# OPT-PROD with SDUM=SCINT-WV and SENSITIVE

Dear FLUKA experts,
The following picture is from the manual “CERN-2005-10.pdf”,page330.
For the first card,lamda=1.280E-05 corresponding to 9.6875eV,in the previous line is 2*10^ 4 photons/MeV,it can be calculated to 19.375%,so why here is 9.686E-02?
The last OPT-PROP with SENSITIVE,does the maximum quantum efficiency are (emission photons/absorbed photons),if yes,why the example not define emission wavelength?Then,what are other value represent,the manual seems not specified

Look forward to your help

Dear Xiong,

• regarding the mismatch in the values of the fraction - it seems you are right! I will consult with my colleagues and if it really is an error, we will fix it in the manual.

• regarding the OPT-PROP card with SENSITIVE - if I understand correctly, the emission wavelength has nothing to do with this card. This card is used to reduce the amount of generated optical photons per primary in order to get an estimate of detected photons by a detector with a given quantom efficiency. In this case, the quantum efficiency of the detector is 0.1, therefore, only 1/10 optical photons are generated. As for the other values, please see the information in the OPT-PROP section of the FLUKA manual.

Dear vojtech，
For the second question in the first picture,does it to say in Liquid Argon the Theoretical value is 2e+4 photons/MeV，but the real photons generated is 2e+3，so the quantum efficiency is the ratio of them equal to 0.1?
If it yes，the card OPT-PROD’s ratio should be (9.6875×0.1×2×10e+4)/1e+6=1.9375%?
I think there maybe something wrong.
Look forward to your help.

According to the values in OPT-PROD/SCINT-WV above, the comment should read 10^4 photons/MeV, and not twice as much. As @vojtech.stransky said, it’s a typo to be indeed fixed in the manual. (For each deposited MeV, 96.9 keV go into scintillation light, corresponding to the generation of 10^4 optical photons of 9.69 eV).

Dear@ceruttif ,
Thank you for your help. Another question is OPT-PROP with SDUM=SENSITIVE as I said above.
As I understand it,OPT-PROD with SDUM=SCINT-WV, OPT-PROP with SDUM=WV-LIMIT and SDUM=blank defines the optical photons’ generate ,transmission and process of transmission,it is a complete process.
but for SDUM=SENSITIV,what is 0th,1st,2nd,3rd sensitivity parameter? At page 330 of the manual,maximum quantum efficiency represent what?

Dear @vojtech.stransky ,
For the SDUM=SENSITIV,I have an idea,you see if it is right(just see the picture in my first question).
With 1MeV energy deposited,the material generate 10e+4 optical photons with wavelength=128nm,so its fraction is 9.686e-2,the material itself can transmit photons from 100nm to 600nm,central is 128nm.At the process of transmission,with refraction,absorption and diffusion,many photons are disappeared，so it is only 10% of generated optical photons are collected.
If it yes,the second to last OPT-PROP card is unnecessary？

Dear Xiong,
the SDUM=SENSITIV is used to tak into account the sensitivity of the optical detector itselfs. This means, that if 10 % of generated photons reach the optical detector, this card would further decrease the amount of photons - 10% of those 10% - therefore 1 % of generated photons would contribute to the signal of the optical detector.

Vojtěch

Dear@vojtech.stransky ,
That is to say the decrease is caused by the transmission in the fiber(for absorption,scatter and so on),then SDUM=blank seems superfluous here ,so what is the difference between them?

Dear Xiong,
let me try to explain a bit more clearly:

• SDUM=blank - sets up the optical properties of a material (such as a scintillator)

• SDUM=SENSITIV - sets up sensitivity of an optical detector (such as a CCD chip)

Is it better understandable now?
Vojtěch

Dear @vojtech.stransky ,
I have understand it ,thank you for your help.