  NEXT-100 is an electroluminescent high pressure Time Projection Chamber
currently under construction. It will search for the neutrino-less double beta
decay in 136Xe at the Canfranc Underground Laboratory. NEXT-100 aims to achieve
nearly intrinsic energy resolution and to highly suppress background events by
taking advantage of the unique properties of xenon in the gaseous phase as the
detection medium. In order to prove the principle of operation and to study
which are the best operational conditions, two prototypes were constructed:
NEXT-DEMO and NEXT-DBDM. In this paper we present the latest results from both
prototypes. We report the improvement in terms of light collection (?~3x?)
achieved by coating the walls of NEXT-DEMO with tetraphenyl butadiene (TPB),
the outstanding energy resolution of 1 % (Full Width Half Maximum) from
NEXT-DBDM as well as the tracking capabilities of this prototype (2.1 mm RMS
error for point-like depositions) achieved by using a square array of 8x8
SiPMs.
