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EN
X-ray surface diffraction experiments performed on polyaniline/camphorsulfonic acid (PANI/CSA) thin films reveal high anisotropy of the five main crystalline peaks. This anisotropy is different for samples cast from m-cresol and cast from trifluoroacetic acid (TFA). Taking advantage of a recently published crystalline unit cell model, intensity distribution maps are calculated for these two types of samples. The anisotropy is in agreement with experiment, further validating the PANI/CSA model and showing that solvent molecules are not present in the unit cell.
PL
Cienkowarstwowe, wykazujące silną anizotropię próbki polianilina/kwas kamforosulfonowy (PANI/CSA) zbadano metodą dyfrakcji powierzchniowej promieniowania rentgenowskiego. Wyniki pomiarów w geometriach: transmisyjnej, odbiciowej i pośrednich wykazały różnice między natężeniami pięciu głównych maksimów krystalicznych. Anizotropia próbek była różna w wypadku użycia różnych rozpuszczalników (m-cresol, kwas trifluorooctowy). Niedawno opublikowany model struktury PANI/CSA wykorzystano do obliczenia map natężeń, a następnie do porównań z wynikami pomiarów. Proponowany model poprawnie opisuje uporządkowanie w próbkach folii z PANI/CSA wylanych z różnych rozpuszczalników, bez konieczności uwzględniania w nim cząsteczek rozpuszczalnika. Świadczy to o tym, że cząsteczki rozpuszczalnika nie występują w strukturze PANI/CSA jako składniki komórki elementarnej.
EN
The search for the model structure of polyaniline/camphorsulfonic acid (PANI/CSA) began approximately twenty years ago and remained an unsolved problem. Recently, a new molecular dynamics based model was published in which the system forms a structure of alternating double layers. Having brought together all available information regarding the system, an artificial intelligence approach was formulated, which resulted in finding a model of the crystalline regions of the polymer system in agreement with various experimental results. The approach is thoroughly described due to its versatility.
PL
Poszukiwania modelu struktury systemu polianilina/kwas kamforosulfonowy (PANI/CSA) rozpoczęły się przed ok. dwudziestu laty, nadal jednak problem pozostaje nierozwiązany. W minionych latach opublikowano nowy model otrzymany w wyniku symulacji metodą dynamiki molekularnej. Zgodnie z jego przewidywaniami w systemie PANI/CSA powstaje struktura naprzemiennych dwuwarstw. Na podstawie dostępnej wiedzy sformułowano wykorzystującą algorytmy sztucznej inteligencji metodę, która doprowadziła do znalezienia modelu wykazującego zgodność z różnego rodzaju doświadczeniami. Ze względu na uniwersalność opracowanej metody, szczegółowo ją opisano.
EN
Nowadays, in positron emission tomography (PET) systems, a time of fl ight (TOF) information is used to improve the image reconstruction process. In TOF-PET, fast detectors are able to measure the difference in the arrival time of the two gamma rays, with the precision enabling to shorten signifi cantly a range along the line-of-response (LOR) where the annihilation occurred. In the new concept, called J-PET scanner, gamma rays are detected in plastic scintillators. In a single strip of J-PET system, time values are obtained by probing signals in the amplitude domain. Owing to compressive sensing (CS) theory, information about the shape and amplitude of the signals is recovered. In this paper, we demonstrate that based on the acquired signals parameters, a better signal normalization may be provided in order to improve the TOF resolution. The procedure was tested using large sample of data registered by a dedicated detection setup enabling sampling of signals with 50-ps intervals. Experimental setup provided irradiation of a chosen position in the plastic scintillator strip with annihilation gamma quanta.
EN
Results of positron annihilation lifetime spectroscopy (PALS) and microscopic studies on simple microorganisms, brewing yeasts, are presented. Lifetime of ortho-positronium (o-Ps) were found to change from 2.4 to 2.9 ns (longer-lived component) for lyophilized and aqueous yeasts, respectively. Also hygroscopicity of yeasts in time was examined, allowing to check how water – the main component of the cell – affects PALS parameters, thus lifetime of o-Ps were found to change from 1.2 to 1.4 ns (shorter-lived component) for the dried yeasts. The time sufficient to hydrate the cells was found below 10 hours. In the presence of liquid water, an indication of reorganization of yeast in the molecular scale was observed. Microscopic images of the lyophilized, dried, and wet yeasts with best possible resolution were obtained using inverted microscopy (IM) and environmental scanning electron microscopy (ESEM) methods. As a result, visible changes to the surface of the cell me mbrane were observed in ESEM images.
