Equivalence ionisation effect of 1 MeV electron and proton space particles and -rays on optical silica

At present, to evaluate the service life of space optical materials on the ground, Co-60 gamma-rays are usually used. However, the irradiation effect of the main space particles (protons, electrons) on materials is obviously different from that of gamma-rays, which causes evaluation errors. In this study, the Monte Carlo method was used to study the transportation of Co-60 gamma-rays, protons, and electrons in the usually used optical materials, silica (SiO2). The number of secondary electrons produced by particles at different energies, and quantities in targets with different thicknesses was obtained, and the dominant effect (ionisation effect) of particles on silica was analysed. Based on the ionisation effect, using the number of secondary electrons as the equivalence parameter, the irradiation effect conversion relation of Co-60 gamma-rays and particles (protons and electrons) on silica was established, which satisfies Boltzmann's function. This work provides a new life evaluation method for Co-60 gamma-rays ground irradiation experiments.