Cosmogenic neutron-capture-produced nuclides in stony meteorites

Journal Article · Sat Mar 29 23:00:00 EST 1986 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB091iB04p0D483· OSTI ID:5939468

Spergel, M S; Reedy, R C; Lazareth, O W; Levy, P W; Slatest, L A

The distribution of neutrons with energies below 15 MeV in spherical stony meteoroids is calculated using the ANISN neutron-transport code. The source distributions and intensities of neutrons are calculated using cross sections for the production of tritium. The meteoroid's radius and chemical composition strongly influence the total neutron flux and the neutron energy spectrum, whereas the location within a meteoroid only affects the relative neutron intensities. Meteoroids must have radii of more than 50 g/cm/sup 2/ before they have appreciable fluxes of neutrons near thermal energies. Meteoroids with high hydrogen or low iron contents can thermalize neutrons better than chondrites can. Rates for the production of /sup 60/Co, /sup 59/Ni, and /sup 36/Cl are calculated with these neutron fluxes and evaluated neutron-capture cross sections and are reported for carbonaceous chondrites with high hydrogen contents, L-chondrites, and aubrites. For most meteoroids with radii <300 g/cm/sup 2/, the production rates of these neutron-capture nuclides increase monotonically with depth. The highest calculated /sup 60/Co production rate in an ordinary chondrite is 375 atoms/min/g-Co at the center of a meteoroid with a 250 g/cm/sup 2/ radius. The production rates calculated for spallogenic /sup 60/Co and /sup 59/Ni are greater than the neutron-capture rates for radii less than approx.50-75 g/cm/sup 2/. Only for very large meteoroids and chlorine-rich samples is the neutron-capture production of /sup 36/Cl important. The results of these calculations are compared with those of previous calculations and with measured activities in many meteorites.

• Research Organization: Department of Natural Science, York College of C.U.N.Y.
• OSTI ID: 5939468
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 91:B4; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics &amp; Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BARYON REACTIONS
BARYONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CAPTURE
CHLORINE 36
CHLORINE ISOTOPES
COBALT 60
COBALT ISOTOPES
COSMIC NEUTRONS
COSMIC RADIATION
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTARY PARTICLES
EVEN-ODD NUCLEI
FERMIONS
HADRON REACTIONS
HADRONS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LIGHT NUCLEI
METEORITES
MINUTES LIVING RADIOISOTOPES
NEUTRAL-PARTICLE TRANSPORT
NEUTRON FLUX
NEUTRON REACTIONS
NEUTRON TRANSPORT
NEUTRONS
NICKEL 59
NICKEL ISOTOPES
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUCLEONS
ODD-ODD NUCLEI
RADIATION FLUX
RADIATION TRANSPORT
RADIATIONS
RADIOISOTOPES
STONE METEORITES
YEARS LIVING RADIOISOTOPES