CERN’s ALPHA experiment measures charge of antihydrogen

Geneva, 3 June 2014. In a paper published today, the ALPHA experiment at CERN 's Antiproton Decelerator (AD) reports a measurement of the electric charge of antihydrogen atoms, finding it to be compatible with zero to eight decimal places. Although this result comes as no surprise, since hydrogen atoms are electrically neutral, it is the first time that the charge of an antiatom has been measured to high precision. "This is the first time we have been able to study antihydrogen with some precision," said ALPHA spokesperson Jeffrey Hangst. "We are optimistic that ALPHA's trapping technique will yield many such insights in the future.  We look forward to the restart of the AD program in August, so that we can continue to study antihydrogen with ever increasing accuracy." Antiparticles should be identical to matter particles except for the sign of their electric charge. So while the hydrogen atom is made up of a proton with charge +1 and an electron with charge -1, the antihydrogen atom consists of a charge -1 antiproton and a charge +1 positron.