Adjustments to the ICVGT Scale of INRIM

At the 8th Temperature Symposium the results have been presented for the Interpolating Constant Volume Gas thermometer at INRIM (then IMGC), featuring a cryogenic pressure transducer, with an expanded uncertainty of less then 1.5 mK. However, for its fixed points this scale still relied on a NPL calibration as carried by rhodium-iron thermometer 232324. After the clarification, in 2005, by the Consultative Committee on Thermometry (CCT) of the definition of the equilibrium hydrogen (e-H2) triple point this scale was due to be adjusted for the isotopic content in the e-H2 fixed point cell. Only when this thermometer was re-calibrated in 2010 at INRIM at the three fixed points of the ICVGT was this adjustment performed, being the isotopic composition of the hydrogen cell known. With the start of the Neon Project in 2005, it became clear that a second adjustment would soon be needed, once the CCT will have decided on the way to deal with the isotopic composition of neon. The paper presents the experimental data of 2010, discusses the stability of the thermometer, and the size of the correction at the hydrogen point and of the likely correction (and its uncertainty) to be applied to the neon point, the isotopic composition of this cell being known as well.