Measurement of the structure functions F2 and FL at Low x

A preliminary measurement of the proton structure function F2 is presented for momentum transfers squared 2 ≤ Q2 ≤ 120 GeV2 and for Bjorken-x values 3 · 10-5 < x < 0.1. The longitudinal proton structure function FL is determined for low x values in the range of 3 ≤ Q2 ≤ 35 GeV2, using two independent methods. The analysis is based on data collected by the HERA experiment H1 in 1997, with a luminosity of 15 pb-1 for Q2 > 10 GeV2 and of 2 pb-1 taken in a dedicated run for Q2 < 10 GeV2. This measurement uses in the low Q2 region the new backward silicon tracker. The accuracy is by nearly a factor of two better than previous results