Abstract
A search for cosmic-ray antiprotons was performed using a balloon-borne experiment with a superconducting magnetic rigidity spectrometer (BESS). We have detected four antiprotons in the kinetic energy range between 300 and 500 MeV, the first antiprotons to be identified by a direct mass measurement. The corresponding flux ratio at the top of the atmosphere is found to be × . No antiprotons were observed in the range between 175 and 300 MeV, resulting in a 90% C.L. upper limit on the flux ratio of 2.9 × .
- Received 20 March 1995
DOI:https://doi.org/10.1103/PhysRevLett.75.3792
©1995 American Physical Society