New method of the precise measurement for the thickness and bulk etch rate of the solid-state track detector

New optical system with an optical displacement sensor has been developed to measure the local thickness of CR-39 track detector. It can be applied to measure locally the thicknesses of whole detector area for making a map of the amount of bulk etch. The accuracy of the thicknesses measurement was found to be ± 0.2 μ m using CR-39 detector. This accuracy is one order of magnitude higher than that of conventional methods, such as the Micrometer method, and is comparable to that of track size measurement under the optical microscope. It will also greatly improve the charge and mass resolutions of CR-39 detector that we can apply to measure galactic cosmic rays (GCRs) nuclei, especially the trans-iron nuclei ( Z ⩾ 30 ) in GCRs.