* Astronomy

Blobrana · L

CP violation

Blobrana · L

It is one the biggest mysteries in physics - where did all the antimatter go? Now a team of physicists claims to have found the first ever hint of an answer in experimental data. The findings could signal a major crack in the standard model, the theoretical edifice that describes nature's fundamental particles and forces.
In its early days, the cosmos was a cauldron of radiation and equal amounts of matter and antimatter. As it cooled, all the antimatter annihilated in collisions with matter - but for some reason the proportions ended up lopsided, leaving some of the matter intact.
Physicists think the explanation for this lies with the weak nuclear force, which differs from the other fundamental forces in that it does not act equally on matter and antimatter. This asymmetry, called CP violation, could have allowed the matter to survive to form the elements, stars and galaxies we see today.

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Blobrana · L

RE: Antimatter

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An intriguing source of gamma rays linked to the high-energy collision of fundamental particles in the centre of our galaxy has been traced to vampire-like binary stars, a study says.
The big smash comes from negatively-charged electrons colliding with their corresponding positively-charged "antiparticle," known as positrons.
When electrons and positrons meet, the event is very brief, for they destroy -- "annihilate" -- each other in a flash of energy.
In 1970s, astronomers discovered a narrow blast of electron-positron annihilation emanating from near the centre of the Milky Way, detectable in the 511 kiloelectron volt (keV) range of gamma-ray energy.

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Blobrana · L

D'où vient le mystérieux nuage d'antimatière présent dans les régions centrales de la Galaxie ? Une équipe européenne d'astrophysiciens, composée notamment de chercheurs du CNRS, de l'Université Paul Sabatier de Toulouse et du CEA(1), a levé une partie du voile en cumulant l'ensemble des données recueillies depuis quatre ans par Integral, un satellite de l'ESA. Ces travaux sont publiés dans la revue Nature du 10 janvier 2008.

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Blobrana · L

Scientists recently announced they have fired the most powerful antimatter beam ever created. Comprised of positrons (antimatter electrons) emitted from a large plate and focused into a beam, the emission strength exceeds the previous record held by a laboratory in Munich, Germany.
Earlier this month, students and faculty at North Carolina State's PULSTAR nuclear reactor saw a positron beam 5x more powerful than any other ever emitted by man. It was created by a device which looks amazingly similar to a warp reactor from Star Trek.
In truth, the PULSTAR reactor is a fascinating piece of equipment. It's comprised of a few dozen distinct components which, when all working together in unison, creates a 1 megawatt pool-type research reactor. It's fired by 4% enriched uranium dioxide in pin-type fuel pellets cladded in zircaloy. This particular type of fuel gives PULSTAR characteristics that are very similar to commercial light water power reactors.

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Japanese EURYI Award winner Dr. Masaki Hori wants to find new ways to store and handle anti-matter.

According to the CPT theorem of particle physics, the antiworld constructed by replacing all the matter particles in the universe with antimatter, inverting their spatial configuration, and reversing the flow of time - would be indistinguishable from our real matter world. One cornerstone of this symmetry is that atoms made of antimatter, i.e. antiatoms, are expected to resonate at exactly the same characteristic optical and microwave frequencies as their matter counterparts; particles and their antiparticles are assumed to have exactly the same mass, and equal and opposite electric charge and magnetic moment. Any deviation, however small, would indicate that this fundamental symmetry of nature is broken.

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Title: The Production of Anti-Matter in our Galaxy
Authors: Pascal Chardonnet, Jean Orloff, Pierre Salati

The discovery of a single anti-helium nucleus in the cosmic ray flux would definitely point toward the existence of stars and even of entire galaxies made of anti-matter. The presence of anti-nuclei in cosmic rays has actually profound implications on the fundamental question of the baryon asymmetry of the universe. It is therefore crucial to determine the amount of anti-matter which our own galaxy already produces through the spallation of high-energy protons on the interstellar gas of the galactic disk. We have used here a coalescence model to assess the amount of anti-deuterium and anti-helium 3 present in cosmic rays together with anti-protons. The propagation of cosmic rays in the galaxy is described through a two-zone diffusion model which correctly describes the observed abundances. We find that the antideuterium/proton ratio exceeds 10^{-9} above a momentum per anti-nucleon of about 4 GeV/c. Would the universe be purely made of matter, the AMS collaboration should be able to detect a few anti-deuterons during the space station stage of the experiment. However, the antihelium3/proton abundance does not exceed 4 10^{-13}. Heavier anti-nuclei are even further suppressed.

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Antimatter in the Milky Way

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Antimatter Chemistry