Study of the neutron radiation hardness of MAPD-3NK2 silicon photomultipliers

The radiation hardness of MAPD-3NK2 photodiodes with deep-buried pixel structures was evaluated under neutron irradiation at fluences ranging from 3.6 × 109to 3.6 × 1012neq/cm². Irradiation induced dark current increase of up to 2060 times, a breakdown voltage shift of (0.37 ± 0.08) V, a photo signal amplitude reduction of (90.1 ± 0.4) %, and a tenfold degradation in amplitude resolution. Partial recovery was observed after 40 days of room-temperature annealing, with dark current decreasing by 35%.Similar performance changes were observed in photodiodes with artificially elevated dark current, indicating that excess current is the primary driver of degradation. This current likely impedes photoelectron detection by occupying pixels or failing to fully quench the avalanche process, thereby reducing photocurrent.