An
antimatter weapon is a hypothetical device using
antimatterIn particle physics, antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles...
as a power source, a propellant, or an explosive for a
weaponA weapon is a tool used to apply force for the purpose of hunting, attack, self-defense, or defense in combat.Weapons can be as simple as a club, or as complex as an intercontinental ballistic missile, and include those that damage individual or group morale.-Prehistoric weapons:Very simple weapon...
. Antimatter weapons do not currently exist due to the cost of production and the limited technology available to produce enough antimatter in sufficient quantities for it to be an acceptable weapon. The
United States Air ForceThe United States Air Force is the aerial warfare branch of the U.S. armed forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on 18 September 1947 under the National Security Act of 1947 - 80 P.L....
, however, has been interested in
militaryA military is an organization authorized by its nation to use force, usually including use of weapons, in defending its country by combating actual or perceived threats. As an adjective the term "military" is also used to refer to any property or aspect of a military...
uses—including
destructiveDestruction is the act of damaging something beyond use or repair. It may also refer to:* Destruction , a German thrash metal band* Destruction , one of the Endless in Neil Gaiman's comic book series The Sandman...
applications—of antimatter since the
Cold WarThe Cold War was the continuing state of political conflict, military tension, and economic competition existing after World War II , primarily between the USSR and its satellite states, and the powers of the Western world, including the United States...
, when it began funding antimatter-related
physicsPhysics is a natural science; it is the study of matter and its motion through spacetime and all that derives from these, such as energy and force...
researchResearch can be defined to be search for knowledge or any systematic investigation to establish facts. The primary purpose for applied research is discovering, interpreting, and the development of methods and systems for the advancement of human knowledge on a wide variety of scientific matters of...
. The primary theoretical advantage of such a weapon is that antimatter and matter collisions, though significantly limited by
neutrinoNeutrinos are elementary particles that often travel close to the speed of light, lack an electric charge, are able to pass through ordinary matter almost undisturbed and are thus extremely difficult to detect. Neutrinos have a minuscule, but nonzero mass...
losses, still convert a larger fraction of the weapon's mass into explosive energy than a
fusion reactionIn nuclear physics and nuclear chemistry, nuclear fusion is the process by which multiple like-charged atomic nuclei join together to form a heavier nucleus...
in a hydrogen bomb, which is on the order of only 0.7%.
On March 24, 2004,
Eglin Air Force BaseEglin Air Force Base is a United States Air Force base located southwest of Valparaiso in Okaloosa County, Florida, United States. It was named in honor of World War I aviator and test pilot Lt Col Frederick Irving Eglin...
Munitions Directorate official Kenneth Edwards spoke at the
NASA Institute for Advanced Conceptsright|200pxNASA Institute for Advanced Concepts was a NASA-funded program that was operated by the Universities Space Research Association for NASA from 1998 until its closure on 31 August 2007. NIAC sought proposals for revolutionary aeronautics and space concepts that could dramatically impact...
http://www.niac.usra.edu/. During the speech, Edwards ostensibly emphasized a potential property of
positronThe positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1, a spin of , and the same mass as an electron. When a low-energy positron collides with a low-energy electron, annihilation occurs, resulting in the production...
weaponry, a type of antimatter weaponry: Unlike
thermonuclear weaponryA nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion...
, positron weaponry would leave behind "no nuclear residue", such as the
nuclear falloutFallout is the residual radiation hazard from a nuclear explosion, aptly named because it "falls out" of the atmosphere into which it is spread during the explosion. It commonly refers to the radioactive dust created when a nuclear weapon explodes. This radioactive dust, consisting of hot...
generated by the
nuclear fissionIn nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts, often producing free neutrons and lighter nuclei, which may eventually produce photons...
reactions which power nuclear weapons. According to an article in
San Francisco Chroniclethumb|right|The Chronicle Building following the [[1906 San Francisco earthquake|1906 earthquake]] and fireSan Francisco Chronicle is Northern California's largest newspaper, and one of the largest in the United States, serving primarily the San Francisco Bay Area, but distributed throughout...
