  We propose a novel detection concept for neutrinoless double-beta decay
searches. This concept is based on a Time Projection Chamber (TPC) filled with
high-pressure gaseous xenon, and with separated-function capabilities for
calorimetry and tracking. Thanks to its excellent energy resolution, together
with its powerful background rejection provided by the distinct double-beta
decay topological signature, the design discussed in this Letter Of Intent
promises to be competitive and possibly out-perform existing proposals for
next-generation neutrinoless double-beta decay experiments. We discuss the
detection principles, design specifications, physics potential and R&D plans to
construct a detector with 100 kg fiducial mass in the double-beta decay
emitting isotope Xe(136), to be installed in the Canfranc Underground
Laboratory.
