Variation of Free Volume in Polyethylene upon Extension Probed by Positron Annihilation Lifetime Technique.

Free Volumes in Polystyrene Probed by Positron Annihilation

Positron annihilation lifetime spectroscopy in nickel ferrite and iron oxide nanopowders

In this study, a positron annihilation lifetime spectrometer was set up and its resolution was optimized. The spectrometer is a fast-slow arrangement with time resolution of 250 ps. To obtain lifetime components and their intensities from analyzing positron annihilation lifetime spectrum, the Pascual software is used. Positrons are from a source of radioactive 22NaCl with 20 μCi activity enclos...

Single shot positron annihilation lifetime spectroscopy

Recent developments in positron trapping technology have made possible experimentation with dense interacting positronium gases. Along with these capabilities comes a need for suitable measurement techniques, and accordingly we have developed a method to measure positronium lifetimes from a single intense burst of positrons. Our method is based on recording the anode signal from a photomultipli...

Investigation of the Temperature Dependence of Free Volume in Polymethylpentene by Positron Annihilation Method

Positron lifetime measurements in polymethylpentene were performed in a wide temperature range. A conventional fast–slow coincidence lifetime spectrometer with plastic scintillators was used. All the measurements were made in vacuum. Additional measurements (X-ray diffraction, differential scanning calorimetry, and mechanical spectroscopy) were also performed to establish properties of samples....

Fractional Free-Volume dependence of Oxygen in Beta-Irradiated Polystyrene Probed by Positron life time

Positron annihilation lifetime (PAL) technique has been employed to investigate the effect of low doses of -irradiation (in air and vacuum) on the type of polymers namely: polystyrene (PS). A conventional fast-slow coincidence system was used for measuring the positron lifetime spectra. The time resolution of the system was ٤٢٢±٢٠ ps (the full width at half maximum (FWHM)) at Na energy window....