Positron scattering by beryllium atoms in the low-energy range (?4.0 eV) was studied within ab initio and semiempirical frameworks. When interpreting static dipole polarizability length as representative quantities of target positron–atom correlations, observables obtained calculation were extrapolated applying a approach. Our results ratify previous ones, since no Ramsauer minimum structures o...

The principle of image formation in tomography is summarised. The principle ofpositron electron annihilation is introduced. The principle of coincidence techniques is illustrated. Detector development and perspectives for positron emission tomography (PET) instrumentation for medical research is presented. The physical processes in in positron annihilation, photon scattering and tomograph desig...

The variational method is applied to the low-energy positron scattering and annihilation problem. ultimate aim of investigation find a computationally economical way accounting for strong electron–positron correlations, including effect virtual positronium formation. study elastic s-wave from hydrogen atom. A generalized eigenvalue problem set up solved obtain positron–hydrogen phase shifts wit...

In recent theoretical study electrons or a positron penetrate through target oil it interacts mainly in two ways, viz, slowing down process and elastic scattering. These complete each other depending upon the electron initial kinetic energy as well atomic number of material. Thus becomes very difficult to sketch exact picture preparation these particles. A comparison our evaluated cross- sactio...

The features of electromagnetic processes are considered which connected with finite size of space region in which final particles (photon, electron-positron pair) are formed. The longitudinal dimension of the region is known as the formation length. If some external agent is acting on an electron while traveling this distance the emission process can be disrupted. There are different agents: m...

The confined variational method is used to generate a basis of correlated Gaussians to describe the interaction region wave function for positron scattering from the H2 molecule. The scattering length was approximately = -2.7a(0) while the zero energy Z(eff) of 15.7 is compatible with experimental values. The variation of the scattering length and Z(eff) with internuclear distance was surprisin...