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CCM Task Group on the Phases for the Dissemination of the kilogram following redefinition (CCM-TGPfD-kg)

Terms of reference

The dissemination of the kilogram after 20 May 2019 will take place in three consecutive phases:

    Present traceability (taking into account the additional uncertainty coming from the new definition),

    Dissemination of the consensus value,

    Dissemination of individual realizations.

Based on "the mise en pratique of the definition of the kilogram" and on "the CCM short note on the dissemination process after the proposed redefinition of the kilogram" the task group will:

    Ensure the correct implementation of the present traceability across the period of the redefinition of the kilogram,

    Propose a detailed calculation of the consensus value and its uncertainty and oversee the transition for the "present traceability" to the use of the consensus value,

    Propose methods to maintain the best possible stability of the consensus value over time (including comparison periodicity),

    Propose clear criteria for moving from the consensus value dissemination phase to the individual realization dissemination phase,

    Maintain a detailed document describing the three dissemination phases for the CCM and the mass community. This document includes the calculation of the consensus value, its uncertainty and time scale as well as any other relevant information related to the dissemination of the kilogram,

    Provide advice to the CCM-WGD-kg and CCM-WGR-kg in all questions regarding traceability of the kilogram during the first two phases above.


  • Dr Stuart Davidson (chair CCM WGD-kg, NPL)


  • Dr Hao Fang (BIPM)
  • Dr Dorothea Knopf (PTB)
  • Ms Maria Nieves Medina (CEM)
  • Dr Lars Nielsen (DFM)
  • Dr Philippe Richard (METAS)
  • Dr Alan Steele (NRC)
  • Dr Michael Stock (BIPM)

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