THE COSMIC-RAY HE-3-HE-4 RATIO FROM 100 TO 1600 MEV AMU-1

Citation
Jj. Beatty et al., THE COSMIC-RAY HE-3-HE-4 RATIO FROM 100 TO 1600 MEV AMU-1, The Astrophysical journal, 413(1), 1993, pp. 268-280
Citations number
31
Categorie Soggetti
Astronomy & Astrophysics
Journal title
ISSN journal
0004637X
Volume
413
Issue
1
Year of publication
1993
Part
1
Pages
268 - 280
Database
ISI
SICI code
0004-637X(1993)413:1<268:TCHRF1>2.0.ZU;2-D
Abstract
The Superconducting Magnet Instrument for Light Isotopes (SMILI) flew for 19 hours on 1989 September 1 with a residual overburden of 5 g cm- 2. It measured the charge, rigidity, and velocity of 30,000 cosmic-ray helium nuclei, with velocity determined by time-of-flight and Cerenko v techniques. Using these data, the flux and isotopic composition of h elium as a function of energy were determined. The observed isotopic c omposition is consistent with that expected from interstellar propagat ion models inferred from the secondaries of CNO, in contrast to earlie r observations which indicated an overabundance of He-3. We discuss co nstraints that this result places on cosmic-ray transport and solar mo dulation models.