Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

Wyszukujesz frazę "BJ" wg kryterium: Wszystkie pola


Tytuł:
Resonance Trapping of Positrons in Solids
Autorzy:
Dryzek, J.
Powiązania:
https://bibliotekanauki.pl/articles/1929062.pdf
Data publikacji:
1993-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
Basing on a new approach to the calculations of the positron trapping rate, an attempt ',was made to explain the prevacancy effects observed in positron annihilation measurements in metals. The defect in the calculation is represented by a complex potential: the real part of it is responsible for the scattering and the imaginary part - for the trapping of incoming positrons. It is shown that the resonance trapping of the positron s-wave and p-wave at low temperature and d-wave and f-wave in prethermal regions provide substantial contributions to the trapping rate of positrons. The calculations were done for the point defect and for the dislocation, taking into account the thermal distribution of the positron energy and the thermal expansion of the crystal lattice. The resonance trapping of positrons could be responsible for prevacancy effects in metals and could help to solve some problems in the study of positron annihilation.
Źródło:
Acta Physica Polonica A; 1993, 83, 3; 293-296
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Trapping Model in Fine Grained Sample
Autorzy:
Dryzek, J.
Powiązania:
https://bibliotekanauki.pl/articles/2007999.pdf
Data publikacji:
1999-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
In the paper we consider the positron trapping model in the sample where the spherical particles were immersed in the medium. The radius of the particles was small enough to take into account the diffusion of positrons. We present the exact solutions of the model for two cases, when transition of the positrons from the particle to the medium was neglected and when it was taken into consideration. The theoretical calculations were applied to description of the positron annihilation in the copper sample where the recrystallization process took place.
Źródło:
Acta Physica Polonica A; 1999, 95, 4; 539-545
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Annihilation of Positrons in Fe-Ni Alloys
Autorzy:
Szuszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/1933545.pdf
Data publikacji:
1995-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
The effect of positron polarization on annihilation characteristics for ferromagnetic alloy samples, Fe$\text{}_{64}$Νi$\text{}_{36}$, Fe$\text{}_{63}$Νi$\text{}_{37}$, Fe$\text{}_{25}$Νi$\text{}_{75}$ and Fe$\text{}_{50}$Νi$\text{}_{50}$, has been studied. It was observed that the global two-quantum annihilation rate depends on mutual orientation of positron beam direction and the sample magnetization. The observed changes of the rate are opposite to the ones which could be expected from the effect of mutual orientation of positron and electron spins on positron backscattering. They can be explained as a result of changing of the relation between 3γ- and 2γ-annihilation probabilities.
Źródło:
Acta Physica Polonica A; 1995, 88, 1; 237-239
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Algorithm for Shifting Positron Annihilation Spectra
Autorzy:
Dryzek, J.
Polak, A.
Powiązania:
https://bibliotekanauki.pl/articles/2024230.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
We present a simple procedure which allows us to shift the positron annihilation spectra, e.g., the Doppler broadening spectrum of the annihilation line. That is especially required when we wish to compare different spectra obtained with a spectrometer with the reduction of background. As an application of the obtained algorithm we present the studies of positron annihilation in carbon material samples.
Źródło:
Acta Physica Polonica A; 2001, 99, 3-4; 355-361
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ortho-Positronium Annihilation in Room Temperature Ionic Liquids
Autorzy:
Hirade, T.
Powiązania:
https://bibliotekanauki.pl/articles/1030029.pdf
Data publikacji:
2017-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
Very new phenomena have been found in room temperature ionic liquids, e.g. oscillation of positronium (Ps) bubble. It is almost impossible to see this kind of phenomenon in usual molecular liquids. The Ps bubble oscillations in N,N,N-trimethyl-N-propylammonium bis(trifluoro-methanesulfonyl)imide (TMPA-TFSI), N-methyl-N-propylpiperidinium bis(trifluoromethane-sulfonyl) imide (PP13-TFSI) and 1-ethyl-3-methylimidazolium thiocyanate (EMIM-SCN) were successfully observed. Even though the Ps bubble size is smaller for EMIM-SCN, the oscillation frequency of the Ps bubble at 10°C above the melting temperatures was quite similar for the other room temperature ionic liquids. Hence, the Ps bubble oscillation is, probably, caused by the repulsive force initiated by the ionic structures in room temperature ionic liquids that can remain at 10-15°C above the melting temperatures.
