Optical photon production and transport

Dear FLUKA experts,
I want to use scintillating material to produce optical photon,then use wavelength-shifting fiber(absorb optical photon with one kind of wavelength and emission optical photon with other kind of wavelength ),final use ordinary fiber to transport.I have some questions here:
1.what is the difference between pre-defined material “PLASCINT” and the real material of wavelength-shifting fiber core(in this case is polystyrene)?Could I use the former to instead the polystyrene?
2.For the card “OPT-PROP”,if I let the SDUM=blank,I must give refractive index,absorption and diffusion coefficient ,but some value is hard to get,so could I not use this SDUM=blank(only SDUM=WV-LIMIT)? For the other words,if I want to achieve my goal,what is essential about “OPT-PROD” and “OPT-PROP”?
Looking forward to your reply.

Dear Xiong,

  1. PLASCINT is a pre-defined compound set according to ICRU standards. In case you know the exact composition of your scintillator, I would suggest to use that instead - the chemical composition and density would be more precise.

  2. For OPT-PROP with SDUM=blank you can also use the default values of given coefficients by leaving the appropriate field blank. The default values are: refraction index = 1, coefficient and absorption coefficient = 0. Here it depends on the level of precision you are after. Do you need to have the absrption and diffusion in your simulation? If yes, then you need to find out the value of these coefficients anyway.

What I am more worried about is the simulation of the wavelength shift. I am not sure how (or even if) this can be done in FLUKA.

Dear Vojtěch,
Thank you for your reply,I have understand the problem.Similarly, I have questions about wave-shifting fibers too.That is:
Today, as I was gathering the three coefficients of OPT-PROD with SDUM=blank,I found that the manual seemly not specify whether the coefficient were for the absorption wavelength or the emission wavelength when used in wavelength-shifting fiber.
Now,as you are not sure FLUKA can used to simulate the wavelength-shifting fiber,this question may be meaningless?

Hi, as mentioned in the manual (Note 1), wavelength shifting can be simulated thanks to the dedicated wvlnsh.f user routine, you can find in the user directory for your own coding.
As for the OPT-PROP input coefficients, their value refers to the central wavelength as input in another OPT-PROP card with WV-LIMIT SDUM. They are calculated runtime for the actual optical photon wavelength by means of a third order series expansion as explained in the Note 2 of the manual page linked above.

A post was split to a new topic: How to use user routines, especially wvlnsh.f