Pion cross section parameterizations for space radiation codes

The space radiation environment consists of energetic particles that originate from the Sun and from sources outside the solar system. It is necessary to understand how these particles interact with materials to design effective radiation shielding. The transport of radiation through materials can be described by the Boltzmann equation. Efficient space radiation transport codes often require parameterized energy-dependent spectral distributions. A recent study showed that pions may contribute considerably to the total dose in galactic cosmic ray environments. Consequently, accurate parameterized pion spectral distributions are needed. In other studies, the Badhwar parameterization has been used for inclusive pion production in high energy nucleon–nucleon and nucleon–nucleus collisions, whereas a thermal model has been used to describe pion production in low energy nuclear collisions. In this paper, the thermal model is parameterized in terms of projectile energy, projectile nucleon number, and target nucleon number. Thermal and Badhwar model predictions of pion spectra from nucleon–nucleus and nucleus–nucleus collisions are compared for projectile energies ranging from 0.3 to 158 A GeV. It is recommended that the thermal model be used for projectile energies between 0.4 and 5 A GeV and the Badhwar model be used for higher projectile energies.