Źródło:
Acta Physica Polonica A; 2017, 132, 5; 1470-1472
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Production of Sodium Silicate Cullets by Using Trona
Autorzy:
Özkan, İ.
Powiązania:
https://bibliotekanauki.pl/articles/1398696.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.35.bj
Opis:
This study focuses on production and characterization of sodium silicate cullet by using trona. Sodium silicate cullets are generally produced by direct fusion of precisely measured portions of soda ash (Na₂CO₃) and quartz (SiO₂). In this study trona (Na₂CO₃· NaHCO₃· 2H₂O) was used as a source of soda ash. For this purpose trona sample was first characterized by X-ray diffraction, scanning electron microscopy, differential thermal analysis/thermal gravimetry and chemical analyses. Different batches were prepared and fused to produce sodium silicates varying in ratio Na₂O· nSiO₂. Produced samples were evaluated by X-ray diffraction and scanning electron microscopy. The results showed that trona can be used instead of soda ash to produce sodium silicate cullets.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 451-454
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Annihilation in Medical Substances of Insulin
Autorzy:
Pietrzak, R.
Szatanik, R.
Powiązania:
https://bibliotekanauki.pl/articles/2043341.pdf
Data publikacji:
2005-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
Positrons lifetimes were measured in medical substances of insulin (human and animal), differing as far as the degree of purity and time of their activity in the organism are concerned. In all of the cases the spectrum of positron lifetime was distributed into three components, with the long-life component ranging from 1.8 to 2.08 ns and the intensity taking on values from 18 to 24%. Making use of Tao-Eldrup model, the average radius of the free volume, in which o-Ps annihilated, and the degree of filling in the volume were determined. It was found that the value of the long-life component for human insulin is higher than that of animal insulin. Moreover, the value of this component clearly depends on the manner of purification of the insulin. It was also noticed that there occurs a correlation between the value of this component and the time after which it begins to be active in the organism, as well as the total time of its activity.
Źródło:
Acta Physica Polonica A; 2005, 107, 5; 852-856
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Annihilation in Obsidians
Autorzy:
Chojcan, J.
Sachanbiński, M.
Powiązania:
https://bibliotekanauki.pl/articles/1933482.pdf
Data publikacji:
1995-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.43.Fs
78.70.Bj
Opis:
Positron lifetime spectra as well as one-dimensional angular correlations of positron annihilation radiation were measured at room temperature for samples of rhyolitic obsidian coming from Iceland, Italy and Armenia. The samples were of different age. One specimen (originating from Iceland) was relatively young, formed in 1980. The others were much older, collected during the 19th century. It was found that the linear dimensions of pores trapping the positronium atoms before their decay as well as the pore concentration in all old obsidians are almost the same independently of the place of their formation. Simultaneously the concentration of the pores in the young sample is about five times lower than in the old specimens. Basing on the result it is suggested to extend the study in order to find out if positron annihilation can be used for the investigation of the age of the volcanic accumulations containing obsidian.
Źródło:
Acta Physica Polonica A; 1995, 88, 1; 103-110
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Annihilation in Helium Charged Ni Samples
Autorzy:
Pająk, J.
Rozenfeld, B.
Powiązania:
https://bibliotekanauki.pl/articles/1929108.pdf
Data publikacji:
1993-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
The angular correlation curves of annihilation quanta and isochronal annealing curves for the plastically deformed nickel samples charged with helium have been measured. The results indicate that helium is effectively trapped at crystal lattice defects and is released from them at the temperature below 350 K.
Źródło:
Acta Physica Polonica A; 1993, 83, 3; 371-374
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Remarks on Reconstruction of Defects Distribution by Positron Lifetime Measurements
Autorzy:
Dryzek, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933485.pdf
Data publikacji:
1995-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
It is well known that the positron trapping rate obtained from positron lifetime measurements depends upon defect concentrations and trapping efficiency. If a distribution of open volume defects exists, a distribution of trapping efficiency also could be present. As an example, the calculation of trapping efficiency as a function of radius of defects in Al is presented. The correct explanation of defect size distribution obtained by positron lifetime measurements needs to introduce some additional assumptions about trapping efficiency.
