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Wyszukujesz frazę "ionization" wg kryterium: Temat


Tytuł:
Initial recombination of ions in ionization chambers filled with hydrocarbon gases
Autorzy:
Gryziński, M.
Golnik, N.
Zielczyński, M.
Powiązania:
https://bibliotekanauki.pl/articles/148268.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
initial recombination
ionization chambers
Opis:
Data on the initial recombination of ions are needed for designing recombination chambers, used in mixed radiation dosimetry in order to obtain information about radiation quality. Nevertheless, experimental data for pressurized gases are scarce, whereas reliable theoretical models are absent. The paper provides experimental data on the initial recombination in hydrocarbon gases (methane, ethane and propane) depending on gas pressure up to 1.8 MPa. The data were derived from the measurements of saturation curves of a tissue equivalent recombination chamber of an REM-2 type, in reference radiation fields of 137Cs and 239Pu-Be sources. Ion recombination due to volume recombination and back diffusion of ions was subtracted from the measured values of ion collection efficiency. The values of gas parameters needed for the subtraction procedure were determined by measurements of saturation curves of the chamber at several dose rates for each gas pressure. The important practical rule resulting from the experiments is that in the first approximation the initial recombination does not depend on the kind of the hydrocarbon gas but only on its density in the chamber.
Źródło:
Nukleonika; 2007, 52, 1; 7-12
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Use of diamond powder in the ionization process
Autorzy:
Brzecka, P.
Janaszczyk, A.
Chuchracki, M.
Mitura, K.
Powiązania:
https://bibliotekanauki.pl/articles/284028.pdf
Data publikacji:
2017
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
diamond powder
ionization
allergic reaction
Źródło:
Engineering of Biomaterials; 2017, 20, no. 143 spec. iss.; 86
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of the work function to study the percentage composition of aluminum alloys
Autorzy:
Chrzanowski, J.
Kravtsov, Y.
Bieg, B.
Powiązania:
https://bibliotekanauki.pl/articles/360149.pdf
Data publikacji:
2014
Wydawca:
Akademia Morska w Szczecinie. Wydawnictwo AMSz
Tematy:
work function
shipbuilding
ionization energy
Opis:
The article uses the analytical equation for the work function of metals, made by one of the authors, to study the structure of aluminum alloys, which are increasingly used in the shipbuilding industry. For example, of selected alloys Al-Cu, Al-Ta and Al-Ti are presented graphically changes in work function depending on the percentage composition of the alloy. Also presented an equation that allows to evaluate the work function for multicomponent alloys.
Źródło:
Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2014, 38 (110); 27-31
1733-8670
2392-0378
Pojawia się w:
Zeszyty Naukowe Akademii Morskiej w Szczecinie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Compensated ionization chamber for (n,α) reaction measurements at a spallation neutron source
Autorzy:
Andrzejewski, J.
Yu, M.
Gledenov, M.
Korejwo, A.
Sobczak, K.
Szałański, P.
Powiązania:
https://bibliotekanauki.pl/articles/146570.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
ionization chamber
pulsed neutron source
Opis:
The new spallation neutron facility n_TOF (neutron time-of-flight) at CERN opens wide possibilities in measurements of neutron induced reaction cross sections. The facility with its excellent energy resolution of neutrons, low repetition rate and most important – with a very high instantaneous luminosity, makes up an extra challenge for experimenters faced by doing measurements at a high peak intensity spallation source. Our proposition is directed to the use of a compensated ionization chamber for the (n, alpha) reaction cross section measurements we plan to carry out in a wide range of neutron energy. First experience gained with using such a kind of detector at ORELA (the Oak Ridge Electron Linear Accelerator) neutron source (ORNL) was very optimistic.
Źródło:
Nukleonika; 2007, 52, 2; 51-57
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrode erosion mechanism in the rod plasma injector type of generator as deduced from the structure of irradiated substrates
Autorzy:
Piekoszewski, J.
Stanisławski, J.
Grotzschel, R.
Matz, W.
Jagielski, J.
Szymczyk, W.
Powiązania:
https://bibliotekanauki.pl/articles/147032.pdf
Data publikacji:
2002
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
plasma alloying
plasma melting
vapor ionization
Opis:
Titanium atoms were alloyed into a polycrystalline alundum substrate using a various number of intense pulses consisting of plasma of the working gas and vapor and low energy ions of Ti eroded from electrodes of the rod plasma injector type generator. It appears that at a single pulse titanium always forms a thin metallic film not mixed with the substrate material. With increasing number of pulses the amount of titanium atoms mixed into the substrate increases, whereas the thickness of the film - decreases. Analyses of phase composition and of structural properties, as well as computer simulations of thermal evolution brought the present authors to the conclusion that increase of number of pulses leads to decrease of melting temperature of the top layer of the substrate. It has also been confirmed that metallic ions eroded from electrodes do not undergo such acceleration like working gas ions do; their energy remains on the 200-300 eV level. It is concluded that erosion of the electrode material occurs during the last phase of the discharge via the vacuum arc mechanism.
