THE COSMIC-RAY ANTIPROTON FLUX BETWEEN 0.62 AND 3.19 GEV MEASURED NEAR SOLAR MINIMUM ACTIVITY

We report on the absolute antiproton flux and the antiproton to proton ratio in the energy range 0.62-3.19 GeV at the top of the atmosphere, measured by the balloon-borne experiment CAPRICE; flown from Lynn Lak e, Manitoba, Canada, on 1994 August 8-9. The experiment used the New M exico State University WiZard/CAPRICE balloon-borne magnet spectromete r equipped with a solid radiator Ring Imaging Cherenkov (RICH) detecto r and a silicon-tungsten calorimeter for particle identification. This is the first time a RICH is used together with an imaging calorimeter in a balloon experiment, and it allows antiprotons to be clearly iden tified over the rigidity range 1.2-4 GV. Nine antiprotons were identif ied in the energy range 0.62-3.19 GeV at the top of the atmosphere. Th e data were collected over 18 hr at a mean residual atmosphere of 3.9 g cm(-2). The absolute antiproton flux is consistent with a pure secon dary production of antiprotons during the propagation of cosmic rays i n the Galaxy.