Measurement of inclusive cross sections at high at and 252 GeV and of the longitudinal proton structure function at HERA

Inclusive double differential cross sections for neutral current deep inelastic scattering are measured with the H1 detector at HERA. The data were taken with a lepton beam energy of  GeV and two proton beam energies of and 575 GeV corresponding to centre-of-mass energies of 225 and 252 GeV, respectively. The measurements cover the region of for GeV up to . The measurements are used together with previously published H1 data at GeV and lower data at , and GeV to extract the longitudinal proton structure function in the region GeV.