Antihelium Is Produced At Serpukhov Accelerator

Five nuclei of antihelium‐3 have been made by Yuri Prokoshkin and his collaborators at the Serpukhov 76‐GeV synchrotron, according to a front‐page report in Pravda. The group bombarded an internal target with protons, defined the momentum of outgoing particles by magnets and measured velocity by time of flight. Out of ${\text{2×10}}^{11}$ negative pions detected by the counters, five particles had the right mass to be ${\mathrm{He}}^3.$