[Gate-users] Coincidences Issue

[Xinjie Cao]

Dear all,

I am doing a sensitivity evaluation test of Biograph Vision, but the result
showed an unignorable sensitivity outside the axial FOV, around 2% away
from the axial edge, which means that there are still some coincidences
detected.

The following is my digitizer and source setting:
```
/gate/physics/Gamma/SetCutInRegion      LYSO .5 mm
/gate/physics/Electron/SetCutInRegion   LYSO .50 mm
/gate/physics/Positron/SetCutInRegion   LYSO .50 mm

#=====================================================
#   D I G I T I Z E R
#====================================================
#       A D D E R
/gate/digitizer/Singles/insert adderCompton
/gate/digitizer/Singles/insert adder

#       R E A D O U T
/gate/digitizer/Singles/insert readout
/gate/digitizer/Singles/readout/setDepth  4
#/gate/digitizer/Singles/insert timeResolution
#/gate/digitizer/Singles/timeResolution/setTimeResolution 0.3 ns


#      E N E R G Y   B L U R R I N G
/gate/digitizer/Singles/insert blurring
/gate/digitizer/Singles/blurring/setResolution 0.15
/gate/digitizer/Singles/blurring/setEnergyOfReference 511. keV

#       E N E R G Y   C U T
/gate/digitizer/Singles/insert thresholder
/gate/digitizer/Singles/thresholder/setThreshold 450. keV
/gate/digitizer/Singles/insert upholder
/gate/digitizer/Singles/upholder/setUphold 650. keV

#       D E A D    T I M E
/gate/digitizer/Singles/insert deadtime
/gate/digitizer/Singles/deadtime/setDeadTime 320 ns
/gate/digitizer/Singles/deadtime/setMode paralysable
/gate/digitizer/Singles/deadtime/chooseDTVolume crystal

#       C O I N C I    S O R T E R
/gate/digitizer/Coincidences/setInputName Singles
/gate/digitizer/Coincidences/setWindow 4.7 ns
/gate/digitizer/Coincidences/setOffset 0. ns
#/gate/digitizer/Coincidences/setDepth 4
/gate/digitizer/Coincidences/MultiplesPolicy takeWinnerIfIsGood

===============================

# SOURCE
/gate/source/addSource F18SphereSource
/gate/source/F18SphereSource/setActivity 100000. becquerel
/gate/source/F18SphereSource/gps/particle e+
/gate/source/F18SphereSource/setForcedUnstableFlag true
/gate/source/F18SphereSource/setForcedHalfLife 6586 s
/gate/source/F18SphereSource/setType backtoback
#/gate/source/F18SphereSource/setAccolinearityFlag      true
#/gate/source/F18SphereSource/setAccoValue 2 deg
/gate/source/F18SphereSource/gps/energytype Fluor18
#/gate/source/F18SphereSource/gps/monoenergy 511. keV


/gate/source/F18SphereSource/gps/type Surface
/gate/source/F18SphereSource/gps/shape Sphere
/gate/source/F18SphereSource/gps/radius 0.15 mm
/gate/source/F18SphereSource/gps/centre 0.0 0.0 {axialOffset} cm
# Gurantees particles will shoot in all directions
/gate/source/F18SphereSource/gps/angtype iso
```
I don't apply noise for now, so I am guessing there might be something
wrong with the digitizer. But I am not sure because I didn't see any
obvious result change no matter how I optimize it. Does anyone have any
idea about that? Any answer will be highly appreciated! Thanks!

Best,
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