  Weakly Interacting Massive Particles (WIMPs) are one of the leading
candidates for Dark Matter. Currently, the most promising method to detect
WIMPs is the direct detection of the recoil energy deposited in a
low-background laboratory detector due to elastic WIMP-nucleus scattering. So
far the usual procedure has been to predict the event rate of direct detection
of WIMPs based on some model(s) of the Galactic halo from cosmology and of
WIMPs from elementary particle physics. The aim of this work is to invert this
process. In this thesis I present methods which allow to reconstruct (the
moments of) the WIMP velocity distribution function as well as to determine the
WIMP mass from the recoil energy spectrum as well as from experimental data
directly. The reconstruction of the velocity distribution function has been
further extended to take into account the annual modulation of the event rate.
Moreover, the reconstruction of the amplitude of the annual modulation of the
velocity distribution and an alternative, better way for confirming the annual
modulation of the event rate have been discussed. On the other hand, the
determination of the WIMP mass by combining two (or more) experiments with
different detector materials has been developed. All formulae and expressions
given here are not only independent of the model of Galactic halo but also of
that of WIMPs. This means that we need neither the as yet unknown WIMP density
near the Earth nor the WIMP-nucleus cross section. The only information which
we need is the measured recoil energies and their measuring times.
