My geometry is a block of tungsten filled with a large number of quartz tubes which are again filled with a liquid scintillator. I measure energy deposited in the scintillator tubes, the number of scintillation photons produced and the number of scintillation photons exiting my tungsten block . At the beginning ( when I had reasonably small number of scintillator tubes in my geometry) I used G4PVPlacement to arrange them inside the tungsten block. Now I have to analysed a setup with >3000 tubes (placed in 5x5X10 cm block), so I decided to arrange them using G4VPVParameterisation. The geometry looks fine and everything runs faster. The measured energy deposition is slightly lower, but what really seems to be a problem is the number of scintillation photons exiting the calorimeter. For the case when 2 GeV e- hits the 5x5X10 cm tungsten block with of 60x60 tubes (diameter 0.8mm):

               |using  G4PVPlacement    |  using  G4VPVParameterisation
------------------------------------------------------------
eDep       |     13192 (keV)               | 14192.1 (keV)
------------------------------------------------------------
noScint    |     1821                         |  0
exiting     

The same seed number is used in the both cases. To get the number of optical photons leaving the calo I used the simple nOfTrack primitive scorer.

Why I do not see any optical photon leaving the calorimeter when G4VPVParameterisation is used?

Thank you

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