Re: Nova - Dirty Bombs - London Scenario question/critque

[Ted de Castro <tdc@XRAYTED.COM>]

Stewart Farber wrote:

>

> Isn't it rather trivial to set up even rather crude real time radiation sensors

> around any major city that could track the presence and movement [of a gamma

> source at least] into or near a city quite easily such that the source could be

> intercepted before it gets to the heart of a city? A helicopter with a radiation

> sensor could pinpoint the location of any vehicle carrying a substantial

> unshielded source [like that hyped in the NOVA program] in a matter of minutes

> and it could be intercepted by authorities before it might be exploded.



As a matter of fact ---- HPI builds a GM detector for LBNL's area

monitoring program that would be absolutely perfect for this.  The 1

inch by 12 inch active area E comp GM tube with a sensitivity of 650,000

counts per mREM detects very small variations in background!



They even have a companion datalogger that needs only power, a modem and

a phone line to interrogate periodically or continuous open line to

monitor in real time. We set up one station that was solar powered (100

watt panel charging 4 group 27 marine batteries) with one of these GM

units, a neutron detector, the datalogger and a radio link for

telemetry.



GM's are inherently stable and robust providing relatively cheap and

reliable low noise readings for years.



These units are sensitive enough that in looking over data logs I could

not only discern annual variation in background but could also detect

when it was raining and local ground saturation!!



Two times I believe I even saw events similar to the industrial

radiography incident mentioned here.  In one case I suspect a vehicle

with an open source driving up a road (like commonly happens when the

source does not retract).  Unfortunately I was never able to confirm any

such event - but the simultaneous readings from two stations about a

mile apart on opposite hilltops with a valley in between with a road

running up the valley - are unmistakable.



No - I don't own stock in HPI!!  (just my conceptual design!)

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