sentences:  Using this technology, the experimental group led by Professor Wang Ganchang in Dubna analysed more than 40,000 photographs which recorded tens of thousands of nuclear interactions taken in the propane bubble chamber produced by a 10 GeV synchrophasotron used to bombard a target forming high energy mesons.On March 9, 1959 they were the first to discover anti-sigma minus hyperon particles (反西格马负超子).The discovery of this new unstable antiparticle, which decays in (1.18±0.07)·10−10 s into an antineutron and a negative pion, was announced in September of that year.