set diffusion coefficient with Cherenkov photon production ON

From: zhiqiu li <zhiqiu.li_at_gmail.com>
Date: Thu, 3 Jan 2013 17:43:09 -0500

Dear group,

I just came across a strange mistake with OPT-PROP, when I simulated
Cherenkov photon production by electron beam incident on a water cube.

I firstly set Diffusion Coefficient = 1.22, and ran the simulation and
got photon spectrum with USRBDX.
Then I set Diffusion Coefficient = -100, hoping that FLUKA would call
function DFFCFF for diffusion coefficient. I have modified DFFCFF.F
and linked to FLUKA, and this function also return 1.22 for diffusion
coefficient for all wavelengths. I don't think there is anything
different, just one is to set through OPT-PROP card, one is to call a
function and get the same value.
But the photon spectra of these two methods were totally different (as
shown in figure spectra comparison.jpg).

I have tried similar procedure for refraction index, and absorption
coefficient, and the resulting photon spectra were identical. So I
really don't know what was wrong with diffusion coefficient setting
here.

I have attached all the files, and thanks in advance for any suggestion.

- Zhiqiu Li

spectra_comparison.jpg
Received on Fri Jan 04 2013 - 00:30:07 CET

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