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

A. S. Beach·J. J. Beatty·A. Bhattacharyya·C. Bower·S. Coutu·M. A. DuVernois·A. W. Labrador·S. McKee·S. A. Minnick·D. Muller·J. Musser·S. Nutter·M. Schubnell·S. Swordy·G. Tarle·A. Tomasch
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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.

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A. S. Beach, J. J. Beatty, A. Bhattacharyya, C. Bower, S. Coutu, M. A. DuVernois, A. W. Labrador, S. McKee, S. A. Minnick, D. Muller, J. Musser, S. Nutter, M. Schubnell, S. Swordy, G. Tarle, A. Tomasch. 2001-11-05. Measurement of the Cosmic-Ray Antiproton to Proton Abundance Ratio between 4 and 50 GeV. https://doi.org/10.1103/physrevlett.87.271101

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