Źródło:
Nukleonika; 2002, 47, 3; 113-117
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Test measurements of thoron concentration using two ionization chambers AlphaGUARD vs. radon monitor RAD7
Autorzy:
Kochowska, E.
Kozak, K.
Kozłowska, B.
Mazur, J.
Dorda, J.
Powiązania:
https://bibliotekanauki.pl/articles/148134.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
radon
thoron
thoron concentration
ionization chamber
Opis:
The experiment aiming at testing the possibility of using AlphaGUARD monitors based on an ionization chamber for thoron measurements is presented. A single AlphaGUARD monitor working in the flow mode was applied to measure thoron concentration in the radon-free atmosphere. The sensitivity (correction factors) of the monitor to thoron was estimated by comparison with a RAD7 portable detector (Durridge Company), based on spectrometric analysis, in the thoron, radon-free atmosphere in a calibration chamber. This depends on the applied flow rate and changes from 8% for the flow rate of 0.3 dm3/min to 36% for 1 dm3/min. It was also revealed that the sensitivity of the monitor to thoron in the diffusion mode is equal to ca. 5% and may be neglected. The method involving two Alpha-GUARD monitors working in two different modes (diffusion and flow) at the same time may be used to evaluate radon and thoron concentration in the natural environmental conditions where usually both isotopes appear together. In this method thoron concentration is estimated as the difference of results obtained from two AlphaGUARD monitors multiplied by the correction factor corresponding to the applied flow rate. The devices based on spectrometric analysis, e.g. RAD7 seem to be a better tool for thoron measurements in the environmental conditions.
Źródło:
Nukleonika; 2009, 54, 3; 189-192
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Precise measurement of chlorine isotopes by thermal ionization mass spectrometry
Autorzy:
Neskovic, O.
Veljkoviç, M.
Velickoviç, S.
Deriç, A.
Miljeviç, N.
Golobocanin, D.
Powiązania:
https://bibliotekanauki.pl/articles/147003.pdf
Data publikacji:
2002
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
chlorine isotopes
mass spectrometry
thermal ionization
Opis:
A procedure for the determination of chlorine isotopic ratios by positive thermal ionization mass spectrometry of the Cs2Cl+ ion has been investigated. The chlorine isotopic composition in CsCl spectroscopically pure has been measured with a precision of 0.034. The chlorine composition in sea water samples has also been determined.
Źródło:
Nukleonika; 2002, 47,suppl.1; 85-87
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Applications of recombination chambers in the dosimetry of high energy radiation fields
Autorzy:
Zielczyński, M.
Golnik, M.
Gryziński, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/147680.pdf
Data publikacji:
2008
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
initial recombination
ionization chambers
high energy radiation
Opis:
High energy radiation fields exist in space, in the atmosphere at the height of commercial flights and in the vicinity of some accelerators. The characteristic features of these fields are their complex composition and broad energy spectrum. Estimation of the absorbed dose in such fields cannot be performed by consideration of the doses from all the radiation field components. The physically possible way to solve the problem is to determine the operational quantity-ambient dose equivalent H* (10). The radiation detector used for the determination of H* (10) should be large enough in order to simulate the ICRU sphere. Its effective wall thickness should not be very different than 10 mm of tissue. The REM-2 type recombination chamber is an example of such a detector. The review paper presents specific challenges of high energy radiation field dosimetry and discusses a number of examples of measurements at high energy accelerators, including some international intercomparisons. We show that the REM-2 chamber is especially suitable for radiation monitoring in the vicinity of high energy accelerators.
Źródło:
Nukleonika; 2008, 53, suppl. 1; 45-52
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vitamin E content and sensory qualities of γ-irradiated sunflower whole grain cookies
Autorzy:
Taipina, M. S.
Lamardo, L. C. A.
Rodas, M. A. B.
del Mastro, N. L.
