AVS 53rd International Symposium
    Vacuum Technology Tuesday Sessions
       Session VT-TuP

Paper VT-TuP9
Comparisons of Vacuum Standards Among NMIJ, NIST, IMGC and KRISS in Medium Vacuum

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Vacuum Technology Poster Session
Presenter: H. Akimichi, NMIJ AIST, Japan
Authors: H. Akimichi, NMIJ AIST, Japan
M. Hirata, NMIJ AIST, Japan
P.J. Abbott, National Institute of Standards and Technology
M. Bergoglio, IMGC, Italy
A. Calcatelli, IMGC, Italy
S.S. Hong, KRISS, Korea
Correspondent: Click to Email
Comparison of vacuum standards was carried out among the National Metrology Institute of Japan (NMIJ), the National Institute of Standards and Technology (NIST), the Instituo di Metrlogia "G. Colonnetti" (IMGC) and the Korea Research Institute of Standards and Science (KRISS) from March 2004 to September 2005. Pressure range was from 0.01 to 1 Pa. Test gas was nitrogen. Spinning rotor gauges were used as transfer standard. After the calibration of the gauge by a static expansion system at NMIJ, rotors of the gauge were removed from their thimbles and packed in clean aluminum foil or clean dust free paper. They were transported to another NMI by hand and calibrated by their primary system, a dynamic system at NIST, a dynamic system and a static system at IMGC and a dynamic system at KRISS. Rotors were driven by electro units and coil heads at each NMIs. After the calibration, rotors were packed again and brought back to NMIJ by hand for re-calibration. Comparisons were done among the effective accommodation coefficient of rotors obtained by calibration at each NMI. While relatively large differences in the coefficient up to 2% (depending rotors) were observed compared with uncertainty at each NMIs, the difference was mainly caused by the change in the coefficient of the rotor during their packing and/or transportation. Mean value of coefficients of 2-6 rotors showed good agreement within 0.5% reasonably estimated from uncertainty of each NMIs. This result shows that the primary standards of NMIs seem to be equivalent to each other. It is important to clarify the way to carry the gauge without change in its accommodation coefficient.