[Gate-users] opticalAdder energy histogram

[Pedro Correia]

Dear users

I’m simulating a PET scanner for small animals, and I’m trying to make a digitizer for the Singles using the opticaladder. My code lines introduced after the Singles digitizer are

/gate/digitizer/name OpticalSingles
/gate/digitizer/insert singleChain

/gate/digitizer/OpticalSingles/insert opticaladder
/gate/digitizer/OpticalSingles/insert readout
/gate/digitizer/OpticalSingles/readout/setDepth 1

The output of this is a root file with a tree filled with Singles (as expected, with the energy spectrum well defined) and a tree with the OpticalSingles. In the leaf energy of the tree OpticalSingles, I wonder which is the energy scale, is it in MeV? In number of detected optical photons? Because my 511 keV peak appears at the position 0.04 in the histogram originated from the data in OpticalSingles energy.

Also the number of events is slightly different than the Singles tree, the Singles tree has always less events than the OpticalSingles (i.e. if I have 200 events in the Singles tree, I may have 230 in the OpticalSingles, some of them for very low “energy”, located at the very left part of the histogram).

I would really appreciate any help on this.
Best regards, 
Pedro Correia
Physics department, University of Aveiro
Portugal