The HERD calorimeter: prototype response to high energy nuclei

Abstract HERD is a space-borne calorimetric experiment that aims to extend current direct measurements of cosmic rays to the PeV energy range. The main feature of the instrument is its ability to measure particles coming from all directions, with the main detector being a deep, homogeneous 3D calorimeter. A large prototype of the calorimeter was tested at CERN in 2023 as part of an extensive beam test campaign. This paper describes the data analysis and performance of the calorimeter prototype for high-energy nuclei. Several important information and parameters for the calibration of the HERD calorimeter are reported.