MEASUREMENT OF LOW-ENERGY ION TRACKS IN CR-39 PLASTIC WITH AN ATOMIC-FORCE MICROSCOPE

We demonstrate that an atomic force microscope allows one to measure t he detailed geometry of etch pits due to heavy ions with kinetic energ ies of 1-10 keV/amu at small distance scales registered in the nuclear track detector CR-39 plastic. With a typical range of a few hundred n m and an etch pit depth on the order of a few tens of nm, these ion tr acks cannot be measured using conventional methods. With the technique developed in this work one is able to study the response of CR-39 pla stic to particles at low ionization rates by precise measurements of l ow energy ion tracks. Among other applications, of particular interest is to explore the response of CR-39 in the regime in which nuclear st opping is comparable to electronic stopping. (C) 1995 American Institu te of Physics.