  The PADME experiment is designed to search for a hypothetical dark photon
$A^{\prime}$ produced in positron-electron annihilation using a bunched
positron beam at the Beam Test Facility of the INFN Laboratori Nazionali di
Frascati. The expected sensitivity to the $A^{\prime}$-photon mixing parameter
$\epsilon$ is 10$^{-3}$, for $A^{\prime}$ mass $\le$ 23.5 MeV/$c^{2}$ after
collecting $\sim 10^{13}$ positrons-on-target.
  This paper presents the PADME detector status after commissioning in July
2019. In addition, the software algorithms employed to reconstruct physics
objects, such as photons and charged particles, and the calibration procedures
adopted are illustrated in detail. The results show that the experimental
apparatus reaches the design performance, and is able to identify and measure
standard electromagnetic processes, such as positron Bremsstrahlung,
electron-positron annihilation into two photons.
