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    Wyświetlanie 1-6 z 6
    Tytuł:
    Self-absorption correction and efficiency calibration for radioactivity measurement of environmental samples by gamma-ray spectrometry
    Autorzy:
    Misiak, R.
    Hajduk, R.
    Stobiński, M.
    Bartyzel, M.
    Szarłowicz, K.
    Kubica, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/147063.pdf
    Data publikacji:
    2011
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    gamma spectrometry
    efficiency calibration
    self-absorption
    environmental
    Opis:
    In this work empirical functions which relate the full-energy peak efficiency with sample height, energy, matrix composition and bulk density for voluminal samples in a cylindrical counting geometry were found. Accurate determination of the radioactivity of gamma-emitting radionuclides in environmental samples requires taking into account self-absorption. For the obtained self-absorption correction factor, a direct transmission method was chosen. Finally, this paper proposes a simple correlation between the self-absorption correction factor and the bulk density and height of the measured sample for a given energy.
    Źródło:
    Nukleonika; 2011, 56, 1; 23-28
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Self-absorption correction in gamma-ray spectrometry of environmental samples - an overview of methods and correction values obtained for the selected geometries
    Autorzy:
    Jodłowski, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/148531.pdf
    Data publikacji:
    2006
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    gamma-ray spectrometry
    self-attenuation
    self-absorption
    correction factor
    Opis:
    Of major concern are the self-absorption correction factors Cs in precise gamma-ray spectrometry of environmental samples. The overview of Cs determination methods (experimental, Monte Carlo calculations, analytical function application) is presented. Among several available methods, the author chose the one proposed by Debertin where the uncertainty level of Cs correction factor is 1÷2%. The point-like detector model is assumed whilst its efficiency is taken to be proportional to the weighted sum (integral) of the number of photons coming from sample volume elements. Computer program was developed to support the computation of Cs by the Debertin's method for samples in cylindrical geometries and Marinelli beakers. The input data are sample dimensions, density and the mass attenuation coefficient. The Cs uncertainty due to an arbitrarily chosen position of a point-like detector would not exceed 1% for the considered photon energies and the sample density range. Utilising this computer program, the relationships Cs(E,ń) were obtained for the applied geometries and a SiO2 matrix to support routine measurements. The SiO2 matrix is widely encountered in environmental spectrometry. This relationship was derived by fitting the computed data with the function Cs(E,ń) in the form proposed by Bolivar. It was shown that while handling this function to samples with the H2O matrix, the error involved in estimations would not exceed 3%.
    Źródło:
    Nukleonika; 2006, 51,suppl.2; 21-25
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Gamma-Ray Spectrometry Laboratory for high-precision measurements of radionuclide concentrations in environmental samples
    Autorzy:
    Jodłowski, P.
    Kalita, S. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/148485.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    gamma-ray spectrometry
    environmental samples
    efficiency
    self-absorption
    coincidence summing
    Opis:
    The paper outlines the methodology used in the Gamma-Ray Spectrometry Laboratory for high-precision measurements of radionuclide activity concentrations in environmental samples. The Laboratory equipment includes a semiconductor detector HPGe with a 42% relative efficiency. The detector is placed in a Pb housing made of bricks 10 cm in thickness. Three measurement geometries are considered: Marinelli beakers 710 cm3 in volume and two cylindrical geometries 121 and 48 cm3 in volume. In the efficiency calibration (E = 32 division sign 1836 keV) mixed gamma standard solutions were used. Obtained experimental efficiency values epsilon were fitted with two quadratic functions. The junction point is that equivalent to 200 keV. Uncertainty of the calibration curve is 2% for E > 200 keV. The relationship between the total efficiency and the energy epsilon t(E) was also found for energies E = 33 division sign 1250 keV. Self-absorption correction factors Cs are calculated by the method proposed by K. Debertin, the uncertainty level being 1 division sign 2% for E > 100 keV. These correction factors are calculated by an original computer program. Coincidence summing correction factors Cc for the selected nuclides are derived using the ETNA computer program, basing on the relationships epsilon(E) and epsilon t(E). Minimum detectable activity (MDA) for selected nuclides encountered in environmental samples was determined for the water matrix. The methodology used was successfully verified in the course of international intercomparison measurements.
