PNo-22 RM 36, 229 –231, 2003.pdf

Radiation Measurements, 1997

The effect of the properties of PADC nuclear track detectors alter exposure to high doses of gamma absorbed doses up to 5x105 Gray (50 Mrad) were studied. The gamma source was a 9.03 PBq (244 KCi), Co-60 source. Results indicate that each of the bulk etch rate (Vb), the tracks etch rate (Vt) and the sensitivity (V) of the detectors increases with the high gamma absorbed dose, but there is a drop in these parameters at the low gamma absorbed dose. Signs of surface roughness were observed by increasin~ the gamma absorbed doses and changes in color observed for doses larger than 2x10 ~ Gray. The temperature of detectors during irradiation time reached 41 °C. The fission fragment tracks (from Cf-252 source) disappeared quickly within the etching time (minutes) for total absorbed doses greater than 3x105 Gray due to their high bulk etch rate.

Gamma irradiation effects on track properties of Polyallyl Diglycol Carbonate (PADC) track detector (PADC-American Acrylics) are studied in the dose range of 10 1 -10 6 Gy. It is observed that due to gamma exposure the bulk and track-etch rates of the detector increases. This increase in both etchrates is more pronounced in post gamma exposed PADC detectors. The etchrate ratio (S) for both pre and post-gamma exposed detectors decreases with increasing etching temperature at the dose of 10 6 Gy. At a higher etching temperature of 70°C, the etch rates ratio becomes almost equal for post gamma exposed detector. Etching efficiency of the detector is found to be much higher when exposed to gamma radiation. However it is observed that at the etching temperature of 70°C, etching efficiency for both pre and post-gamma exposed samples tends to become almost equal to the pristine one.

Radiation measurements, 2001

Polyallyldiglycol carbonate (PADC) detectors were exposed to dierent doses of gamma radiation ranging from 10 1 to 10 6 Gy from a 60 Co source. The eect of gamma doses on etch-rates were studied. Etch-rate values were found to increase at the dose of 10 6 Gy for all types of PADC detectors. The in¯uence of gamma exposure on sensitivity and etching eciency of these detectors was also determined. The experimental results are presented and discussed. 7

Radiation Measurements, 2007

Various studies have been performed to determine the response of Lexan polymer to gamma irradiations. The track recording properties of certain polymers are changed under the influence of electromagnetic radiations and environmental conditions. In the present work, the effect of gamma irradiation on the activation energies of bulk and track etching in case of Lexan samples have been investigated. The attempt has also been made to study the influence of temperature on the bulk and track etch rates of gamma irradiated polymer. The studies reveal an increase in the bulk and track etches rates with gamma-dose. However, the activation energy associated with track and bulk etch rates at a given temperature and at a constant concentration decreases with gamma-dose.

Thermal properties of PADC-Homalite Nuclear Track Detector is studied in the dose range of 10 1 -10 6 Gy and compared with the pristine one. Thermal analysis of the pristine Homalite detector reveals that first step of weight loss of the detector takes place in the temperature range of 370 0 C to 420 0 C, which is endothermic in nature. Due to gamma exposure the thermal stability of the detector does not change very significantly till the dose of 10 4 Gy. However, at the dose of 10 5 Gy and above, the detector loses its weight at lower temperature. Further, it is observed that at the dose of 10 6 Gy, in addition to two endothermic transition, another minor endothermic transition is also seen in the temperature range 245 0 C to 270 0 C.

Beni-Suef University Journal of Basic and Applied Sciences, 2014

The present study aims to determine the effect of heat treatment on the bulk etch rate of un-irradiated and gamma irradiated CR-39 detector. Track density and the damage in samples surface due to the heat treatment have also studied for the un-irradiated and gamma irradiated CR-39 detector. The samples of CR-39 polymer track detector has been exposed to g-ray from 60 Co source with doses 0, 10, 50, and 100 kGy then exposed to aparticles from the air radon gas. These samples have been annealed at 50, 100 and 150 C for different annealing times then etched in 6.25 N NaOH solution at 70 C for 6 h. The variation of bulk etch rate and the track density as a function of annealing temperature have been studied. The bulk etch rate increases with gamma dose and with increasing both of the annealing time and the annealing temperature. The decrease of track density with increasing the annealing time and the damage of annealed gamma irradiated CR-39 samples clarify serious degradation under the effect of heat treatment.

Journal of Nuclear Science and Technology, 1976

Radiation Measurements, 2001

The depth-dependent bulk etch rate has been examined for the gamma-irradiated CR-39 at doses ranging from 20 to 100 kGy. The thickness of the damaged region in gamma-irradiated CR-39 plastics, in which the bulk etch rate was signiÿcantly enhanced, was found to be limited in the thin layer near the surface and decreases with increasing the dose-rate, while it barely depend on the total dose. This indicates that it is possible to apply CR-39 plastics as high dose gamma-dosimeter by assessing both the bulk etch rate in the damaged region and its thickness in principle.

Thermo gravimetric analysis of PADC (American Acrylics) detector exposed to gamma radiation indicates that due to gamma exposure, thermal stability of the detector decreases than the pristine one. Also, further due to chemical etching of the detector, the thermal stability decreases as comparison to the unetched one. The endothermomic behavior of the detector due to loss of weight normally changes in the temperature range of around 375 0 C. Due to gamma exposure, this endothermic transition takes place at a lower temperature of around 350 0 C. Chemical etching of the detector further lowers the temperature of this endothermic transition. The amount of heat involved for the endothermic transition is around 5.66 J g -1 for the pristine sample, whereas for irradiated samples, it is found to be 20.95 J g -1 .