[Gate-users] system choice for energy centroid

[Marc Chamberland]

Thanks, Devin. That’s much more clear.

I’ve never used anything but the default policy. However at first sight, it looks like you’re doing everything right. Maybe someone with more experience can chime in, but it’s also possible this is a bug. If you’re comfortable with C++, I’d suggest you take a quick look at the area of the code where the error message is produced and see if anything jumps at you.

Marc


On Jun 3, 2015, at 10:04, Devin VanElburg <vanelbud at tbh.net<mailto:vanelbud at tbh.net>> wrote:

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<mailto: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

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