Crystallographic orientation dependence of mean etchable fission track length in apatite: An empirical model and experimental observations

Journal Article · · American Mineralogist; (United States)

OSTI ID:5638283

Donelick, R A ^[1]

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1. Rensselaer Polytechnic Inst., Troy, NY (United States)

Partially annealed thermal-neutron-induced fission tracks in apatite exhibit mean etchable lengths that range continuously between a maximum for tracks oriented parallel to the crystallographic c-axis and a minimum for tracks perpendicular to c. A simple empirical model quantifies this crystallographic orientation dependence based on the assumption that the mean etchable fission track length at any angle to the c-axis is given by the corresponding radius of an ellipse. The ellipse has semiaxes equal to, respectively, the mean track lengths parallel (l{sub c}) and perpendicular (l{sub a}) to the c-axis. The elliptical model is tested against 61 isothermal partial annealing experiments performed on thermal-neutron-induced fission tracks in Tioga apatite. It is found to adequately characterize etchable fission track length distributions in partially annealed apatites when l{sub a} {ge} 8.4 {mu}m. The difference between l{sub c} and l{sub a} increases systematically and continuously as both mean lengths decrease, and fission-track lengths are distributed normally about their mean with a standard deviation of ca. 0.75 {mu}m, regardless of crystallographic orientation and relative degree of partial annealing. For l{sub a} < 8.4 {mu}m, the elliptical model apparently fails because tracks at relatively high angles to the c-axis experience greatly accelerated etchable length reduction.

• OSTI ID: 5638283
• Journal Information: American Mineralogist; (United States), Journal Name: American Mineralogist; (United States) Vol. 76:1-2; ISSN AMMIA; ISSN 0003-004X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure &amp; Phase Studies
360605* -- Materials-- Radiation Effects
58 GEOSCIENCES
580000 -- Geosciences
ANNEALING
APATITES
BARYONS
CRYSTAL STRUCTURE
CRYSTALLOGRAPHY
DIMENSIONS
DISTRIBUTION
ELEMENTARY PARTICLES
FERMIONS
FISSION TRACKS
HADRONS
HEAT TREATMENTS
LENGTH
MATHEMATICAL MODELS
MINERALS
NEUTRONS
NUCLEONS
ORIENTATION
PARTICLE TRACKS
PHOSPHATE MINERALS
THERMAL NEUTRONS