Accelerator Microbeam Techniques

Abstract

The analytical potential of nuclear interactions induced by accelerated charged particles was demonstrated during the earliest investigations into nuclear structure, when yields of some emitted radiations were interpreted in terms of the number of nuclei available for interaction in the target material. Subsequently, shortly after Hevesy⁽¹⁾ demonstrated that neutron irradiation could provide the basis of analytical measurement, Seaborg and Livingood⁽²⁾ measured the gallium content of iron after irradiation with accelerated deuterons. Analytical techniques based upon charged-particle irradiation were initially overshadowed by methods exploiting neutron irradiation, since simple, sensitive neutron-activation procedures were available and the nuclear reactor offered an intense radiation source capable of irradiating many samples simultaneously. Application of charged-particle techniques was thus largely restricted to the determination of those elements which could not be conveniently measured after neutron activation. These were mainly light elements since (1) high specific activity could be induced in light elements by charged-particle bombardment, and (2) small quantities of characteristic activity from the element to be determined could be isolated by chemistry from large quantities of other activities induced in the sample, for example from a major constituent.