, Edwards has granted funding specifically for positron weapons
technology developmentTechnological development is the process of research and development of technology. Many emerging technologies are expected to become generally applied in the near future....
, focusing research on ways to store positrons for long periods of
timeTime is a component of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects...
, a significant technical and scientific difficulty.
There is considerable skepticism within the physics community about the viability of antimatter weapons.
According to an article on the website of the
CERNThe European Organization for Nuclear Research , known as CERN , , is the world's largest particle physics laboratory, situated in the northwest suburbs of Geneva on the Franco–Swiss border, established in 1954...
laboratories, which produces antimatter on a regular basis, "There is no possibility to make antimatter bombs for the same reason you cannot use it to store energy: we can't accumulate enough of it at high enough density. (...) If we could assemble all the antimatter we've ever made at CERN and annihilate it with matter, we would have enough energy to light a single electric light bulb for a few minutes."
http://public.web.cern.ch/Public/Content/Chapters/Spotlight/SpotlightAandD-en.html
Acquiring and storing antimatter
Antimatter production and containment are major obstacles to the creation of antimatter weapons. Quantities measured in grams would be required to achieve destructive effect comparable with conventional nuclear weapons; one gram of antimatter annihilating with one gram of matter produces 180
terajoulesThe joule , named for James Prescott Joule, is the derived unit of energy in the International System of Units. It is the energy exerted by a force of one newton acting to move an object through a distance of one metre...
, the equivalent of 42.96 kilotons of
TNTTrinitrotoluene , or more specifically, 2,4,6-trinitrotoluene, is a chemical compound with the formula C
6H
23CH
3. This yellow-coloured solid is a reagent in chemistry but is best known as a useful explosive material with convenient handling properties...
(approximately 3 times
the bomb dropped on HiroshimaLittle Boy was the codename of the atomic bomb dropped on Hiroshima on August 6, 1945 by the B-29 Superfortress Enola Gay, piloted by Colonel Paul Tibbets of the 393d Bombardment Squadron, Heavy, of the United States Army Air Forces. It was the first atomic bomb to be used as a weapon...
- and as such enough to power an average city for an extensive amount of time).
In reality, however, all known technologies for producing antimatter involve particle accelerators, and they are highly inefficient and expensive. In 2008, the annual production of antiprotons at the Antiproton Decelerator facility of CERN was several picograms at a cost of $20 million. Thus, at the current level of production, one gram of antimatter would cost $100 quadrillion and would take 2 billion years to produce.
Since the first creation of artificial antiprotons in 1955, production rates increased nearly geometrically until the mid 1980's; but no significant improvements have been made in the last two decades. The reason for this was that physical laws such as the small cross-section of antiproton production in high-energy nuclear collisions make it difficult and perhaps impossible to drastically improve the production efficiency of antimatter.
Even if it were possible to convert energy directly into particle/antiparticle pairs without any loss, a large-scale power plant generating 2000
MWeMWE may refer to:*Manufacturer's Weight Empty*McDermott Will & Emery*Midwest Express, an airline*Merowe Airport - IATA code*Multiword expressionMWe may refer to:*Megawatt electrical...
would take 25 hours to produce just one gram of antimatter. Given the average price of electric power around $50 per megawatt hour, this puts a lower limit on the cost of antimatter at $2.5 million per gram. They suggest that this would make antimatter very cost-effective as a rocket fuel, as just one milligram would be enough to send a probe to
PlutoPluto, formal designation 134340 Pluto, is the second-largest known dwarf planet in the Solar System and the tenth-largest body observed directly orbiting the Sun...
and back in a year, a mission that would be completely unaffordable with conventional fuels. Incidentally the cost of the
Manhattan ProjectThe Manhattan Project was the codename for a project conducted during World War II to develop the first atomic bomb. The project was led by the United States, and included scientists from Denmark, The United Kingdom and Canada...
