ANTIMATTER...THE MOST VOLATILE SUBSTANCE KNOWN TO MAN

ANTIMATTER...THE MOST VOLATILE SUBSTANCE KNOWN TO MAN

A single droplet of antimatter contains the explosive power of a ten kiloton bomb (Hiroshima.)Antimatter is extremely unstable and explodes when it comes in contact with absolutely anything (even air.)

Nonetheless, antimatter is now being produced at CERN in Switzerland, where anti-particles are accelerated around a 27-mile-long circular tunnel... traveling so fast that they complete the enormouscircle over 11,000 times per second.

Antimatter is routinely produced at CERN (more than 10 million particles per second.) The World-wide Web was invented at CERN. The world's largest magnet, weighing more thanthe Eiffel tower, is at CERN. CERN's biggest accelerator is 27 kilometers around, andparticles travelling near the speed of light lap it over 11,000 times each second.

In 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 ofparticles. For example, an antielectron (a positron, an electron with a positive charge) and an antiproton (a proton with a negative charge) could form an antihydrogen atom in the same way thatan electron and a proton form a normal matter hydrogen atom. Furthermore, mixing matter and antimatter would lead to the annihilation of both in the same way that mixing antiparticles and particles does, thus giving rise to high-energy photons (gamma rays) or other particle–antiparticle pairs.

There is considerable speculation as to why the observable universe is apparently almost entirelymatter, whether there exist other places that are almost entirely antimatter instead, and what mightbe possible if antimatter could be harnessed, but at this time the apparent asymmetry of matter and antimatter in the visible universe is one of the greatest unsolved problems in physics. The process by which this asymmetry between particles and antiparticles developed is called baryogenesis

An antimatter weapon is a hypothetical device using antimatter as a power source, a propellant, or anexplosive for a weapon. Antimatter weapons do not currently exist as far as we know outside fiction (such as Star Trek's photon torpedo). The United States Air Force, however, has been interested in militaryuses—including destructive applications—of antimatter since the Cold War, when it began funding antimatter-relatedphysics research. The primary theoretical advantage of such a weapon is that antimatter and matter collisions convert 100% of mass into energy while comparatively a fusion reaction in a hydrogen bomb is on the order of 0.7%.

The History of Antimatter
The history of antimatter begins in 1928 with a young physicist named Paul Dirac and a strange mathematical equation...

The equation, in some way, predicted the existence of an antiworld identical to ours but made out of antimatter. Was this possible? if so, where and how could we search for antimatter?
From 1930, the search for the possible constituents of antimatter, antiparticles, began, and it has been the main influence behind a major scientific and technical evolution over the last 70 years.

CERN physicists Alvaro de Rújula and Rolf Landua answer your most frequently asked questions.
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• What can antimatter be used for?

There are several different uses for antimatter, the main one being for medical diagnostics where positrons are used to help identify different diseases with the Positron Emission Tomography (or PET scan). For other uses, we are still in the first phases of development and it's difficult to foresee what will happen in the next ten years!

• Can we use antimatter to propel a car or a spaceship?

In principle, yes, but in practice it is very difficult. You all know that the Star Trek Spaceship Enterprise flies around powered by antimatter. But in reality, making antimatter is so difficult that it is hard to foresee it ever being used as a propellant fuel. In order to propel a matter spacecraft weighing several tons up to the speed of light, you would need an equal amount of antimatter and, using the present technology, it would take millions and millions of years to produce a sufficient amount.
However, if you had a gram of antimatter, you could drive your car for about 100.000 years!

• Is it possible to build an antimatter weapon?

The military use of antimatter has the same limitations as spaceship propulsion: both would require a huge amount of antimatter, taking million of years to produce.
But if you define a weapon as something which shoots bullets, an accelerator could be considered an antiparticle gun! But we are talking about single particles, so the amount of energy you release when you shoot one of these "bullets" is so small you wouldn't even tickle your enemy.

• How do you store antimatter?

Antiparticles have either a positive or a negative electrical charge, so they can be stored in what we call a trap which has the appropriate configuration of electrical and magnetic fields to keep them confined in a small place. Of course, this has to be done in good vacuum to avoid collisions with matter particles.
Antiatoms are electrically neutral, but they have magnetic proprieties that can be used to keep them in "magnetic bottles".

