Proposal for VEPP-4M beam energy measurement using magnetic spectrometer with Compton calibration and photon detector

摘要

A method for circular e$^-$/e$^+$ accelerator beam energy measurement isproposed. Coordinate of an electron (or a positron) in a focusing magneticspectrometer built in a circular accelerator depends on its energy, twospectrometer parameters, and the circulating beam energy. The spectrometerparameters can be defined using minimum electron energies from Comptonbackscattering with two laser wavelengths, and an additional photon coordinatedetector. The photon detector is calibrated at once at well-known beam energy.The VEPP-4M collider has appropriate equipment for the method implementation:built-in focusing magnetic spectrometer, Compton calibration system with twolasers and a photon coordinate detector. Thus, the proposed technique could beimplemented with minimum efforts; tests and further upgrade are planned. Thebeam energy can be defined with expected uncertainty better than $10^{-4}$.