Pulsed UV laser-induced modifications in optical and structural characteristics of alpha-irradiated PM-355 SSNTD.
Pre- and postalpha-exposed PM-355 detectors were irradiated using UV laser with different number of pulses (100, 150, 200, 300, and 400). UV laser beam energy of 20mJ per pulse with a pulse width of 9ns was incident on an area of 19.6mm2 of the samples. XRD spectra indicated that for both reference and UV-irradiated samples, the structure is amorphous, but the crystallite size increases upon UV irradiation. The same results were obtained from SEM analysis. Optical properties of PM-355 polymeric solid-state nuclear track detectors were also investigated. Absorbance measurements for all PM-355 samples in the range of 200-400nm showed that the absorption edge had a blue shift up to a certain value, and then, it had an oscillating behavior. Photoluminescence spectra of PM-355 at 250nm revealed a decrease in the broadband peak intensity as a function of the number of UV pulses, while the wavelengths corresponding to the peaks had random shifts.
Changes induced in structure and optical properties of PM-355 nuclear track detector due to laser irradiation
ABSTRACT PM-355 is a class of polymeric solid-state nuclear track detectors which has a lot of applications in several radiation detection fields. Samples from sheets of PM-355 have been exposed to infrared (IR) laser fluences ranging from 1 to 12.8 J/cm2. The effect of IR laser radiation on the structural properties of PM-355 has been investigated using X-ray diffraction and Fourier transform infrared spectroscopy. The results indicate that the samples exhibit chain scission under the effect of laser irradiation up to 4.2 J/cm2, thus producing free radicals that led to the formation of new bonds started and continued until 12.8 J/cm2. This reduces the ordering structure, giving the PM-355 polymer more resilience. In addition, the laser irradiation at the fluence range 4.2–12.8 J/cm2 led to a more compact structure of PM-355, which resulted in an improvement in its isotropic nature with an increase in Vickers hardness and refractive index. Further, the color changes due to laser irradiation were computed using the transmission data in the wavelength range of 370–780 nm. It is found that the color intensity, which is the color difference between the irradiated samples and the non-irradiated one, increases with increasing the laser fluence, largely depending on the proportions of the blue color component.
Experimental study of energy spectra of ion beams from gas-puff Z-pinch plasma
Employing a compact Thomson ion energy analyser recently developed, clear parabolic tracks of argon ions on CR-39 plastics and energy spectra of ion beams produced in gas-puff Z-pinch plasma have been obtained. The results shows that the maximum ion energy is about 1 MeV. The ion spectrum distribution increases down to the lowest energy, at which the distribution was measured, and can be expressed approximately by .