  NEXT is a high-pressure (10-15 bar) xenon Time Projection Chamber dedicated
to neutrinoless double beta decay searches. NEXT-DEMO is a large prototype of
the NEXT experiment, constructed to demonstrate the feasibility of the NEXT
detector concept, in particular the capability of the TPC to achieve an optimal
energy resolution at the Xe Qbb energy (2.458 MeV). It has been operating at
IFIC, in Valencia, for one year and a half and a number of results has been
achieved. Recently, the reflector panels of the prototype have been coated with
a wavelength shifter (TPB), in order to improve light collection. We have
obtained an energy resolution of 2.3% FWHM at 511 keV, using Na-22 radioactive
sources, corresponding to 1% FWHM once extrapolated to Qbb.
