Solid State Nuclear Track Detection has a special place, due to its individual advantages, among other techniques. This procedure is called “detector etching” after which, track may be seen under an optical microscope. Some parameters such as concentration and temperature of etchant and the etching time should be obtained for maximum efficiency, which are depended upon characteristic of track forming particle and kind of detector. One aim of the present research is to obtain these conditions for CR-39 detector. Therefore 241 Am alpha particles with energy of 5.48 MeV were detected by CR-39 detector. Best etching conditions for these particle tracks were achieved 6 normal aqueous solution of NaOH at 70 12 ℃ '> . Maximum detection efficiency at these conditions was found to be 75.9 %, after 6.5 hours and by counting number of visible tracks. Also some computer programs were used for track simulation and extract track parameters. Experimental results were compared with outputs of these programs, which showed a good agreement with CR39 code results. Also the range of alpha particle was determined with SRIM and MCNPX codes, which had a good agreement with each other. Bulk etch rate is depended on different parameters such as etching conditions, so some methods for determination of this quantity were evaluated. Keywords: 1- Solid State Nuclear Track Detector , 2- TD , 3- CR-39 , 4- chemical etching , 5- Alpha particle , 6- heavy ion particles
