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No photons detected when ngamma = 2

Posted: Thu Feb 20, 2020 4:52 am
by Pu239
Hi,
With 2.1.31 when I use ngamma = 2, no photons are detected but the run finishes fine. With analog mode things work fine. I used the photon data libraries from http://montecarlo.vtt.fi/download/photon_data.zip

I had a patched 2.1.30 (patches from this forum) that ngamma = 2 worked fine. Any thoughts?

Input to repeat issue:

Code: Select all

% --- Natural uranium cylinder in air

surf 1 cyl 0.0 0.0  5.0
surf 2 cube 0.0 0.0 0.0 10.0

cell 1 0 uranium -1
cell 2 0 air      1 -2
cell 3 0 outside  2

% --- Materials:

mat uranium -19.0
92234.73c   0.00540
92235.73c   0.72000
92238.73c  99.27000

mat air -1.20500E-03
 6000.73c  -1.24000E-04
 7014.73c  -7.52324E-01
 7015.73c  -2.94416E-03
 8016.73c  -2.31781E-01
18036.73c  -3.88624E-05
18038.73c  -7.70386E-06
18040.73c  -1.27804E-02

% --- Data:

set declib "/home/kosmickitty/local/serpent_2/data/sss_endfb7.dec"
set nfylib "/home/kosmickitty/local/serpent_2/data/sss_endfb7.nfy"
set acelib "/home/kosmickitty/local/serpent_2/data/xsdir_sss"
set pdatadir "/home/kosmickitty/local/serpent_2/data/photons/"

% --- Geometry plot:

plot 3 500 500

% --- Flux plot:
det 1 n
mesh 8 4 1 3 500 500

det 2 p
mesh 8 4 2 3 500 500

% --- Run:
set pop 5000 20 10

% mode 1 reports non-zero det 2 and det p1
% mode 2 reports zero
set ngamma  2

Re: No photons detected when ngamma = 2

Posted: Thu Feb 20, 2020 12:37 pm
by Ville Valtavirta
Hi,

the weight limits for implicit photon production are not correctly set in 2.1.31. To fix this you will need to add the lines

Code: Select all

  /* Implicit photon production */

  WDB[DATA_PHOTON_IMPL_WMIN] = 0.1;
  WDB[DATA_PHOTON_IMPL_NMAX] = 10.0;
to the end of initdata.c.

This bug will be fixed in future updates.

-Ville

Re: No photons detected when ngamma = 2

Posted: Thu Feb 20, 2020 9:12 pm
by Pu239
Wonderful, thanks for the fix it worked.