Precise Energy Measurements in Experiments on VEPP-4M Collider

The series of experiments on mass measurements of J/Ψ, Ψ ψ, ψ′, X and D mesons have been done on VEPP4-M collider. The accuracy of obtained masses values for Ψ mesons exceeded world value more than 3 times. Experiment on mass measurement of tau lepton is in progress. All these experiments require absolute energy calibration of the beams. Resonant depolarization technique has been used for most accurate energy measurement with relative accuracy of 1 ppm (10^-6). Compton backscattering effect is used in developing facility for fast energy measurements. Möller scattering of the beam on polarized gas jet target has been used for beam polarization measurements.