  We report results of analysis of the ASCA observation of the Low Mass X-ray
Binary dipping source XB1916-053 made on 1993, May 2nd. We have shown that the
spectra can be well fitted by the same two-component model previously used to
give good explanations of the very different dip sources X1755-338 and
X1624-490, consisting of point-source blackbody emission from the neutron star
plus extended Comptonised emission from the accretion disk corona. In
XB1916-053, all levels of dipping can be fitted using kT_bb= 2.14+/-0.28 keV
and power law photon index = 2.42 +/-0.21. Dipping is shown to be due to large
increases of column density for the point-like blackbody, combined with the
extended power law component being progressively covered by absorber until in
the deepest parts of dips, the partial covering fraction approaches unity. This
approach differs radically from the ``absorbed plus unabsorbed'' approach
previously used in spectral modelling of XB1916-053 and similar sources, in
which the normalisation of the unabsorbed component is allowed to decrease
markedly in dipping, behavior generally attributed to the effects of electron
scattering. Thus we have shown that spectral evolution in XB1916-053 can be
explained simply in terms of photoelectric absorption without the need for
substantial electron scattering. This explanation is supported by calculation
of the relative importance of photoelectric absorption and electron scattering
in the absorbing region which shows that little electron scattering is expected
in the ASCA energy band.
