= K, = 1-(16.69 f 1.33) ppm.The uncertainty of 1.33 ppm has the significance of a standard deviation and includes our best estimate of random and known or suspected systematic uncertainties. The mean time of the measurement is May 15, 1988. Combined with the recent measurement of the NBS ohm in SI units: Q N B \ / Q = Ki2 = 1-(1.593 f 0.022) ppm, this leads to a Josephson frequency/voltage quotient of E, = E,[1 + (7.94 f 0.67) ppm] where Eo = 483 594 GHz/V.

Abstruct-Results from NBS experiments to realize the ohm and the watt, to determine the proton gyromagnetic ratio by the low field method, to determine the time dependence of the NBS representation of the ohm using the quantum Hall effect, and to maintain the NBS representation of the volt using the Josephson effect, are appropriately combined to obtain an accurate value of the fine-structure constant and of the quantized Hall resistance in SI units, and values in SI units of the Josephson frequency-to-voltage quotient, Planck constant, and elementary charge.

No abstract

In this paper we present the uncertainty evaluation of a new cryogenic current comparator (CCC) bridge designed to compare two-terminal 1 MΩ and 10 MΩ standard resistors with the quantized Hall resistance (QHR) and then scale from these values to other values between 10 kΩ and 1 GΩ.