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Chapter One “Introduction” Chapter One “Introduction” Chapter One “Introduction” Chapter One “Introduction” Chapter One “Introduction” Chapter One “Introduction” Chapter One “Introduction” Chapter One “Introduction” Chapter One “Introduction” Chapter One “Introduction” ChapterOnly 14 pages are availabe for public view
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Abstract
The aim of the present work was to study the effect of gamma rays on CR-39 detectors that exposed to 252-CF source of F.F and 241-Am source of alpha-particles at a wide range of Energy by studying optical properties and track parameters for ɤ-irradiated CR-39 detectors. Some samples exposed to f.f for 2 second only then all track parameters were calculated like (bulk etch rate VB, track diameters were determined for circular and elips tracks, first appearance. The time taken just the track firstly appears and saturation time (tcut-off) of saturated diameters and projected track length (L0) of normally and inclined incident fission tracks were estimated for different removal layers (h) and other samples irradiated to alpha-particles from241- Am source. Then the track parameters, track diameters-D, first appearance, saturation time, Range of the particles inside the detector, response function V, critical angle ϴc, etching efficiency-η, and registration efficiency) were measured. Samples of CR-39 track detector etchant at different etching time and different removal layers with NaOH etchant solution and-6.25 N at temperature 70˚C. the result would be A linear relationship between D and γ-doses (Dγ) up to 500 kGy was obtained. VB was determined at different Dγ, and a linear relationship was obtained up to 300 kGy. EIT was between 17-25 min for pristine sample and ranged between 1-5 min at 300 kGy and tcut-off was from 125 to140 min for pristine and reached to nearly 8 min at 500 kGy. The optical properties of detector were studied by using the FTIR and UV-Vis spectroscopy, where it was calculated (absorbance, the optical energy band gap direct and indirect, Urbach energy, refractive index and number of carbon atom). from UV-Vis spectrophotometric study, an inversely linear relation of the band gap energies (Egap) as a function of Dγ was obtained and found to decrease from 3.73 to 3.44 eV and 3.93 to 3.82 eV for indirect and direct transitions, respectively. In addition, a systematic increase of Urbach energy (EU) from 0.47 to 0.71 eV was recorded with ɤ-ray doses of irradiated CR-39TM detectors, for direct and indirect methods, was recorded. The results reflected a potential possibility of using γ-irradiated CR-39TM in dosimetric measurements through the different studied parameters. The CR-39 which is the type of SSNTDS used as a detector for mixed field of ionizing radiation.