[Gate-users] Back to Back source

[Emmanuel BRARD]

Hi again,

Well this is more like :
Whatever I set it won't consider my command(s) and I will have two gammas with an accolinearity 
I if remove the accolinearity flag test in the file GateBacktoBack.cc I can get it works but then of course I cannot have accolinerity anymore. 

Regarding what you wrote :
¨If you set the AccolinearityFlag at false (default value)¨ I still have some non pure btb emission
¨If you set the flag at true with the AccoValue variable at 0 (default value)¨ The same 

I suppose that could be related to the Set functions not setting anything ... ? It is as if the flag test in the file GateBacktoBack.cc is always true. I am not interested in accolinearity (with b2b) for the time being this is why my simple solution was to remove the test from the source file. 

Again I had only a quick look yesterday at home because I cannot recompile Gate here at the lab. 

Thanks,

-----Message d'origine-----
De : Seb [mailto:sebastien.jan at cea.fr] 
Envoyé : mardi 22 février 2011 11:10
À : Emmanuel BRARD
Cc : gate-users at lists.opengatecollaboration.org
Objet : Re: [Gate-users] Back to Back source

Hi,

To summarize the situation:
If you set the AccolinearityFlag at false (default value), it will work fine and Gate generates a pure b2b emission.
If you set the flag at true with the AccoValue variable at 0 (default value), you generate again a pure b2b emission.
BUT : When you set AccoValue != 0 , a bug appears......it will be fixed for next release.

Regarding the GatePositronAnnihilation class, the 2 gammas are generated with the accolinearity and it is well validated.

Hope this help

Seb
> Dear All,
>
> I tried once with the two macro commands here-under but I still have 
> some accolinear photon pairs but if I use a modified version of GateBackToBack.cc in which there is no accolinarity support at all, then everything work well. I would assume that the accolinearity is not correctly supported by this version. I should have a look at how this is implemented for a positron source and copy the implementation for the btb source but I thought maybe this is a known issue by the developers and that It will be fixed in the next release.
>
> Regards,
>
> --
> BRARD Emmanuel
> emmanuel.brard at alumni.u-psud.fr
> Medical Physics - PhD Student
> IPHC IMABIO Bat 25 - 23 rue du Loess
> 67037 Strasbourg Cedex 2
> FRANCE
>
>
>
> -----Message d'origine-----
> De : Alexandre Dupas [mailto:alexandre.dupas at gmail.com]
> Envoyé : lundi 21 février 2011 11:57
> À : Emmanuel BRARD
> Cc : gate-users at lists.opengatecollaboration.org
> Objet : Re: [Gate-users] Back to Back source
>
> Dear Emmanuel,
>
> Since, I don't really know what bugs are corrected by the BackToBack.cc you use, I would suggest to try setting the accolinearity to 0 deg and accolinearity flag to false using the following commands:
>
> /gate/source/twogamma/setAccolinearityFlag false 
> /gate/source/twogamma/setAccoValue 0 deg
>
> and looking if the result still contains some accolinear photon pairs.
> As I said previously, using Gate v5 (with some patches), we don't have such issues anymore but I cannot say about Gate v6.
>
> Best regards,
> Alexandre
> --
> Alexandre Dupas
> Postdoctoral Research Fellow
> INSERM U698, CHU X. Bichat, Médecine Nucléaire
>
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