Źródło:
Acta Physica Polonica A; 1995, 88, 1; 125-128
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Annihilation Methods by Use of LSO Scintillators
Autorzy:
Hirade, T.
Oka, T.
Powiązania:
https://bibliotekanauki.pl/articles/1339992.pdf
Data publikacji:
2014-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
$Lu_2SiO_5$:Ce (LSO) scintillator is one of the scintillators used for positron emission tomography because of its high efficiency of gamma-ray detection. We tried to use LSO for positron annihilation lifetime and age-momentum correlation measurements because the high efficiency is needed to reduce the positron irradiation effect during measurements. The high efficiency with reasonable time resolution was successfully obtained by use of the dynode signals from photomultiplier tubes.
Źródło:
Acta Physica Polonica A; 2014, 125, 3; 825-828
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Annihilation in Internally Oxidized Copper
Autorzy:
Misheva, M.
Nancheva, N.
Feschiev, N.
Powiązania:
https://bibliotekanauki.pl/articles/1929106.pdf
Data publikacji:
1993-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
The positron lifetimes in internally oxidized polycrystalline copper, annealed at different temperatures, were measured. It was found that the dispersed alumina particles act as positron traps. Estimation of concentration of defects was made in the frames of the trapping model.
Źródło:
Acta Physica Polonica A; 1993, 83, 3; 365-369
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Defects in Some Hydrogenated Metallic Materials Studied by Positrons
Autorzy:
Mikhalenkov, V. S.
Powiązania:
https://bibliotekanauki.pl/articles/2024976.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
The measurements of angular correlation of annihilation radiation and positron lifetime were performed to study defects in commercial stainless steel and nickel subjected to deformation and electron irradiation. It follows from variation of S-parameter derived from angular correlation of annihilation radiation spectra that hydrogen charging of Fe-Cr-Ni-Mn austenite steel results in appearance of modest amount of vacancies which agglomerate into small clusters during annealing at low temperatures. Electron irradiation produces much more defects, so that subsequent hydrogenation does not add much to their concentration. The major part of defects anneals out gradually to 700 K. The residual part is preserved up to 950 K. This fact testifies to bonding state of vacancies. Nickel of 3N purity was prepared in three initial states, i.e. cold-rolled and hydrogenated before and after deformation. In an initial state all samples contain, along with simple defects, vacancy clusters. Their size and concentration are much larger in hydrogenated samples, as compared with merely cold-rolled one. Annealing above 400 K causes growth of cluster size and decrease in their concentration. At 500 K clusters are observed to disappear in cold-rolled sample, while in the sample hydrogenated after deformation they survive to 600 K.
Źródło:
Acta Physica Polonica A; 2001, 99, 3-4; 415-422
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurements of Positrons Lifetimes in Corroded Nickel
Autorzy:
Pietrzak, R.
Szatanik, R.
Szuszkiewicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/2008182.pdf
Data publikacji:
1999-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
An attempt was undertaken at making use of a technique of taking measurements of lifetimes of positrons emitted from $\text{}^{22}$Na source to investigate corroded nickel. It was found that after corrosion in HCl vapours mean positrons lifetime, the second component of positrons lifetimes as well as its intensity rise along with the corrosion time.
Źródło:
Acta Physica Polonica A; 1999, 95, 4; 647-651
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Annihilation Study of Defects in the Cage-Type Uranium Compound
Autorzy:
Rubaszek, A.
Powiązania:
https://bibliotekanauki.pl/articles/1336614.pdf
Data publikacji:
2014-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
Opis:
The electron and positron properties of the $UIr_2Zn_{20}$ compound of the Fd-3m cage-type crystal structure are studied. The characteristics for the perfect crystal are compared with their counterparts in the elements containing Ir and Zn vacancy. The presence of the vacancy hardly influences the electron charge density around individual atoms. In contrast to electrons, the positron is strongly localized inside the vacancy and the transfer of positron charge is observed. The positron lifetime, τ, appears to be strongly sensitive to the presence and type of the vacancy. Furthermore, this parameter calculated for the perfect crystal is very close to the experimental value for Zn. Here the theoretical values of τ depend on the approach applied to the electron positron (e-p) correlations.
Źródło:
Acta Physica Polonica A; 2014, 125, 3; 737-740
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies