The activation analysis of carbon in silicon with the aid of 3He ions compared to that with deuterons

The activation analysis of C in Si according to 12C (3He, α)11C shows both advantages and drawbacks when compared with deuteron activation. With identical particle energies the sensitivity is lower for 3He ions but interference reactions are remarkable only at higher energies and the activity ratio 11C/13N is becoming more favourable with increasing decay time. The longer half-life of 11C facilitates chemical treatment, and the measurement can be performed at normal temperature. Otherwise, the irradiation and measuring times required are longer. Main disadvantages are the poor availability of the cyclotron as a 3He accelerator and the difficulty to obtain an optimum particle current of 0.3 ... 0.6 μAcm-2. Detection limits are 1 x 1014 at.cm-3 with 3He and 3 x 1014 at.cm-3 with deuterons. (author)