Measurement of the Positron to Electron Ratio in Cosmic Rays above 5 GeV
Abstract
As part of a series of experiments to search for antimatter in cosmic rays, the New Mexico State University balloon-borne magnet spectrometer was configured for a flight to study positrons. Two completely new instruments, a transition radiation detector and a silicon-tungsten imaging calorimeter, were added to the magnet spectrometer. These two detectors provided a proton rejection factor better than 3 x 104. This instrument was flown from Fort Sumner, New Mexico, at an average depth of 4.5 g cm-2 of residual atmosphere for a period of 25 hr. We report here the measured fraction of positrons e+/(e+ + e-) from ~5 to 60 GeV at the top of the atmosphere. Our measurements do not show any compelling evidence for an increase in this ratio with energy, and our results are consistent with a constant fraction of 0.078 +/- 0.016 over the entire energy region.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 1996
- DOI:
- Bibcode:
- 1996ApJ...457L.103G
- Keywords:
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- ISM: COSMIC RAYS;
- ELEMENTARY PARTICLES
