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From: bl@hplabsb.UUCP (Bruce T. Lowerre)
Newsgroups: net.politics,net.sci
Subject: Re: Small Nuclear Bombs
Message-ID: <3484@hplabsb.UUCP>
Date: Fri, 16-May-86 13:07:23 EDT
Article-I.D.: hplabsb.3484
Posted: Fri May 16 13:07:23 1986
Date-Received: Sun, 18-May-86 03:16:02 EDT
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Organization: Hewlett Packard Labs, Palo Alto CA
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> >     I was talking to an ex-LLL physicist once who told me that there 
> > is an isotope of Californium with a *very small* critical mass (a few
> > grams, I think it was). This opened the theoretical possibility of a
> > hand grenade sized nuclear weapon.
> > 
> 
> Californium, isn't that one of those wonderful man-made elements whose shelf
> life can be measured in microseconds? No wonder it's "theoretically" possible.

Californium, symbol Cf, Atomic number 98, has the following isotopes:

At. weight		half life		decay mode
----------------------------------------------------------
244			25 minutes		a, K
245			44 minutes		a, K
246			35.7 hours		a
247			2.4 hours		K
248			250 days		a
249			470 years		a
250			12 years		a
251			>>18 days		a
252			2.2 years		a
253			~20 days		B
254			55 days

a = alpha, B = beta, K = orbital capture

In any case, hardly microseconds.