New measurement of the cosmic-ray positron fraction from 5 to 15 GeV.
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 nonstandard 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.
Beatty
J J
JJ
Department of Physics, Pennsylvania State University, University Park, PA 16802, USA.
Bhattacharyya
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A
Bower
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Coutu
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Duvernois
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McKee
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Minnick
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Müller
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Musser
J
J
Nutter
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Labrador
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Schubnell
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Swordy
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Tarlé
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Tomasch
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