Application of imaging plate technique for separate detection of 3H and 14C

A tracer technique using 14C, which is a β-decaying radioactive isotope, is being planed to understand the carbon migration behavior in fusion devices. An imaging plate (IP), which is a radiation image detector successfully applied for the tritium analysis of plasma-facing walls, easily detects β-electrons from 14C and would give a detailed 14C deposition profiles, hence the IP method can be one of the postmortem measurements of the 14C deposition. However, since β-electrons from tritium would superpose those from 14C, it is essential to differentiate β-electrons of 14C from those of tritium. To do this, we have developed a film insertion technique in which a thin film is inserted between a specimen and IP to prohibit lower energy electrons passing through the film. It is found that 14C concentrations as small as 10 Bq/cm2 (∼2.6 × 1012 14C/cm2) can be detected, indicating that this technique keeps the advantage of 14C as a high sensitivity tracer, and making two-dimensional 14C profiling possible without any disturbance of co-existing tritium.