Large angle production of stable particles heavier than the proton and a search for quarks at the CERN intersecting storage rings

Measurements have been performed on production of particles with mass 1.5 GeV/ c² and charge ⩾ {2}/{3} for θ_lab = 62.5° and s = 53 GeV. At p_T = 0.7 GeV/ c the relative rate of production of antideuterons to π ^- is (5 ± 1) × 10 ^-5. The deuteron to antideuteron ratio is 3.7 ± 1.2. No new stable particle has been amongst 0.7 × 10 ⁸ charged particles entering our detector.