[Gate-users] system choice for energy centroid

[Devin VanElburg]

Hello Marc, 

I'll try and explain a little better what I'm trying to do. I have
defined my system as a PETscanner and attached the daughter volumes as
follows:

/gate/systems/PETscanner/level1/attach headblock
/gate/systems/PETscanner/level2/attach crystalboard
/gate/systems/PETscanner/level3/attach crystal
/gate/systems/PETscanner/layer0/attach lyso
/gate/lyso/attachCrystalSD

where 'crystal' is repeated as a cubicArray (24x24) and 'headblock' is
repeated twice with a ring repeater. I now have two opposing lyso
crystals with the attached CrystalSD. When using the default readout
policy:

/gate/digitizer/Singles/readout/setPolicy TakeEnergyWinner

My simulation runs fine, and the root output I receive is expected
(511keV peak as I am using a Na-22 source for positron annihilation) for
both Singles and Coincidences. However, when I try:

/gate/digitizer/Singles/readout/setPolicy TakeEnergyCentroid

I get a break with the following message:

[systems/PETscanner::FindComponent]:
    Could not find the request system component 'crystal'!

-------- EEEE ------- G4Exception-START -------- EEEE -------
*** G4Exception : ProcessPulseList
      issued by : GateReadout::ProcessPulseList
Failed to get the array component corresponding to the crystal. Abort.

*** Fatal Exception *** core dump ***
-------- EEEE -------- G4Exception-END --------- EEEE -------


*** G4Exception: Aborting execution ***
Aborted (core dumped)


What I take from this is that I need to use a system that I can attach a
volume to a so-called 'crystal' level. I've been playing with
cylindricalPET and redefined my system as follows:

/gate/systems/cylindricalPET/rsector/attach headblock
/gate/systems/cylindricalPET/module/attach crystalboard
/gate/systems/cylindricalPET/crystal/attach crystal
/gate/systems/cylindricalPET/layer0/attach lyso
/gate/lyso/attachCrystalSD

that way, I have attached my 'crystal' volume to a 'crystal' level in
the system hierarchy as I assume the error message suggested. Even
still, I get the break segmentation violation. I also get the same error
when switching to TakeEnergyCentroid for the cylindricalPET example that
GATE supplies. The wiki says to ensure the Depth is taken just above the
crystal, which I did. In fact I tried running it with the depth at all
levels and they all failed. I'm at a loss, I can't seem to get the
TakeEnergyCentroid policy to work despite my best efforts!

By the way, ignore my comment with my previous email concerning the
number of plates with a ring repeater. That was a readout depth issue
and it's working now.

I'd appreciate any help I can get here!

Regards,
Devin Van Elburg

------------------------
Physics w/ c/ Biomedical Physics
Lakehead University




>>> Marc Chamberland  06/02/15 5:00 PM >>>
Hi Devin,

I’m not sure I understand what you’re trying to do and what failed to
work. Can you provide more details?


Also, did you attach a crystalSD to your plates, as outlined here:
http://wiki.opengatecollaboration.org/index.php/Users_Guide_V7.1:Attaching_the_sensitive_detectors#The_crystalSD


Cheers,
Marc



__________________________

Marc Chamberland, PhD
Department of Physics
Carleton University
Ottawa (ON) 

On Jun 2, 2015, at 16:49, Devin VanElburg <vanelbud at tbh.net> wrote:

Hello gate users,

I am simulating a PET system with two plates. I would like to use the
takeEnergyCentroid option for the digitizer's readout. However, I need
to attach a volume to a 'crystal' of a system (according to the error
message I keep getting). Thus a PETscanner system cannot work since it
uses level1-4 and layers for system attachment. The I tried a
cylindricalPET system with a ring repeater of 2, and that also didn't
work. Interestingly, cylindricalPET works for a 4+ plate ring system,
but no singles or coincidences in the output for 2-3 plates (with only
the ring repeat number changed). Can anyone offer any insight as to what
I should do?

Regards,
Devin Van Elburg

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