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The Computer Code for Calculations of the Positron Distribution in a Layered Stack Systems

100%
Siemek K., Dryzek J.
Acta Physica Polonica A
|
2014
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vol. 125
|
issue 3
833-836
EN
In this paper we present experimental and theoretical studies of the implantation profile of positrons emitted from ^{22}Na radionuclide into layered sample. The measured profile for the nonsymmetrical, around the positron emitter, stack of aluminium and silver foils was measured using the depth scanning of implantation profile technique. For the description of the obtained results two theoretical approaches were applied. The first one was the Monte Carlo simulation using the GEANT4 tool kit. The generated profile does not reproduce accurately the experimental profile. We proposed the multiple scattering model based on the fact that a positron due to backscattering can travel as an energetic particle several times through the whole sample before it annihilates. In this model absorption is also taken into account. The multiple scattering model algorithm was implemented in the LYS-1 program. The calculated profile using the LYS-1 program reproduces the experimental profile with much better accuracy.
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Slow Positron Beam Studies of the Stainless Steel Surface Exposed to Sandblasting

42%
Horodek P., Dryzek J., Kobets A., Kulik M., Lokhmatov V., Meshkov I., Orlov O., Pavlov V., Rudakov A., Sidorin A., Siemek K.
Acta Physica Polonica A
|
2014
|
vol. 125
|
issue 3
714-717
EN
The paper presents slow positron beam studies of the stainless steel grade 304 AISI samples annealed in the flow N_2 atmosphere and sandblasted under different pressure from 1 to 7 bar. Heating of specimens caused formation of an additional layer on the surface which can be identified as oxides. Sandblasting reduces the thickness of the oxide layer and also defects concentration (vacancies as we suppose) decreases in dependence on pressure applied during blasting. Additionally, the atomic concentrations of oxygen have been obtained using nuclear methods (Rutherford backscattering and nuclear reactions) in the near surface layers of the studied samples.
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