[SystemSafety] Solar Storms and Charging Procedures for Electric Cars

Peter Bernard Ladkin ladkin at rvs.uni-bielefeld.de
Thu Apr 11 15:31:25 CEST 2013

On 4/11/13 3:13 PM, SPRIGGS, John J wrote:
>> At least some people in the avionics community have argued that SEUs in commercial
>> aircraft at cruise are likely mainly to be neutrons (that was the suggestion that raised
>> the scepticism of my particle-physicist colleagues).
> I think the argument is that charged particles can be stopped by a fairly thin piece of metal, e.g. the avionics box itself, but a free neutron can pass through.  So, if you have "cosmic rays" in there, they "are likely mainly to be neutrons".

Yes, that is the argument of the armchair physicist.

I went through a series of publications by people then working for the Boeing Radiation Laboratory, 
in the usual "respected" scientific journals for this sort of thing. They referred to it being 
"established" or "well established", so I followed the reference trail. It led back to a short 
experiment in the neutron accelerator at Los Alamos. They put a DRAM half-in and half-out of the beam.

Two results.

1. They found significantly more SEUs in the half-in part.

2. Unfortunately, there was a heavy asymmetry about the flips. A significantly greater number were 
flipped from 1 to 0 than from 0 to 1 (or the other way round - I forget and am currently too lazy to 
look it up).

Only 1 supports the neutron hypothesis. 2 contradicts it. Conclusion: "it's neutrons!"

Figure it out. I took this to an experimental-physicist colleague and he said "yeah, seems about 
average. 80% of the stuff that's done is nonsense. The IEEE publishes it anyway."

For a moment I thought he was talking about software engineering..........

> Where are these free neutrons supposed to originate?

Good question. One of many. Another is "explain phenomenon 2".


Prof. Peter Bernard Ladkin, Faculty of Technology, University of Bielefeld, 33594 Bielefeld, Germany
Tel+msg +49 (0)521 880 7319  www.rvs.uni-bielefeld.de

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