Powiązania:
https://bibliotekanauki.pl/articles/147792.pdf
Data publikacji:
2008
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
ionization radiation
cookies
vitamin E
sensory evaluation
Opis:
The sources of vitamin E in the diet are oils, margarines, seeds, nuts and cereal grains. Industrialized sunflower whole grain cookies were treated with gamma irradiation and evaluated for changes in vitamin E content and sensory properties. Radiation doses were 0.0, 1.0 and 3.0 kGy, the dose rate was 3.5 kGy/h. Irradiation at 1 and 3 kGy resulted in no changes in vitamin E content measured as α-tocopherol equivalents by a colorimetric measurement based method. A sensory panel composed of 22 trained members found that irradiation even at 1 kGy induced certain small, but statistically significant differences in sensory characteristics for appearance, aroma, texture and flavor attributes. From the obtained results, it is possible to conclude that there was a notorious stability of the vitamin content of the product submitted to γ-irradiation at the assayed doses. Meanwhile, irradiation at room temperature of this ready to eat food item caused small but statistically significant effects on sensory (marketing) attributes.
Źródło:
Nukleonika; 2008, 53, suppl. 2; 81-84
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wykorzystanie elektrometru Keithley 6517A w układzie kompensacji Townsenda
Use of a Keithley 6517A electrometer in the Townsend compensation circuit
Autorzy:
Knyziak, A. B.
Powiązania:
https://bibliotekanauki.pl/articles/151599.pdf
Data publikacji:
2014
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
metoda zerowa
prąd jonizacyjny
null metod
ionization current
Opis:
W niniejszym artykule przedstawiono możliwość wykorzystania elektrometru firmy Keithley typ 6517A w metodzie zerowej, która jest najdokładniejszą z metod pomiaru małych prądów DC i ładunków elektrycznych. Metoda ta eliminuje główne źródła błędów jak prąd upływowy i zjawisko absorpcji dielektrycznej ładunku elektrycznego. W artykule przedstawiono i omówiono dokładnie metodę zerową. Metoda ta została porównana z innymi znanymi metodami pomiaru małych prądów DC i ładunków elektrycznych. Wyniki tych porównań zostały przedstawione i omówione w artykule. Dzięki zerowej metodzie można otrzymać względną niepewność standardową około 0,003% dla prądu o wartości 3 pA i stabilność długoterminową około 0,01%. Na podstawie uzyskanych wyników i doświadczeń budowane są obecnie systemy pomiarowe w Głównym Urzędzie Miar, np. systemy pomiarowe dla stanowisk wzorca pierwotnego dawki pochłoniętej w wodzie i kermy w powietrzu.
A ionization chamber is the most widely used type of dosimeter for precise measurements. The typical values of charge or current to be measured by ionization chambers can be estimated from the fact that an exposure of 1 R (Roentgen is now a historical unit of the exposure dose) generates a charge of 2.58∙10-10 C in 1 cm3 of room temperature air at pressure 1 atm. In most practical cases, ionization currents are very small, in the range from 1 µA to 0.1 fA, so their measurement requires careful technique and appropriate instrumentation. Making a measurement with a ionization chamber requires a high-voltage power supply and an electrometer. The electrometer measures current or charge in the range 200 fA to 1 µA (current mode) and 2 pC to 10 mC (charge mode) with the maximum resolution of 1 fA or 10 fC and the accuracy better than 0.5%. Its long term stability is 0.1% per year. These parameters are insufficient for measurements in which there are used ionization chambers as the primary standard. There are also problems with the calibration of these electrometers on a satisfactory level. This paper presents the possibility of using a digital Keithley 6517A electrometer in the null method which is the most accurate method measuring very low DC currents and electrical charges. This method eliminates the leakage current and the capacitor dielectric absorption phenomenon. The null method is presented and discussed. This method is compared with the known measuring methods and the results of comparison are summarized and discussed. Thanks to the null method there can be achieved the relative standard uncertainty of 0.003% for the current about 3 pA and the long term stability about 0.01%. The results of the research are used at the Central Office of Measures in the Laboratory of Ionizing Radiation and Color Standards. Based on these studies new measuring systems are being built at the Central Office of Measures, e.g. a measuring system for the primary standards of absorbed dose to water and air kerma.
Źródło:
Pomiary Automatyka Kontrola; 2014, R. 60, nr 3, 3; 164-166
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of initial recombination of ions created in quasi-pulsed radiation fields
Autorzy:
Zielczyński, M.
Golnik, N.
Gryziński, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/146942.pdf
Data publikacji:
2008
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
initial recombination
volume recombination
ionization chambers
pulse radiation
Opis:
A new method is proposed for the determination of ion collection efficiency due to initial recombination process only, in a high pressure ionization chamber, operating in a quasi-pulsed radiation field. It is shown that the influence of undesirable volume recombination can be eliminated using a semi-empirical formula. The unknown function of the chamber polarizing voltage, included to the formula, can be found experimentally in the investigated radiation field, using the approach proposed in the paper. The function is the same for all radiation fields with similar time structure.
