HiDRa - High-resolution Calorimeter for $e^+ e^-$

The forthcoming generation of colliders demands advanced mass resolutions for the Higgs H, W and Z bosons when decaying into jets. Dual-readout calorimetry achieves this by making use of two independent measurements of the hadronic shower energy, leveraging the distinct factors of Cherenkov and scintillation light produced in a calorimeter equipped with two types of optical fibres. This allows for event-by-event compensation of the electromagnetic fraction. In this context, we present HiDRa, a 65 × 65 × 250 cm3 dual-readout fibre calorimeter prototype currently under construction. The primary objective is to assess the performance in terms of linearity and resolution when exposed to a high-energy particle beam. The paper will focus on strategic choices made to offer scalable solutions for the mechanics and readout electronics. The insights gained from the evaluation of HiDRa will be key for the construction of a full 4π calorimeter at a future collider.