  We report on the first deep X-ray survey with the XMM-Newton observatory
during the performance verification phase. The field of the Lockman Hole, one
of the best studied sky areas over a very wide range of wavelengths, has been
observed. A total of ~100 ksec good exposure time has been accumulated.
Combining the images of the European Photon Imaging Camera (EPIC) detectors we
reach a flux limit of 0.31, 1.4 and 2.4 X 10^{-15} erg cm^{-2} s^{-1},
respectively in the 0.5-2, 2-10, and 5-10 keV band. Within an off-axis angle of
10 arcmin we detect 148, 112 and 61 sources, respectively. The log(N)-log(S)
relation in the three bands is compared with previous results. In particular in
the 5-10 keV band these observations present the deepest X-ray survey ever,
about a factor 20 more sensitive than the previous BeppoSAX observations. Using
X-ray spectral diagnostics and the set of previously known, spectroscopically
identified ROSAT sources in the field, the new sources can be classified.
XMM-Newton detects a significant number (~40%) of X-ray sources with hard,
probably intrinsically absorbed X-ray spectra, confirming a prediction of the
population synthesis models for the X-ray background.
