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Idea Re: Optical Photon Wave Length Shifting 

Forum: Processes Involving Optical Photons
Re: Question Optical Photon Wave Length Shifting (Eric)
Date: 14 Dec, 2010
From: Benton Pahlka <Benton Pahlka>

Hi Eric,

The source code G4OpWLS.cc is useful to look at and pretty easy to follow. In your code, you'll want to make sure that you have input for the WLS absorption length as well as the emission spectrum. By spectrum, I mean at least two input values, it could be more. If you're modeling (plastic) scintillator, then (I suggest) you need a primary emission spectrum, a "bulk" absorption spectrum, a WLS absorption spectrum and a WLS emission spectrum. G4OpWLS does the absorption and emission together, so it's just one instantiation.

You might consider making a histogram of the final wavelength (or energy) of WLS photons that you detect.

Best,

Benton

On Tue, 14 Dec 2010 01:18:37 GMT, Eric wrote:

> Hello-
> 
> I am working on a model of a scintillator that has an absorption/
> re-emission characteristic. I implemented this according to example 5.7
> here:
> http://geant4.web.cern.ch/geant4/UserDocumentation/UsersGuides/ForApplicationDeveloper/fo/BookForAppliDev.pdf
> 
> When I run my simulation, this is part of the result:
> 
> *********************************************************************************************************
> * G4Track Information:   Particle = opticalphoton,   Track ID = 95,   Parent ID = 1
> *********************************************************************************************************
> 
> Step#      X         Y         Z        KineE    dEStep   StepLeng  TrakLeng    Volume     Process
>     0    8.2 mm  -9.18 mm  -3.24 mm   3.36 eV      0 eV      0 fm      0 fm   Scintillator    initStep
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     1   8.61 mm  -9.34 mm  -3.22 mm   3.36 eV      0 eV    438 um    438 um   Scintillator  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     2   8.61 mm  -9.34 mm  -3.22 mm   3.36 eV      0 eV      0 fm    438 um        World  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     3   2.15 mm   1.25 cm  -2.13 mm   3.36 eV      0 eV   2.28 cm   2.33 cm   Scintillator  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     4   2.15 mm   1.25 cm  -2.13 mm   3.36 eV      0 eV      0 fm   2.33 cm        World  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     5  -2.98 mm   5.44 mm  -1.72 mm   3.36 eV      0 eV   8.75 mm    3.2 cm   Scintillator       OpWLS
> 
> *********************************************************************************************************
> * G4Track Information:   Particle = opticalphoton,   Track ID = 96,   Parent ID = 95
> *********************************************************************************************************
> 
> Step#      X         Y         Z        KineE    dEStep   StepLeng  TrakLeng    Volume     Process
>     0  -2.98 mm   5.44 mm  -1.72 mm   3.23 eV      0 eV      0 fm      0 fm   Scintillator    initStep
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     1  -8.37 mm   9.55 mm    781 um   3.23 eV      0 eV   7.22 mm   7.22 mm   Scintillator  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     2  -8.37 mm   9.55 mm    781 um   3.23 eV      0 eV      0 fm   7.22 mm        World  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     3   4.01 mm  -1.21 cm   9.96 mm   3.23 eV      0 eV   2.65 cm   3.38 cm   Scintillator  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     4   4.01 mm  -1.21 cm   9.96 mm   3.23 eV      0 eV      0 fm   3.38 cm        World  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     5    3.1 mm  -4.68 mm   1.27 cm   3.23 eV      0 eV   7.92 mm   4.17 cm   Scintillator  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     6    3.1 mm  -4.68 mm   1.27 cm   3.23 eV      0 eV      0 fm   4.17 cm        World  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     7   3.77 mm  -1.21 cm   1.19 cm   3.23 eV      0 eV   7.52 mm   4.92 cm   Scintillator  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     8   3.77 mm  -1.21 cm   1.19 cm   3.23 eV      0 eV      0 fm   4.92 cm        World  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>     9  -8.43 mm    9.5 mm    9.3 mm   3.23 eV      0 eV    2.5 cm   7.42 cm   Scintillator  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>    10  -8.43 mm    9.5 mm    9.3 mm   3.23 eV      0 eV      0 fm   7.42 cm        World  Transportation
> CYL_ST_SteppingVerbose::StepInfo() : verbose level = 1
>    11    962 um   2.61 mm   8.08 mm   3.23 eV      0 eV   1.17 cm   8.59 cm   Scintillator       OpWLS
> 
> Notice that the last step in each is "OpWLS." I would expect that there
> would be two calls to this though, one for absorption and one for
> emission, so I find it odd that the particle ends there.
> 
> Does anyone have an explanation for this? Or a clue as to where I might
> be going wrong?
> 
> Thanks!
> 

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1 Question: Re: Optical Photon Wave Length Shifting   (Eric - 16 Dec, 2010)
1 Disagree: Re: Optical Photon Wave Length Shifting   (Gumplinger Peter - 16 Dec, 2010)
1 Ok: Re: Optical Photon Wave Length Shifting   (Eric - 17 Dec, 2010)
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2 Idea: Re: Optical Photon Wave Length Shifting   (Benton Pahlka - 17 Dec, 2010)
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