Źródło:
Nukleonika; 2008, 53, suppl. 2; 33-36
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical study of the effect the hydroxyl subgroups on the electronic properties of iso-indene molecule
Autorzy:
Obayes, Abbas Ibrahim
Hasan, Nahida B.
Aboud, Hamed Ibrahem
Mohammed, Mohammed Ahmed
Powiązania:
https://bibliotekanauki.pl/articles/1191969.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
DFT
energy gap
ionization potential
hardness and IR-spectrum
Opis:
In this work, six molecules model are optimized at B3LYP/6-31G** density functional theory. Electronic properties of iso-indene molecules were investigated depending on the three parameters (B3LYP) by density functional theory method. The best geometry for all molecules were investigated at (6-31G**) basis sets. The total energies, energy gaps, ionization potentials, electron affinities and softness were calculated for the studied molecules. Adding the (OH) ion and Nitrogen, Sulfur atoms to the iso-indene molecules leads to decrease the energy gap and the hardness of the studied molecules. The IR-spectra shows the effect of adding the (OH) ion and Nitrogen, Sulfur atoms in the ring on the vibrations of the reference molecule, the electronic properties and IR spectrum for all molecules were investigated by Gaussian 03 program.
Źródło:
World Scientific News; 2016, 50; 49-63
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diagnostics of the plasma parameters based on the K X-ray line positions for various 4d and 4f metals
Autorzy:
Szymańska, E.
Syrocki, Ł.
Słabkowska, K.
Polasik, M.
Powiązania:
https://bibliotekanauki.pl/articles/148868.pdf
Data publikacji:
2016
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
plasma diagnostic
outer-shell ionization
K X-ray lines
Opis:
This paper shows the theoretical predictions of the outer-shell ionization effect on the positions of Kα1,2, Kβ1,3, and Kβ2 X-ray lines for some 4d-transition metals (molybdenum and palladium) and 4f rare-earth elements (dysprosium and ytterbium). The ionization energy shifts have been evaluated using the multiconfiguration Dirac-Fock method, containing Breit interaction and quantum electrodynamic (QED) corrections. The presented results are important for obtaining the information about some parameters of plasma generated by different sources, especially by pulsed power machine and short-pulse lasers.
Źródło:
Nukleonika; 2016, 61, 4; 437-441
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of Electroflotation Beneficiation of Low-Sulphide and Refractory Gold-Bearing Raw Materials
Autorzy:
Berkinbayeva, Ainur
Atanova, Olga
Kenzhaliyev, Bagdaulet
Efremova, Yuliya
Powiązania:
https://bibliotekanauki.pl/articles/2202224.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
electroflotation
gold-bearing raw material
ionization
electric potential
microbubbles
Opis:
The paper presents the results of experiments with electroflotation beneficiation of gold-bearing raw materials. Three variants of ore samples with 0.56, 1.2 and 5.9 g/t gold grades, which also have different mineralogical and phase composition, were taken as objects of study. Based on the ionization effects, as well as changes in electrostatic and electrokinetic properties of the flotation pulp components, different electrode locations in the flotation chamber were considered. Experiments have shown that for electroflotation processing of raw materials with weakly acidic and neutral medium, positive electric potential of pulp, as well as raw materials with complex mineralogical composition, the negative electrode (cathode) should be placed at the surface of foaming and concentrate assembly, and the positive electrode (anode) in the pulp flow. For electroflotation of raw materials with neutral, alkaline pH and negative electric potential of the pulp, the anode is placed at the surface of the concentrate formation and the cathode is placed in the pulp flow. Thus, additional electrolytic treatment of mineral slurry in the flotation process can increase the gold recovery in the flotation concentrate by an average of 20–30%.
Źródło:
Journal of Ecological Engineering; 2022, 23, 11; 95--100
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An impact of physical phenomena on admittances of partially-depleted SOI MOSFETs
Autorzy:
Tomaszewski, D.
Łukasiak, L.
Gibki, J.
Jakubowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/308410.pdf
Data publikacji:
2001
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
SOI MOSFET
floating body
avalanche ionization
recombination
displacement current
admittance
Opis:
An influence of the selected physical phenomena: impact ionization in silicon and time variation of internal electric field distribution in partially-depleted (PD) SOI MOSFETs on several C-V characteristics of these devices is presented. The role of avalanche multiplication in the so-called "pinch-off" region is discussed in a more detailed way. The analysis is done using a numerical solver of drift-diffusion equations in silicon devices and using an analytical model of the PD SOI MOSFETs. The calculations results exhibit the significance of proper modelling of the phenomena in the floating body area of these devices.
Źródło:
Journal of Telecommunications and Information Technology; 2001, 1; 57-60
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł

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