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    Wyświetlanie 1-5 z 5
    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:
    Measurement of anthropogenic radionuclides in post-Fukushima Pacific seawater samples
    Autorzy:
    Lutter, G.
    Tzika, F.
    Hult, M.
    Aoyama, M.
    Hamajima, Y.
    Marissens, G.
    Stroh, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/148313.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    detection limit
    Fukushima
    gamma-ray spectrometry
    Monte Carlo
    radiocesium
    underground laboratory
    Opis:
    Following the accident at the Daiichi Fukushima nuclear power plant in 2011, a vast number of Pacific seawater samples from many locations far from Fukushima have been collected by Japanese investigators. Due to dilution, the activities of radionuclides from North Pacifi c seawater samples are very low, which calls for extraordinary measures when being measured. This study focuses on the metrological aspects of the gamma-ray spectrometry measurements performed on such samples in two underground laboratories; at HADES (by JRC- -IRMM in Belgium), and at Ogoya (by Kanazawa University in Japan). Due to many samples and long measurement times, all available HPGe detectors needed to be employed. In addition to single coaxial detectors, this involved multidetector systems and well detectors. Optimization of detection limits for different radionuclides and detectors was performed using Monte Carlo simulations.
    Źródło:
    Nukleonika; 2015, 60, No. 3, part 2; 545-550
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Np-237 incineration study in various beams in ADS setup QUINTA
    Autorzy:
    Kilim, S.
    Strugalska-Gola, E.
    Szuta, M.
    Bielewicz, M.
    Tyutyunnikov, S. I.
    Furman, W. I.
    Adam, J.
    Stegailov, V. I.
    Powiązania:
    https://bibliotekanauki.pl/articles/146295.pdf
    Data publikacji:
    2018
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    Np-237
    accelerator-driven system
    ADS
    gamma-ray spectrometry
    fission
    neutron capture
    Opis:
    Neptunium-237 samples were irradiated in a spallation neutron fi eld produced in accelerator-driven system (ADS) setup QUINTA. Five experiments were carried out on the accelerators at the JINR in Dubna – one in carbon (C6+), three in deuteron, and one in a proton beam. The energy in carbon was 24 GeV, in deuteron 2, 4 and 8 GeV, respectively, and 660 MeV in the proton beam. The incineration study method was based on gamma-ray spectrometry. During the analysis of the spectra several fi ssion products and one actinide were identifi ed. Fission product activities yielded the number of fi ssions. The actinide (Np-238), a result of neutron capture by Np-237, yielded the number of captures. The main goal of this work was to fi nd out if and how the incineration rate depended on parameters of the accelerator beam.
    Źródło:
    Nukleonika; 2018, 63, 1; 17-22
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Cosmogenic radionuclides in the Sołtmany (L6) meteorite
    Autorzy:
    Laubenstein, M.
    Giampaoli, A.
    Janowski, P.
    Mietelski, J. W.
    Powiązania:
    https://bibliotekanauki.pl/articles/411508.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Meteorytowe
    Tematy:
    meteorite
    ordinary chondrite
    short-lived radionuclides
    cosmogenic radionuclides
    gamma-ray spectrometry
    52Mn
    Opis:
    Cosmogenic radionuclides were measured in two specimens of the Sołtmany chondrite (L6) that fell on April 30, 2011. The first fragment (154.9 g) was measured 12 days after the fall and the second piece (120 g), 53 days after the fall. Both fragments were measured by means of non-destructive gamma ray spectroscopy. The first specimen was examined with an ultra-low background high purity germanium (HPGe) detector in a deep underground laboratory. A standard low-background HPGe detector was used to examine the second fragment in a ground level laboratory. Twelve cosmogenic nuclides were detected in the activity range of 0.030 m・Bq g–1 until 1.5 m・Bq g–1 Their activities place constraints on the exposure history of the meteorite and reflect the effect of solar modulation of galactic cosmic rays during the solar maximum. On the activities of expected radionuclides 60 Co (< 0.0075 m・Bq g–1) and 44 Ti (< 0.023 m・Bq g–1) only upper limits could be given. Sołtmany is part of a group of only 14 meteorites where 52 Mn (5.591 d half life) could be determined.
    Źródło:
    Meteorites; 2012, 2, No. 1-2; 45-51
    2299-0313
    2299-1220
    Pojawia się w:
    Meteorites
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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