CRTs and Radon Daughters

Hello All,

I just joined the list and have a question. I've surveyed various CRTs

in my home with a Ludlum Model 3 with 44-9 pancake probe. Most read

200-300cpm (~50-100uR). However one, a computer monitor, read slightly

higher, 400-500cpm. I cleaned off half of the screen, then re-surveyed

after a day of use, to my surprise the count had jumped to

3000(~1.0mR)! The uncleaned portion remained at 400-500cpm as before.

After a day of no use, the "Hot" count dropped to 500, the other down to

just above background. After powering up for only a few minutes, the

counts jumped back to 3000/450. The radiation appears to be alpha and

beta...I can turn the probe over to the aluminum side and the readings

drop to near background. All readings were made with the monitor off,

~1/2" from the screen.

This is my father's monitor, a cheaply made Packard Bell unit with

screen static like a Van De Graff. My monitor, just a few feet away, a

newer Sony, remains just above background. Should I be concerned with

the 3000cpm reading...a possible radon problem, or just a crt that acts

as an excellent precipitator.

Thanks,

Preston

psbax@bellsouth.net

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