Re: Glow in the Dark Watches -REPLY

[RADPROJECT <RADPROJECT@aol.com>]

In a message dated 97-12-17 12:40:35 EST, you write:

<< hberger@trinity.tamu.edu (David Hearnsberger)
 Sender:	radsafe@romulus.ehs.uiuc.edu
 Reply-to:	radsafe@romulus.ehs.uiuc.edu
 To:	radsafe@romulus.ehs.uiuc.edu (Multiple recipients of list)
 
 Yesterday a colleague of mine kept alarming our Hand and Foot Gas flow
 proportional counter on her left hand. After some trouble shooting I did a
 gamma spec on her watch with an HPGe. The analysis revealed Eu-152 and
 Eu-154. A separate gas flow measurement indicated ~1600 dpm on the face of
 the watch. The manufacturer of the watch is Seiko. Has anyone ever heard
 of Europium being used to illuminate a watch dial? Any insight into this
 will be greatly appreciated. Thanks in advance.
 
 >> Some years ago, a similar problem on exiting a controlled side of a Part
50/61 lab, I was auditing disclosed that my Seiko watch was the source of the
alarm. A long low-background count disclosed that not only was Pm-147 present,
but a number of fission products. In checking on the matter, I found that the
Japenese purchase Pm-147 from the British reprocessing centers and that there
is invariably some fission product contamination. I'd have to dig around to
find the gamma spec results [which I have in some dead files] showing the
fission product contamination present, but there is no doubt today's Seiko
watches can set off a simple pancake GM frisker or a more sensitive hand and
foot monitor due to activity  in the luminous paint.

Stewart Farber
Consulting Scientist
email: radproject@aol.com