EN
In this paper, we present prospects for using the Jagiellonian positron emission tomograph (J-PET) detector to search for discrete symmetries violations in a purely leptonic system of the positronium atom. We discuss tests of CP and CPT symmetries by means of ortho-positronium decays into three photons. No zero expectation values for chosen correlations between ortho-positronium spin and momentum vectors of photons would imply the existence of physics phenomena beyond the standard model. Previous measurements resulted in violation amplitude parameters for CP and CPT symmetries consistent with zero, with an uncertainty of about 10−3. The J-PET detector allows to determine those values with better precision, thanks to the unique time and angular resolution combined with a high geometrical acceptance. Achieving the aforementioned is possible because of the application of polymer scintillators instead of crystals as detectors of annihilation quanta.
EN
The J-PET detector being developed at the Jagiellonian University is a positron emission tomograph composed of the long strips of polymer scintillators. At the same time, it is a detector system that will be used for studies of the decays of positronium atoms. The shape of photomultiplier signals depends on the hit time and hit position of the gamma quantum. In order to take advantage of this fact, a dedicated sampling front-end electronics that enables to sample signals in voltage domain with the time precision of about 20 ps and novel reconstruction method based on the comparison of examined signal with the model signals stored in the library has been developed. As a measure of the similarity, we use the Mahalanobis distance. The achievable position and time resolution depend on the number and values of the threshold levels at which the signal is sampled. A reconstruction method as well as preliminary results are presented and discussed.
EN
The Jagiellonian Positron Emission Tomograph (J-PET) collaboration is developing a prototype time of flight (TOF)-positron emission tomograph (PET) detector based on long polymer scintillators. This novel approach exploits the excellent time properties of the plastic scintillators, which permit very precise time measurements. The very fast fi eld programmable gate array (FPGA)-based front-end electronics and the data acquisition system, as well as low- and high-level reconstruction algorithms were specially developed to be used with the J-PET scanner. The TOF-PET data processing and reconstruction are time and resource demanding operations, especially in the case of a large acceptance detector that works in triggerless data acquisition mode. In this article, we discuss the parallel computing methods applied to optimize the data processing for the J-PET detector. We begin with general concepts of parallel computing and then we discuss several applications of those techniques in the J-PET data processing.
EN
The polystyrene doped with 2,5-diphenyloxazole as a primary fluor and 2-(4-styrylphenyl)benzoxazole as a wavelength shifter prepared as a plastic scintillator was investigated using positronium probe in wide range of temperatures from 123 to 423 K. Three structural transitions at 260, 283, and 370 K were found in the material. In the o-Ps intensity dependence on temperature, the significant hysteresis is observed. Heated to 370 K, the material exhibits the o-Ps intensity variations in time.
9
Content available remote Rekonstrukcja kół zębatych z zastosowaniem systemów CMM/CAD/RP
PL
W artykule przedstawiono metodykę rekonstrukcji kół zębatych przekładni lotniczych z zastosowaniem powiązanych systemów CMM/CAD/RP. Współrzędnościowe techniki pomiarowe (CMM) oraz systemy CAD umożliwia identyfikację i odtwarzanie geometrii kół zębatych, natomiast systemy RP dają możliwość wykonania prototypu zrekonstruowanego koła zębatego.
EN
This paper presents a reconstruction methodology of the transmission airline gears connected systems using CMM/CAD/RP. The use of coordinate measuring techniques (CMMs) and CAD systems enables to identify and reconstruct gear geometry. In contrast, while the RP systems make it possible to create a prototype with the reconstructed gear.
EN
The structure of polyaniline (PANI) protonated with camphorsulphonic acid (CSA) has been subject to research for a long time. Despite several, various models being proposed throughout the years, there is still no model widely accepted as the only correct and final one of its crystalline phase. In this paper a computer program named MoleculeEditor is described. Created basing on the concepts of an existing but significantly different program named CrystalFinder, it is a software dedicated to finding a model of the crystalline regions of the PANI/CSA system based on an input X-ray diffraction pattern. In its search it takes advantage of the genetic algorithm technique for optimizing the model parameters to fit the computed diffraction pattern to the one loaded as input. A successful example of it being employed to find the parameters of a prepared beforehand, fictional structure of the system, is presented. Conclusions drawn from this application of the prepared software cannot be ignored in the further search for the actual model of this complex system using this program. Obtaining results from MoleculeEditor for actual, experimental data is however still in progress.
