Kinetic model for the relationship between mean diameter shortening and age reduction in glass samples

Author(s)

Guedes‚ S. ; Iunes‚ PJ ; Hadler Neto‚ JC ; Bigazzi‚ G. ; Tello S‚ CA ; Alencar‚ I. ; Palissari‚ R. ; Curvo‚ EAC ; Moreira‚ P.

• Document type: Journal article
• Source: Radiation Measurements; v. 39, n. 6, p. 647-652, 2005.

Abstract

Fission tracks in glass samples are shortened when they experience thermal treatment. Consequently, the observable dimensions associated with track length also diminish. The dimension normally used to characterize track size is the mean diameter of the etched track at the surface, D. Another consequence of length shortening is the reduction of surface density, p, implying a reduction of the fission-track age. In this work, a kinetic model is developed to describe the relationship between fission-track mean diameter shortening and surface fission-track density reduction in glass samples, based on geometrical and etching hypotheses. The result is a two-parameter equation given by rho/rho(0) = (D/D(0))(2(1+1/n)) (4h(2) + D(0)(2)/4h(2)+D(0)(2)(D/D(0))(2))(2) (4h(2) - D(0)(2)/4h(2)-D(0)(2)(D/D(0))(2))(1/n) (1) in which h is the thickness of the layer removed during etching and n is a parameter related to the latent track geometry and etching reaction rate. The equation was compared with experimental data on Australite glass found in the literature and with fresh data on Macusanite glass presented in this work. The model fits the experimental curves quite well, showing that it describes the etching effects correctly (within its limitations). In addition, the model equation derived in this work can be very useful in age correction of partially annealed glass samples. (c) 2005 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 00/03960-5 - History of exhumation of the South American plataform in the Southeastern Brazil: thermochronology by fission track analysis and ar/ar and sm/nd systematics
• Grantee: Peter Christian Hackspacher
• Support Opportunities: Research Projects - Thematic Grants