(to produce the first atomic bomb) is estimated at $20 billion in 1996 prices
Most scientists however would doubt whether such efficiencies could ever be achieved.
The second problem is the containment of antimatter. Antimatter annihilates with regular matter on contact, so it would be necessary to prevent contact, for example by producing antimatter in the form of solid charged or magnetized particles, and suspending them using electromagnetic fields in near-perfect vacuum. Another, more hypothetical method is the storage of antiprotons inside fullerenes . The negatively charged antiprotons would repel the electron cloud around the sphere of carbon, so they could not get near enough to the normal protons to annihilate with them.
In order to achieve compactness given macroscopic weight, the overall electric charge of the antimatter weapon core would have to be very small compared to the number of particles. For example, it is not feasible to construct a weapon using positrons alone, due to their mutual repulsion. The antimatter weapon core would have to consist primarily of neutral antiparticles. Extremely small amounts of
antihydrogenAntihydrogen is the antimatter counterpart of hydrogen. Whereas the common hydrogen atom is composed of an electron and proton, the antihydrogen atom is made up of a positron and antiproton....
have been produced in laboratories, but containing them (by cooling them to temperatures of several
millikelvinsThe kelvin is a unit increment of temperature and is one of the seven SI base units. The Kelvin scale is a thermodynamic temperature scale where absolute zero, the theoretical absence of all thermal energy, is zero kelvin...
and trapping them in a
Penning trapPenning traps are devices for the storage of charged particles using a homogeneous static magnetic field and a spatially inhomogeneous static electric field. This kind of trap is particularly well suited to precision measurements of properties of ions and stable subatomic particles which have...
) is extremely difficult. And even if these proposed experiments were successful, they would only trap several antihydrogen atoms for research purposes, far too few for weapons or spacecraft propulsion. Heavier antimatter atoms have yet to be produced.
The difficulty of preventing accidental detonation of an antimatter weapon may be contrasted with that of a nuclear weapon. In an antimatter weapon, any failure of containment would immediately result in energy release, which would probably further damage the containment system and lead to the release of all of the antimatter material, causing the weapon to explode at some very substantial fraction of its full yield. By contrast, a modern nuclear weapon will explode with a significant yield if and only if the chemical explosive triggers are fired at precisely the right sequence at the right time, and a neutron source is triggered at exactly the right time. In short, an antimatter weapon would have to be actively kept from exploding; a nuclear weapon will not explode unless active measures are taken to make it do so.
Effects of antimatter detonation
More than 99.9% of the mass of neutral antimatter is accounted for by
antiprotonThe antiproton is the antiparticle of the proton. Antiprotons are stable, but they are typically short-lived since any collision with a proton will cause both particles to be annihilated in a burst of energy...
s and
antineutronThe antineutron is the antiparticle of the neutron. It was discovered by Bruce Cork in 1956, a year after the antiproton was discovered. An antineutron has the same mass as a neutron, and no net electric charge. However, it is different from a neutron by being composed of antiquarks, rather than...
s. Their annihilation with
protonThe proton is a subatomic particle with an electric charge of +1 elementary charge. It is found in the nucleus of each atom but is also stable by itself and has a second identity as the hydrogen ion, H
+...
s and
neutronThe neutron is a subatomic particle with no net electric charge and a mass slightly larger than that of a proton.Neutron are usually found in atomic nuclei. The nuclei of most atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of protons in a...
s is a complicated process. A proton-antiproton pair can annihilate into a number of charged and neutral relativistic
pionIn particle physics, a pion is any of three subatomic particles: , and . Pions are the lightest mesons and play an important role in explaining low-energy properties of the strong nuclear force.-Basic properties:...
