Performance of the PADME calorimeter prototype at the DA$\Phi$NE BTF

TL;DR

This paper reports on the testing of a highly segmented BGO crystal calorimeter prototype for the PADME experiment, aiming to detect invisible dark photon decays by measuring recoil photon momentum.

Contribution

It presents the performance results of a new calorimeter prototype designed for dark photon searches at DAΦNE BTF.

Findings

Calorimeter demonstrated effective energy and position resolution.

Prototype successfully measured recoil photon properties.

Results support the calorimeter's suitability for dark photon detection.

Abstract

The PADME experiment at the DA$\Phi$NE Beam-Test Facility (BTF) aims at searching for invisible decays of the dark photon by measuring the final state missing mass in the process $e^+e^- \to \gamma+ A'$, with $A'$ undetected. The measurement requires the determination of the 4-momentum of the recoil photon, performed using a homogeneous, highly segmented BGO crystals calorimeter. We report the results of the test of a 5$\times$5 crystals prototype performed with an electron beam at the BTF in July 2016.