Release notes for FLUKA 2025.1.2

This is a minor respin of fluka2025.1

This respin fixes a few issues.
  • An issue with Inverse Compton in magnetic fields which could have resulted in a crash when too long steps are requested. Thanks to Nicola Mazziotta for pointing it out;
  • A rare bug during scintillation photon production, which could have occurred in the wrong position. Thanks to Paola for finding and fixing it;
  • A rare bug during scintillation photon production with an user spectrum routine, which could have occurred in a photon generated with more energy than the emitting particle. Thanks to Paola for finding and fixing it;
  • A rare bug in BME which could result in a crash;
  • An extremely rare infinite loop in geometry. Thanks to Pavel Degtiarenko for pointing it out;
  • An extremely rare crash in evaporation;
  • An extremely rare issue for very low energy light, exotic, ions interacting in inverse kinematics;
  • A minor issue with pion production at intermediate energies;
  • At the same time several improvements have been implemented in the Fluka coding, particularly concerning rounding management at the highest energies.

    A (repeated) recommendation:


    when tracking in vacuum with dis-homogeneous magnetic fields it is recommended to activate the Runge-Kutta-Gill method instead of the default algorithm. Runge-Kutta is much more accurate and converges at the correct results with step lengths at least a factor ten or more longer than those required for a similar accuracy with the default algorithm. For homogeneous fields the default algorithm is exact.

    A (repeated) second recommendation:

    when tracking in dis-homogeneous magnetic and/or electric fields, please set in the relevant regions the maximum step length to a fraction of the scale of variation of the fields (use the STEPSIZE card).

    A reminder of the new FLUKA official reference (please read and quote!):

    F. Ballarini et al., "The FLUKA code: Overview and new developments", European Physics Journal Nuclear Science and Technology, Vol. 10, 16 (2024) https://doi.org/10.1051/epjn/2024015

    All users are urged to update to this respin. This is particularly important because the improvement, and a few of the issues, can change the random number sequence also for problems not affected by the crashes listed above. As usual, assistance will be provided only for the latest release/respin.

    The FLUKA developers