🚀 go-pugleaf

In article <1993Jan9.095853.2229@pollux.lu.se>, magnus@thep.lu.se (Magnus Olsson) writes:
> In article <1993Jan8.192720.1@fnalnl.fnal.gov> higgins@fnalnl.fnal.gov (Bill Higgins-- Beam Jockey) writes:
>> H. Poth and collaborators have done work on
>>antiprotonic atoms, where a negative antiproton orbits a positive
>>nucleus for a short time (it's a nice probe of nuclear physics).  
> 
> And to clarify a little: "A short time" in this context is very short
> indeed. I don't know the lifetime for an antiproton-proton system, but
> the analogous electron-positron system, the positronium "atom", only
> lives for about a microsecond before the electron and positron
> annihilate each other.

I was vague because I was in a hurry.  Looking at the reference more
carefully (H. Poth, "Antiprotonic, Hyperonic, and Antihydrogen Atoms,"
*Proceedings of the First Workshop on Antimatter Physics at Low
Energy*, Fermilab, 1986-- it may not be the definitive source of
information, but had the advantage of being on the shelf in my
office), I see that Poth says the delay between capture of a p-bar
into an atomic orbit and its annihilation is less than 1E-10 seconds
in most solids and liquids.

> NOTE: I'm *not* dismissing antimatter as an energy source for
> spaceships. I'm only saying that it will take a very long time before
> it becomes even remotely practical.

"A very long time" in this context is more than a few microseconds. 
These physicists are so addicted to their jargon!

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