One of the most crucial challenges in today particle physics and cosmology is the determination
of the neutrino absolute mass scale. Currently, the only model independent method to set a limit
neutrino mass is the study of the nuclear beta spectrum end-point. Performing a calorimetric
measurement of the end point of the Electron Capture decay spectrum of 163 Ho, the HOLMES
experiment aims at pushing down the sensitivity on the smallest neutrino mass at the order of
∼ eV. In its final configuration HOLMES will deploy an array of 1000 microcalorimeters based
on Transition Edge Sensors with gold absorbers in which the 163 Ho will be ion implanted with a
target activity of 300 Hz/det. In order to achieve a statistical sensitivity on the neutrino mass in
the eV range, there are stringent requirements on the detector performances: fast time resolution
(∼ 1 μs) to solve pile-up events and an energy resolution of few eV at the Q-value (2.8 keV).
Furthermore, the detectors must be multiplexable. The best technique to easily readout such a
number of detector with a common readout line is the microwave frequency domain readout.
We outline the HOLMES project with its physics reach and technical challenges together with
its status and perspectives. In detail, we report the status of HOLMES activities concerning the
163 Ho isotope production, the TES and multiplexed array read-out and the isotope embedding
process.