• What does antimatter look like?

Matter and antimatter are identical. Looking at an object means seeing the photons coming from that object; however, photons come from both matter and antimatter. If there were a distant galaxy made out of antimatter, you couldn't distinguish it from a matter galaxy just by seeing the light from it.

How can you be so sure there is not antimatter around?

If there was antimatter here, around us, it would annihilate with matter and we would see light coming out. But we don't...
About the possibility of antimatter in space (antistars or antigalaxies), theorist have reasons to believe that the Universe is all made of matter. But we are not 100% sure, and that's way there are experiments, like AMS*, which are going to look for it.

• If the only difference between a particle and its antiparticle is the charge, how do you distinguish a neutron from an antineutron ?Neutrons are made of quarks, and antineutrons are made of antiquarks. Quarks and antiquarks have opposite charges, even though they sum up to zero in both cases.
And a very good way to recognize them is to put a neutron close to an antineutron and see how they immediately annihilate.

• What about antiphotons?

Photons have zero charge and do not contain inside objects that are charged, so a photon can not be distinguished from an antiphoton. Photon and antiphotons are the same thing, i.e. the photon is its own antiparticle.

• How do sound waves propagate in antimatter?

If there is a difference between matter and antimatter, it is very very tiny, that's why we are doing experiments here at CERN to investigate it. They are so similar that sound waves, that are vibrations of matter or antimatter, would be identical. An antimatter piano would sound exactly as a matter one.

• How does the gravitational field act on antimatter?

The gravitational force depends from the energy of an object, and since matter and antimatter have both positive energy, gravitation acts on them in the same way.
This means that an object made of matter and one made of antimatter would both stand on the floor, the latter one not flying off the sky...

• How mach antimatter can you make in one accelerator cycle?

Here at CERN we can produce 50 millions antiprotons in each cycle (about once a minute), that allows us to make a few hundred antihydrogen atoms.
The number could be 10 times higher in particular configurations of the accelerator. This sounds a lot, but expressed in grams it is a billionth of a gram in a year.

• How much does it cost to produce antimatter?

If we count on the production CERN has done over the last 10 years (about 1 billionth of a gram), it has cost a few hundred millions Swiss francs.

• How long will it take to have "new results" out of the AD?

The experiments took about three years to set up, and now that they are ready, it will take a year or two to understand the production of antihydrogen and how to contain it. Then the first studies can be done, where we compare atoms and antiatoms, and this will be two or three years from now.

AMS:'Alpha Magnetic Spectrometer'
About 15 billion years ago, matter and antimatter were created in a gigantic Big Bang in equal amounts, at least according to today's best theory. It is therefore surprising that our Earth, the solar system, and our galaxy (the Milky Way) do not contain any antimatter.

To explain this absence, scientists have come out with two possibilities: either antimatter completely disappeared during the history of universe, or matter and antimatter have been separated from each other to form different regions of the universe.

In the second case, we would be located in a region where only matter exists (or rather what we call 'matter'), but some antimatter coming from an 'anti' region outside our galaxy could still have a chance to reach us. This antimatter would be in the form of anti-nuclei (like anti-Helium, anti-Carbon, etc..) as opposed to lighter antiparticles (such as antiprotons) which are also created in high energy collisions between ordinary matter. To search for this extragalactic antimatter, the best way is to place a particle detector in space.

A world-wide collaboration of physicists, lead by Nobel prize laureate Prof. Samuel Ting of MIT, decided to build the 'Alpha Magnetic Spectrometer', or AMS. AMS is a high energy particle detector which will try to detect the passage of such very small amounts of antimatter, while orbiting at an altitude of a few hundred kilometers above the atmosphere.

Some of the main challenges of the project are very technical: having to be carried on the Space Shuttle, each component of the apparatus has to be miniaturized as much as possible to keep the total volume to a maximum of 10 cubic meters and the weight to a maximum of 3 tons (a typical high energy apparatus at LEP with the similar detecting principles is about 1000 cubic meters in volume and 100 tons in weight).

Even more important is the power consumption: AMS should not need more than 2 kW (kilowatts) of electricity, provided by the solar panels of the Space Station. And 2kW is less than what a kitchen oven needs!