[Gate-users] Phantom Scatter Events detected as Primary Events

[RAMESHwar]

Dear GATE users
I am using GATE version5 on 32 bit linux, to get the phantom scatter events
distribution of small animal PET imaging. After analysing the ASCII singles
and coincidences for compton scatter in phantom, I am getting the scatter
events distribution but seems that some scatter events are placed as
primary events in distribution. I have attached a jpeg image of it.
I tried this using back-to-back source and e+ fluro sources of point and
line shape , also using no gantry in geometry. I tried with using
different crystals of BGO, LSO,  LYSO.  But in all cases I gets  some
primary events in phantom scatter distribution.
Can anyone  help/explain to solve this issue.

Regards
Ramesh

My source mac are:
1. back-to-back

/gate/source/addSource FOVUniSource

/gate/source/FOVUniSource/setActivity 10000000.0 becquerel

/gate/source/FOVUniSource/setType backtoback

/gate/source/FOVUniSource/gps/particle gamma

/gate/source/FOVUniSource/gps/energytype Mono

/gate/source/FOVUniSource/gps/monoenergy 0.511 MeV

/gate/source/FOVUniSource/gps/type Volume

/gate/source/FOVUniSource/gps/shape Cylinder

/gate/source/FOVUniSource/gps/radius 1.6 mm

/gate/source/FOVUniSource/gps/halfz 15.0 mm

/gate/source/FOVUniSource/gps/centre 0. -17.5 0. mm

/gate/source/FOVUniSource/gps/confine NULL

/gate/source/FOVUniSource/gps/angtype iso

/gate/source/FOVUniSource/gps/mintheta 0.0 deg

/gate/source/FOVUniSource/gps/maxtheta 180.0 deg

/gate/source/FOVUniSource/gps/minphi 0.0 deg

/gate/source/FOVUniSource/gps/maxphi 360.0 deg

/gate/source/FOVUniSource/setAccolinearityFlag true

/gate/source/FOVUniSource/setAccoValue 0. deg
/gate/source/list
2. e+ source

/gate/source/addSource sourceF18

/gate/source/sourceF18/setActivity 1000000. becquerel

/gate/source/sourceF18/gps/particle e+

/gate/source/sourceF18/setForcedUnstableFlag true

/gate/source/sourceF18/gps/energytype Fluor18

/gate/source/sourceF18/setForcedHalfLife 6586 s

/gate/source/sourceF18/gps/type Volume

/gate/source/sourceF18/gps/shape Cylinder

/gate/source/sourceF18/gps/radius 1.6 mm

/gate/source/sourceF18/gps/halfz 15. mm

/gate/source/sourceF18/gps/centre 0. -17.5 0. mm

#/gate/source/sourceF18/vis/setColor green

/gate/source/sourceF18/gps/confine NULL

/gate/source/sourceF18/gps/angtype iso

/gate/source/list

P.S. I have seen some posting regarding this on SPECT but could not find it
useful.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Phantom Scatter Error.JPG
Type: image/jpeg
Size: 16799 bytes
Desc: not available
URL: <http://lists.opengatecollaboration.org/mailman/private/gate-users/attachments/20120301/33123853/attachment.jpe>