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Date: 22 Jul 92 09:21:28 GMT
From: Bill Higgins-- Beam Jockey <>
Subject: How Much Nothing for Antimatter? (was Re: Propulsion questions)

In article <4184@astroatc.UUCP>, ott@astroatc.UUCP (Michael Ott) writes:
> Just exactly how do you store antimatter?  I would think perhaps magnetically
> suspended in a vaccuum, but can "vaccuum-enough" vaccuums be created?

Sure.  Here we store antiprotons by circulating them in a synchroton
ring called the Antiproton Accumulator.  The vacuum there is 1E-10
torr.  I presume this is comparable to the similar facility at CERN.
The beam lifetime in such a vacuum is of order weeks, I think.

We put them to work by injecting them counterclockwise into the
Tevatron, our superconducting synchrotron.  There the vacuum is
somewhat worse, typically 1E-9 torr.  (The walls of the beampipe are
at 4.5K, so they act as cryopumps, which helps, but there are six
kilometers of pipe with thousands of places for potential leaks.) The
Accumulator works at 6 GeV beam energy, the Tevatron between 150 and
900 GeV.  

Another method for storing p-bars in small numbers is in the traps
used by Gerald Gabrielse and collaborators at the University of
Washington.  I don't know what their vacuum is, but it must be good; 
they once kept a single electron trapped for ten months.  Hans Dehmelt
received a Nobel Prize in physics for developing this technique, and I
imagine you could find details in his prize speech, published a few
years ago in *Reviews of Modern Physics*.  Or dig up papers by

There have been one or two books on antimatter experiments, sources,
and storage.  The pop version, as we've already mentioned in this
thread, is *Mirror Matter* by Bob Forward and Joel Davis.  Uh-oh,
our library's node seems to be down so I can't fetch you any more
technical titles.

Bill Higgins, Beam Jockey              | "I'm gonna keep on writing
Fermi National Accelerator Laboratory  | songs until I write the song
Bitnet:           HIGGINS@FNAL.BITNET  | that makes the guys in
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                                            --John Prine

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