Experimental and simulated etched track profiles for two relativistic ions treated under different etching conditions: How to shape different track envelopes

Abstract

PADC polymer sheets of thickness 650 μm were exposed to normal incident high energy ions of 7 GeV Si and 17.48 GeV Ni with particle density ≈ 103 particles/cm2. Chemical etching was carried out under soft and strong etching conditions, and parameters of track diameter and cone length variation with depths were measured and recorded at successive times during the etching process, including snapshots of the etched track profiles. A computer program using a sophisticated chemical etching model including a variation of the bulk etching rate of the detector material was used. This program uses experimental data of a variable bulk etch rate with depth (Vb (z)) and an average longitudinal (Vt) etching rate, for each etching condition and ion. A good agreement is obtained between simulation and experiment in all cases, which validates the choice of the model used and the constant Vt approximation. It is shown that the same latent track due to a given ion gives different three-dimensional shapes depending on the chemical etching conditions used. The production of etched tracks with funnel shapes is one of the originalities of this work. The simulation tool developed allows for exploring the production of microcavities with specific shapes using polymer sheets exposed to high-energy ions.