JAST
2012 March;3(1):42-71.
Published online 2012 March 15.
doi:http://dx.doi.org/10.5355/JAST.2012.42
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| Copyright ⓒ 2010 Journal of Analytical Science & Technology |
| New Gamma-Spectrometry Technologies for Environmental Sciences |
| Pavel P. Povinec |
| Comenius University, Faculty of Mathematics, Physics and Informatics, Department of Nuclear Physics and Biophysics, SK-84248 Bratislava, Slovakia |
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Corresponding Author:
Pavel P. Povinec ,Tel: +421 260295544, Fax: +421 265425882, Email: povinec@fmph.uniba.sk |
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ABSTRACT |
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| HPGe-spectrometers operating in underground laboratories represent the most important recent achievements in the radiometric sector mainly because of better sensitivity, which enabled to decrease a sample size by about a factor of ten, and to carry out new applications of radionuclides as tracers of environmental processes. |
| Keywords: radiometrics, HPGe-spectrometer, background, Monte Carlo simulation, underground laboratory, atmospheric radioactivity, global fallout, Chernobyl accident, Fukushima accident, radionuclide seawater profiles |
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FIGURES |
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Fig.1
Large volume (270 L) seawater sampler (top) and Rosette multi-bottle sampler with 20 L bottles. |
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Fig.2
Large volume tanks (400 L) for separation of radionuclides from seawater on the shipboard. |
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Fig.3
Interaction of a primary high energy cosmic-ray proton with an atmospheric nucleus with production of secondary particles. |
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Fig.4
Measured muon fluxes in underground laboratories (data compilation from literature). |
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Fig.5
Measured muon fluxes in underground laboratories (data compilation from literature). |
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Fig.6
Calculated muon energy loss in standard rock from ionization, bremsstrahlung, pair production and nuclear reactions. |
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Fig.7
Simulated (bottom) and measured (top) background spectra of a HPGe detector (modified after [4]). |
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Fig.8
Monte Carlo simulated background spectra of a HPGe detector in a lead shield of different thickness. |
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Fig.9
Normalized integral background counting rates (40-2700 keV) of HPGe detectors operating underground. The solid line represents the muon flux normalized to the surface laboratory. Abbreviations of underground laboratories: MPI – Max Planck Institut für Kernphysik (Heidelberg, Germany); IAEA – International Atomic Energy Agency (Environmental Laboratories in Monaco); VKTA – Verein für Kernverfahrenstechnik und Analytik (Rossendorf, Germany), LLRL – Low-level Radioactivity Laboratory, Kanazawa University (Japan); IRMM - Joint Research Centre, Institute of Reference Materials and Metrology (Geel); PTB – Physikalisch-Technische Bundesanstalt (Braunschweig, Germany); LNGS - Laboratori Nationali del Gran Sasso (Assergi, Italy); LSM – Laboratoire Souterrain de Modane (Modane, France). |
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Fig.10
Geometry for calculation of muon interactions with HPGe detectors using the GEANT code. |
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Fig.11
Simulation of muon pass through a HPGe detector using a GEANT code (muon momentum 50 GeV/c; energy deposited in the crystal was 1717 keV). |
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Fig.12
High-energy part of the HPGe-detector gamma-spectrum. |
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Fig.13
Geometry of the HPGe-NaI(Tl) anti-Compton gamma-spectrometer. |
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Fig.14
Monte Carlo simulated background spectra of an anti-Compton gamma-spectrometer with 100 % HPGe detector located in underground laboratory at 20 m w.e. (horizontal position – solid line; vertical position – dots). |
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Fig.15
Background reduction factors for the anti-Compton gamma-spectrometer at sea level (open circles – vertical position; dots – horizontal position). |
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Fig.16
Measured background gamma-spectrum of a well HPGe detector (200 % relative efficiency to 7.6 cm diameter x 7.6 cm long NaI(Tl) detector) placed in a lead shield of 12.5 cm thickness in the IAEA underground laboratory in Monaco. |
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Fig.17
137Cs activity concentrations in atmospheric aerosols in the Bratislava air (Slovakia, Central Europe). |
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Fig.18
137Cs seawater profiles across Pacific (30°S), Indian (20°S) and Atlantic (30°S) Oceans. The observed 137Cs levels indicate transport of water masses from the North Pacific to the South Pacific (to the Tasman Sea), via Indonesian Seas to the Indian Ocean, and then via Agulhas current to the South Atlantic Ocean (modified from [18-20]. |
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