Study of the scattering and annihilation of low energy positron with noble atom

الملخص EN

Although the electron and positron scattering experiments have been studied for long time, the construction of the scattering potential is still under the studies and it is one of the most important matter which influence the parameters calculations such as the phase shift ( 0 δ ), scattering length (Ao) , cross section (σ ) , elastic and inelastic where they play as a major role in evaluating the electron- positron annihilation process.

In the present calculation we model the positron target system by a complex interaction potential v(r), it consist from static potential Vst (r), the correlation polarization potential Vsp(r) and the absorption Vabs (r).

Using the above mentioned potentials, values of scattering length, phase shift, cross section is calculated and used to work out the annihilation parameters.

The calculation suggests that the features of the model potentials can produce reliable total cross section for positron atom scattering at a certain impact energies.

The annihilation parameter (Zeff) is one of the essential factors in it.

Two different formula have been applied for low positron energy interact with atomic and ionic system where as the most recent one of (Zeff) is used and it’s distinguished on that of the atom is that it can calculate the annihilation parameter for P and D wave in addition to the S- wave.

Throughout (Zeff) we evaluated the annihilation parameters (σ a ,λ a ,τ ) and electron density dependents.

A good comparison of the factors have been made.

We have borrowed some explicit and implicit well known formula in evaluations the inelastic cross section of positron with free atom.

In general the comparison our data with the other is good for a certain channels and so well for some other channels.