Precision Separated-Oscillatory-Field Measurement of the <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="italic">n</mi><mspace></mspace><mo>=</mo><mspace></mspace><mn>10</mn><mn></mn><mi></mi><mrow><msup><mrow></mrow><mrow><mo>+</mo></mrow></msup></mrow><mrow><msub><mrow><mi>F</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow><mo>−</mo><mrow><msub><mrow><mrow><msup><mrow></mrow><mrow><mo>+</mo></mrow></msup></mrow><mi mathvariant="italic">G</mi></mrow><mrow><mn>4</mn></mrow></msub></mrow></math></span> Interval in Helium: A Precision Test of Long-Range Relativistic, Radiative, and Retardation Effects

C. H. Storry; N. E. Rothery; E. A. Hessels

doi:10.1103/PhysRevLett.75.3249

Precision Separated-Oscillatory-Field Measurement of the $n = 10^{+} F_{3} - {^{+} G}_{4}$ Interval in Helium: A Precision Test of Long-Range Relativistic, Radiative, and Retardation Effects

C. H. Storry, N. E. Rothery, and E. A. Hessels

Phys. Rev. Lett. 75, 3249 – Published 30 October 1995

Abstract

We have measured the ${}^{+}F_{3}$ - ${}^{+}G_{4}$ interval in $n = 10$ of helium to be 2017.3258(4) MHz (an accuracy of 200 ppb). The measurement uses a fast neutral beam and Ramsey separated-oscillatory-field microwave-induced transitions. When compared to recent high-precision variational calculations, it provides a high-precision test of physics (including relativistic, radiative, and retardation effects) on the large distance scale of these Rydberg atoms. The comparison indicates either that the expected long-range Casimir effect is not present, or the presence of new long-range physics.