ac-Josephson-Effect Determination ofehwith Sub—Part-Per-Million Accuracy

Abstract

PHYSICAL REVIEW LETTERS 30 MARCH 1970 dR LM /dr* = [V LM (r)-u 2 ]K LM .Fortunately, the problem has a solution (many, in fact, since it turns out that one of the functions/, g, h, k, or n may be chosen arbitrarily).If we let n(r) = l-2m/r where m is the mass of the Schwarzschild field we find that f(r) = [x(X + l)r 2 + 3\mr + 6m 2 ]/r 2 (\r + 3m), g(r) = 1,and that r* = r + 2mln(r/2m-l),so thatwhere T/ , x /l-2m\2x 2 (X + l)r 3 + 6X 2 mr 2 4.18Xm 2 r + 18m 3 ,-.Note that the system (4) written as a single second-order equation assumes formally the Schrodinger formThanks are due to John A. Wheeler for conversations in which he suggested the approach to use in finding an effective-potential form for the even-parity equations.An ac-Josfephson-effect determination of e/h has been made using a new method. The accuracy of the result referred to the local voltage standard is 0.13 ppm. The accuracy referred to the National Bureau of Standards as-maintained volt is 0.46 ppm. The final value is 2e/A = 483.593 65 ±0.000 22 MHz//LtV 69NBS (0.46 ppm).The work of Parker, Taylor, and Langenberg 1 * 2 constant 2e/h. High-accuracy determinations of has established the ac Josephson effect in sys-the Josephson frequency-voltage ratio have been terns of weakly coupled superconductors as an reported by Parker et al. 2 and by Petley and Morimportant factor contributing to our knowledge of ris. 5 The former has recently been reassessed the fundamental physical constants 3 and as a po-and revised by Denenstein et al. 6 Both now have tential dc voltage standard. 4 Both of these appli-quoted one-standard-deviation uncertainties of cations are based upon the fact that in a Joseph-2.2 ppm and are in excellent agreement. A sigson-junction device biased at a dc potential dif-nificant increase in the accuracy with which the ference V, there exists a super cur rent oscillat-frequency-voltage ratio could be determined ing at a frequency v-2eV/h; the frequency-volt-would have important implications for our knowage ratio is thus simply the fundamental physical ledge of the fundamental physical constants and 738

New Theoretical Values of the2P3Fine-Structure Splittings of Helium

“…In a recent paper on the experimental test of the theory of muonic atoms, Dixit et al 1 have reported measurements of muonic x-ray energies in a number of elements in the energy range 150-440 keV. They picked for measurement only the higher transitions in atoms with spherical nuclei and made special efforts to measure these transitions with an absolute precision of 15-21 eV.…”

“…The prinicpal correction to the Dirac energy in this energy range turns out to be that due to e ~-e + vacuum polarization. These corrections were calculated by Fricke 2 ; and, using these calculated numbers, Dixit et al 1 arrived at their theoretical values for the transition energies. Corrections due to nuclear polarization, the screening effect due to electrons, the Lamb shift and relativistic corrections to the reduced mass, etc.…”

Innovative metrology - key to progress

“…On the basis of the 1967 comparison, our values and those of the University of Pennsylvania [6,18,19] are unlikely to differ by more than about 0.5 ppm.…”

Order(memμ)α2Fulton1, Owen2, Repko3 1971Phys. Rev. Lett.28030View full textAdd to dashboardCite

“…4 It has also been observed 1 ' 2 that the present accurate experimental values for v m and MJU/MB permit an independent determination of the fine-structure constant a with an accuracy comparable with that of the Josephson effect. 5 For these reasons, it is desirable to have a theoretical expression for v m which accurately accounts for the muon recoil.…”