Resnuclei error

Dear Fluka experts,
I am studying the activation of the air surronding a D-T neutron generator, inside (INPU region) and outside (INSHIEL region) the primary polyethylene/graphite shield. I have set the essential cards for activation, including PHYSICS, IRRPROFI, DCYTIMES, RADDECAY, RESNUCLE and DCYSCORE. Currently, I am interested to obtain Bq/cmc at t=0 after 3 hours of irradiation with a primary beam of 2e8 n/s.

Punita.flair (5.9 KB)
Punita.inp (5.8 KB)

I have two questions:

  1. Even if I ran a simulation of 5e8 histories, the relative percentage error printed in sum.lis and tab.lis files is 99% for all radionuclides produced in both regions. These uncertainties make the result meaningless. What could be wrong? I would be expected lower uncertainties in the inner region (INPU) because there the activation events should be more likely.
    Punita_23_sum.lis (8.0 KB)
    Punita_23_tab.lis (15.5 KB)

  2. Is it possible to plot RESNUCLEI in 2-D diagram to see, for example, the location where the production of a radionuclide take place?

Thank you


Dear Corrado,

  1. You appear to run one single cycle, which by construction prevents the calculation of the statistical error (hence the symbolic 99%). You should divide your statistics over 5 cycles or so, allowing the FLUKA post-processing utilities run by Flair to evaluate the statistical error by comparing the different cycle results.
  2. USRBIN allows you to get even a 3D spatial distribution of RES-NUCL (note that - as for RESNUCLEi - they are scored where they stop, which does not always coincide with where they are produced).

Dear Francesco,
thank you very much.