Measurement of the Lamb Shift in H,n= 2

The current methods for measuring the Lamb shift δ in the hydrogen atom (n = 2) have been considered. The possibility of the determination of the proton radius from the available theoretical and experimental data has been estimated. The Lamb-shift value obtained by the "atomic interferometer" proved to be 1057.8514(19) MHz. The corresponding values of the mean-square proton radius are ⟨r2⟩1/2 = 0.76 ± 0.01 fm (for δtheor. = 1057.864(14) MHz) and ⟨r2⟩1/2 = 0.59 ± 0.02 fm (for δtheor. = 1057.910(10) MHz).