S tudent P ractice in JINR Fields of Research Dubna 13.7.-31.7.2011
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Transcript of S tudent P ractice in JINR Fields of Research Dubna 13.7.-31.7.2011
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Student Practicein JINR Fields of Research
Dubna 13.7.-31.7.2011
Vlasta Zdychová, Martina BenešováCTU in Prague Czech Republic
Pavol Blahušiak, Alexander Szabó, Juraj SaboUK in Bratislava Slovakia
Supervisor: prof. M. V. Frontasyeva
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Neutron Activation Analysis
Department of NAA and Applied ResearchDivision of Nuclear Physics
Frank Laboratory of Neutron Physics Joint Institute for Nuclear Research
Dubna
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Introduction
• NAA was discovered in 1936 by G. Hevesy (Hungary) and H. Levi (Denmark), who found the samples containing REE.
• Neutron activation analysis is an isotope specific analytical technique for the qualitative and quantitative determination of elemental content.
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How NAA works
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Energy distribution of neutron flux
Thermal 0.025 eV-0.5 eVEpithermal 0.5 eV-100 keVFast 100 keV-25 MeV
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Types of NAA
• Destructive (radiochemical) – the resulting radioactive sample is chemically decomposed and the elements are chemically separated.
• Non-destructive (instrumental) – sample is kept intact and the radionuclides are determined, taking advantage of the differences in decay rates via measurements at different decay intervals.
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Characteristics of INAA
• Non-destructive analysis• Multi-element analytical technique• The chemical form and physical state of the
elements do not influence the activation and decay process
• Suitable even for determination of masses in the order of 10–6–10–9 g and less
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IBR-2 Pulsed Reactor at FLNP in JINR • average heat power 2 MW
• peak pulse power 1500 MW
• average thermal neutron
flux 1013 cm-2s-1
• 3-loop cooling system
ensures appropriate
conditions for biological
samples (60-70°C)
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Principal technological scheme of the reactor
1 - Reactor Vessel2 - Core3 - Main Movable Reflector4 - Additional Movable Reflector 5 - Moderator6 - Stationary Reflector7 - I Cooling Loop8 - II Cooling Loop9 - Na pump10 - Heat Exchanger Na/air11 - Intermediate Heat Exchanger
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Project Regata - Biomonitoring of atmospheric deposition of heavy metals and other
elements
• Moss collection• Preparation of samples for irradiation • Pellets irradiation• Detection of activated elements • Analysis
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Preparing of samples
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Analysis of spectra
• peak recognition• peak fitting• assignment of specific peaks to radionuclides• determination of
activity from peak area
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Conclusion
• Theory of NAA• Preparing of samples for irradiation• Calibration and adjustment of semiconductor
detectors • Analysis of gamma spectra• Determination activity and concentrations of
interested elements
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Thank you for your attention
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References
• P. Bode, J. J. M. de Goeij, Activation Analysis, Encyclopedia of Environmental Analysis and Remediation
• P. Bode, Instrumental and organizational aspects of a neutron activation analysis laboratory
• M. V. Frontasyeva, Neutron Activation Analysis in the Life Sciences
• http://archaeometry.missouri.edu/naa_overview.html• http://flnp.jinr.ru/34/