Determined the bulk etch rate VB by different methods for nuclear track detector CR-39

In this study, the bulk etch rate (VB) was measured by three different methods forCR-39 with a thickness of 200µm and an area of (1 × 1 cm2), where CR_39 was irradiated through from Am241source with energy of alpha particles is 2.6MeV and at an angle of fall perpendicular to the surface of the CR-39 detector, the detector etching with (NaOH) at a concentration of 6.25N and (70 ± 1°C) and showing the effects formed on the surface of the detector with time periods ranging from (0.25h) and the formed effects were photographed In the detector at different eching times using an optical microscope of the type (XSZ-H Series Biological Microscope) equipped with a digital camera of the type (MADC_5A) connected to a personal computer, in order to find the length, thickness and diameters of the track formed on the surface of the detector.VB determind by methods are: Removed thickness method, the second method, the saturation track method, and the diameter-length method (D_L method), as the first method does not require irradiation of the detector, but the other two methods require irradiation of the detector and measurement of lengths and diameters And the time of proving the effect, and we found that the values of VB rate for the three methods, the removed thickness method, the saturation track method, and the diameter-length of the effect ((D_L method) respectively are:, (1.206, 1.204, 1.271 (µm/h) and compare the results between the mentioned methods, as we found that they are close.