1. AA&A spring 20021

2. 2 "Portrait of the Artist as a Landscape" W.S. Taft, 1997

3. AA&A spring 20023 X-rays X-ray source guts spine film Radiography Excitation beam: X-rays, electrons, ions, protons X-ray energy analyzer sample X-rays Spectroscopies—XRF and PIXE

4. AA&A spring 20024 What else can we probe with? Recall NAA: irradiate sample with neutrons Converts some nuclides into radioactive elements –Gamma rays—analysis of spectra gives nuclide, hence elemental composition—NAA Normally small samples place in reactor core Also possible—irradiation of full painting (if small) in beam outside reactor Analogous to X-ray emission spectroscopies –Irradiating beam leaves sample in excited state –Returns to quiescent state by characteristic radiation

5. AA&A spring 20025 Same information from both? Yes and no— –Both give us elemental analysis of materials of the painting –NAA —Sensitivity depends on accidents of the nuclear physics –X-ray emission good sensitivity but varies smoothly with atomic number: not useful for lightest elements

6. AA&A spring 20026 Neutron radiography???? Try same setup as for X-rays—— neutron source painting film For some problems, yes O-ring example from Ward tour For paintings, NO too little absorption by thin paint layer

7. AA&A spring 20027 What about those beta rays? Neutron induced typically gives both gamma and beta activity Betas (electrons) will expose photographic film Let’s try “autoradiography”

8. AA&A spring 20028 Autoradiography painting film neutron source Nuclides activated by neutrons Film exposed by electrons Two step process How to know what you’re seeing?? count gammas at the same time some information about source of beta activity neutron electron gamma

9. AA&A spring 20029 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

10. AA&A spring 200210 RadiationPhysicsElement analysisRadiography X-rays atomicXRF, PIXEX-radiography NeutronsnuclearNAAautoradiography Four techniques

11. AA&A spring 200211