  We review the current status of liquid noble gas radiation detectors with
energy threshold in the keV range, wich are of interest for direct dark matter
searches, measurement of coherent neutrino scattering and other low energy
particle physics experiments. Emphasis is given to the operation principles and
the most important instrumentation aspects of these detectors, principally of
those operated in the double-phase mode. Recent technological advances and
relevant developments in photon detection and charge readout are discussed in
the context of their applicability to those experiments.
