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Home  ⪧  Research  ⪧  Particle Physics  ⪧  PADME

PADME

PADME (Positron Annihilation into Dark Matter Experiment) is an experiment aimed at searching light dark matter particles, and in particular a dark photon. Some theoretical models imply a new force, connecting our world to a dark matter sector. This so-called “fifth force” would be associated to a mediator (or portal) called dark photon, i.e. a particle similar to the ordinary photon, mediating the electromagnetic interaction, but with a not vanishing mass.

In order to produce it, PADME makes use of annihilation events of a positron beam, produced and accelerated by a LINAC, and the atomic electrons of a thin diamond target (1/10 of mm), through the missing mass technique: by precisely measuring the energy and position of the photon produced in the e+ e- interaction, it is possible to reconstruct the presence of an additional, invisible particle. This is possible thanks to the performance of the PADME main detector, a scintillating crystal calorimeter, realized with the BGO elements recuperated from the dismantled L3 experiment at the CERN LEP collider.

The construction of the PADME experiment was completed at the end of 2018 and two runs were performed in 2019 and 2020. Two data-sets of approximately 5 x 10¹² positrons on target were collected with a secondary beam (545 MeV energy) and a primary beam (450 MeV energy). Only a fraction of positrons crosses the target interacting with the electrons of the Carbon atoms, producing electrons, positrons and photons. It is precisely in these interactions that a dark photon could be hiding.

The experiment is currently in the data analysis phase, aimed at finding some evidence (or the exclusion) of the existence of the dark photon, in this energy range.

As future development, it has been proposed to use one of the two rings of the DAFNE collider for stretching the positron beam pulses from the LINAC, and thus increase the statistics, up to a factor 1000, making use of the resonant extraction technique (POSEYDON project) and of channeling effects in bent crystals (SHERPA project). Results from PADME will complement data in the search of dark sector particles using different experimental techniques (like electron-positron colliders or through meson decays) and in different mass ranges.

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Websites:

• PADME International

Thesis Opportunities:

For information regarding thesis opportunities, please contact: Paolo Valente.

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Local Coordinator

Paolo Valente

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