A new design of 238Pu activity sources for use in intercomparison exercises.

Abstract In the framework of a BIPM 238 Pu comparison exercise, a new design for α -radiation counting sources was developed. These sources are constructed with a gold-coated Vyns film stretched over a stainless-steel disk. To improve the crystallization of the radioactive salt, the physical properties of the gold-coated polymer surface which receives the radioactivity deposit is modified. A pad of polystyrene micro-spheres (Estapor ® K-007) mixed with a wetting agent (Tween 20 ® ) is directly electrosprayed before the radioactive drop is deposited. After hot air-drying, the source is finally sealed with a thin Vyns film covering the entire radioactive spot. This new design makes it possible to create 238 Pu sources that are easy and safe to handle, homogeneous and stable during ageing.