Resolve non-isotropic pion emission in the INCL++ simulation model

Resolve the ongoing problem of non-isotropic emission of certain generated pions in the INCL++ low-energy antiproton-annihilation simulation model.

Background

The paper uses the INCL++ physics list in GEANT4 to simulate low-energy antiproton annihilations on the materials surrounding the GBAR experiment’s microchannel plate detectors. This model substantially improves the simulated charged-pion multiplicities compared with the BERT physics list.

However, the simulation still exhibits non-isotropic emission for certain generated pions. Although the authors state that this issue does not affect their analysis because they use a ratio of simulations at two detector positions, the problem remains an unresolved limitation of the underlying simulation model.

References

Despite an ongoing problem with the non-isotropic emission of certain generated pions it was decided to use this code as a base for this work.

— Monitoring antiproton numbers with a CMOS detector in a dense-track environment  (2609.04078 - Regenfus et al., 3 Sep 2026) in Section 3, subsection “Model description”