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Principles of NAA

Egyptian Atomic Energy Authority-Egypt Second Research Reactor ETRR-2 Department of Neutron Activation Analysis, Frank Laboratory of Neutron Physics Joint Institute for Nuclear Research, Dubna, Russia. Principles of NAA. Mohamed Abdullah Mohamed El SAIED. Supervisor Dr. Marina FRONTASYEVA.

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Principles of NAA

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  1. Egyptian Atomic Energy Authority-Egypt Second Research Reactor ETRR-2 Department of Neutron Activation Analysis, Frank Laboratory of Neutron Physics Joint Institute for Nuclear Research, Dubna, Russia Principles of NAA Mohamed Abdullah Mohamed El SAIED Supervisor Dr. Marina FRONTASYEVA

  2. Theory of NAA: Neutron capture by a target nucleus followed by the emission of gamma rays

  3. Pulsed fast reactor IBR-2 Dubna

  4. Ch1-Ch4 –irradiation channels, S- intermediate storage, DCV- directional control valves, • L- loading unit, RCB- radiochemical glove-cell, U- unloading unit, SU- separate unit, • SM- storage magazine, R- repacking unit, D- Ge(Li) detector, AA- amplitude analyser, • CB- control board, CC- CAMAC controller, R1-R3- the rooms where the system is located

  5. Neutron energy spectra and irradiation channels • Neutron energy spectra • in irradiation channels CH1()and CH2 (curve) The main characteristics of the irradiation channelsat 1.5 MW

  6. Sampling Sample Preparation Irradiation Steps of Neutron Activation Analysis Measurements Data Analysis Calculations

  7. Sample preparation for NAA

  8. Irradiation: After delayed time td : For a counting time tc : A: number of decay per second (activity) N: number of atom of target isotopes; l: decay time Tirr: irradiation time , s: activation cross section , f : neutron Flux

  9. Measurements: Using semiconductor detector :HPGe

  10. Analysis of gamma-ray spectra:

  11. Using Gamma-ray Counts to Calculate Element Concentration irradiate the unknown sample and a comparator standard containing a known amount of the element of interest together in the reactor. If the unknown sample and the comparator standard are both measured on the same detector, then one needs to correct the difference in decay between the two OR

  12. Advantages: • No sample digestion, extraction, volume loss, or dilution required. • No potential for contamination due to handling or laboratory chemicals. • One simple procedure can analyze 30+ elements simultaneously. • High sample volume capabilities. • Cost effective & affordable for small and large sample quantities. • Quick turnaround – standard results available within 5-10 working days. • Faster turnarounds possible – 24 hrs to 3 days. • Limited sample volume capability – gram, milligram and microgram in many cases. • High precision – reproducibility of quality controls over long periods of time (years) is often better than 2% relative standard deviation (RSD). • Primary analytical method used by the National Institute of Standards & Technology (NIST) to certify elemental concentrations in Standard Reference Materials (SRMs). Applications: • Polymers, resins, adhesives, and organic solids . • Pharmaceutical materials . • Semiconductor and high-purity . • Fine chemicals, solvents, and organic liquids . • Catalysts. • Environmental. • Nutritional & epidemiological . • Forensic. • Archeological. • Development of performance standards .

  13. Thanks for your Attentions

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