FIGURE 1. Antihydrogen annihilation.

The ATHENA experiment has produced the first cold anti-atoms¹, detected through their destruction in collisions with matter particles. The annihilation of the antiproton produces secondary particles, which, picked up in the surrounding detectors (blue), can be traced back (yellow dashed lines) to the annihilation point. Similarly, the annihilation of the positron produces a distinctive back-to-back two-photon signature (red dashed lines). The overlap of the two annihilation points signifies that the positron and antiproton were bound together in an atom of antihydrogen.

ATHENA/CERN