Dependence of the triple point temperature of neon on isotopic composition and its implications for the ITS-90

The paper summarizes the results of an International Project started in 2003 aimed at formulating a correction for the variability of isotopic composition found in 'natural' neon, and presently not taken into account by the ITS-90 definition, whose consequent ambiguity leads to a combined uncertainty uc = 160 μK, whereas uc = 30-50 μK for the rest of the budget. After a very short summary of the Project results (a detailed Final Report will be published later) recommendations for the correction function are presented, in agreement with both the experimental data and the theoretical calculations.