Release of FLUKA 4-1.0

It is our pleasure to announce that a new release of the FLUKA code, FLUKA 4-1.0, has been issued and can be downloaded from here.

Please find at the bottom of this message the list of included changes, addressing in particular various matters recently discussed on the user forum ( link).

With our best regards,

The FLUKA developer team at CERN and collaborating institutes



  • Spin and parity of the compound nucleus are now accounted for during the evaporation and Fermi break-up stages.
  • Photonuclear cross sections on 46Ti, 48Ti, 181Ta, and 208Pb have been slightly adjusted in the Giant-Dipole-Resonance region to remove spurious features.


  • An additional version of the source routine, source_newgen.f, with a cleaner structure that facilitates access to newcomers and several built-in options, has been made available as beta release in the src/user/ directory. (The traditional source.f is still fully operational and preexisting user-customized source routines remain totally compatible).
  • The usrmed.f user routine has now three additional arguments (TXXPOL, TYYPOL, and TZZPOL) carrying the particle polarization direction.
  • The sixth parameter (WHAT(6)) of the GLOBAL card, interpreted as REAL*8 units, now allows the user to customize the size of the blank common.
  • Prompt and decay electromagnetic transport thresholds, as possibly altered by the RADDECAY card, are now explicitly written in the output file.


  • As an unintentional side effect of the photofission restoring in 4.0, an excessive fission yield was reported for some material (e.g. Ta). This has now been cured.
  • The two crashes reported in have been solved.
  • In the SPOTBEAM card, flat angular divergences along X and Y directions appeared swapped and angles were misinterpreted as half-angles (instead of full angles). The respective corrections have been implemented.
  • The crash reported in (due to an uninitialized variable in a low-energy proton reaction) has been solved.
  • Ions channelled in a bent-crystal now experience the suppression of large-angle single scattering, previously not active.
  • The angular distribution of photoelectrons generated by polarized photons has been restored.
  • Two rare PEANUT crashes, leading respectively to an index out of bounds and to an undefined particle mass, have been solved.
  • XSIZERO and AXSIZERO are no longer included in the HAD-CHAR generalized particle.
  • The rare crash reported in (due to a misinitialized tolerance in USRBIN scoring) has been fixed.