A measurement of cosmic-ray beryllium isotopes from 200 to 1500 MeV per nucleon.
Abstract
A balloon-borne superconducting magnetic spectrometer was used in the measurement of cosmic-ray isotopic abundances from lithium through oxygen in the energy range 200-1500 MeV per nucleon. Except for Be-7 all isotopic composition is essentially energy-independent. Be-10 is nearly absent, indicating a mean cosmic-ray age of 6(-3, +10) x 10 to the 6th years. Above about 500 MeV per nucleon, Be-7 drops dramatically in abundance relative to Be-9 and C. By 1500 MeV per nucleon, the relative abundance of Be-7 has become one-half of its lower-energy value. Since Be-7 is the only isotope measured which decays by electron capture, this result is interpreted as indicating that higher-energy Be-7 had an appreciable probability of not being stripped of all its electrons before entering interstellar space where electron pickup is negligible.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1978
- DOI:
- 10.1086/156616
- Bibcode:
- 1978ApJ...226..355B
- Keywords:
-
- Abundance;
- Beryllium Isotopes;
- Cosmic Rays;
- High Energy Interactions;
- Interstellar Matter;
- Balloon-Borne Instruments;
- Graphs (Charts);
- Magnetic Rigidity;
- Space Radiation;
- Cosmic Rays:Isotopic Abundances