Isotopes of neon in the galactic cosmic rays

Journal Article · Sat Sep 01 04:00:00 EDT 1979 · Astrophys. J., Lett. Ed.; (United States)

DOI:https://doi.org/10.1086/183043· OSTI ID:5940321

Garcia-Munoz, M; Simpson, J A; Wefel, J P

The University of Chicago instrument on board the IMP7 satellite has been used to measure the abundances of /sup 20/Ne and /sup 22/Ne in the galactic cosmic rays during 1973--1977, over the general energy range approx.60--230 MeV per nucleon. The instrument shows a mass resolution of 0.7 amu (sigma), which was confirmed by calibrating a backup instrument at the LBL Bevalac with separated beams of neon isotopes. The ratio /sup 22/Ne//sup 20/Ne measured at the orbit of Earth is 0.54 +- 0.07, assuming a fraction /sup 21/Ne/Ne=10% in the arriving cosmic rays. Using standard solar modulation and cosmic-ray propagation models, the cosmic-ray source ratio inferred is /sup 22/Ne//sup 20/Ne=0.38 +- 0.07 (/sup 20/Ne//sup 22/Ne=2.6 +- 0.5), significantly greater than the present solar system ratio. Propagation effects or cross-section uncertainties cannot account for such a large abundance of /sup 22/Ne, and thus this measurement provides evidence that the cosmic rays come from a source region where the /sup 22/Ne abundance is substantially greater than in solar system material.

• Research Organization: Enrico Fermi Institute, University of Chicago
• OSTI ID: 5940321
• Journal Information: Astrophys. J., Lett. Ed.; (United States), Journal Name: Astrophys. J., Lett. Ed.; (United States) Vol. 232:2; ISSN AJLEA
• Country of Publication: United States
• Language: English

Related Subjects

640101* -- Astrophysics & Cosmology-- Cosmic Radiation
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
CHEMICAL COMPOSITION
COSMIC NUCLEI
COSMIC RADIATION
COSMIC RAY SOURCES
CROSS SECTIONS
EVEN-EVEN NUCLEI
IONIZING RADIATIONS
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
MEASURING INSTRUMENTS
NEON 20
NEON 22
NEON ISOTOPES
NUCLEI
RADIATION DETECTORS
RADIATIONS
SOLAR SYSTEM
STABLE ISOTOPES