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1
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New Porosimetric Method Based on the 3γ Annihilation Rate. Applications to Materials Science and Medical Imaging

100%
Jasińska B., Zgardzińska B.
Acta Physica Polonica A
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2017
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vol. 132
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issue 5
1616-1619
EN
A new parameter δ based on 3γ annihilation is proposed. It describes the porosity of the materials containing small intermolecular voids below 1 nm. It can be applied to material investigation to compare changes in the material porosity depending on temperature or pressure as well as to study of ageing or manufacturing processes. Particularly it is dedicated to prepare the new imaging method and can be used during positron emission tomography diagnosis allowing determination the kind or stage of pathogenic alteration.
2
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Investigations of Resorcinol under High Pressure

100%
Tydda M., Jasińska B.
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vol. 125
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issue 3
812-815
EN
The investigation of intermolecular free volumes in resorcinol was conducted under high pressure, hydraulic pressure and gas (argon or nitrogen) atmosphere. The sizes of free volumes were estimated basing on the mean lifetime of ortho-positronium (o-Ps). In the first case, a monotonous change of lifetime and intensity was observed for the o-Ps component while the range of pressure was 0-477 MPa. On the other case, the samples were put into the pressure chamber filled with argon or nitrogen in the range of pressure from 0 to 450 MPa. When the pressure chamber was filled with a gas, the appearance of an additional o-Ps component has been found. In the nitrogen atmosphere, the material crushed when the gas pressure reached about 200 MPa, and the mean lifetime of the longest o-Ps component increased.
3
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Redistribution of o-Ps in Porous Vycor Glass. Crystallization of Silica at High Temperatures

100%
Śniegocka M., Jasińska B.
Acta Physica Polonica A
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2006
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vol. 110
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issue 5
721-727
EN
The positron annihilation lifetime spectroscopy was applied to study the porous Vycor glass annealed at the temperatures between 950 and 1050 K. With increased temperature the spectra show significant decrease in o-Ps lifetime and intensity in the pores, while the rise of intensity in the small intermolecular voids is observed. Similar changes are observed as a function of annealing time at fixed temperature depending on the time and temperature of thermal treatment. They can originate from partial crystallization of the silica in the material under study.
4
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Crystallization Process in Porous and Nonporous Vycor Glass

81%
Jasińska B., Dawidowicz A., Pikus S.
Acta Physica Polonica A
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2005
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vol. 107
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issue 5
724-728
EN
Three stages of thermal and chemical processing of Vycor glass were carried out. Raw material, the glass with small and big pores was studied. In each stage of study various crystallinity degrees of investigated material were obtained. The relation between crystallinity degree and the intensity of o-Ps components was determined. In nonporous material a high correlation between o-Ps intensity and crystallinity degree was found. In porous material the decrease in total o-Ps intensity can be a measure of the crystallinity degree.
5
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Three-Quantum Annihilation in Porous Vycor Glass

81%
Jasińska B., Wawryszczuk J., Zaleski R.
Acta Physica Polonica A
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2005
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vol. 107
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issue 5
821-825
EN
Three methods of determination of 3γ o-Ps decay intensity are compared. The estimate of 3γ fraction obtained from classical lifetime measurements can be distorted due to a higher absorption of theγ quanta from the continuous spectrum of three-quantum decay, compared to two-quantum one.
6
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Void Shapes and o-Ps Lifetime in Molecular Crystals

81%
Jasińska B., Kozioł A., Goworek T.
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vol. 95
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issue 4
557-561
EN
The size and shape of the free volume in molecular crystals was estimated from crystallographic data. The o-Ps lifetime values were calculated from respective models and compared with the experimental data. The best agreement for channel-like voids has been obtained for the value of DR parameter equal 0.19 nm. The threshold value of radius allowing Ps trapping in the void was found to be (0.12-0.13) nm.
7
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Liquation of Vycor Glasses - Study by Positron Annihilation Lifetime Method

81%
Jasińska B., Dawidowicz A., Radkiewicz S.
Acta Physica Polonica A
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2001
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vol. 99
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issue 3-4
379-384
EN
Two Vycor glasses of different percentages of the components were liquated between 725 K and 950 K and leached in order to produce pores. Little intermolecular voids characterized by ortho-positronium lifetime valueτ_2≈1.5 ns were observed simultaneously. At the first stage of pore formation the intensity I_2 decreased considerably for both glasses, while at liquation temperatures higher than 825 K it increased again. The increase in I_2 resulted from changes in the properties of the bulk material. The growth ofτ_2 in this range of temperatures was also observed.
8
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The Influence of the Temperature on Positron Annihilation Lifetime Spectra in Porous Sol-Gel Glass Doped with Ag Nanoparticles

