1. Student Practice in JINR Fields of Research Dubna 13.7.-31.7.2011 Vlasta Zdychová, Martina Benešová CTU in Prague Czech Republic Pavol Blahušiak, Alexander Szabó, Juraj Sabo UK in Bratislava Slovakia Supervisor: prof. M. V. Frontasyeva

2. Neutron Activation Analysis Department of NAA and Applied Research Division of Nuclear Physics Frank Laboratory of Neutron Physics Joint Institute for Nuclear Research Dubna

3. 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.

4. How NAA works

5. Energy distribution of neutron flux Thermal 0.025 eV-0.5 eV Epithermal 0.5 eV-100 keV Fast 100 keV-25 MeV

6. 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.

7. 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

8. IBR-2 Pulsed Reactor at FLNP in JINR average heat power 2 MW peak pulse power 1500 MW average thermal neutron flux 1013 cm -2 s -1 3-loop cooling system ensures appropriate conditions for biological samples (60-70°C)

9. Principal technological scheme of the reactor 1 - Reactor Vessel 2 - Core 3 - Main Movable Reflector 4 - Additional Movable Reflector 5 - Moderator 6 - Stationary Reflector 7 - I Cooling Loop 8 - II Cooling Loop 9 - Na pump 10 - Heat Exchanger Na/air 11 - Intermediate Heat Exchanger

10. 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

11. Preparing of samples

12. Analysis of spectra peak recognition peak fitting assignment of specific peaks to radionuclides determination of activity from peak area

13. 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

14. Thank you for your attention

15. 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/