Bulk etch characteristics of colorless LR 115 SSNTD

The colorless LR 115 solid-state nuclear track detector (SSNTD) (from DOSIRAD) is based on cellulose nitrate and was first studied in view of its applicability in radiobiological experiments with alpha particles. In this paper, the bulk etch characteristics were studied. We first showed that the shape of the alpha-particle tracks are irregular with blurred contours under the optical microscope. This has made measurements of track diameters very difficult. The phenomenon was explained in terms of the roughness of the detectors. As a result, the common method used to determine the bulk etch rates through measurements of opening diameters of tracks is not valid. We then proposed the surface profilometry method for determination of the removed active-layer thickness during etching. The bulk etch rates with 2.5 N aqueous solution of NaOH as the etchant, with and without magnetic stirring were determined for etching temperatures of 40, 50 and 60 °C. The data supported the Arrhenius type equation. The corresponding activation energies were determined. Finally, relationships were derived between the residual active-layer thickness and the infrared transmittances at different wave numbers. The infrared transmittances were found useful in revealing the active-layer thickness of the colorless LR 115 SSNTD, the correlations being described by quadratic relationships.