Ground

Radiation at ground level includes: particles originating from cosmic ray interactions in the atmosphere, mainly neutrons; radioactive decay from radon in the ground. Until recently the effects of radiation at ground level could be ignored, but the continuous miniaturisation and complexity of modern integrated circuit technology is making them increasingly sensitive to radiation, especially from single event effects (SEE). Cars, trains and planes are embedding increasingly complex electronics into their control systems and although the probability of catastrophic failure remains small, the risks still have to be assessed. A further concern is the impact of extreme solar weather events on the control systems such as solar flares and coronal mass ejections. As in the case of the aviation industry, determining SEE sensitivity is best achieved in the appropriate radiation test facilities, and from this we can estimate the SEE rates for the operational radiation environment.