A Parameterisation ofγ-ray production cross-sections for pp interactions in a broad energy range

Andrew M Taylor

doi:10.1051/epjconf/201510502002

Abstract

Using different Monte Carlo codes such as Geant 4.10, Pythia 8.18, SIBYLL and QGSJET, as well as compiling published data on pp interactions close to the kinematic threshold, we parametrize the energy spectra and production rates of gamma-rays by simple but quite accurate (≤ 20%) analytical expressions in a broad range from the kinematic threshold to PeV energies.

Highlights

High energy astrophysics bridges several major disciplines in physics, broadly drawing on solid foundations in particle physics enabling new areas in high energy astrophysics to be investigated
The restricted energy range for which the pion production cross-section and the differential crosssection for the γ -ray secondaries have been probed forces the use of descriptions beyond the energy range for which they have been tested ranges. This fact, coupled to the large proton energy range which astrophysical processes probe via this process, and the multitude of Monte Carlo extrapolations available, motivate a simple analytic template capable of encapsulating these descriptions
We take here the total and elastic p–p cross section data compiled by the Particle Data Group (PDG) [3]

Summary

Introduction

High energy astrophysics bridges several major disciplines in physics, broadly drawing on solid foundations in particle physics enabling new areas in high energy astrophysics to be investigated. The restricted energy range for which the pion production cross-section and the differential crosssection for the γ -ray secondaries have been probed forces the use of descriptions beyond the energy range for which they have been tested ranges. This fact, coupled to the large proton energy range which astrophysical processes probe via this process, and the multitude of Monte Carlo extrapolations available, motivate a simple analytic template capable of encapsulating these descriptions. Very hot astrophysical plasma calculations as well as the increasing sensitivity of the γ -ray instruments such as Fermi–LAT satellite, which has recently observed γ -ray spectra that reveal a sub-GeV bump, require accurate γ -ray production cross sections at low energies near the p–p kinematic threshold

Inclusive π 0 production cross section and multiplicity

80 PDG data

Parametrization of the γ -ray differential cross section

Findings

Discussion and conclusions