Experimental Double-Differential Light-Ion Production Cross Sections for Silicon at 95 MeV Neutrons

Abstract

The importance of cosmic radiation effects in aircraft electronics has recently been highlighted. At commercial flight altitudes, as well as at sea level, the most important particle radiation is due to neutrons, created in the atmosphere by spallation of nitrogen and oxygen nuclei, induced by cosmic-ray protons. When, e.g., an electronic memory circuit is exposed to neutron radiation, charged particles can be produced in a nuclear reaction. The charge released by ionization can cause a flip of the memory content in a bit, which is called a single-event upset (SEU). A similar logic error in one of the storage registers of a microprocessor may trigger an unanticipated loop that cannot be escaped without turning the unit off.To get a deeper understanding of these phenomena, more detailed cross section information on neutron-induced charged-particle production at intermediate energies is needed. To this end, double-differential cross sections of inclusive light-ion production in silicon, induced by 95 MeV neutrons, have been measured. The experiment was performed using the MEDLEY setup, which consists of eight three-element particle telescopes, covering the angular range 20° – 160°. The charged particles were identified using ΔE – ΔE – E techniques. By using an active target, consisting of a 300 μm thick Si detector, the energy loss in the target itself could be measured and corrected for.