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Wyświetlanie 1-9 z 9
Tytuł:
A new approach to the presentation of the positron annihilation lifetime spectroscopy results, n-alkanes
Autorzy:
Zgardzińska, B.
Standzikowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/1057935.pdf
Data publikacji:
2017-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
36.10.Dr
78.70.Bj
82.30.Gg
Opis:
The standard form of the positron annihilation lifetime spectroscopy results presentation are two plots of o-Ps lifetime and intensity as a function of external factor, e.g. temperature, pressure. Both o-Ps parameters change (stepwise) when in the medium phase transitions occur. For a more complete picture of the structural changes occurring in the matter we suggest to use an additional plot, in the coordinates, (τ₃, I₃). The hydrocarbons are selected to show the advantages following from the presentation of the results in the intensity-lifetime (INTI) plot.
Źródło:
Acta Physica Polonica A; 2017, 132, 5; 1496-1500
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Positron Irradiation on Positronium Formation in n-Alkanes
Autorzy:
Pietrow, M.
Zgardzińska, B.
Powiązania:
https://bibliotekanauki.pl/articles/2047152.pdf
Data publikacji:
2006-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
36.10.Dr
61.80.Fe
78.70.Bj
Opis:
Positronium formation probability was investigated as a function of irradiation time and temperature for some long-chain saturated hydrocarbons (alkanes). Intensity of ortho-positronium component in the lifetime spectrum depends on the concentration of trapped excess electrons, but also on concentration of radicals and ions acting as electron scavengers. The results indicate the existence of two kinds of electron traps; those which are not emptied by thermal treatment disappear after several days of positron irradiation.
Źródło:
Acta Physica Polonica A; 2006, 110, 5; 641-648
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time Calibration of the J-PET Detector
Autorzy:
Skurzok, M.
Silarski, M.
Alfs, D.
Białas, P.
Shivani, S.
Curceanu, C.
Czerwiński, E.
Dulski, K.
Gajos, A.
Głowacz, B.
Gorgol, M.
Hiesmayr, B.
Jasińska, B.
Kisielewska-Kamińska, D.
Korcyl, G.
Kowalski, P.
Kozik, T.
Krawczyk, N.
Krzemień, W.
Kubicz, E.
Mohammed, Muhsin
Pawlik-Niedźwiecka, M.
Niedźwiecki, S.
Pałka, M.
Raczyński, L.
Raj, J.
Rudy, Z.
Sharma, N.
Sharma, S.
Shopa, R.
Wieczorek, A.
Wiślicki, W.
Zgardzińska, B.
Zieliński, M.
Moskal, P.
Powiązania:
https://bibliotekanauki.pl/articles/1033283.pdf
Data publikacji:
2017-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
06.20.fb
36.10.Dr
11.30.Er
24.80.+y
Opis:
The Jagiellonian positron emission tomograph project carried out in the Institute of Physics of the Jagiellonian University is focused on construction and tests of the first prototype of PET scanner for medical diagnostic which allows for the simultaneous 3D imaging of the whole human body using organic scintillators. The J-PET prototype consists of 192 scintillator strips forming three cylindrical layers which are optimized for the detection of photons from the electron-positron annihilation with high time-and high angular resolutions. In this article we present time calibration and synchronization of the whole J-PET detection system by irradiating each single detection module with a ²²Na source and a small detector providing common reference time for synchronization of all the modules.
Źródło:
Acta Physica Polonica A; 2017, 132, 5; 1641-1644
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aerogel IC3120 Under High Pressure Exerted Mechanically and by Nitrogen
Autorzy:
Gorgol, M.
Zgardzińska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1033290.pdf
Data publikacji:
2017-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
36.10.Dr
61.43.Gt
74.62.Fj
Opis:
Highly porous IC3120 silica aerogel was subjected to the high pressure up to 450 MPa while the positron annihilation lifetime spectra were collected. The pressure was delivered to the investigated samples in two ways: by pistons and by gas (nitrogen) penetrating the aerogel. The evolution of all PALS parameters was discussed. With the increase of the pressure, shortening of ortho-positronium lifetimes (different, depending on the pressure method introduced) was observed. Similarity between the dependence of the longest-lived o-Ps component lifetime on the pressure, for the sample affected with nitrogen molecules and pure nitrogen was observed. It suggests, that the nitrogen fills the largest free volumes of the aerogel. The pressure exerted mechanically causes much smaller decrease of free volume available for positronium. The comparison of PALS results with the electron microscopy images, obtained after removing the pressure, confirmed that more intense and lasting changes were caused by affecting the aerogel with the pistons.
Źródło:
Acta Physica Polonica A; 2017, 132, 5; 1531-1534
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ortho-Positronium in Alkanes under High Pressure
Autorzy:
Goworek, T.
Zgardzińska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1812529.pdf
Data publikacji:
2008-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
36.10.Dr
61.80.Fe
71.60.+z
78.70.Bj
Opis:
Phase transitions in n-alkanes were observed by using the positron annihilation lifetime method. In the case of alkanes, application of pressure is equivalent to temperature lowering (1 K corresponds to ≈4 MPa). When argon at high pressure penetrates the sample one observes a non-monotonous dependence of the melting point on pressure. This effect is observed also in even-numbered alkanes, in which there is no rotator phase.
