Release of FLUKA 4-4.1

Dear FLUKA users,


It is our pleasure to announce that a new minor release of the FLUKA code, version 4-4.1, has been issued and can be downloaded from the Official CERN FLUKA website:

See the release notes at the bottom of this message for a detailed account of all novelties.

For consistency, please update to the latest version of Flair, available from


With our kindest regards,

The FLUKA developer team at CERN and Collaborating Institutes


=== Fluka-4.4.1 ===



  • Promoted the default mean excitation energy of the pre-defined compound WATER from its earlier value of I=75 eV to I=78 eV, following ICRU Report No. 90.
  • For pointwise low-energy neutron inelastic interactions, in the neutron energy range between threshold and the first energy for which data are available, the ejectile energy distribution is smoothly scaled within kinematic limits from the latter.



  •  The combination of constant magnetic field (with arbitrary orientation) and interpolated 2D/3D field is now allowed.



  •  Fixed a bug whereby the b_arcdpa and c_arcdpa parameters of compound materials were not honored: an effective weighted average of arc-DPA over constituents was performed (DPA-NRT if arc-DPA parameters were not explicitly defined). The damage threshold was always taken from the compound. In this version, instead, the damage threshold, b_arcdpa, and c_arcdpa of compound materials are taken from the MAT-PROP card for the compound (if present); otherwise a weighted arc-DPA coherently taking the damage threshold, b_arcdpa, and c_arcdpa of all constituents is performed.
  • Fixed an error, whereby the damage function to obtain Si 1-MeV neutron equivalent fluence was inconsistently interpolated for neutrons below 15 MeV  when treated point-wise.
  • Fixed a rare bug whereby Fermi break-up channels of 12C to >=3 fragments were discarded in case a 12C Hoyle state was encountered in the previous call to the Fermi break-up module.
  • Fixed a tabulation error which led to an index out of bounds for neutrons of exactly 20 MeV being treated point-wise.
  • Fixed a bug whereby the profiler was not active in case of a purely EMF problem without scorings.
  • Fixed a bug whereby a nuclear-geometry variable for light fragments was not properly updated. Residual production from light-nuclei interactions is   thereby slightly improved.
  • Fixed a bug whereby a stack variable carrying particle progeny information for radiobiological scoring was not properly initialized in some residual cases, as reported in these forum posts: