This Letter of Intent has been submitted to the Scientific Committee of the
INFN Laboratori Nazionali del Gran Sasso (LNGS) in March 2004. It describes a
novel facility at the LNGS to study the double beta decay of 76Ge using an
(optionally active) cryogenic fluid shield. The setup will allow to scrutinize
with high significance on a short time scale the current evidence for
neutrinoless double beta decay of 76Ge using the existing 76Ge diodes from the
previous Heidelberg-Moscow and IGEX experiments. An increase in the lifetime
limit can be achieved by adding more enriched detectors, remaining thereby
background-free up to a few 100 kg-years of exposure.Comment: 67 pages, 19 eps figures, 17 tables, gzipped tar fil