[ RadSafe ] Lethal Amount of Po-210 - any gamma?

Michael McNaughton mcnaught at lanl.gov
Wed Dec 13 10:48:05 CST 2006

In my experience, it is very rare for a change in cosmic rays to be 
detectable as a change of gammas at ground level. I have a dozen 
environmental high-pressure ion chambers that have been recording outdoor 
gamma exposure rates (microR/h) every 15 minutes for about 10 years. The 
detectors range in altitude from 5500 ft to 7500 ft. At these altitudes, I 
have only once seen an increase that was a result of cosmic rays; that was 
an increase of 0.5 microR/h averaged over the first 15 minutes of a solar 
flare. I don't see any increase on December 5. (The data are online at 
http://newnet.lanl.gov/ ; e.g., try 
http://newnet.lanl.gov/gamma_graph.asp?span=7&loc=14  or 
http://newnet.lanl.gov/gamma_graph.asp?span=7&loc=0 ; if you need help, 
please ask.)

Regarding the possibility of a radioctive package, it would be interesting 
to know if Kai's gamma reading was different at various locations along the 
aisle of the airplane. I suppose a radioactive package would approximate a 
point source.


At 04:49 PM 12/12/2006, Jim Hardeman wrote:
>Kai --
>Just a guess, but take a look at 
>http://www.sec.noaa.gov/ftpmenu/plots/proton.html ... looks like the flux 
>of high-energy solar protons has been elevated by several orders of 
>magnitude since sometime on 12/5 and is just now coming back down to normal.

Mike McNaughton
Los Alamos National Lab.
email: mcnaught at LANL.gov or mcnaughton at LANL.gov
phone: 505-667-6130; page: 505-664-7733

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