Cobalt-60 gamma irradiation of silicon test structures for high-luminosity collider experiments

During the era of the High Luminosity LHC (HL-LHC) the devices in the experiments will be subjected to increased radiation levels with fluxes of neutrons and charged hadrons in the inner detectors reaching up to approximately $\mathrm{2.3\times10^{16}\:n_{eq}/cm^2}$ and total ionization doses up to around 1.2 Grad. A systematic program of radiation tests with neutrons and charged hadrons is being carried out by the CMS and ATLAS Collaborations in order to cope with the higher luminosity of HL-LHC and the associated increase in the pile-up events and radiation fluxes. In this work, results from a complementary radiation study with $^{60}$Co-$\upgamma$ photons are presented. The doses are equivalent to those that the outer layers of the silicon tracker systems of the two experiments will be subjected to. The devices in this study are p-type diodes and MOS capacitors.