2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/201159We present a determination of the LEP beam energy using "radiative return" fermion-pair events recorded at centre-of-mass energies from 183 GeV to 209 GeV. We find no evidence of a disagreement between the OPAL data and the LEP Energy Workings Group's standard calibration. Including the energy- averaged 11 MeV uncertainty in the standard determination, the beam energy we obtain from the OPAL data is higher than that obtained from the LEP calibration by 0+-34(stat.)+-27(syst.)MeV24 pages, 5 figures, Submitted to Phys. Letts. BHigh Energy Physics - Experimenttext