Xref: utzoo rec.radio.amateur.misc:2330 sci.electronics:19907
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!ub!kitty!larry
From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: rec.radio.amateur.misc,sci.electronics
Subject: Re: How to measure/detect X-ray (cheap)?
Summary: Thermoluminescent Dosimetry (TLD)
Keywords: personal dosimetry, film, TLD
Message-ID: <4923@kitty.UUCP>
Date: 6 May 91 03:13:48 GMT
References: <1991May1.161415.4235@swbatl.sbc.com> <4916@kitty.UUCP> <1991May4.005946.730@wsrcc.com>
Followup-To: rec.radio.amateur.misc,sci.electronics
Organization: Recognition Research Corp., Clarence, NY
Lines: 29

In article <1991May4.005946.730@wsrcc.com> alison@wsrcc.com (Alison Chaiken) writes:
>How do TLD dosimeters work?  I know how film badges work!

	TLD dosimeters work on the principle of thermoluminescence resulting
from radiation exposure.  When certain crystalline phosphors, such as lithium
fluoride and calcium fluoride, are exposed to ionizing radiation, emitted
electrons are trapped in crystalline lattice imperfections.  As long as the
crystalline phosphor is maintained at close to ambient temperature, such
electrons remain trapped for long periods of time (like months).  When the
phosphor is subsequently heated, the trapped electrons are released,
thereby resulting in emission of visible light energy.

	Integration of the measurement of visible light energy emitted during
heating of the TLD material may be correlated to an integrated radiation dose.
A readout of a TLD dosimeter is sometimes referred to as a "glow curve" - it
is a plot of emitted energy against time during the heating of the TLD
element.

	TLD dosimeters have two advantages over film dosimeters: (1) they
may be reused by annealing of the element - a slower heating process following
that used for readout; (2) the readout process may be totally automated,
with less likelihood of human error.

	TLD dosimetry was developed during the 1950's, and became really
popular starting in the early 1970.s

Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
VOICE: 716/688-1231       {boulder, rutgers, watmath}!ub!kitty!larry
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