from UNIGE-CentreUniversitaireD'Informatique-LeCUI Website
Introductory note
This has led to a whole series of
technical-level publications, mostly in scientific journals, as well
as to a number of papers in leading journals such as The New York
Times (Huge production of antimatter planned, 27 August 1985, p.
C1 and C3) and Nature (Antimatter underestimated, 26 February
1987, p. 754), which however have received very little attention.
In particular, the most important technical mistake is to suggest that large quantities of antimatter are needed to make a very powerful bomb: this is wrong. As is explained below, and confirmed by numerous professional publications (see three recent ones at the end of this Web page), tiny amounts of antiprotons are sufficient to initiate huge thermonuclear explosions.
Indeed, on the order of one microgram of antiprotons (or antihydrogen) is enough to trigger a multi-ton or multi-kiloton thermonuclear explosion!
At CERN (the European Laboratory for Particle Physics), on the evening of the 17 to the 18 of July 1986, antimatter was captured in an electromagnetic trap for the first time in history. Due to the relatively precarious conditions of this first successful attempt, it was only possible to conserve the antiprotons for about ten minutes.
This was, nevertheless, much longer than the Americans
Bill Kells of Fermilab and Gerald Gabrielse of the University of
Washington had hoped for.
They would
thus be able to complete, in their own laboratory, a most important
experiment for the theory of the unification of the fundamental
physical forces, that of comparing, with a precision greater than
one part per billion, the masses of the proton and antiproton.
But, they will also attempt a number of complex manipulations such as, the production of antihydrogen, the injection of antiprotons into superfluid helium, the search for metastable states in ordinary matter, etc. Various crucial experiments that should, in the near future, help to determine whether or not antimatter could become a new source of nuclear energy for civilian and military applications.
For the more delicate experiments, they could certainly bring their vintage 1987 or 1988 bottles of antimatter to Los Alamos.
There, up in the peaceful mountains of
New Mexico, they could perfect nuclear weapons free of radioactive
fall-out, beam weapons projecting thermonuclear plasma jets, gamma-
or X-ray lasers, or other still more secret weapons, all triggered
by antimatter.
A concept more than 40 years old...
For instance, it is quite possible that Edward Teller, the father of the American H-bomb, already had ideas of eventual military applications when he published in 1947, with Enrico Fermi, an article treating the capture of negative particles heavier than electrons by matter [2].
It is just as
significant to notice that since 1945, about half of Teller's
non-classified publications and many articles published by Andrei Sakarov, the
father of the Soviet H-bomb, are concerned in one way
or another with antimatter.
However, as shown for example in an article by A.S. Wightman [4] (studying specifically the problem of the capture of antiprotons by deuterium and tritium), or in an article by J. Ashkin, T. Auerbach and R. Marschak [5] (trying to calculate the result of the interaction between an antiproton and a nucleus of ordinary matter), the major problem at that time was that there wasn't any experimental data on which one could make a precise prediction of what would happen, for example, when a proton and antiproton met.
Nevertheless, well founded theoretical
arguments already permitted a good understanding of the two
essential characteristics of such a so-called annihilation reaction,
a reaction in which the masses of a particle and its antiparticle
are totally transformed into energy.
The first, is that the release of usable energy per unit mass is greater in annihilation than in any other nuclear reaction. One proton-antiproton annihilation releases 300 times more energy than a fission or fusion reaction.
The second, is
that when antimatter is brought in the proximity of matter,
annihilation starts by itself, without the need of a critical mass
as in fission, and without the ignition energy needed in fusion.
Thus the problem of igniting the H-bomb
was resolved by using an A-bomb as a trigger, and the existence of
the antiproton remained theoretical until 1955.
Evidently many attempts were made to discover the antiproton, using the same method, but without success.
With the detectors available at that time and knowing only its mass and electrical charge, it was practically impossible to identify with any certitude the antiproton within the cosmic radiation. It had to be artificially produced. For that an accelerator, much more powerful than anything built up until that time, was needed.
Briefly, this is how antimatter is produced: protons are accelerated close to the speed of light, and then projected at a target.
The ensuing collision is so violent, that
part of the energy is transformed into particle-antiparticle pairs.
Once this accelerator was built in 1955 at Berkeley, antiprotons
were "seen" for the first time.
In 1956, they forwarded a hypothesis: If instead of annihilating with a simple hydrogen nucleus, the antiproton annihilated with a proton or neutron situated in the heart of a complex atom, such as carbon or uranium, the nucleus in question would literally explode.
This would result in a very large local
energy deposition, thus bringing to light again, in theory, many
civilian and military applications of antimatter.
Finally, it was possible to study, on a large scale, the meeting of antiprotons with nuclei.
As a result, it has been possible to demonstrate that the energy deposition, although less than Teller (or others more recently [8]) had hoped for, is sufficient to assure the feasibility of military applications of antimatter.
On the other hand, due to its very high
cost and the enormous amount of energy needed to produce it, it has
also become clear that antimatter could never become a usable source
of energy for a power-plant.
We thus discovered that it is possible to build a H-bomb, or a neutron bomb, in which the three to five kg of plutonium are replaced by one microgram of antihydrogen.
The result would be a bomb so-called "clean" by the militaries, i.e., a weapon practically free of radioactive fall-out, because of the absence of fissile materials (Fig.2).
The revived military interest
This corresponds to a minimum production rate of 1013 antiprotons per second, six orders of magnitude higher than that at CERN today (107 antiprotons per second). But, in theory, there exist numerous ways to increase this rate [9].
What we were unaware of, was that since the summer of 1983, the RAND Corporation had been carrying out a study for the U.S. Air Force, "examining the possibilities for exploiting the high energy release from matter-antimatter annihilation" [10]. Similar concerns had equally sprouted-up in the Soviet Union [11]. The RAND study was completed in 1984.
