The cosmic-ray He-3/He-4 ratio from 200 MeV per nucleon(-1) to 3.7 GeV per nucleon(-1)

O. Reimer, W. Menn, M. Hof, M. Simon, A.J. Davis, A.W. Labrador, R.A. Mewaldt, S.M. Schindler, L.M. Barbier, E.R. Christian, K.E. Krombel, J.W. Mitchell, J.F. Ormes, R.E. Streitmatter, R.L. Golden, S.J. Stochaj, W.R. Webber, Ib Lundgaard Rasmussen

    Research output: Contribution to journalJournal articleResearchpeer-review


    The abundances of cosmic-ray helium isotopes between 0.2 and 3.7 GeV nucleon(-1) were measured by the Isotope Matter Antimatter Experiment (IMAX) during a flight from Lynn Lake, Manitoba, Canada on 1992 July 16-17. The IMAX balloon-borne magnetic spectrometer realized a direct measurement of the charge, the velocity, and the rigidity of cosmic rays using plastic scintillators, a high-resolution time-of-flight system, and two silica-aerogel Cerenkov counters in conjunction with a drift chamber/multiwire proportional chamber tracking system. About 75,000 helium isotopes are identified by their mass using the velocity versus magnetic rigidity technique. The measured He-3/He-4 ratios are corrected to the top of the atmosphere, and a comparison with previous data is given. The observed isotopic composition is found to be generally consistent with the predictions of a standard leaky box model of cosmic-ray transport in the Galaxy.
    Original languageEnglish
    JournalAstrophysical Journal
    Issue number1
    Pages (from-to)490-502
    Publication statusPublished - 1998


    • nuclear reactions
    • abundances
    • acceleration of particles
    • cosmic rays
    • nucleosynthesis
    • balloons


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