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Forum: Processes Involving Optical Photons
Re: None Transmission of Optical Photons
Re: Feedback Re: Transmission of Optical Photons (Gumplinger Peter)
Date: 16 Jul, 2009
From: <>

Benton and Peter,

Thank you both for your helpful suggestions, I've tried to implement them and here's what I've discovered so far.

As per Benton's suggestion I've put in some code to see what's going on at my volume boundaries and had the program keep a running tally of the different options.

Number of optical photons created: 320

Boundary Event:                    # Of Occurances
Absorption                              0
Fresnel Reflection                      5
Fresnel Refraction                      323
Detection                               0 (Not surprising, no detector defined)
No Refractive Index                     265
        Of these,
              PreVolume expHall, PostVolume Detector: 22
              PreVolume Wrap,    PostVolume tracker: 242
              PreVolume WrapCap, PostVolume ALRing:  1
Total Internal Reflection               81
Spike Reflection                        27
Lambertion Reflection                   27
Lobe Reflection                         39
Back Scattered                          29
Not A Boundary                           0
Same Material                            1
Step Too Small                          208
        Of these,
              PreVolume expHall, PostVolume Detector: 122
              PreVolume Wrap, PostVolume Tracker;      85
        Also note that when StepTooSmall occured I called the GetStepLength()
        function to see what the step size was and on each of these occurances
        it came up to be 0 cm. I'm not sure the significance of this.

I'm confused as to why I'd have the No Refractive Index occurring so much, it looks to me as if every material has has the correct number of indexes defined. Could this be related to the step too small issue? I am in the process of trying different step sizes, so far no difference.

I thought perhaps there was some kind of geometry overlap going on so after some work I got DAWN and DAVID installed and figured out how to work them. According to DAVID the .prim file produced by the run shows no overlapping of boundaries.

DAVID Output:

Reading file: g4_00.prim Data reading completed

*** 7 primitives ***

Investigating intersections of surfaces Intersection investigation completed

--------------------------------------------------------- !!! Number of intersected volumes : 0 !!! !!! Congratulations ! \(^o^)/ !!! ---------------------------------------------------------

File g4david.prim is generated

I am currently running through Peter's suggestion of looking at the optics starting from only 1 boundary and adding on each one at a time but I thought I'd post this and see if it provided any insight into my problem. I'm not an optics person, as is probably evident, and most of the significance of this boundary output eludes me.

Many Thanks! Jason

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1 Feedback: Re: Transmission of Optical Photons   (Gumplinger Peter - 16 Jul, 2009)
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