[ RadSafe ] Californium vs. Americium

[Don Jordan]

I believe Franz is correct that a Po-210Be "initiator" was a component of
the early atomic weapons.  I recall from Richard Rhodes' "The Making of the
Atomic Bomb" that the designers faced the problem of ensuring that at least
1 neutron would be produced in the few microseconds when the core was at
maximum compression and couldn't rely on the random chance of a SF neutron.
They made a device in which the Po-210 and the Be were largely separated
until detonation, upon which they mixed intimately and gave a reasonable
assurance that a few neutrons would be present (the number I recall is 9).
I believe that Rhodes also claimed that this was the most secret component
of the first weapons and that its design was still highly classified when he
wrote his book in the late 70's or early 80's.  The Manhattan Project had a
very short time frame for use, so shelf life wasn't a problem

Don Jordan
RAM Services, Inc.
DonJordan at ramservicesinc.com
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