Transcript Summer practice Dubna 13.7.-31.7.2011

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
Neutron Activation Analysis
Department of NAA and Applied Research
Division 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 eV
Epithermal 0.5 eV-100 keV
Fast 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 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
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/