Calibration of the PADME beam monitoring calorimeter

A hypothesis for a new light particle of 17 MeV mass (X17) is currently being investigated at several nuclear and particle physics experiments, one of which is the Positron Annihilation into Dark Matter Experiment (PADME), based at Laboratori Nazionali di Frascati - INFN, Italy. To probe the existence of the X17 particle at PADME, a high-precision measurement of the beam characteristics is required. In 2024, a dedicated test run campaign was conducted to calibrate the beam monitoring calorimeter. Two main effects have been recognised as significant for the data analysis of PADME, namely a radiation-induced performance degradation and an energy loss in the passive material in front of the detector. In this paper, the main results from the 2024 test run are presented, and the luminosity corrections made in the PADME X17 analysis are discussed.