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

Neutron Activation Analysis

Department of NAA and Applied ResearchDivision of Nuclear Physics

Frank Laboratory of Neutron Physics Joint Institute for Nuclear Research

Dubna

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.

How NAA works

Energy distribution of neutron flux

Thermal 0.025 eV-0.5 eVEpithermal 0.5 eV-100 keVFast 100 keV-25 MeV

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.

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

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)

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

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

Preparing of samples

Analysis of spectra

• peak recognition• peak fitting• assignment of specific peaks to radionuclides• determination of

activity from peak area

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

Thank you for your attention

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/