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<http://sfgate.com/cgi-bin/article.cgi?file=/c/a/2004/10/04/MNGM393GPK1.DTL>Air 
Force pursuing antimatter weapons
Program was touted publicly, then came official gag order
- Keay Davidson, Chronicle Science Writer
Monday, October 4, 2004

The U.S. Air Force is quietly spending millions 
of dollars investigating ways to use a radical 
power source -- antimatter, the eerie "mirror" of 
ordinary matter -- in future weapons.

The most powerful potential energy source 
presently thought to be available to humanity, 
antimatter is a term normally heard in 
science-fiction films and TV shows, whose heroes 
fly "antimatter-powered spaceships" and do battle 
with "antimatter guns."

But antimatter itself isn't fiction; it actually 
exists and has been intensively studied by 
physicists since the 1930s. In a sense, matter 
and antimatter are the yin and yang of reality: 
Every type of subatomic particle has its 
antimatter counterpart. But when matter and 
antimatter collide, they annihilate each other in 
an immense burst of energy.

During the Cold War, the Air Force funded 
numerous scientific studies of the basic physics 
of antimatter. With the knowledge gained, some 
Air Force insiders are beginning to think 
seriously about potential military uses -- for 
example, antimatter bombs small enough to hold in 
one's hand, and antimatter engines for 24/7 
surveillance aircraft.

More cataclysmic possible uses include a new 
generation of super weapons -- either pure 
antimatter bombs or antimatter-triggered nuclear 
weapons; the former wouldn't emit radioactive 
fallout. Another possibility is antimatter- 
powered "electromagnetic pulse" weapons that 
could fry an enemy's electric power grid and 
communications networks, leaving him literally in 
the dark and unable to operate his society and 
armed forces.

Following an initial inquiry from The Chronicle 
this summer, the Air Force forbade its employees 
from publicly discussing the antimatter research 
program. Still, details on the program appear in 
numerous Air Force documents distributed over the 
Internet prior to the ban.

These include an outline of a March 2004 speech 
by an Air Force official who, in effect, spilled 
the beans about the Air Force's high hopes for 
antimatter weapons. On March 24, Kenneth Edwards, 
director of the "revolutionary munitions" team at 
the Munitions Directorate at Eglin Air Force Base 
in Florida was keynote speaker at the NASA 
Institute for Advanced Concepts (NIAC) conference 
in Arlington, Va.

In that talk, Edwards discussed the potential 
uses of a type of antimatter called positrons.

Physicists have known about positrons or 
"antielectrons" since the early 1930s, when 
Caltech scientist Carl Anderson discovered a 
positron flying through a detector in his 
laboratory. That discovery, and the later 
discovery of "antiprotons" by Berkeley scientists 
in the 1950s, upheld a 1920s theory of antimatter 
proposed by physicist Paul Dirac.

In 1929, Dirac suggested that the building blocks 
of atoms -- electrons (negatively charged 
particles) and protons (positively charged 
particles) -- have antimatter counterparts: 
antielectrons and antiprotons. One fundamental 
difference between matter and antimatter is that 
their subatomic building blocks carry opposite 
electric charges. Thus, while an ordinary 
electron is negatively charged, an antielectron 
is positively charged (hence the term positrons, 
which means "positive electrons"); and while an 
ordinary proton is positively charged, an 
antiproton is negative.

The real excitement, though, is this: If 
electrons or protons collide with their 
antimatter counterparts, they annihilate each 
other. In so doing, they unleash more energy than 
any other known energy source, even thermonuclear 
bombs.

The energy from colliding positrons and 
antielectrons "is 10 billion times ... that of 
high explosive," Edwards explained in his March 
speech. Moreover, 1 gram of antimatter, about 
1/25th of an ounce, would equal "23 space shuttle 
fuel tanks of energy." Thus "positron energy 
conversion," as he called it, would be a 
"revolutionary energy source" of interest to 
those who wage war.

It almost defies belief, the amount of explosive 
force available in a speck of antimatter -- even 
a speck that is too small to see. For example: 
One millionth of a gram of positrons contain as 
much energy as 37.8 kilograms (83 pounds) of TNT, 
according to Edwards' March speech. A simple 
calculation, then, shows that about 50-millionths 
of a gram could generate a blast equal to the 
explosion (roughly 4,000 pounds of TNT, according 
to the FBI) at the Alfred P. Murrah Federal 
Building in Oklahoma City in 1995.

