الملخص

The aim of this research is study of tracks growth experimentally and theoretically in cellulose nitrate LR-115 detector .The detector of 12jam thickness is irradiated normally by alpha particles with incident energies from 1 to 5MeV and incident angle 90°,by using 24lAm source , The etching of the detector Pieces was implemented by using chemical etchant NaOH with concentration 10% and temperature (60±1°C) ,A computer program ,(TRACK_TEST) also used for calculating track parameters as tracks depth and plotting track-wall profiles and contours of the track opening .The results showed that a maximum energy lost is occurred when the energy of the a-particles is about 2MeV. The tracks' tip for incident alpha energies 1 and 2MeV appeared in a spherical phase which is called rounded or over etched phase ,while a sharp phase for energies 3,4 and 5MeV was investigated . It was found that the track's depth which is calculated by computer program greater than that measured experimentally and that the percentage difference between two can be about 38% for 3MeV.