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Forum: Hadronic Processes
Re: Question 152Eu (Lise-Lotte Andersson)
Re: None Re: 152Eu (L.G. Sarmiento)
Date: 03 Mar, 2011
From: Laurent Desorgher <Laurent Desorgher>

Dear Pico,

According to what you write the problem is rather a geometrical one than an hadronic model one. I would therefore recommand you to post your message to the geometry forum. If you can not solve your issue on changing the geometry from macro command. You could also consider to use the GDML like geometry, where you provide your geometry description in xml format. See examples/extended/persistency/gdml.

Best regards

Laurent

On Mon, 28 Feb 2011 17:46:51 GMT, L.G. Sarmiento wrote:

> Dear forum people,
> 
> It looks like I pinned down the problem in the simulation and now I come
> again to ask for your advice.
> 
> The situation is the following: Since 152Eu is a calibration source. I
> programmed the rod that holds the calibration source inside the chamber
> as something you can include or exclude by means of a DetectorMessenger
> i.e. you can place it or not via a macro and it was not included by
> default.
> 
> Since the only 'controversial' part of the code was precisely the
> placement or not of the rod, I decided to change that and hard coded the
> "rod" (remember: not present by default) and it turns out that it makes
> a lot of difference.
> 
> Please follow the links and you will find the spectra, for the different
> scenarios, between 500keV and 1500keV (same range shown by Lisa for the
> simulation AND the experiment), and please pay special attention to the
> intensities of the peaks located at ~780keV, ~960keV and 1400keV.
> 
> If you let the source "hanging in the air" without placing the
> holder(rod) you find this:
> -> Never placing the "removing line" in the macro. (rod not present by
> default)
> http://dl.dropbox.com/u/18580197/152Eu_NO_holder.png
> -> Removed via Detector Messenger
> http://dl.dropbox.com/u/18580197/152Eu_macro_NO_holder.png
> (they are exactly the same between them since the rod was never there
> BUT the geometry gets recomputed anyway, details below).
> 
> If on the other hand you place the holder via the macro you get this:
> http://dl.dropbox.com/u/18580197/152Eu_macro_holder_2.png
> (you may notice that this is nothing but the original problem)
> 
> BUT, on the other hand if you hard-code the rode from the beggining
> (holder_flag set to true in the details below), this is what you get:
> http://dl.dropbox.com/u/18580197/152Eu_coded_holder.png
> (and this is the desired result !!!!)
> 
> So, wrapping up: the problem comes to the fact that there is something
> wrong in the way I include the rod and here comes the part where I want
> to learn how to avoid fix the situation properly.
> 
> The relevant parts of the code are the following:
> 
> G4LogicalVolume DetectorConstruction::Construct()
> {
> ...
> if(holder_flag) ConstructSampleHolder(); //holder_flag=false by default
> ...
> }
> 
> void DetectorConstruction::ConstructSampleHolder()
> {
> ...
> ... PhysicalVolume definition and placement of the rod inside the
> chamber
> ...
> }
> 
> The relevant part from the DetectorMessenger is this:
> 
> if ( command == sampleHolderCmd )
> {
>  G4bool flag = sampleHolderCmd->GetNewBoolValue(newValue);
>  detector->setHolder_flag(flag);
>  detector->UpdateGeometry(); //Should I implement a RemoveDaughterVolume
> function?
> }
> 
> And this is what the UpdateGeometry() method does:
> 
> void DetectorConstruction::UpdateGeometry()
> {
>   // Cleanup old geometry
>   G4GeometryManager::GetInstance()->OpenGeometry();
>   G4PhysicalVolumeStore::GetInstance()->Clean();
>   G4LogicalVolumeStore::GetInstance()->Clean();
>   G4SolidStore::GetInstance()->Clean();
>   G4RunManager::GetRunManager()-> GeometryHasBeenModified();
>   G4RunManager::GetRunManager()->DefineWorldVolume(Construct());
> }
> 
> 
> What am I doing wrong here? The volume looks ok in the heprep
> visualization(!).
> 
> Many thanks for the time you spent helping me/us and I apologize if this
> is not the right forum to ask this follow-up question.
> 
> 
> /Pico
> 

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