28 Dec
2006
28 Dec
'06
7:37 p.m.
My board was 36" awa and was exposed to
17.8R/min. When ever you
[halve] the distance from the tube the radiation is increased 4 times
(the inverse square law).
Inverse square really applies only to non-collimated sources - as an
extreme example, consider your typical laser pointer, which is perhaps
half as bright at 500 feet as it is at one inch. :-)
I don't know enough about X-ray tubes to know whether they follow
inverse square or not, but I'd be hesitant to assume they do. (Or, of
course, it could be that you already considered this and know inverse
square applies, and this is all irrelevant.... :-)
There were some weird symptoms when ever the linear
accelerator was
ramped up, but that could have been from the dual magnetrons taking
30,000v at 30A pulses to 6MeV. The main power coax cable is 1.5"
diameter carrying 10,000v at 100A, but they said it was very well
shielded.
Well, yes, but for that kind of power, "very well shielded" may well
mean "all it does is crash all electronics within 10 metres, instead of
permanently demagnetizing everything within a kilometer". :-)
Years ago, I once had the privilege to approach a superconducting-loop
"permanent magnet". Something like half a building away there were
warning signs saying to carry nothing magnetic past this point. They
said that if it quenches somehow, (a) it suddenly is up around room
temperature, from the dissipated heat, and (b) it takes something like
a day to remagnetize it, even after chilling it back to superconducting
temperature again. I hate to think what the magnetic-field transient
occurring when it quenches must do to anything conductive in the
vicinity....
/~\ The ASCII der Mouse
\ / Ribbon Campaign
X Against HTML mouse at rodents.montreal.qc.ca
/ \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B