DETERMINATION OF THE VONKLITZING CONSTANT AND THE FINE-STRUCTURE CONSTANT THROUGH A COMPARISON OF THE QUANTIZED HALL RESISTANCE AND THE OHMDERIVED FROM THE NIST CALCULABLE CAPACITOR

This paper describes a recent determination of the von Klitzing consta nt and the fine-structure constant by comparisons of values of the ohm as defined in the International System of Units (SI), derived from th e National Institute of Standards and Technology (NIST) calculable cro ss-capacitor, and values of the international practical unit of resist ance derived from the integral quantum Hall effect. In this determinat ion, the comparisons were made in a series of measurements lasting thr ee years. A small difference is observed between this determination an d an earlier comparison carried out in this laboratory and reported in 1988. The most recent value of the fine-structure constant based on t he experimental value and theoretical expression for the magnetic mome nt anomaly of the electron, which has the smallest uncertainty of any value currently available, is consistent with both of these results. T he new value exceeds the 1990 conventional value of the von Klitzing c onstant RK-90 by slightly more than twice the relative standard uncert ainty of the present measurement, which is 2.4 x 10(-8).