CaltechAUTHORS
Published April 10, 2000 | Version Published
Journal Article Open

The Absolute Flux of Protons and Helium at the Top of the Atmosphere Using IMAX

Creators

  • 1. ROR icon University of Siegen
  • 2. ROR icon Max Planck Institute for Extraterrestrial Physics
  • 3. ROR icon California Institute of Technology
  • 4. ROR icon University of Chicago
  • 5. ROR icon Goddard Space Flight Center
  • 6. ROR icon New Mexico State University
  • 7. ROR icon Technical University of Denmark

Abstract

The cosmic-ray proton and helium spectra from 0.2 GeV nucleon^(-1) to about 200 GeV nucleon^(-1) have been measured with the balloon-borne experiment Isotope Matter-Antimatter Experiment (IMAX) launched from Lynn Lake, Manitoba, Canada, in 1992. IMAX was designed to search for antiprotons and light isotopes using a superconducting magnet spectrometer together with scintillators, a time-of-flight system, and Cherenkov detectors. Using redundant detectors, an extensive examination of the instrument efficiency was carried out. We present here the absolute spectra of protons and helium corrected to the top of the atmosphere and to interstellar space. If demodulated with a solar modulation parameter of Φ = 750 MV, the measured interstellar spectra between 20 and 200 GV can be represented by a power law in rigidity, with (1.42 ± 0.21) × 10^4R^(-2.71±0.04) (m^2 GV s sr)^(-1) for protons and (3.15 ± 1.03) × 10^3R^(-2.79±0.08) (m^2 GV s sr)^(-1) for helium.

Additional Information

© 2000. The American Astronomical Society. Received 1999 July 1; accepted 1999 November 23. We thank the technical crews from New Mexico State University, Goddard Space Flight Center, California Institute of Technology, and the Universität Siegen for their dedicated support. We are grateful to the National Scientific Balloon Facility for carrying out a successful flight of the IMAX payload. IMAX was supported in the United States by NASA under RTOP 353-87-02 (GSFC) and grants NAGW-1418 (NMSU/BBMF) and NAGW-1919 (Caltech) and in Germany by the Deutsche Forschungsgemeinschaft (DFG) and the Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie (BMBF).

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Eprint ID
55002
Resolver ID
CaltechAUTHORS:20150219-102725410

Related works

Describes
http://adsabs.harvard.edu/abs/2000ApJ...533..281M (URL)

Funding

NASA
RTOP 353-87-02
NASA
NAGW-1418
NASA
NAGW-1919
Deutsche Forschungsgemeinschaft (DFG)
Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie

Dates

Created
2015-02-23
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Updated
2021-11-10
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Caltech Custom Metadata

Caltech groups
Space Radiation Laboratory
Other Numbering System Name
Space Radiation Laboratory
Other Numbering System Identifier
2000-14