Antihydrogen

Scientists hope that studying antihydrogen may shed light on the question of why there is more matter than antimatter in the observable universe, known as the baryon asymmetry problem.

It was first trapped by the Antihydrogen Laser Physics Apparatus (ALPHA) team at CERN[2][3] in 2010, who then measured the structure and other important properties.

They did this under three different experimental conditions: The two controls, off-resonance and no-laser, were needed to ensure that the laser illumination itself was not causing annihilations, perhaps by liberating normal atoms from the confinement vessel surface that could then combine with the antihydrogen.

The results were in good agreement with predictions based on normal hydrogen and can be "interpreted as a test of CPT symmetry at a precision of 200 ppt.

[8] Recent theoretical framework for negative mass and repulsive gravity (antigravity) between matter and antimatter has been developed, and the theory is compatible with CPT theorem.

The antiproton, on the other hand, is made up of antiquarks that combine with quarks in either neutrons or protons, resulting in high-energy pions, that quickly decay into muons, neutrinos, positrons, and electrons.

The first antihydrogen was produced in 1995 by a team led by Walter Oelert at CERN[11] using a method first proposed by Charles Munger Jr, Stanley Brodsky and Ivan Schmidt Andrade.

Subsequently, CERN built the Antiproton Decelerator (AD) to support efforts towards low-energy antihydrogen, for tests of fundamental symmetries.

[19] Experiments by the ATRAP and ATHENA collaborations at CERN, brought together positrons and antiprotons in Penning traps, resulting in synthesis at a typical rate of 100 antihydrogen atoms per second.

[22] In November 2010, the ALPHA collaboration announced that they had trapped 38 antihydrogen atoms for a sixth of a second,[23] the first confinement of neutral antimatter.