Źródło:
Acta Physica Polonica A; 2008, 113, 5; 1379-1383
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positronium in Phase IV and Rotator Phase of Long-Chain Alkanes
Autorzy:
Zgardzińska, B.
Goworek, T.
Powiązania:
https://bibliotekanauki.pl/articles/1812555.pdf
Data publikacji:
2008-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
36.10.Dr
61.80.Fe
71.60.+z
78.70.Bj
Opis:
Ortho-positronium lifetime and intensity was measured as a function of temperature and pressure for some n-alkanes in which so-called "phase IV" appears. This phase is characterized by slightly increased ortho-positronium lifetime compared to low-temperature phases. It was found that the effect of quenching positronium by light does not appear in all phases from phase IV upwards. The lifetime in the rotator phases becomes equal to that in liquids, and only the change of positronium formation intensity allows to detect the solid-liquid transition in positron lifetime measurements.
Źródło:
Acta Physica Polonica A; 2008, 113, 5; 1551-1555
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ortho-Positronium in Some n-Alkanes; Influence of Temperature and Pressure
Autorzy:
Zgardzińska, B.
Pietrow, M.
Goworek, T.
Wawryszczuk, J.
Powiązania:
https://bibliotekanauki.pl/articles/2047166.pdf
Data publikacji:
2006-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
36.10.Dr
61.80.Fe
71.60.+z
78.70.Bj
Opis:
Positron lifetime spectra were measured for a series of odd-numbered n-alkanes from C$\text{}_{11}$H$\text{}_{24}$ to C$\text{}_{19}$H$\text{}_{40}$ as a function of temperature and pressure. The ortho-Ps lifetimes in the rotator phase and the increase in intensity at the transition to that phase can be explained by location of Ps in the vicinity of kink-type conformers. The relation between o-Ps lifetime and molecule length can be described in the framework of extended Tao-Eldrup model. One can eliminate the effect of intensity rise in time by sample illumination or by application of high pressure. A decrease in temperature by 1 K is equivalent to an increase in pressure by about 4 MPa.
Źródło:
Acta Physica Polonica A; 2006, 110, 5; 747-753
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positronium Formation with Trapped Electrons in n-Alkanes
Autorzy:
Zgardzińska, B.
Goworek, T.
Powiązania:
https://bibliotekanauki.pl/articles/1505332.pdf
Data publikacji:
2011-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
36.10.Dr
36.20.Fz
61.80.-x
72.20.Jv
78.70.Bj
Opis:
Positronium (Ps) formation during self-irradiation by positrons was observed in n-alkanes of various carbon chain length. The rise of Ps intensity with time of irradiation is the result of positronium formation with trapped excess electrons. In the range T < 190 K the saturation value of positronium intensity changes with temperature mainly due to the change of positron mobility. With the increase of the irradiation dose the process of charging traps is slowing down and this effect is ruled mainly by interaction of excess electrons with ionization products during electron's migration to the traps.
Źródło:
Acta Physica Polonica A; 2011, 119, 3; 328-331
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Method to Produce Linearly Polarized Positrons and Positronium Atoms with the J-PET Detector
Autorzy:
Mohammed, Muhsin
Białas, P.
Curceanu, C.
Czerwiński, E.
Dulski, K.
Gajos, A.
Głowacz, B.
Gorgol, M.
Hiesmayr, B.
Jasińska, B.
Kisielewska, D.
Korcyl, G.
Kowalski, P.
Kozik, T.
Krawczyk, N.
Krzemień, W.
Kubicz, E.
Pawlik-Niedźwiecka, M.
Niedźwiecki, S.
Pałka, M.
Raczyński, L.
Raj, J.
Rudy, Z.
Sharma, N.
Sharma, S.
Shivani, ---
Skurzok, M.
Silarski, M.
Wieczorek, A.
Wiślicki, W.
Zgardzińska, B.
Zieliński, M.
Moskal, P.
Powiązania:
https://bibliotekanauki.pl/articles/1030045.pdf
Data publikacji:
2017-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.75.Fr
41.75.Ht
77.22.Ej
36.10.Dr
85.75.Mm
87.57.uk
Opis:
A method for creating linearly polarized positrons and ortho-positronium (o-Ps) atoms with the J-PET detector is presented. The unique geometry and properties of the J-PET tomography enable one to design a positron source such that the quantization axis for the estimation of the linear polarization of produced o-Ps can be determined on the event by event basis in a direction of the positron motion. We intend to use ²²Na or other β⁺ decay isotopes as a source of polarized positrons. Due to the parity violation in the beta decay, the emitted positrons are longitudinally polarized. The choice of the quantization axis is based on the known position of the positron emitter and the reconstructed position of the positronium annihilation. We show that the J-PET tomography is equipped with all needed components.
Źródło:
Acta Physica Polonica A; 2017, 132, 5; 1486-1489
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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