Use of the methods of accelerator physics in precision measurements of particle masses at the VEPP-4 complex with the KEDR detector

Abstract

Based on precision measurements of the beam energy using the resonant depolarization and Compton backscattering methods, it is possible to conduct high-precision experiments in the field of high-energy physics at the VEPP4M electron-positron collider with the KEDR detector. The J/ψr- and ψ(2s)-meson masses measured at the VEPP4M collider ar e among the ten most precisely known masses of elementary particles measured over the whole physical history. The degree of accuracy that we attained in determining theτlepton mass by the threshold behavior of the e+e- τ+τ reaction cross section is the best in the world. Systems automatically controlling the temperature of the distillate that cools the magnets of the main accelerating structure and the RF accelerating cavities of the VEPP4M collider have been developed, produced, and placed in operation in order to increase the efficiency of the complex. Simultaneous measurements of the transverse displacement and the angle of inclination of the beam near the interaction point can be taken with the aid of a multipinhole X-ray camera.