The version published in 1985 constitutes a
serious evaluation of the development possibilities of such an
undertaking, in view of military applications.
This same report mentions four main categories of applications:
In addition to the advantages related to its extremely high energy density and ease of ignition, annihilation has two important characteristics:
With the help of magnetic fields, very intense pion beams can be created, to the order of 100 mega-amperes per microgram of antiprotons.
Such beams, if directed along the axis of an adequate device, can drive a magneto-hydrodynamic generator, generate a beam of electromagnetic waves, trigger a cylindrical thermonuclear explosion, or pump a powerful X-ray laser.
In the last case, for example, the pions' energy could be used to transform in a very uniform plasma, a long cylinder of a substance such as selenium, whose ionized atoms have excited states favorable to the spontaneous emission and amplification of coherent X-rays.
But this is only one of the many
concepts that permit, thanks to antimatter, to conceive X-ray lasers
having efficiencies ten to a thousand times higher than those pumped
by any other known energy sources.
As long as antiprotons made in Europe
(on Swiss Territory), could be bottled and brought back to the
United States, the RAND Corporation concludes that a
production/accumulation facility, such as the one at CERN, although
desirable, wouldn't in the near future have to be built in the
United States [12].
In this context, it also
wouldn't be surprising if a blunder was made...
In
the beginning of July 1986, these same Americans were supposed to go
to Madrid, where a full session of the Fourth International
Conference on Emerging Nuclear Systems was dedicated to
antimatter energy concepts. At this same conference we were to
present the point of view that the only realistic applications for
annihilation energy were in the military domain
[13].
Ten days before the conference, they announced their withdrawal without giving any convincing explanations. The participants quickly realized that the American Authorities had undoubtly reevaluated the military importance of antimatter, and had probably prevented the Los Alamos Scientists from coming to Madrid [14].
Thus exposing that scientists working at
CERN, and coming from a non-European weapons laboratory, had
other than fundamental research interests, that were obviously
militarily sensitive.
In fact, the arms control treaties presently in force deal only with fission related devices and materials [15]: atomic bombs, nuclear reactors and fissile materials.
By removing the fission fuse from
thermonuclear weapons, antimatter triggered H-bombs and neutron
bombs could be constructed freely by any country possessing the
capacity, and be placed anywhere, including outer-space.
This possibility would considerably reduce the need for underground nuclear explosions, thus rendering ineffective any attempt to slow the arms race by an eventual comprehensive nuclear test-ban treaty [16].
A nuclear test laboratory of this type
could be based around a large heavy-ion accelerator
[16], which would provide a
means of massive antimatter production, as well as a driver to study
the compression and explosion of thermonuclear fuel pellets.
Thus, for each particle there exists an
antiparticle having the same mass and spin but opposite electrical
charge. Furthermore, particles and antiparticles can appear or
disappear in pairs, due to the transformation of energy into matter
and vice-versa.
They are produced by accelerating protons (or other particles) to energies such that, when they collide with a target, a part of the energy is transformed into particle-antiparticle pairs. In practice, when using a fixed target, as a function of invested energy, the maximum antiproton production yield occurs when the protons are accelerated to an energy of about 120 Gev.
Since less than one collision out of thirty produces an antiproton, and since the mass of an antiproton corresponds to only 0.94 GeV, the energy efficiency is very poor. From this point of view, a better solution would be to use a collider-ring in which the antiprotons would be produced by the head-on collisions of protons turning in opposite directions.
In theory, an even higher yield could be obtained if conditions similar to the original "Big Bang" could be recreated in the laboratory, conditions in which proton-antiproton production becomes spontaneous.
Such conditions might be found in
quark-gluon plasmas, which could be produced in high-energy
heavy-ion collisions, which are presently the subject of intense
research [C].
This is a problem much more difficult to resolve than that of production. It took almost thirty years before a solution was found at CERN. This required the invention of "stochastic cooling", a technique to decrease the width of the antiproton velocity distribution (see La Recherche April 1984 p.508-511).
It is then possible to concentrate the
collected antiprotons into a very small beam, to accumulate them in
storage rings, and finally slow them down to energies such that they
can be brought to a standstill in electromagnetic traps.
This is obtainable only in enclosures that are sealed (after filling) and cooled to the temperature of liquid helium.
It is therefore practically impossible to measure the
vacuum level, so that doing the experiment itself is the only way to
verify the technique. If this method is successful, it will be
possible to make transportable bottles with a capacity of 1012 to
1013 antiprotons [E].
The first consists of making antihydrogen by combining
antiprotons with positrons, and then trying to form solid
antihydrogen pellets which could be stored and manipulated with the
help of various electromagnetic and optical levitation techniques.
Very high storage densities would be obtained, but only in cryogenic
enclosures and extremely good vacuums.
In fact, if all antimatter particles have a tendency to spontaneously annihilate when coming into contact with matter (be it the effects of electromagnetic attraction in the case of positrons and antiprotons, or van der Waals forces for antihydrogen), the existence of metastable states of antiprotons in condensed matter can not be ruled out a priori [F].
For example, if a very low energy antihydrogen atom is diffused into a solid, it moves about until its positron annihilates with an electron.
The antiproton may then take
the place of this electron, and under some conditions, remain
confined at certain points within the crystalline structure. At
present the kind of substance to be used isn't known, but an
enormous variety of chemical compounds and crystal types are
available for the search of an optimum material.
Also, similar to the electron pairs
responsible for superconductivity, antiprotons might possibly form
Cooper pairs if placed in a metal, becoming thereby unable to lose
kinetic energy by shock, and thus to annihilate.
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