    Źródło:
    Nukleonika; 2010, 55, 2; 143-148
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Collinear double-pulse laser-induced breakdown spectroscopy using Nd:YAG laser generating two nanosecond pulses of regulated energy ratios
    Autorzy:
    Skrzeczanowski, Wojciech
    Skórczakowski, Marek
    Żendzian, Waldemar
    Powiązania:
    https://bibliotekanauki.pl/articles/27311741.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    dual-pulse laser
    double-pulse LIBS
    signal enhancement
    self-absorption
    factorial analysis
    Opis:
    In the paper results of single- and double-pulse LIBS (Laser-Induced Breakdown Spectroscopy) measurements in collinear geometry are described. The experiments were performed using a unique self-made Nd:YAG laser operating in the Q-switching regime, where the laser transmission losses are switched. Such a laser allowed for an easy and quick change of the operating mode (one and two pulses), free shaping of the energy ratio of the two pulses (division of the energy of a single pulse into two parts) and a smooth change of the delay time between pulses in the range from 200 ns to 10 μs. To our knowledge, such a laser was used in LIBS measurements for the first time. LIBS experiments revealed strong self-absorption depending on energy ratios carried out in the first and second laser pulse in the double-pulse mode. This was confirmed also by statistical factorial analysis of LIBS spectra. Plasma temperature and LIBS signal enhancement were measured both for energy proportions between the first and the second laser pulse and for the first-to-second-pulse delay.
    Źródło:
    Metrology and Measurement Systems; 2023, 30, 2; 273--287
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of the new Monte Carlo code AlfaMC to the calibration of alpha-particle sources
    Autorzy:
    Jurado Vargas, M.
    Fernández Timón, A.
    García Orellana, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/148497.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    alpha-particle spectrometry
    code AlfaMC
    Monte Carlo simulation
    scattering and self-absorption
    Opis:
    Measurements of α-particle sources require corrections to the counting rate due to scattering and self- -absorption in the source and the backing material. In this study, we describe a simple procedure to estimate these corrections using the new Monte Carlo code AlfaMC to consider the effects of scattering and self-absorption conjointly, and so to determine the activity of α emitters. The procedure proposed was applied to 235UO2 sources deposited on highly polished platinum backings. In general, the dependence of the efficiency with source thickness was in good agreement with a simple model considering a linear and a hyperbolic behavior for thin and thick sources, respectively, although significant deviations from this model were found for very thin sources. For these very thin sources, the Monte Carlo simulation revealed to be as a required method in the primary calibration of α-particle sources. The efficiency results obtained by simulation with AlfaMC were in agreement with available efficiency data.
    Źródło:
    Nukleonika; 2015, 60, No. 3, part 2; 651-655
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Absorption coefficient along a propagated ultra-short laser pulse in the air based on Kramers–Kronig relations
    Autorzy:
    Malekshahi, M
    Naghavi, K
    Powiązania:
    https://bibliotekanauki.pl/articles/173894.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    ultra-short laser pulse
    refractive index
    self-phase modulation
    absorption coefficient
    Kramers–Kronig relations
    Opis:
    In this manuscript, some effects such as nonlinear Kerr, stimulated Raman, and plasma generation effects lead to obtaining the nonlinear refraction index of the air along an intense ultra-short laser pulse based on one-dimensional propagation analysis. The variations in the pulse frequency by the self-phase modulation effect are investigated for achieving the functionality of the refractive index to the frequency. The mentioned functionality allows implementing Kramers–Kronig relations to measure the absorption coefficient. Results indicate that the front of the laser pulse faces a high rate of the energy loss whereas the back of the pulse experiences a gain. The implementation of Kramers–Kronig relations for a theoretical calculation of absorption coefficient variation along a laser pulse propagating in the air in which we have simultaneously taken into account the three above-mentioned effects distinguishes our work from other studies.
    Źródło:
    Optica Applicata; 2015, 45, 4; 501-512
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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