Response of Silicon Solar Cells to Neutrons in Post-Detonation Monitoring

In this study, we evaluated the feasibility of using solar photovoltaic (PV) panels for the detection of prompt neutrons from a nuclear denotation. Monte Carlo (MC) simulations were performed to evaluate the response of silicon (Si) solar cells (SCs) to neutrons and support the experiments. The response of Si SCs to fission spectrum neutrons was measured experimentally using the fast neutron beam of a research reactor. Steady-state neutron measurements indicated a clear response of the Si SCs, which correlated with changes in the neutron intensity. Time-modulated neutron measurements performed using a neutron chopper demonstrated a clear transient response of Si SCs to neutrons, which was observed in the signal power spectral density plots containing peaks corresponding to frequencies of neutron pulses produced by the chopper. The resulting signal was found to be small, which was attributed to the extremely small active neutron interaction volume inside the SCs. In a real detonation scenario, the transient neutron flux is expected to be higher, and the effective neutron interaction volume of large area solar PV panels is much larger, which could significantly boost the signal. The study, overall, demonstrated the potential of large area solar PV panels or a solar farm for prompt detection and identification of a nuclear detonation.