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

Theory of NAA:

Neutron capture by a target nucleus followed by the emission of gamma rays

Pulsed fast reactor IBR-2 Dubna

S C h1 C h3 C h0 C h4 C h2 C d BS BS R C B U L D C V S M 32 S U d28 R d28 R 1 d16 D D D R 2 A A C C IBM P C C B R 3 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

Neutron energy spectra and irradiation channels

10 10 10 14 13 12 10 10 10 10 10 10 11 10 9 8 7 6 10 10 5 4 10 10 3 2 10 10 1 0 10 10 -1 -2 10 -2 10 -1 10 0 10 1 10 2 10 3

E (eV)

10 4 10 5 10 6 10 7 Neutron energy spectra in irradiation channels CH1(  ) and CH2 (curve) The main characteristics of the irradiation channels at 1.5 MW Irradiation site Ch1 Ch2 Ch3 Ch4 Neutron flux density (n/cm 2 s) 10 12 Thermal Cd-coated 1.23

Gd-coated 4.2

Resonance 3.31

2.96

7.5

7.6

4.32

4.1

7.7

7.7

Fast T 0 C 70 60 30-40 30-40 Channel diam., mm 28 28 30 30 Channel length, mm 260 260 400 400

Steps of Neutron Activation Analysis

Sampling Sample Preparation Irradiation Measurements Data Analysis Calculations

Sample preparation for NAA

Irradiation:

After delayed time t d : For a counting time t c : A: number of decay per second (activity) N: number of atom of target isotopes; l: decay time T irr: irradiation time , s: activation cross section , f : neutron Flux

Measurements: Using semiconductor detector :HPGe

Analysis of gamma-ray spectra

:

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

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 .

Thanks for your Attentions