Cosmic ray background effects on the neutron intercepting silicon chip (NISC)

Cosmic rays are mainly composed of galactic and solar particles. Galactic particles have enormous energies and interact in the atmosphere causing cascades of secondary particles, which can travel through the atmosphere and reach sea level. The origin of the cosmic terrestrial neutrons is galactic particles and these neutrons contribute almost 97% of the cosmic rays at sea level. Solar particles originate from the sun and have less energy compared to galactic particles. Almost all the solar particles are absorbed in the atmosphere before reaching sea level. The solar particle flux depends on the 11-year solar cycle and varies by multiple orders of magnitude between these cycles. In this study, cosmic ray induced soft errors in the neutron intercepting silicon chip (NISC) are investigated via the NISC Soft Error Analysis Tool (NISCSAT), which uses Geant4 as the transport and tracking engine. The NISC is a new unconventional neutron monitoring/detection system, designed to enhance the soft error occurrences in the semiconductor memories by introducing 10B-enriched regions in the memory node structure. The main driving force comes from the reaction products of 10B (n,α) 7Li reaction because both α and 7Li particles can induce soft errors in the memory. Since the 10B (n,α) 7Li reaction strictly depends on the incoming neutron energy and has a high cross-section at the thermal neutron energies, effects of the background cosmic thermal neutrons on the NISC are investigated in this study.