Charge-Collection and Single-Event Upset Measurements at the ISIS Neutron Source

Abstract

Charge-collection measurements at the VESUVIO instrument at ISIS are described. Neutron SEU cross sections in SRAM-based FPGAs are measured. Results are compared to equivalent data from Los Alamos Neutron Science Center ICE House. The rate of single-event effects due to fast neutrons at VESUVIO is approximately 15% of that at LANSCE. In addition there is a strong thermal and epithermal component, sufficient to cause many events in devices containing small amounts of 10B. The effects of low-energy neutrons on a commercial CCD contaminated with traces of 10B are described. Cadmium shielding is found to be incompletely effective in separating the effects of fast and slow neutrons, and the implications for testing protocols and instrument design are discussed.