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Re: Glow in the Dark Watches
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You may be seeing the extremely low intensity (.004%?) 121.2 keV gamma from
Pm-147, which is being misidentified as Eu-152 and Eu-154 (each of which has a
gamma around 121 keV)
Pm-147 is commonly used in self-luminous watches (See 10CFR30.19)
Scott Dixon
sadixon@oppd.com
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Received: 17 Dec 1997 11:34:34 Sent: 17 Dec 1997 11:33:51
From:"David Hearnsberger " <server@romulus.ehs.uiuc.edu>
To: Multiple,recipients,of,list,radsafe@romulus.ehs.uiuc.edu
Subject: Glow in the Dark Watches
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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.
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David W. Hearnsberger phone: (409)845-7551 *
Texas A&M University fax: (409)862-2667 *
Nuclear Science Center email: hberger@trinity.tamu.edu*
FE Box 89 Bldg. 1095 *
College Station, Texas *
77840 *
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