Exposing a fibre-based dual-readout calorimeter prototype to beams of electrons

As a part of the R&D for detectors to employ at future $e^+e^-$ colliders,a prototype of a fibre calorimeter with dual readout has been built and exposed to electron beams at DESY and CERN. With a length of 1 m and a lateral size of $\sim$10 cm it almost fully contains electromagnetic showers. The central part of the detector was equipped with 320 Silicon Photomultipliers (SiPMs) spaced by 2 mm and individually read out, yielding a very high granularity sampling of the electromagnetic shower. The data-taking in 2021 was mainly devoted to testing the operation of the SiPMs in real beam conditions, and to the definition of the calibration procedure and the measurement of the light yield of the fibres. Preliminary results of the tests are discussed in the contribution.