CERN experiment improves precision of antiproton mass measurement with new innovative cooling technique

In a paper published today in the journal Science, the ASACUSA experiment at CERN reported new precision measurement of the mass of the antiproton relative to that of the electron. This result is based on spectroscopic measurements with about 2 billion antiprotonic helium atoms cooled to extremely cold temperatures of 1.5 to 1.7 degrees above absolute zero. In antiprotonic helium atoms an antiproton takes the place of one of the electrons that would normally be orbiting the nucleus. Such measure