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New Measurement of the Cosmic-Ray Positron Fraction from 5 to 15 GeV

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

We present a new measurement of the cosmic-ray positron fraction at energies between 5 and 15 GeV with the balloon-borne HEAT-pbar instrument in the spring of 2000. The data presented here are compatible with our previous measurements, obtained with a different instrument. The combined data from the three HEAT flights indicate a small positron flux of non-standard origin above 5 GeV. We compare the new measurement with earlier data obtained with the HEAT-e+- instrument, during the opposite epoch of the solar cycle, and conclude that our measurements do not support predictions of charge sign dependent solar modulation of the positron abundance at 5 GeV.

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J. J. Beatty, A. Bhattacharyya, C. Bower, S. Coutu, M. A. DuVernois, S. McKee, S. A. Minnick, D. Muller, J. Musser, S. Nutter, A. W. Labrador, M. Schubnell, S. Swordy, G. Tarle, A. Tomasch. 2004-12-09. New Measurement of the Cosmic-Ray Positron Fraction from 5 to 15 GeV. https://doi.org/10.1103/physrevlett.93.241102

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