While it is possible that cosmic rays affect DRAM, the majority of the single-bit errors are due to a failure in the memory cell itself, as the paper shows a high correlation between error rates and utilization, while radiation-induced errors should be randomly distributed. Even if you get a rad-induced glitch, I believe it's more likely to be caused by alpha-radiation from the chip itself. I don't know for any study that specifically looks for cosmic rays, say, placing the control system in a lead box. Also, dupe.