EN
This article is focused on data acquisition system (DAQ) designed especially to be used in positron emission tomography (PET) or single-photon emission computed tomography. The system allows for continuous registration of analog signals during measurement. It has been designed to optimize registration and processing of the information carried by signals from the detector system in PET scanner. The processing does not require any rejection of data with a trigger system. The proposed system possesses also an ability to implement various data analysis algorithms that can be performed in real time during data collection.
12
Content available remote Simulations of γ quanta scattering in a single module of the J-PET detector
EN
This article describes the simulations of the scattering of annihilation γ quanta in a strip of a plastic scintillator. Such strips constitute the basic detection modules in a newly proposed positron emission tomography (PET), which utilizes plastic scintillators instead of inorganic crystals. An algorithm simulating the chain of Compton scatterings was elaborated and a series of simulations have been conducted for the scintillator strip with a cross-section of 5×19 mm. The results indicate that secondary interactions occur only in the case of about 8% of the events and only 25% of these events take place in the distance larger than 0.5 cm from the primary interaction. Also, the light signals produced at the primary and secondary interactions overlap with the delay, the distribution of which is characterized by a full width at half-maximum (FWHM) of about 40 ps.
EN
This paper describes three methods regarding the production of plastic scintillators. One method appears to be suitable for the manufacturing of plastic scintillators, revealing properties which fulfill the requirements of novel positron emission tomography scanners based on plastic scintillators. The key parameters of the manufacturing process are determined and discussed.
14
Content available remote List-mode reconstruction in 2D strip PET
EN
Using a theory of list-mode maximum likelihood expectation-maximization (MLEM) algorithm, in this contribution, we present a derivation of the system response kernel for a novel positron emission tomography (PET) detector based on plastic scintillators.
15
Content available remote J-PET analysis framework for the prototype TOF-PET detector
EN
Novel time-of-flight positron emission tomography (TOF-PET) scanner solutions demand, apart from the state-of-the-art detectors, software for fast processing of the gathered data, monitoring of the whole scanner, and reconstruction of the PET image. In this article, we present an analysis framework for the novel STRIP-PET scanner developed by the J-PET collaboration in the Institute of Physics of the Jagiellonian University. This software is based on the ROOT package used in many particle physics experiments.
EN
A novel PET detector consisting of strips of polymer scintillators is being developed by the Jagiellonian Positron Emission Tomograph (J-PET) collaboration. The map of efficiency and the map of geometrical acceptance of the two-strip J-PET scanner are presented. The map of efficiency was determined using the Monte Carlo simulation software GEANT4 Application for Tomographic Emission (GATE), which is based on GEANT4. Both maps were compared using a method based on the χ2-test.
EN
The complexity of the hardware and the amount of data collected during the PET imaging process require application of modern methods of efficient data organization and processing. In this article, we will discuss the data structures and the flow of collected data from the novel TOF-PET medical scanner that is being developed at the Jagiellonian University. The developed data format reflects the registration process of the γ quanta emitted from positron electron annihilation, front-end electronic structure, and required input information for the image reconstruction. In addition, the system database fulfills possible demands of the evolving J-PET project.
18
Content available remote Computing support for advanced medical data analysis and imaging
EN
We discuss computing issues for data analysis and image reconstruction of positron emission tomography based on time-of-flight medical scanner or other medical scanning devices producing large volumes of data. Service architecture based on grid and cloud concepts for distributed processing is proposed and critically discussed.
19
Content available remote Calibration of photomultipliers gain used in the J-PET detector
EN
Photomultipliers are commonly used in commercial PET scanner as devices that convert light produced in scintillator by gamma quanta from positron-electron annihilation into electrical signal. For proper analysis of obtained electrical signal, a photomultiplier gain curve must be known, since gain can be significantly different even between photomultipliers of the same model. In this article, we describe single photoelectron method used for photomultiplier calibration applied for J-PET scanner, a novel PET detector being developed at Jagiellonian University. A description of calibration method, an example of calibration curve, and a gain of few Hamamatsu R4998 photomultipliers are presented.
EN
A method of the determination of a γ-quantum absorption point in a plastic scintillator block using a matrix of wavelength-shifting (WLS) strips is proposed. An application of this method for the improvement of position resolution in newly proposed positron emission tomography (PET) detectors based on plastic scintillators is presented. The method enables to reduce parallax errors in the reconstruction of images, which occurs in the presently used PET scanners.
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