Studying the Effects of He-Ne Laser Beam and Gamma Radiation on CR-39 Detectors Irradiated by α-particles Using Some Spectroscopy Techniques

    The aim of the present work was to study the effect of alpha-particles, gammarays and (He-Ne) laser beam on the track registration and optical properties of  CR-39 detectors. Twenty-four detectors divided into five groups. First group:include nine detectors  were exposed to different powers of (1, 5 and 10 mW) of laser beam at  times (5, 10 and 15 min) and then irradiated to alpha-particles from 226 Ra source. Then it was measured following track parameters, track diameters-D,track density-ρ, and calculated the bulk etching rate-V B , track etching rate-V ,critical angle-Ө , etching efficiency-η, Sensitivity-S, tching ratio rate-V.The results show there was increased in the values of -D, ρ, V cB, VT and Ө with increasing of the exposure times of laser beam at (1, 5 and 10 mW) powers, and decrease in the values of-η, S and V with increasing in the exposure time of laser beam at_1 mW power, while increasing within increase of exposed times of laser beam at (5 and 10 mW) powers. And found the appropriate etching time of CR-39 track detector at etching time of -4 h with NaOH etchant solation and-6.25 N at temperature 60 o C. Second group: includes un-irradiated detector as a control.Third group: include five detectors from CR-39 detector it was irradiated by gamma radiation from 60 Co source with doses (300, 500, 800, 1200 and 1600 kGy). Fourth group: include third groups where it was exposed to laser beam at 10 mW power for 15 min. Fifth group: include nine detectors were exposed to powers-1, 5 and 10 mW of  laser beam at times (5, 10 and 15 min). The optical properties of  detector were studied by using the UV-Vis. and FTIR spectroscopy.Where it was calculated the optical energy band gap and number of carbon atom to groups (Second, Third, Fourth and Fifth). The results of ultraviolet spectra show increasing in the absorbance-A of detector with increasing in the time exposure of laser beam at different powers and gamma doses, and also  decreasing in the optical energy band gap and increasing in the number of carbon atom with
increasing in the exposure time of  laser beam at different powers and gamma doses. As for the FTIR spectra show change in the peak position of the bands detector to groups (Third, Fourth and Fifth).