In this paper we report positron lifetime results obtained under high-power steady-state and transient optical excitation. We present a model to analyse the results. The method has been applied to vacancy clusters in natural diamond, for which we self-consistently analyse optoelectronic constants such as optical absorption cross section and hole recombination cross section. The temperature depe...

Quantum Monte Carlo methods are used to investigate the binding of a positron to the alkali-metal hydrides, XH (X = Na and K). We obtain positron affinities for the NaH and KH molecules of 1.422(10) eV and 2.051(39) eV, respectively. These are considerably larger than the previous results of 1.035 eV and 1.273 eV obtained from multireference single- and double-excitation configuration interacti...

Axial distributions of plasma and floating potentials, electron number density and the electron energy distribution function (EEDF) have been measured in the double layer (DL) region of an He discharge constriction. Excitation processes in the constriction region are studied. Using a linearization method for the nonstationary balance equations and choosing appropriate discharge conditions, ...

in the present paper axial distributions of plasma and floating potentials, electron and iondensities and eedf have been measured in the dl region of a hg discharge constriction. an attempt hasbeen made for the resolution of opposing charged layer structures in dl. excitation processes in theconstriction region are studied. using the linearization method for the nonstationary balance equationss...

In a partially ionized hypersonic flow field, electron collision plays a significant role in energy re-distribution and in the production of excited states of atoms and molecules that can subsequently radiate. Thus electron collision data is part of the database used in modelling high speed entry flows. First principles computational methods for the calculation of electron-impact data are revie...

The rate of annihilation of low-energy positrons in many molecular gases is orders of magnitude larger than can be explained on the basis of simple collisions. Developments in positron beam technology have enabled the first energy-resolved measurements of this annihilation process. The results of these experiments provide direct evidence that the large observed values of annihilation rate are d...

In this research, the modal parameters of a beam in free-free condition are extracted by performing different experiments in laboratory. For this purpose, two different techniques are employed. The first methodology is considered as a time domain method in Operational Modal Analysis. While the other one is frequency domain impact hammer test which is categorized as an Experimental Modal Analysi...