1. AA&A spring 20021 NAA—Suggested applications coal, metals, sediments, ores, tissues, bone, synthetic fibers, alloys, bullets, crystals, gems, glass, hair, gunshot residues, moon samples, wheat spores, wood, tree leaves, tree needles, plastic films, rocks, salts, shells, skin, soil, sugar, teeth, minerals, metals, meteorites, obsidian, ocean sediments, oxides, and fingernails (but no artists’ pigments???)

2. AA&A spring 20022

3. 3 Neutron Activation Analysis NAA Some NAA and also a reactor tour (Wisconsin)Some NAAreactor tour Excellent review of NAA (Missouri)review of NAA The Ward Lab web site (Cornell)Ward Lab

4. AA&A spring 20024 Neutron induced radioactivity Irradiate sodium (Na23) sample with neutrons –Neutron captured to give Na24 in excited state –Jumps to lowest state of Na24—> emits gamma-ray(s) (photon) –With 1/2 life 15 hours: Na24 emits electron to become Mg24 (beta decay) And another gamma (photon) Electrons —> autoradiography (next week) Gammas —> NAA Similar story for many (not all) elements

5. AA&A spring 20025 Nuclear vs. atomic spectra Electronic transitions in atoms –Spectral lines in the visible (~500 nm), ultra-violet (~10-400 nm), X-rays (~0.01-10 nm) –Photon energies ~ 2 eV, ~ 3-100 eV, ~ 100 eV -100 keV Neutron or proton transitions in nuclei –Spectral lines at even shorter wavelengths –Photon energies ~ 100 keV-??? MeV = gamma rays Nuclear emits gamma ray(s) characteristic of particular isotope (nuclide)

6. AA&A spring 20026 e e Gamma-ray spectrometer Q Voltage supply Germanium crystal e h h h e + — display Multichannel pulse- height analyzer gamma ray energy counts

7. AA&A spring 20027 Multielement analysis Peaks at energies characteristic of various nuclides Peak heights proportional to number of nuclei

8. AA&A spring 20028 Preferential nuclide selection activity irradiation time short 1/2-life long 1/2-life short long activity delay time short long short 1/2-life long 1/2-life

9. AA&A spring 20029 Advantages of NAA Simultaneous analysis for many elements Chemical preparation rarely necessary Non-destructive testing Reliable quantitative results Very high sensitivity (for some elements)

10. AA&A spring 200210 Sensitivity for different elements 19 elements not even listed! 2 3 5 23 22 12 4 2 73 1 atom in a million-million in a 1 gram sample 1 atom in a hundred thousand in a 1 gram sample Bottom line— great analysis technique—IF you’ve got the right problem 10 -12 g

11. AA&A spring 200211 NAA—Suggested applications coal, metals, sediments, ores, tissues, bone, synthetic fibers, alloys, bullets, crystals, gems, glass, hair, gunshot residues, moon samples, wheat spores, wood, tree leaves, tree needles, plastic films, rocks, salts, shells, skin, soil, sugar, teeth, minerals, metals, meteorites, obsidian, ocean sediments, oxides, and fingernails (but no artists’ pigments???)

12. AA&A spring 200212 Swimming pool

13. AA&A spring 200213 Reactor guts