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Most of the thermometers used for the dissemination of the International Temperature Scale of 1990 (ITS-90) to the industry are long-stem Standard Platinum Resistance Thermometers (SPRTs). In the low temperature range, they are generally used from the triple point of water (273.16 K) down to the triple point of argon (83.805 8 K). The lack of equipment for routinely calibrating thermometers below 83 K (except comparisons at the nitrogen boiling point) limits their use at lower temperatures. The LNE-Cnam has recently developed an innovative calorimeter to improve the calibration of long-stem SPRTs at the triple point of argon and to extend the calibration range down to the oxygen triple point (54.358 4 K). Results show that at the argon triple point further investigations are needed to ascertain a reduction of the calibration uncertainty, with respect to the previous system developed by the laboratory. At the oxygen triple point, uncertainties are below the millikelvin level. With this device, the LNE-Cnam...

Mechanisms for double-electron capture producing projectile doubly-excited states in Ne10++He collisions are studied. Emphasis is given to slow collisions with projectile energies of a few keV. At these impact energies the production of configurations 3lnl′ of nonequivalent electrons (n⩾6) is dominant. The creation of these nonequivalent electron states Ne8+(3lnl′) with n⩾6 originates from dielectronic processes involving electron-electron interaction. The present close-coupling calculations are compared with our recent measurements of absolute double-capture cross sections. A fairly good agreement between theory and experiment is found, especially for the total double capture as well as for the significantly populated configurations 3l6l′.Mechanisms for double-electron capture producing projectile doubly-excited states in Ne10++He collisions are studied. Emphasis is given to slow collisions with projectile energies of a few keV. At these impact energies the production of configurations 3lnl′ of nonequivalent electrons (n⩾6) is dominant. The creation of these nonequivalent electron states Ne8+(3lnl′) with n⩾6 originates from dielectronic processes involving electron-electron interaction. The present close-coupling calculations are compared with our recent measurements of absolute double-capture cross sections. A fairly good agreement between theory and experiment is found, especially for the total double capture as well as for the significantly populated configurations 3l6l′.

We report an extension of the molecular treatment of Ion‐Atom collisions at intermediate impact energies. It is first analysed how the ionization mechanism is taken into account through the population of bound excited states, leading mainly to a saturation of electron capture cross‐sections. Finally, the introduction of molecular pseudostates in the expansion of the time dependant electronic wave function allows to explicitly take into account the ionization channel and to calculate with a good accuracy ionization, excitation and electron capture cross sections in a large range of impact velocities (0.1

We present a theoretical study of the mechanisms leading to the formation of doubly excited states of the series 3l3l’ (or 4l’) and 2lnl’ in N7+, O8+ and C6+‐He low energy collisions. The importance of both direct transitions from the entry channel (involving electron‐electron interaction couplings) and transitions through a single electron capture channel has been analyzed for a range of impact velocities between 0.2 and 0.6 a.u.