Measurement of the Cosmic-Ray Antiproton to Proton Abundance Ratio between 4 and 50 GeV

Abstract

We present a new measurement of the antiproton to proton abundance ratio, pbar/p, in the cosmic radiation. The HEAT-pbar instrument, a balloon borne magnet spectrometer with precise rigidity and multiple energy loss measurement capability, was flown successfully in Spring 2000, at an average atmospheric depth of 7.2 g/cm^2. A total of 71 antiprotons were identified above the vertical geomagnetic cut-off rigidity of 4.2 GV. The highest measured proton energy was 81 GeV. We find that the pbar/p abundance ratio agrees with that expected from a purely secondary origin of antiprotons produced by primary protons with a standard soft energy spectrum.

arXiv comment4 pages, 3 figures; accepted for publication in PRL

References in corpus (4)

• Precision Measurement of Cosmic-Ray Antiproton Spectrum
• Local Flux of Low-Energy Antiprotons from Evaporating Primordial Black Holes
• Cosmic-Ray Antiprotons from Neutralino Annihilation into Gluons
• Constraints on the Intergalactic Transport of Cosmic Rays

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