Antimatter | SciByte 5

Did you know …

• If an Atom was the size of a football field, the nucleus would be the size of a pea
• Positrons (anitmatter Electrons) are used in PET medical scanners
• By convention, the charge of an electron is −1, while that of a proton is +1, and neutron have no net electric charge

Paul Dirac

• Formulated the Dirac equation [provided a description of electrons, elementary spin -½ particles; first theory to fully account for relativity in the context of quantum mechanics],  which describes the behaviour of fermions
• Predicted the existence of antimatter in 1928

Carl David Anderson

• best known for his discovery of the positron in 1932, an electron with the same mass as normal electrons, but with a positive charge
• Physicists soon concluded that every particle of matter has its own antiparticle with the same mass but opposite charge.

Antimatter

• Antimatter is like a mirror image of matter. For every matter particle (a hydrogen atom, for example), a matching antimatter particle is thought to exist (in this case, an antihydrogen atom) with the same mass, but the opposite charge.
• In 1955 the both the antineutron and antiproton were discovered
• Just half a gram of antimatter would have the explosive force of 20 Hiroshimas but at current production rates it would take billions of years to make
• All the antimatter that has been created so far in laboratories (since the 1930s) would not light up a lightbulb.

Naturally occurring source – Earth’s Van Allen Belt]  :

• Around both the Earth and Jupiter, there are belts of radioactive plasma that contain antimatter.

Naturally occurring sources – Thunderstorms

• American Astronomical Society has discovered antimatter originating above thunderstorm clouds [Antimatter caught streaming from thunderstorms on Earth]
• A thunderstorms produces an electrical field, Electrons become accelerated upwards
• As the electrons accelerate upwards towards thinner atmosphere they accelerate to nearly the speed of light
• The accelerated electrons strike an atom and emit Gamma Ray photons [estimates are that ~500 Terrestrial Gamma Ray Flashes per day]
• When gamma rays pass near the nuclei of atoms, they can turn their energy into two particles: an electron-positron pair. [scientists now think that all TGFs emit electron/positron beams]

CERN [European Organization for Nuclear Research]

• International organization whose purpose is to operate the world’s largest particle physics laboratory, which is situated in the Northwest suburbs of Geneva on the Franco–Swiss border and began operating in 2008. [Location MAP]
• The term “CERN” is also used to refer to the laboratory itself, which employs approximately 2,600 full-time employees, as well as some 7,931 scientists and engineers representing 580 universities and research facilities and 80 nationalities.

• “Most of the data is discarded,” Steven Goldfarb told the crowd via a video link from the ATLAS control room in Geneva. “If we took all the data we would be storing a petabyte of data every second, which is about a thousand of the disks that you can buy at the store.”

Creating Antihydrogen @ ALPHA (Antihydrogen Laser Physics Apparatus)

• The experiment begins by making a cloud of positrons and a cloud of antiprotons.

• The antiprotons are created in an accelerator by smashing high-energy protons into a stationary target and then slowed and cooled in a series of steps involving a storage ring and electromagnetic traps.
• The positrons are produced by a radioactive source and then accumulated and cooled in a special trap.
• The clouds are injected into a superconducting magnetic trap, where they mix for about 1 s to create antihydrogen.
• The charged positrons and antiprotons are then ejected from the trap, leaving behind neutral antihydrogen. While most of this antihydrogen is moving too quickly to be trapped, atoms with very little kinetic energy are held by a magnetic field gradient.

Trapping Antimatter @ ALPHA

• Trapping antimatter is difficult, because when it comes into contact with matter, the two annihilate each other. So a container for antimatter can’t be made of regular matter, but is usually formed with magnetic fields.
• These precious atoms of antimatter are then held in a kind of magnetic bottle, chilled to more than 272 degrees below zero
• Scientists who’ve been trapping antihydrogen atoms at the European Organization for Nuclear Research (CERN) in Geneva say isolating the exotic particles has become so routine that they expect to soon begin experiments on this rare substance
• “hope that by 2012 we will have a new trap with laser access to allow spectroscopic experiments on the antiatoms,” Fajans said in a statement
• The team has now managed to capture 112 antiatoms in this new trap for times ranging from one-fifth of a second to 1,000 seconds, or 16 minutes and 40 seconds.

Antihydrogen

• To date, since the beginning of the project, Fajans and his colleagues have trapped 309 antihydrogen atoms in various traps and was trapped for the first time November 2010
• It has now been trapped for 16 minutes and 40 seconds
• ALPHA physicists have planned two key experiments to be started later this year. One will determine if antihydrogen reacts to light the same way hydrogen does, the other will compare how they interact with gravity

• At the moment, the anti-hydrogen atoms are held in their bottle at just half a degree above absolute zero. For the gravity experiments, conditions would need to be a few thousandths of a degree above the theoretically coldest achievable temperature

Detection

• Scientists could detect the trapped antiatoms by turning off the magnetic field and allowing the particles to annihiliate with normal matter, which creates a flash of light
• There may also be antimatter elsewhere in the universe, and a detector, the Alpha Magnetic Spectrometer, has just been delivered to the International Space Station to look for it

AMS-02 : Alpha Magnetic Spectrometer

• Designed to search for various types of unusual matter by measuring cosmic rays
• The launch of Space Shuttle Endeavour flight STS-134 carrying AMS-02 took place on 16 May 2011, and the spectrometer was installed on 19 May 2011
• AMS-02 tracks its first particle on the ISS!

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Additional Information

• CERN Press Release
• LiveScience : Ephemeral Antimatter Trapped for Amazingly Long 16 Minutes
• Large Hadron Collider Rap
• LHC @ Home – Donate your computers computing power
• Japan Times : Warp-drive quest for the Big Bang’s ‘lost’ material
• BBC : Antimatter atoms are corralled even longer
• nature physics : Confinement of antihydrogen for 1,000 seconds
• WIKI – Large Hadron Collider
• NASA : NASA’s Fermi Catches Thunderstorms Hurling Antimatter into Space
• Universe Today : Fermi Telescope Catches Thunderstorms Hurling Antimatter into Space
• Comic : Difference in Real Science vs Movie Science

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