Unlike regular nuclear bombs, positron bombs 
wouldn't eject plumes of radioactive debris. When 
large numbers of positrons and antielectrons 
collide, the primary product is an invisible but 
extremely dangerous burst of gamma radiation. 
Thus, in principle, a positron bomb could be a 
step toward one of the military's dreams from the 
early Cold War: a so-called "clean" superbomb 
that could kill large numbers of soldiers without 
ejecting radioactive contaminants over the 
countryside.

A copy of Edwards' speech onNIAC's Web site 
emphasizes this advantage of positron weapons in 
bright red letters: "No Nuclear Residue."

But talk of "clean" superbombs worries critics. " 
'Clean' nuclear weapons are more dangerous than 
dirty ones because they are more likely to be 
used," said an e-mail from science historian 
George Dyson of the Institute for Advanced Study 
in Princeton, N.J., author of "Project Orion," a 
2002 study on a Cold War-era attempt to design a 
nuclear spaceship. Still, Dyson adds, antimatter 
weapons are "a long, long way off."

Why so far off? One reason is that at present, 
there's no fast way to mass produce large amounts 
of antimatter from particle accelerators. With 
present techniques, the price tag for 
100-billionths of a gram of antimatter would be 
$6 billion, according to an estimate by 
scientists at NASA's Marshall Space Flight Center 
and elsewhere, who hope to launch 
antimatter-fueled spaceships.

Another problem is the terribly unruly behavior 
of positrons whenever physicists try to corral 
them into a special container. Inside these 
containers, known as Penning traps, magnetic 
fields prevent the antiparticles from contacting 
the material wall of the container -- lest they 
annihilate on contact. Unfortunately, because 
like-charged particles repel each other, the 
positrons push each other apart and quickly 
squirt out of the trap.

If positrons can't be stored for long periods, 
they're as useless to the military as an armored 
personnel carrier without a gas tank. So Edwards 
is funding investigations of ways to make 
positrons last longer in storage.

Edwards' point man in that effort is Gerald 
Smith, former chairman of physics and Antimatter 
Project leader at Pennsylvania State University. 
Smith now operates a small firm, Positronics 
Research LLC, in Santa Fe, N.M. So far, the Air 
Force has given Smith and his colleagues $3.7 
million for positron research, Smith told The 
Chronicle in August.

Smith is looking to store positrons in a 
quasi-stable form called positronium. A 
positronium "atom" (as physicists dub it) 
consists of an electron and antielectron, 
orbiting each other. Normally these two particles 
would quickly collide and self-annihilate within 
a fraction of a second -- but by manipulating 
electrical and magnetic fields in their vicinity, 
Smith hopes to make positronium atoms last much 
longer.

Smith's storage effort is the "world's first 
attempt to store large quantities of positronium 
atoms in a laboratory experiment," Edwards noted 
in his March speech. "If successful, this 
approach will open the door to storing militarily 
significant quantities of positronium atoms."

Officials at Eglin Air Force Base initially 
agreed enthusiastically to try to arrange an 
interview with Edwards. "We're all very excited 
about this technology," spokesman Rex Swenson at 
Eglin's Munitions Directorate told The Chronicle 
in late July. But Swenson backed out in August 
after he was overruled by higher officials in the 
Air Force and Pentagon.

Reached by phone in late September, Edwards 
repeatedly declined to be interviewed. His 
superiors gave him "strict instructions not to 
give any interviews personally. I'm sorry about 
that -- this (antimatter) project is sort of my 
grandchild. ...

"(But) I agree with them (that) we're just not at 
the point where we need to be doing any public 
interviews."

Air Force spokesman Douglas Karas at the Pentagon 
also declined to comment last week.

In the meantime, the Air Force has been 
investigating the possibility of making use of a 
powerful positron-generating accelerator under 
development at Washington State University in 
Pullman, Wash. One goal: to see if positrons 
generated by the accelerator can be stored for 
long periods inside a new type of "antimatter 
trap" proposed by scientists, including 
Washington State physicist Kelvin Lynn, head of 
the school's Center for Materials Research.

A new generation of military explosives is worth 
developing, and antimatter might fill the bill, 
Lynn told The Chronicle: "If we spend another $10 
billion (using ordinary chemical techniques), 
we're going to get better high explosives, but 
the gains are incremental because we're getting 
near the theoretical limits of chemical energy."

Besides, Lynn is enthusiastic about antimatter 
because he believes it could propel futuristic 
space rockets.

"I think," he said, "we need to get off this 
planet, because I'm afraid we're going to destroy 
it."

E-mail Keay Davidson at 
kdavidson@sfchronicle.com.

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