Track Formation Under Temperature and Pressure

Abstract

This chapter discusses the influence of two external ion irradiation parameters on ion track formation: temperature and pressure. In natural environments where fission tracks are generated, both parameters can be significantly elevated compared with ambient conditions. This particularly applies to fission tracks formed several thousand metres below the earth’s surface, which are relevant for oil and gas exploration (Augustine et al., in Proceedings, Thirty-First Workshop on Geothermal Reservoir Engineering, 2006, [1]). The majority of irradiation experiments that simulate fission tracks, however, are conducted under ambient conditions for practical reasons. Lang et al. have investigated track formation under high temperature ($250\,^{\circ }\hbox {C}$) and in the presence of elevated pressure (0.75 GPa), by irradiating zircon within a heatable high-pressure cell (Lang et al., in Earth Planet Sci Lett 274, 355–358, 2008, [2]). The track sizes were measured with TEM and indicate a small, positive correlation between track cross-section and a simultaneous increase in temperature and pressure during track formation. The present work systematically investigates the influences of temperature and pressure independently in quartz and apatite. The results are explained by using existing models for track formation.