Ionisation diagram, explaining the effect of secondary particles that are generated (directly or indirectly) by CR protons and electrons through ionisation, pion decay (π⁰, π^±), BS, and pair production (pair). The secondary particles include electrons (e⁻, due to primary and secondary ionisation), positrons and electrons (e^±, due to pair production and π^± decay; also electrons produced in secondary ionisation are included), and photons (γ, due to BS and π⁰ decay), all contributing to the respective ionisation routes.