Modern techniques based on cyclotron beams for materials characterization

Some applications of elemental analysis methods (Particle Induced X-ray Emission-PIXE, Particle Induced Gamma-ray Emission-PIGE, Charged Particle Activation-CPA, Rutherford Backscattering-RBS) in characterization of various materials (archaeological objects-copper and lead coins, ceramics, glass, polymers, metals) at the Bucharest Cyclotron are presented. To analyze archaeological samples, we used in vacuum PIXE (4.7 MeV alpha-particles) and in air PIXE (3 MeV protons). Maximum sensitivities were obtained in the 22 ≤ Z ≤ 30 region. For light elements determination (0, Na, Mg, Al, Si) fast neutron activation analysis (FNAA) method, based on 13.5 MeV deuteron beam on a thick Be target (7.8x108 n/cm2.s flux at 20 cm behind the target, average energy ca. 5.5 MeV) was used. For P and S determination in polymers, the CPA method was used (22 MeV alpha particles and 14 MeV protons, respectively). The 2120 keV gamma-ray of 34mCI radioisotope (Ti1/2=32.5 min.) was measured by a 70 cc Ge(Li) detector. RBS technique is a remarkable application of 3-5 MeV alpha particle beams. Two cases of surface absorbed fluorine and chlorine determination by PIGE and RBS are reported. Studies on dose and energy dependence of blistering and flaking on stainless steels, Ni, Cu, Mo produced by 3.0, 4.7 and 6.8 MeV He+ ions irradiation are also presented. Using SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy) techniques, irradiation phenomena as sponge- and wave-like structures, submicron cracks, micro-craters, helium bubbles on matrix, grain boundaries, loops and Ti C precipitates are illustrated. We report the experimentally determined values for the blisters average diameter and for the critical fluences inducing blistering. It is discussed the potential validity in these cases of the stress-induced model of blistering