s. Neutral pions, in turn, decay almost immediately into gamma rays; charged pions travel a few tens of meters and then decay further into
muonThe muon is an elementary particle similar to the electron, with negative electric charge and a spin of . Together with the electron, the tauon, and the three neutrinos, it is classified as a lepton. It is the unstable subatomic particle with the second longest mean lifetime , behind the neutron...
s and
neutrinoNeutrinos are elementary particles that often travel close to the speed of light, lack an electric charge, are able to pass through ordinary matter almost undisturbed and are thus extremely difficult to detect. Neutrinos have a minuscule, but nonzero mass...
s. Finally, the muons decay into
electronAn electron is a subatomic particle that carries a negative electric charge. It has no known substructure and is believed to be a point particle. An electron has a mass that is approximately 1836 times less than that of the proton. The intrinsic angular momentum of the electron is a half integer...
s and more neutrinos. Most of the energy (about 60%) is carried away by neutrinos, which have almost no interaction with matter and thus escape into outer space.
The overall structure of energy output from an antimatter bomb is highly dependent on the amount of regular matter in the area surrounding the bomb. If the bomb is shielded by sufficient amounts of matter, the gamma rays are absorbed and the pions slow down before decaying. Part of the kinetic energy is thus transferred to the surrounding atoms, which heat up.
In any practical form however, the weapon could not simply be a ball of antimatter floating in space. There would have to be a significant amount of supporting hardware surrounding the antimatter. Also, in order to maximize the power of the bomb, it would be designed to mix the antimatter with matter in the least amount of time.
The effect of a large antimatter bomb would likely be similar to that of a nuclear explosion of similar size. The reacting antimatter would release about half of its energy in a form immediately available to the environment, superheating the casing and components of the bomb and the surrounding air, and turning it into an ultrahot plasma which then emits Thermal Radiation in the full EM spectrum. A quantity as small as a kilogram of antimatter would release 1.8×10
17 JThe joule , named for James Prescott Joule, is the derived unit of energy in the International System of Units. It is the energy exerted by a force of one newton acting to move an object through a distance of one metre...
(180 petajoules) of energy. Given that roughly half the energy will escape as non interacting neutrinos, that gives 90 petajoules of combined blast and EM radiation, or the rough equivalent of a 20 megaton thermonuclear bomb.
Antimatter catalyzed weapons
Antimatter catalyzed nuclear pulse propulsionAntimatter catalyzed nuclear pulse propulsion is a variation of nuclear pulse propulsion based upon the injection of antimatter into a mass of nuclear fuel which normally would not be useful in propulsion...
proposes the use of antimatter as a "trigger" to initiate small nuclear explosions; the explosions provide thrust to a spacecraft. The same technology could theoretically be used to make very small and possibly "fission-free" (very low
nuclear falloutFallout is the residual radiation hazard from a nuclear explosion, aptly named because it "falls out" of the atmosphere into which it is spread during the explosion. It commonly refers to the radioactive dust created when a nuclear weapon explodes. This radioactive dust, consisting of hot...
) weapon (see
Pure fusion weaponA pure fusion weapon is a hypothetical hydrogen bomb design that does not need a fission "primary" explosive to ignite the fusion of deuterium and tritium, two heavy isotopes of hydrogen . Such a weapon would require no fissile material and would therefore be much easier to build in secret than...
). Antimatter catalysed weapons could be more discriminate and result in less long-term contamination than conventional nuclear weapons, and their use might therefore be more politically acceptable.
Igniting fusion fuel requires at least a few kilojoules of energy (for laser induced fast ignition of fuel precompressed by a z-pinch), which corresponds to around 10
−13 gram of antimatter, or 10
11 anti-hydrogen atoms. Fuel compressed by high explosives could be ignited using around 10
18 protons to produce a weapon with a one kiloton yield. These quantities are clearly more feasible than those required for "pure" antimatter weapons, but the technical barriers to producing and storing even small amounts of antimatter remain formidable.
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