“Realisation of the becquerel”—reducing the impact of equipment failure

• The goals of the “Realisation of the becquerel” project of CCRI(II) are presented.
• Reproducible source holder designed and tested.
• New ionisation chamber design with better definition of sensitive volume proposed.
• The advantages of the new design are discussed.

The goal of the CCRI(II) “Realisation of the becquerel” project is to design a reproducible radioactivity standard which will increase the robustness of the current international reference system for radioactivity measurements. Tests performed with a first prototype ionisation chamber of this project, built in 2005, are presented. Based on experience with the first prototype, a new design was proposed in 2010 aiming at achieving the very ambitious project goals. The article discusses the status of the project and the advantages of the new design.