While researching radiation effects on RAM soft errors, I ran across an interesting paper from IBM: http://www.research.ibm.com/journal/rd/ziegl/ziegler.html
In the paper, they cite some research looking at neutron upsets of memory chips. The neutron flux was 1E5 /sq cm/sec (substantially higher than any fusors). Of some interest, though, is the observation that they had to dramatically reduce the flux of the beam to actually quantify the neutron sensitivity.
here's a quote of the relevant paragraph...
1984--Testing of sensitivity of bipolar memory chips to cosmic ray particles Experiments were set up by Yourke, Wortzman, Tolat, and Enger to expose two cache modules, each containing 72 bipolar memory chips, to a dilute neutron beam in California. The first memory module was set up in a quiescent "radiation cave'' and left running for a complete week (no radiation was present during this period). It operated flawlessly, with no fails. Then, a dilute beam of neutrons, about 6 in. (15 cm) in diameter (about the size of the 72 chips of the cache module) and with a flux of less than 10/cm-s was introduced into the cave, with the neutron beam aimed to pass through the cache (Figure 7). Within 20 seconds of the beam incidence, the tester registered a cache parity check, and it recovered within a few seconds to normal operation. At 40 seconds into the test it took another "hit,'' and while it was recovering a third hit occurred at 42 seconds into the experiment. The beam of neutrons was further reduced until accurate quantitative measurements could be made of the cross section for neutron-induced soft fails. Both memory modules, designed several years apart, showed the same sensitivity to radiation.
Created on Wednesday, January 17, 2001 2:19 PM EDT by James Lux