Autor: Brusa, R. S. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Low Energy Cross-Sections for Positron Interactions with Cyclic Hydrocarbons
Autorzy:: Karwasz, G. P.
Pliszka, D.
Brusa, R. S.
Perazzolli, C.
Powiązania:: https://bibliotekanauki.pl/articles/2042198.pdf
Data publikacji:: 2005-04
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 34.85.+x
39.90.+d
Opis:: 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.
Źródło:: Acta Physica Polonica A; 2005, 107, 4; 666-672
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 2.

Tytuł:: Positron Scattering on Atoms and Molecules in the Limit of Low Energy
Autorzy:: Karwasz, G. P.
Brusa, R. S.
Pliszka, D.
Idziaszek, Z.
Nowakowska, H.
Powiązania:: https://bibliotekanauki.pl/articles/2047133.pdf
Data publikacji:: 2006-11
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 34.85.+x
39.90.+d
Opis:: 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.
Źródło:: Acta Physica Polonica A; 2006, 110, 5; 605-614
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 3.

Tytuł:: Systematic Measurements of Doppler-Coincidence Spectra for Positron Annihilation in Pure Metals and Semiconductors
Autorzy:: Deng, W.
Pliszka, D.
Brusa, R. S.
Karwasz, G. P.
Zecca, A.
Powiązania:: https://bibliotekanauki.pl/articles/2030758.pdf
Data publikacji:: 2002-06
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 71.60.+z
78.70.Bj
Opis:: Doppler-broadening measurements of the electron-positron annihilation line in twenty six elements are presented. The adopted coincidence technique allows to reduce the background and point out the contribution of positron annihilation with core electrons. The changes of the high momentum contribution is presented for selected examples and a semiempirical analysis of the dependence on electronic structure is performed. Measured data are in a good agreement with recent theoretical calculations and can be used to identification of impurities surrounding open volume defects.
Źródło:: Acta Physica Polonica A; 2002, 101, 6; 875-892
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 4.

Tytuł:: Surfaces of Electron-Emitting Glasses Studied by a Slow Positron Beam
Autorzy:: Pliszka, D.
Gazda, M.
Kusz, B.
Trzebiatowski, K.
Karwasz, G. P.
Deng, W.
Brusa, R. S.
Zecca, A.
Powiązania:: https://bibliotekanauki.pl/articles/2025748.pdf
Data publikacji:: 2001
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 71.60.+z
78.70.Bj
Opis:: Semi-conducting glasses used for electron multipliers and microchannel plate devices are obtained by surface modification of Pb or Bi-reach silicon-based glasses. The reduced layer extends down to 200-500 nm, much more than the effective depth of the electron-emitting layer. By the use of slow-positron beam we monitor the structural changes undergoing in near-to-surface layers after isothermal annealing. The measurements suggest a possible correlation between secondary-electron emission coefficient and the Doppler-broadening S-parameter. On these samples there were also performed atomic force microscopy, secondary electron emission, differential scanning calorimetry, and electric conductivity measurements.
Źródło:: Acta Physica Polonica A; 2001, 99, 3-4; 465-472
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

Artykuł

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