The recent development of Accelerator-based Gamma-induced Positron Annihilation Spectroscopy (AGPAS) has shown the possibility of probing residual stress in thick materials by Doppler broadening measurements [1]. In those measurements, the residual stresses were reflected in the line shape parameters of the 511 keV annihilation peak. However, since positron lifetime spectroscopy is a powerful t...

The generalized gradient correction method for positron-electron correlation effects in solids @B. Barbiellini et al., Phys. Rev. B 51, 7341 ~1995!# is applied in several test cases. The positron lifetime, energetics, and momentum distribution of the annihilating electron-positron pairs are considered. The comparison with experiments shows systematic improvement in the predictive power of the t...

The positron annihilation lifetime spectroscopy was used to investigate the free volume hole size of ethylene octane copolymers as a function of deformation in the range from 0 to 110% in steps of 10%. For each degree of deformation a series of 5–6 positron annihilation lifetime spectra was collected in situ. All spectra of a given series were analysed simultaneously. They were resolved into th...

We show that recent monojet searches in electron-positron annihilation experiments can be used to extend significantly the limits on the mixing of a massive fourth generation neutrino with the electron neutrino. When combined with other limits from hadron decays and secondary vertex searches in hadron and electron-positron annihilation experiments, bounds of /Urd12 5 10B6 for neutrino masses of...

f = τoPs/τoPs(vac), (1) where τoPs and τoPs(vac) are o-Ps lifetime in the sample and in vacuum, respectively. Three-quantum annihilation studies become competitive to the traditional positron annihilation lifetime spectrometry (PALS), in particular in the relation to porous media and positron beam technique [1]. Below we compare the results of estimation of 3γ intensity obtained by several clas...