Versions
FLUKA: 4-5.0
Flair: 3.4-2
Description
Dear FLUKA Experts,
I am writing this post because I have noted inconsistencies when modeling a Cs-137 radioisotope source with the latest FLUKA version (4-5.0).
Before running shielding simulations, I tested the source term by calculating the ambient dose equivalent rate of a Cs-137 point source in air at 1 m and comparing it with its reference value found in standards and in the literature (i.e., about 0.09 mSv/h/GBq at 1 m).
To do so, I used the BEAM card with ISOTOPE option, plus a HI-PROPE card with Z=55 and A=137 together with the RADDECAY (Semi-Analogue mode) and DCYSCORE cards for transport and scoring, respectively.
With FLUKA 4-4.1 I had obtained the expected result, but with version 4-5.0 the dose rate is about 0.18 mSv/h/GBq (double the reference value). The photon fluence is also twice as high.
If instead I simulate Ba-137m directly (by setting Z=56, A=137 and Isom.: -1 in HI-PROPE), I still obtain a correct value for the dose rate and photon fluence, in agreement with expectations (half of the Cs-137 case).
I attach here the input files I used to simulate the dose rates from Cs-137 and Ba-137m, and the photon spectra obtained in both cases (with materials set to VACUUM to clearly identify photon lines).
Could you please check if there is an error in my input setup that explains the overestimation when simulating Cs-137?
Thank you very much in advance,
Sincerely,
Matteo
Input files
Cs137_Test.inp (1.6 KB)
Ba137m_Test.inp (1.6 KB)