X-Rays

[Andy Finney <andy@xxxxxxxxxxxxxxxx>]

Willem-Jan wrote:

"Natural/background radiation at such high altitudes is probably a
magnitude larger than X-ray fogging...."

I hope you're wrong about that. The air crew would be wearing lead 
underwear ... or perhaps you only fly Concorde WJ :-) I have a friend 
with connections to the NRPB (National Radiological Protection Board) 
and next time I see him I'll ask him. This could also make it risky 
to take film into areas with lots of granite, like Cornwall, which 
are famous for higher levels of background radiation.

I did once pass my DV camcorder through an x-ray scanner (at the 
European Parliament rather than an airport) while it was recording 
and there was a distinct short burst of static on sound and vision, 
of a few lines duration (and so of the order of 100-200 
microseconds), as the camera was scanned (I assume). You get a 
similar effect if your camera is hit by a beam of RADAR. In the case 
of the RADAR, the frequency of the pulses in the beam is within the 
reception range of a UHF television which is lower than x-rays of 
course. The video from the Falklands war was full of such RADAR 
bursts, showing especially well in night shots.

... and the 'lost tribe' X-ray incident happened over 15 years ago 
and was reported to production staff as a warning against 
unintelligent x-ray machines at remote airports. (I'm not sure 
whether the Invision machines were around then.) Perhaps you're 
referring to another incident: there have been plenty of them.

On the other hand ... where would urban myths be without things like 
discussion groups on the Internet.  BBC Radio Producers used to be 
allowed to take taxis rather than use the underground because it was 
alleged that the high magnetic fields from the motors could erase 
tapes. Eventually I discovered that the risk was only there if you 
put the tape on the floor over a motor, which usually meant one of 
the four motor cars in a normal tube train.

Cheers

Andy
Invisible Light (http://www.atsf.co.uk/ilight/)
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