[Gate-users] Z position

[Chen, Yu]

The peak in bottom is due to your geometry setting: the sensitive detector is the same as
world size at -z, then no photons can escape your SD. You need to set your world size in z
slightly bigger.

None of your three plots makes sense to me. Maybe next time you can look only those with
small globalPosX, Y events.

Yu Chen, Ph.D.
University of Massachusetts Medical School
Division of Nuclear Medicine
55 Lake Avenue North
Worcester, MA 01655-0243
Phone:  (508) 856-6123
Fax:    (508) 856-4572



-----Original Message-----
From: gate-users-bounces at lists.healthgrid.org on behalf of venialgo_e
Sent: Thu 2/14/2008 8:16 AM
To: gate-users at lists.healthgrid.org
Subject: [Gate-users] Z position
 
Hello Gate users,

I'm studying the effect of Depth Of Interaction in a crystal of NaI. I  
simulated a detector of 30cm x 40 cm x 2.5 cm using a source with  
several emission angles.

the detector is:

/gate/scanner/daughters/name cristalIoduro
/gate/scanner/daughters/insert box
/gate/cristalIoduro/geometry/setXLength 5 cm
/gate/cristalIoduro/geometry/setYLength 5 cm
/gate/cristalIoduro/geometry/setZLength 2.5 cm
/gate/cristalIoduro/placement/setTranslation  0 0 -1.25 cm
/gate/cristalIoduro/setMaterial NaI
/gate/cristalIoduro/vis/setColor red
/gate/cristalIoduro/attachCrystalSD


the source is:

/gate/source/addSource cesio
/gate/source/cesio/setActivity 20000 becquerel
/gate/source/cesio/gps/centre 0. 0. 1 cm
/gate/source/cesio/gps/particle gamma
/gate/source/cesio/gps/energytype Mono
/gate/source/cesio/gps/monoenergy 0.622 MeV
/gate/source/cesio/gps/type Volume
/gate/source/cesio/gps/shape Sphere
/gate/source/cesio/gps/radius 0 cm
/gate/source/cesio/gps/angtype iso


1)In the first case the emission angle is:
/gate/source/cesio/gps/mintheta    0. deg
/gate/source/cesio/gps/maxtheta    0. deg
/gate/source/cesio/gps/minphi      0. deg
/gate/source/cesio/gps/maxphi      360. deg

2)In the second, it is:
/gate/source/cesio/gps/mintheta    0. deg
/gate/source/cesio/gps/maxtheta    3. deg
/gate/source/cesio/gps/minphi      0. deg
/gate/source/cesio/gps/maxphi      360. deg

3)In the last, it is:
/gate/source/cesio/gps/mintheta    0. deg
/gate/source/cesio/gps/maxtheta    20. deg
/gate/source/cesio/gps/minphi      0. deg
/gate/source/cesio/gps/maxphi      360. deg


And The questions about Z positions of the singles are:


1)In the first case , why are there a lot of counts only on the  
crystal's top face?.

2)In the second case, why are there more counts in one half of the  
crystal than the other?

3)In the third case. why is there a peak of counts, in the crystal's  
bottom face ?.


P.D.: I attached the macro files for each case, and gif files with the  
Z position's histograms  of the singles, also.

   Thanks in advance,

   Esteban Venialgo





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