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1

Device for Compressibility and Thermal Expansion Study up to 3 GPa

100%

Krupski M., Krupska A.

Acta Physica Polonica A

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2016

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vol. 130

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issue 6

1324-1325

EN

We present the realization of a project of a device utilizing a standard high-pressure chamber adapted to compressibility and thermal expansion measurements of solids at hydrostatic pressures up to 3 GPa. The device has been tested on the triglycine sulphate crystal (TGS).

2

Positron Scattering on Atoms and Molecules in the Limit of Low Energy

63%

Karwasz G., Brusa R., Pliszka D., Idziaszek Z., Nowakowska H.

Acta Physica Polonica A

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2006

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vol. 110

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issue 5

605-614

EN

Starting from experimental cross-sections for positron scattering in argon and nitrogen, we examine different energy ranges. In the zero-energy limit the cross-section falls with energy and can be described by modified effective range theory for polarization potential. In a few eV range the cross-sections are constant vs. energy. As far as it is possible to force the elastic scattering phase shifts in a way that both experimental differential cross-sections are reproduced and the total cross-section remains constant in energy, such a model lacks the physical justification. Only the virtual-positronium model, developed recently by Gribakin, reproduces a constant dependence of the total cross section in a few eV energy range.

3

Low Energy Cross-Sections for Positron Interactions with Cyclic Hydrocarbons

63%

Karwasz G., Pliszka D., Brusa R., Perazzolli C.

Acta Physica Polonica A

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2005

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vol. 107

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issue 4

666-672

EN

We report total cross-section measurements for positron scattering on cyclic hydrocarbons: benzene, aniline, and cyclohexane. Measurements were done by an absolute transition method in the energy range 1.5-20 eV (0.4-20 eV for cyclohexane). High cross-sections for all measured molecules were observed at low energies. In the case of cyclohexane the cross-section in the zero energy limit tends to a constant value. In aniline a weakly accented peak slightly above the positronium formation threshold is observed. Similar but less visible bump was observed in the case of benzene. Measurement of total cross-sections in nitrogen and argon used for calibration of the apparatus are also presented.

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3 Acta Physica Polonica A

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2 Brusa R.

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1 Krupska A.

1 Krupski M.

1 Nowakowska H.

1 Perazzolli C.

Device for Compressibility and Thermal Expansion Study up to 3 GPa

Positron Scattering on Atoms and Molecules in the Limit of Low Energy

Low Energy Cross-Sections for Positron Interactions with Cyclic Hydrocarbons