  The NEXT (Neutrino Experiment with a Xenon TPC) project is an international
collaboration aimed at finding evidence of neutrinoless double beta decay using
gaseous xenon. The current phase of the project involves the construction and
operation of NEXT-100, which is designed to hold 100 kg of xenon at 15 bar and
is expected to start commissioning in the first quarter of 2024. NEXT-HD will
be a tonne scale experiment following NEXT-100 and will incorporate a symmetric
design, with one cathode and two anodes. For this detector, the collaboration
is considering to implement a barrel of wavelength-shifting fibers read-out by
silicon photomultipliers to measure the energy of the particles interacting in
the gaseous xenon. In this document, we will discuss the characteristics of
this approach and provide an update on the related R&D efforts.
