In Wednesday’s issue of Nature, a new paper describes a potentially useful way of measuring the interactions between normal matter and exotic particles, like antiprotons and unstable items like kaons or elements containing a strange quark. The work is likely to be useful, as we still don’t understand the asymmetry that has allowed matter to be the dominant form in our Universe.
But the study is probably most notable for the surprising way that it collected measurements. A small research team managed to put an antiproton in orbit around the nucleus of a helium atom that was part of some liquid helium chilled down to where it acted as a superfluid. The researchers then measured the light emitted by the antiproton’s orbital transitions.