Measurement of the proton structure function F-2 and sigma(gamma*p)(tot) at low Q(2) and very low x at HERA

A small electromagnetic sampling calorimeter, installed in the ZEUS experiment in 1995, significantly enhanced the acceptance for very low x and low Q(2) inelastic neutral current scattering, e(+)p --> e(+)X, at HERA. A measurement of the proton structure function F-2 and the total virtual photon-proton (gamma*p) cross-section is presented for 0.11 less than or equal to Q(2) less than or equal to 0.65 GeV2 and 2 x 10(-6) less than or equal to x less than or equal to 6 x 10(-5), corresponding to a range in the gamma*p c.m. energy of 100 less than or equal to W less than or equal to 230 GeV. Comparisons with various models are also presented. (C) 1997 Published by Elsevier Science B.V.