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We proposed and tested a method of experimental determination of the upper limit of RF resonator axis inclination to the beam axis. The electric field transverse component by such a perturbation deflects the particle trajectory. In the horizontal plane, a distortion of the closed orbit leads to a difference in the energies and spin precession frequencies of electrons and positrons in a storage collider with a single ring. EFFECT OF PERTURBATION OF RF RESONATOR AXIS INCLINATION Since the deflection is caused by the transverse electric field on the beam axis, the closed orbits of electrons and positrons differ from each other. Therefore, in the case of radial deflection angle in the RF resonator, there are differences in the energies (and the spin frequencies) of electrons and positrons. These differences are defined as [1]: = −2 . (1) Here ηx is the dispersion function at the resonator location, α is the momentum compaction factor, and Π is the machine circumference. With a 10-3 rad inclination angle in the equivalent resonator, which is in the center of the VEPP-4M technical section, the systematic error in the CPT invariance test [2] based on comparison of the spin frequencies of electrons and positrons [1] will be 7.7·10-9 against the planned 510-9 accuracy. With the same angular perturbation for each of the five resonators in the technical section [3], the contribution to the energy shift does not exceed 2.510-9. Due to the random distribution of the perturbations, the total contribution can be even smaller with the given spread of the angles. The energy recovery of an equivalent particle in each resonator is described by the following equation: ∆ = , , (2) where URF,i is the voltage amplitude in the ith RF resonator, and φ0 is the equilibrium phase. The total energy losses per revolution are ∑∆ = . Then the angle of deflection equals to = ∆ , (3) where is the corresponding angle of inclination. DESCRIPTION OF METHOD The proposed method consists in resonant excitation of betatron oscillations by modulating the frequency of the RF system master oscillator (see Fig. 1). There are five RF resonators (R2, R3, R4, R5, and R6) operating in the main mode E010 in the technical section of VEPP-4M. Parameters of the resonators are given in Table 1. Table 1: Parameters of Resonators Resonator ηx

Determination of RF resonator axis inclination to beam axis in electron-positron storage ring