The LHCb experiment aims to collect a dataset of 300 fb$^{-1}$ in its high-luminosity phase. Such an objective calls for challenging upgrades of all the detector systems to successfully operate at a peak luminosity of $1.5 \times 10^{34}~\rm cm^{-2} s^{-1}$.
The future electromagnetic calorimeter, named PicoCal, will have to face a high radiation dose and mitigate a harsh occupancy, keeping the current energy resolution.
To meet these requirements, the calorimeter regions are redesigned with finer granularity, longitudinal segmentation, and a timing resolution of approximately 20 ps.
The candidate technologies are Spaghetti calorimeter (SpaCal) with garnet scintillating crystals (GAGG) and tungsten absorber in the innermost region, SpaCal with scintillating plastic fibres and lead absorber in the intermediate area, and Shashlik with polystyrene tiles, lead absorber, and fast WLS fibres in the outer part.
An additional timing layer based on microchannel-plate technology was investigated.
This proceeding summarises the proposed new features and the status of the art of the R&D project, reporting results from test-beam activities.