81%
Gorgol M., Jasińska B., Reisfeld R., Levchenko V.
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vol. 125
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issue 3
778-781
EN
Silver nanoparticles with continuous size distribution from 10 to 20 nm were incorporated into porous glass produced using sol-gel technique. Positron annihilation lifetime spectroscopy was used to compare obtained material with an undoped reference glass. The positron annihilation lifetime spectroscopy measurement were made in a broad temperature range (from - 180C to 200°C). The experimental lifetime values were compared with the predictions of the extended Tao-Eldrup model of the temperature range. Experimental results for the reference material were in agreement with the model, except for a small discrepancy at low temperatures. In doped material substantial changes and non-monotonous temperature dependences of intensity and lifetime values were observed. Heating the material to 200C resulted in reorganization of the material structure.
9
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Testing the Extended Tao-Eldrup Model. Silica Gels Produced with Polymer Template

62%
Śniegocka M., Jasińska B., Wawryszczuk J., Zaleski R., Deryło-Marczewska A., Skrzypek I.
Acta Physica Polonica A
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2005
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vol. 107
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issue 5
868-873
EN
The temperature dependence of o-Ps lifetime in the pores calculated from extended Tao-Eldrup model was compared to the experimental data, collected for a set of silica gels synthesized using the polymer template technique. For the sample with average pore radii 2.0 nm rather good agreement between the model and experiment was found. For the sample with narrow pores (near 1.0 nm) the lifetime spectrum was complex. Except the range of highest temperatures the lifetimes are far from model calculations.
10
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Analysis Procedure of the Positronium Lifetime Spectra for the J-PET Detector

28%
Dulski K., Zgardzińska B., Białas P., Curceanu C., Czerwiński E., 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 M., Pawlik-Niedźwiecka M., Niedźwiecki S., Pałka M., Raczyński L., Raj J., Rudy Z., Sharma N., Sharma S., Shivani S., Shopa R., Silarski M., Skurzok M., Wieczorek A., Wiślicki W., Zieliński M., Moskal P.
Acta Physica Polonica A
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2017
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vol. 132
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issue 5
1637-1640
EN
Positron annihilation lifetime spectroscopy has shown to be a powerful tool to study the nanostructures of porous materials. Positron emission tomograph is a device allowing imaging of metabolic processes e.g. in human bodies. A newly developed device, the Jagiellonian PET will allow positron annihilation lifetime spectroscopy in addition to imaging, thus combining both analyses providing new methods for physics and medicine. In this contribution we present a computer program that is compatible with the Jagiellonian PET software. We compare its performance with the standard program LT 9.0 by using positron annihilation lifetime spectroscopy data from hexane measurements at different temperatures. Our program is based on an iterative procedure, and our fits prove that it performs as good as LT 9.0.
11
Content available remote

Time Calibration of the J-PET Detector

28%
Skurzok M., Silarski M., Alfs D., Białas P., Shivani, 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 M., 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.
Acta Physica Polonica A
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2017
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vol. 132
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issue 5
1641-1644
EN
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.
12
Content available remote

Preliminary Studies of J-PET Detector Spatial Resolution

28%
Pawlik-Niedźwiecka M., Niedźwiecki S., Alfs D., 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., Mohammed M., Pałka M., Raczyński L., Raj J., Rudy Z., Shivani, Silarski M., Skurzok M., Sharma N., Sharma S., Shopa R., Strzelecki A., Wieczorek A., Wiślicki W., Zgardzińska B., Zieliński M., Moskal P.
Acta Physica Polonica A
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2017
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vol. 132
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issue 5
1645-1648
EN
The J-PET detector, based on long plastic scintillator strips, was recently constructed at the Jagiellonian University. It consists of 192 modules axially arranged into three layers, read out from both sides by digital constant-threshold front-end electronics. This work presents preliminary results of measurements of the spatial resolution of the J-PET tomograph performed with ²²Na source placed at selected position inside the detector chamber.
13
Content available remote

Human Tissue Investigations Using PALS Technique - Free Radicals Influence

28%
Jasińska B., Zgardzińska B., Chołubek G., Pietrow M., Gorgol M., Wiktor K., Wysogląd K., Białas P., Curceanu C., Czerwiński E., Dulski K., Gajos A., Głowacz B., Hiesmayr B., Jodłowska-Jędrych B., Kamińska D., Korcyl G., Kowalski P., Kozik T., Krawczyk N., Krzemień W., Kubicz E., Mohammed M., Pawlik-Niedźwiecka M., Niedźwiecki S., Pałka M., Raczyński L., Rudy Z., Sharma N., Sharma S., Shopa R., Silarski M., Skurzok M., Wieczorek A., Wiktor H., Wiślicki W., Zieliński M., Moskal P.
Acta Physica Polonica A
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2017
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vol. 132
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issue 5
1556-1558
EN
The positron annihilation lifetime spectroscopy was applied to the samples of the human uterine leiomyomas and the normal myometrium tissues taken from the selected place of the uterus during a surgery. The method indicated differences in values of the measured positron annihilation lifetime spectroscopy parameters (lifetimes and intensities) between healthy and diseased tissue samples. The additional measurements were performed either in darkness or in presence of visible light which influenced the free radicals present in both kind of tissues and, as a result, made changes in free annihilation and o-Ps decay lifetime and intensity values.
14
Content available remote

A Method to Produce Linearly Polarized Positrons and Positronium Atoms with the J-PET Detector

28%
Mohammed M., 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.
Acta Physica Polonica A
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2017
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vol. 132
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issue 5
1486-1489
EN
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.
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