Etch Induction Time in Cellulose Nitrate Track Detectors

An etch parameter almost unnoticed previously, etch induction time, has been measured in Kodak Pathé cellulose nitrate track detector films using ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$, and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ ions of known low energy per unit mass for calibration. The etch induction time appears to vary with the parameter $\frac{{\left(\frac{\mathrm{dE}}{\mathrm{dx}}\right)}_{W<\mathrm{}1000\mathrm{}}}{Z^{*}}$ where $Z^{*}$ is the effective ion charge and ${\left(\frac{\mathrm{dE}}{\mathrm{dx}}\right)}_{W<\mathrm{}1000\mathrm{}}$ is the restricted energy loss, calculated for a $\delta$-ray cutoff energy of 1000 eV.