Release notes for FLUKA 2025.1.3

This is a minor respin of fluka2025.1

This respin fixes a few issues:

  • An extremely rare issue with scoring after photomuon production which could result in an array out of boundary if that interaction is the very first one of a shower;

  • An excessively strict normalization check when computing X-ray reflection at boundaries, which could very rarely result in a spurious error message and abort (thanks to R. dos Santos Augusto for pointing it out);

  • A crash when scoring dose to water (generalized particle DOSE-H2O) when there is no radiobiological database defined. Now dose to water works even if there is no radiobiological database defined. (thanks to R. dos Santos Augusto for pointing it out);

  • An issue with the usxrea auxiliary routine which did not write correctly the xxx_tab.lis file (please note that the usxsuw auxiliary routine is writing the xxx_tab.lis file correctly, only in case the summed file was reprocessed with usxrea the issue would have appeared);

Minor improvement:

  • Photonuclear interaction in the GDR range for alpha-cluster light nuclei have been slightly improved;

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