Characterisation and performance of the PADME electromagnetic calorimeter

TL;DR

The paper details the design, calibration, and performance evaluation of the PADME electromagnetic calorimeter, crucial for detecting dark photons by measuring gamma-ray energy and position in the PADME experiment.

Contribution

It introduces the specific design, calibration procedures, and performance results of the PADME calorimeter, highlighting improvements over previous prototypes.

Findings

Achieved effective energy resolution and detection efficiency.

Demonstrated calibration techniques for uniform response.

Validated calorimeter performance for dark photon search.

Abstract

The PADME experiment at the LNF Beam Test Facility searches for dark photons produced in the annihilation of positrons with the electrons of a fix target. The strategy is to look for the reaction $e^{+}+e^{-}\rightarrow \gamma+A'$, where $A'$ is the dark photon, which cannot be observed directly or via its decay products. The electromagnetic calorimeter plays a key role in the experiment by measuring the energy and position of the final-state $\gamma$. The missing four-momentum carried away by the $A'$ can be evaluated from this information and the particle mass inferred. This paper presents the design, construction, and calibration of the PADME's electromagnetic calorimeter. The results achieved in terms of equalisation, detection efficiency and energy resolution during the first phase of the experiment demonstrate the effectiveness of the various tools used to improve the calorimeter performance with respect to earlier prototypes.