High Energy Heavy Ion RBS, ERDA and Channelling

Abstract

In recent years, a significant number of high-energy Tandem accelerators has become available for materials science applications, thus allowing Rutherford scattering techniques (such as RBS, ERDA and channelling) to utilise heavier and more energetic ion beams when desirable. The basic concepts will be discussed, with special emphasis on the advantages and limitations of extending it to much heavier ions than the 1–3 MeV 4He beam that is normally used. Note that, for most RBS and channelling applications to materials science problems, the traditional and widely available beam of 1–3 MeV 4He ions will continue to be the optimum choice. Nevertheless, in certain RBS applications, the improved mass resolution achievable with heavier ion beams of comparable velocity (i.e., ∼ 1 MeV/mass unit) offers an important advantage. On the other hand, with the ERDA technique, there are always significant advantages in using the heaviest ion beam available (for example, 200 MeV 197Au or 130 MeV 127I ions), provided a 2-dimensional ΔE+E detector system is available. In such cases, ERDA becomes a semi-universal analytical technique in which almost all elements up to at least mass 100 may be analysed simultaneously as a function of depth.