[Gate-users] unwanted scatter events in primary spectrum

[Simon Stute]

Also, did you use the /gate/.../gps/.../monoenergy command ???

On Tue, Aug 31, 2010 at 3:16 AM, Simon Stute <gate.stute at gmail.com> wrote:

> Hi Samuel,
>
> Did you try a point source forced to emit along a line directly in a huge
> unique crystal made of a material with extremely high Z, and everything in
> vacuum ?? :-)
> Otherwise, if it will not result in a "segmentation violation", try the
> same experience but defining the world (or an object of the same size than
> the world) made of crystal material and attached as crystalSD, and with the
> point source inside in the center.
>
> And did your Tc99m emit only 140,5 keV gamma rays ??
>
> At least, use the G4tracking verbosity, set a pause after each singles
> detection with an abnormal energy, and track the particles by your eyes :-)
>
> Good luck !
> Simon
>
>
> On Tue, Aug 31, 2010 at 12:47 AM, Samuel BURG <samuel_burg at yahoo.fr>wrote:
>
>>
>>
>> Hi Gaters,
>>
>>
>> I have a crazy issue with scattering and primary spectra (SPECT simulation
>> with
>> Tc99m)
>>
>> when I create a primary spectrum from root data save from a gate
>> simulation
>> there are to many events out of the dedicated energy spike, and it look
>> like
>> event tagged as primary events are in fact scatter events.
>>
>> this occurred in numerous different situations/configurations. I haven't
>> find
>> any configuration who doesn't produce such a problem, even with the SPECT
>> benchmark.
>>
>> here's all what I have tested, nothing solving the issue :
>> - 32 / 64 bits arch
>> - single CPU / SMP / Cluster
>> - GATE version 4.0 / 5.1
>> - source shape : point / cylinder
>> - collimator : with / without
>> - PMT back compartment : single volume / complex multi volumes
>> - disabling all  non-crystal volume (setting all material to "Air", or
>> removing
>> all volumes from simulation)
>>
>> - different energyCut
>> - crystal material : NaI / NaI(Tl)
>> - with very basic digitizer (only adder) or very complex digitizer (all
>> SPECT
>> modules but optic tracking)
>> - same issue with the benchmark (root output and ASCII output)
>> - same results using different fields of the root file to asses with event
>> is
>> primary or scatter : RayleighVolName, RayleighPhantom, RayleighCrystal,
>> comptVolName, comptonPhantom, comptonCrystal
>>
>> Software versions :
>> OS : GNU Linux, Ubuntu 10.4 LTS, x86_64
>> GATE : 4.0 & 5.1
>> root : 5.20/00      24 June 2008
>> clhep : v2.0.3.2
>> geant4 : 4.9.1.p02
>> gcc : 4.2.x (replacing system default 4.4.x)
>>
>> What's crazy is that in the sample file
>> gate_v4.0.0/benchmarks/benchmarkSPECT/Results_benchmark.doc the primary
>> spectrum
>> looks like a primary  spectrum, and when I run the benchmark, the primary
>> spectrum has some additional scatter event !
>>
>> So, there is something I really don't understand here, and it turns me
>> crazy !
>>
>> Attached :-> too big files, not attached, use sendspace links below
>> - the outputs of the SPECTbenchmark compressed with 7z, ascii files and
>> root
>> files.
>> - screen capt. of the sprectra I have with my own processing and with the
>> root
>> processing of the benchmark (root output)
>> - results of the processing of ASCII output
>>
>> someone has an idea before I break down ?
>>
>> Best regards,
>>
>> Samuel
>>
>> Link for files on sendspace (ask me if you have any trouble downloading
>> the
>> files):
>> http://www.sendspace.com/file/vo7sa0
>> http://www.sendspace.com/file/0ofue2
>> http://www.sendspace.com/file/nvw4ef
>> http://www.sendspace.com/file/w1m0va
>> http://www.sendspace.com/file/seshz9
>> http://www.sendspace.com/file/xck3rt
>>
>> -----------------------------------------------------------
>> Samuel Burg
>>
>>
>> Mail : <samuel_burg at yahoo.fr>
>> -----------------------------------------------------------
>> "Aw, come on, who would be so stupid as to insert a cast
>> to make an error go away without actually fixing the error?"
>> Apparently everyone.
>> -- Raymond Chen  --
>> -----------------------------------------------------------
>>
>>
>>
>> _______________________________________________
>> Gate-users mailing list
>> Gate-users at lists.opengatecollaboration.org
>> http://lists.opengatecollaboration.org/mailman/listinfo/gate-users
>>
>
>