FLUKA version: 4-3.4, released on: 2023-09-29

Novelties of minor 4-3.n releases are displayed in italics and blue.

PHYSICS IMPROVEMENTS:

• A new point-wise treatment has been included for the interactions of low-energy neutrons (below 20 MeV), controlled by the new LOW-PWXS card. The download of at least one additional package is required, as detailed here.

• As of version 4-3.0, FLUKA is aligned with DPMJET v19.3.2, fixing spurious features in kaon spectra from nucleus-nucleus collisions at energies of ~10 GeV/n. As of version 4-3.2, FLUKA is aligned with DPMJET v19.3.5, fixing a rare crash due to a slightly mismatching value of the nuclear mass unit. As of version 4-3.4, FLUKA is aligned with DPMJET v19.3.6, fixing a rare compilation/linking issue.

• Scoring of athermal-recombination-corrected displacements per atom (arc-DPA) has been added, requiring two new user-specified parameters, as detailed in the MAT-PROP card documentation. Generalized particle DPA-NRES (#245) has been deprecated and replaced by the Norgett-Robinson-Torrens DPA-NRT.

• The emission of synchrotron radiation photons along charged particle steps, in vacuum regions subject to a magnetic field, has been implemented and is requested via the SYRASTEP card.

• Mass distribution of 226Ra fission fragments was corrected, addressing this forum post

• Reworked sampling of the target nucleus thermal motion for the elastic scattering of thermal neutrons, correcting an artifact that led to neutron fluxes slightly skewed towards energies lower than kT, affecting in particular light target nuclei.

• The parametrized reaction cross section of protons on deuterium below 5.5 MeV was refined to better reproduce experimental data available from EXFOR for the (p,g) and (p,n) channels, removing an unphysical rise below few MeV.

• The hitherto missing decay products of 11Be have been added, thus addressing the issue raised in this forum thread

• The reaction cross section for proton on B has been extended below 1 MeV, thus addressing the 5th item in this forum thread

• The JEFF-3.3 package for point-wise neutron interactions below 20 MeV has been updated to include new S(a,b,T) thermal scattering law tabulations. The latter feature a better energy and angle resolution, and now account for 58 binding environments (instead of 20 in the previous version). This new JEFF-3.3 package supersedes the old one, and must be downloaded as usual from https://flukafiles.web.cern.ch/neutron

• For events involving the combined emission of neutrons as well as charged particles, the neutron is now sampled first, thus assuring a more faithful adherence to the inclusive neutron emission spectra of the database.

• The erroneous decay products branchings of 99Tc have been corrected, thus addressing the issue in this forum thread

TECHNICAL IMPROVEMENTS:

• The new DETGEB card allows the user to apply a Gaussian broadening to energy deposition spectra scored with the DETECT card.

• The maximum number of regions of interest (ROI) in voxel geometries has been increased from 100 to 400.

• In the source_newgen.f user routine, sampling from a spectrum file (energy, intensity) was added.

• The code manual has been recast in restructured text format, providing the user with three consistent versions: text, pdf, and html. The latter is accessible at https://flukafiles.web.cern.ch/manual .

• Nuclear recoils with the same atomic and mass number as the target isotope  now contribute to RESNUCLEi scoring only when reaching a different geometry region.

• Kshort and Klong scorings now also include the respective contribution of K0 and K0bar, and viceversa.

• A simplified version of mgdraw (mgdraw_empty.f) is now offered for convenience, in addition to the original mgdraw.f.

• C++ header files are now provided for the FLUKA commons.

• The maximum number of heavy secondaries emitted during nuclear evaporation has been increased to 120, in order to accommodate a large (yet physical) number of heavy secondaries observed during a rare nuclear interaction between heavy nuclei which led to a crash in previous versions of the code.

• The FLUKA manual features newly formatted tables and several typo and error corrections.

Several bugs were fixed (see release notes for a complete list).