Silver isotopic anomalies in iron meteorites: cosmic-ray production and other possible sources

Conference · Fri Apr 18 04:00:00 EST 1980

OSTI ID:5320495

Reedy, R C

The sources of excess /sup 107/Ag observed in iron meteorites by Kaiser, Kelly, and Wasserburg (1980) are examined, with emphasis on the reactions of cosmic-ray particles with palladium. The cross sections for the production of the silver isotopes from palladium by energetic cosmic-ray particles are evaluated or estimated and used to calculate spallogenic production rates relative to that of /sup 53/Mn from iron. The upper limit for the production rate of excess /sup 107/Ag by galactic-cosmic-ray particles is 400 atoms/min/kg(Pd) which, over an exposure age of 10/sup 9/ years, would make only 1% of the observed excesses of /sup 107/Ag. Neutron-capture reactions with Pd isotopes produce mainly /sup 109/Ag. Binary fission of a siderophilic superheavy element would be expected to yield more /sup 109/Ag than /sup 107/Ag. An intense proton irradiation in the early solar system probably would produce a lower ratio of (/sup 107/Pd//sup 108/Pd) to (/sup 26/Al//sup 27/Al) than observed in meteorites. Therefore the presence of excess /sup 107/Ag in iron meteorites with large Pd/Ag ratios very likely is due to the incorporation of 6.5 x 10/sup 6/-year /sup 107/Pd of nucleosynthetic origin in these meteorites.

• Research Organization: Los Alamos Scientific Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5320495
• Report Number(s): LA-UR-80-1199; CONF-800361-1
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALUMINIUM 26
ALUMINIUM ISOTOPES
BARYON REACTIONS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
CHARGED-PARTICLE REACTIONS
CHEMICAL COMPOSITION
COSMIC RADIATION
ELEMENTS
HADRON REACTIONS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPE RATIO
ISOTOPES
LIGHT NUCLEI
METALS
METEORITES
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEOSYNTHESIS
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
PALLADIUM
PLATINUM METALS
PROTON REACTIONS
RADIATIONS
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
SILVER 107
SILVER ISOTOPES
SOLAR SYSTEM EVOLUTION
STABLE ISOTOPES
TRANSITION ELEMENTS
YEARS LIVING RADIOISOTOPES