[gate-users] coincidence window size and few scatter event

Yun Dong dongyun at iit.edu
Wed May 10 05:16:16 CEST 2006

Hi GATE users:

I set up a testing 2D PET system simulated by GATE, and investigated 
its output ASCII files. When I use very small coincidences window, 
1ps, I find that the timing difference between two singles of each 
coincidence event in gateCoincidences.dat is larger than 1 ps. My 
question is, whether GATE exists default coincidence window size when 
we set much smaller coincidence window, such as 1 ps?

My another question: in the above simulation of system, I get very 
small scatter events, about ~1%; it's much fewer than 10~20% in 

Thanks for any suggestion and idea.



# W O R L D
/gate/world/geometry/setXLength 900 mm
/gate/world/geometry/setYLength 900 mm
/gate/world/geometry/setZLength 10 mm

# C Y L I N D R I C A L
/gate/world/daughters/name cylindricalPET
/gate/world/daughters/insert cylinder
/gate/cylindricalPET/setMaterial Air
/gate/cylindricalPET/geometry/setRmax 437.5 mm
/gate/cylindricalPET/geometry/setRmin 412.5  mm
/gate/cylindricalPET/geometry/setHeight 8 mm

# resector
/gate/cylindricalPET/daughters/name rsector
/gate/cylindricalPET/daughters/insert box
/gate/rsector/placement/setTranslation 425 0 0 mm
/gate/rsector/geometry/setXLength 25 mm
/gate/rsector/geometry/setYLength 54 mm
/gate/rsector/geometry/setZLength 6.45 mm
/gate/rsector/setMaterial Air
/gate/rsector/vis/setColor yellow

# C R Y S T A L
/gate/rsector/daughters/name crystal
/gate/rsector/daughters/insert box
/gate/crystal/geometry/setXLength 25 mm
/gate/crystal/geometry/setYLength 6.45 mm
/gate/crystal/geometry/setZLength 6.45 mm
/gate/crystal/setMaterial Air
/gate/crystal/vis/setColor red

# layer 0
/gate/crystal/daughters/name LSO
/gate/crystal/daughters/insert box
/gate/LSO/geometry/setXLength 25 mm
/gate/LSO/geometry/setYLength 6.45 mm
/gate/LSO/geometry/setZLength 6.45 mm
/gate/LSO/setMaterial LSO
/gate/LSO/vis/setColor red

# R E P E A T C R Y S T A L
/gate/crystal/repeaters/insert cubicArray
/gate/crystal/cubicArray/setRepeatNumberX 1
/gate/crystal/cubicArray/setRepeatNumberY 8
/gate/crystal/cubicArray/setRepeatNumberZ 1
/gate/crystal/cubicArray/setRepeatVector 0 6.75 0 mm

# R E P E A T M O D U L E
/gate/rsector/repeaters/insert ring
/gate/rsector/ring/setRepeatNumber 48 

# A T T A C H S Y S T E M
/gate/systems/cylindricalPET/rsector/attach rsector
/gate/systems/cylindricalPET/crystal/attach crystal
/gate/systems/cylindricalPET/layer0/attach LSO

# A T T A C H L A Y E R SD

# P H A N T O M
/gate/world/daughters/name phantom
/gate/world/daughters/insert cylinder 
/gate/phantom/geometry/setRmax 101 mm
/gate/phantom/geometry/setHeight 8 mm
/gate/phantom/placement/setTranslation 0 0 0 mm
/gate/phantom/setMaterial Silicon 
/gate/phantom/vis/setColor grey 
# A T T A C H P H A N T O M S D

# P H Y S I C S
/gate/physics/gamma/selectCompton standard
/gate/physics/gamma/selectPhotoelectric standard
/gate/physics/gamma/selectRayleigh lowenergy
/gate/physics/setElectronCut 1000. km
/gate/physics/setXRayCut 1. GeV
/gate/physics/setDeltaRayCut 1. GeV
/gate/physics/verbose 2

# I N I T I A L I Z E
#/random/resetEngineFrom node1.rndm
/gate/systems/cylindricalPET/verbose 0

# S O U R C E S
/gate/source/addSource twogamma
/gate/source/twogamma/setActivity 10000. becquerel
/gate/source/twogamma/setType backtoback
/gate/source/twogamma/gps/particle gamma
/gate/source/twogamma/gps/energytype Mono
/gate/source/twogamma/gps/monoenergy 0.511 MeV
/gate/source/twogamma/gps/type Volume
/gate/source/twogamma/gps/shape Cylinder
/gate/source/twogamma/gps/radius 100 mm
/gate/source/twogamma/gps/halfz 3.225 mm
/gate/source/twogamma/gps/angtype iso
/gate/source/twogamma/gps/mintheta 90. deg
/gate/source/twogamma/gps/mintheta 90. deg
/gate/source/twogamma/gps/minphi 0. deg
/gate/source/twogamma/gps/maxphi 360. deg
/gate/source/twogamma/gps/centre 0. 0. 0. cm

# D I G I T I Z E R
/gate/digitizer/Singles/insert adder
/gate/digitizer/Singles/insert readout
/gate/digitizer/Singles/readout/setDepth 1
/gate/digitizer/Coincidences/setWindow 1. ps

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