Radioactivation analysis with heavy ion beams

Abstract

Heavy ion activation analysis (HIAA) was evaluated for the determination of low Z elements Z (LESSTHEQ) 8. These target species were bombarded with ion beams of 3 (LESSTHEQ) Z (LESSTHEQ) 8 and energies (TURN) 1 MeV/amu. The experimental effort focused on nuclear reactions yielding (beta)('+) emitting isotopes with half-lives of (GREATERTHEQ) 10 seconds. With the beams and energies considered, only elements of Z (LESSTHEQ) 8 activate. The sample depth probed is shallow (a few mg/cm('2)). Hence, HIAA is well suited for the determination of lowest Z species in thin layers. Four heavy ion beams, ('6)Li, ('9)Be, ('12)C, and ('14)N, were found to induce reactions which could be employed for trace analysis. Percent interferences (the activity created from an equal amount of the interfering target element) were calculated from experimental data. Carbon can be analyzed via the ('6)Li reaction ('12)C(('6)Li,(alpha)n)('13)N. Beryllium produces a 500% interference from the reaction ('9)Be(('6)Li,2n)('13)N. Lithium was determined via the reaction ('7)Li(('12)C,n)('18)F with only a 5% interference from boron. HIAA with ('9)Be allowed for trace determination of boron and nitrogen. The reactions involved are ('10)B(('9)Be,n)('18)F, ('11)B(('9)Be,2n)('18)F, and ('14)N(('4)Be,(alpha)n)('18)F. For boron determination, there is a 50% interference from nitrogen and a 0.5% interference from carbon. For nitrogen analysis, boron and carbon present a 200% and 1% interference, respectively. Nitrogen activates lithium and beryllium: ('6)Li(('14)N,d)('18)F, ('7)Li(('14)N,t)('18)F, and ('9)Be(('14)N,(alpha)n)('18)F. For determination of either element a 100% interference is caused by the other element if present. ...