No subject

radioactive element. Using the buildup and decay of the daughters in the
thorium decay series, the age of a gas lantern mantle can be determined."

Keywords: Laboratory experiments and apparatus, Other topics in radioactive
decay and in-beam spectroscopy

DOI: 10.1119/1.13490

I have the paper buried in my old papers, but it appears one can purchase it
via the above link if interested.

Stewart Farber
=======================

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Stewart Farber
Sent: Wednesday, July 11, 2012 2:11 PM
To: 'The International Radiation Protection (Health Physics) Mailing List'
Subject: Re: [ RadSafe ] Texsport Item #14210 - Lantern Mantles

Using "real" lantern mantles for a calibration is neat. I recall using two
of the major peaks in the complex decay series of Th-232 and its daughters
to do a two point energy calibration of a portable Ge detector I was using
away from home.  Plus despite the prohibition of carrying "radioactive"
materials on a plane I would think you won't end up in Guantanamo being
mistaken for a terrorist by bringing a lantern mantle on-board, or trying to
create a dirty bomb.

However, the total gamma activity in a lantern mantle changes with time.
After being made with fresh Th, the activity declines for the first 5 years
or so, and then increases from 5 to 20 years before reaching equilibrium.
See the following for some good general info on Thorium put together by
ORAU's Paul Frame:

<http://www.orau.org/ptp/collection/consumer%20products/thoriumgeneralinfo.h
tm>

I recall seeing a paper 30 years ago by a Professor from a small NYState
college regarding determining the age of a lantern mantle based on the ratio
of various isotopes present.

But no matter what, a lantern mantle does make a great item to demonstrate
aspects of natural radioactivity.  And if it is a "standard" real mantle, it
should be do problem in counting contrary to what Chris Alston happened to
see. Several Coleman mantles I have show 20,000 cpm or more with a standard
pancake GM [ Ludlum 44-9 for example] on contact. If you don't see 15K cpm
or more, you've been give a substandard Th mantle. Bear in mind that there
are non-Th mantles on the market. However, the non-Th mantles are not as
good, and a black market has sprung up among people who want to get their
hands on the real stuff yielding max brightness so they don't walk into
trees at night while camping,  on their way to the bathrooms.

Perhaps you can file a complaint with your State AG Consumer Protection
division that you've been victimized in purchasing a substandard Chinese
product as a consumer and have NOT received the full amount of radioactivity
you've paid for!! :-) And please, I'm kidding about being cheated of your
radioactivity. It's been shown previously on this List that an attempt at
humor is sometimes not recognized as being facetious.


Stewart Farber, MSPH
Farber Medical Solutions, LLC
Bridgeport, CT 06604
SAFarber at optonline.net
203-441-8433


-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of John R Johnson
Sent: Wednesday, July 11, 2012 12:30 PM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Texsport Item #14210 - Lantern Mantles

Mike

Mantle containing Th are useful because they can be used for calibrations.
Just make sure that they are left in the package they were sold in.


John


On Wed, Jul 11, 2012 at 8:02 AM, Brennan, Mike (DOH) <
Mike.Brennan at doh.wa.gov> wrote:

> My take, only somewhat flip, is that you can't trust a Chinese product
> contains what it is supposed to and only what it is supposed to, even
> if what it is supposed to contain is something that would freak out
> many environmentalists.
>
> -----Original Message-----
> From: radsafe-bounces at health.phys.iit.edu
> [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Chris Alston
> Sent: Tuesday, July 10, 2012 3:38 PM
> To: The International Radiation Protection (Health Physics) Mailing
> List
> Subject: [ RadSafe ] Texsport Item #14210 - Lantern Mantles
>
> Folks
>
> The packets of these mantles, the which are Made in China, give as the
> primary ingredients nitrates and hydroxides of Th.  Another
> ingredient, for what it is worth, is cerium.  They are also labelled
> with all sorts of cautionary messages in re proper handling, including
> warnings that they emit radioactive materials, and that California
> knows them to be carcinogenic.  I see no significant readings, i.e.,
> there may be a slight excursion above background with a pancake GM at
> contact, but certainly not the check-source-worthy output one would
> expect.  Does anyone have a take on this?  It has occurred to me that
> the packet may be intended for use with mantles from one supplier, but
> was filled in the factory with mantles of the same spec from a
> different supplier.
>
> TIA and
>
> Cheers
> cja


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