Comparison of replicated isotopic-composition assays and thermal analyses on neon

In the last ten years a comprehensive study has been conducted on neon of different isotopic compositions, including high-purity 20Ne and 22Ne, for thermometric purposes—the effect of isotopic composition on the triple point temperature of neon 1–4 and references therein. The studies necessarily included, in particular, assays on the isotopic composition of more than twenty samples of high chemical purity neon of ‘natural’ composition of commercial origin. These assays were obtained at different times from three different laboratories. Some were also replicated, in order to further check the consistency of the results. As an integral part of the studies, thermal analyses were performed on these samples, consisting in the, repeated, high-accuracy (better than ≈50 K) determination of the liquidus-point temperature of the triple point, as resulting from the calorimetric determination of the full melting plateau at this point in metal cells where each sample was permanently sealed, according to the almost 40-years-old experience and technique of INRIM 2. The paper summarises the results obtained, discusses the problems arising from them, namely the inconsistencies observed for a number of samples, as evident from Figure 1. Some justifications are attempted for these inconsistencies.