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Casting Light on Antimatter: Fundamental Physics with Bottled Antihydrogen Atoms

Balance The existence of antimatter was first predicted by Dirac in 1928. The antielectron (now called the positron) and the antiproton were discovered experimentally in 1932 and 1955, respectively. It then took, however, more than half a century before physicists were able to create and control the atomic form of antimatter, the antihydrogen atom, in sufficient quantity to be able to study its properties.

The hydrogen atom, the simplest atomic system consisting of a proton orbited by an electron, has played a central role in developments of modern physics. By studying antihydrogen, an antiproton orbited by an antielectron, we wish to precisely probe the fundamental symmetries between matter and antimatter. In particular, CPT (charge, parity, time-reversal) symmetry underpins relativistic quantum field theory, and the Equivalence Principle is a key assumption in Einstein’s General Relativity. A violation of these symmetries, even at a very minute level, would force a radical change in the way we understand subatomic physics at its deepest level.  In this talk, I will discuss how we produce, control, and perform precision measurements on antihydrogen atoms that are “bottled” in the ALPHA antihydrogen trap at CERN.