24-28 February 2020
Budker Institute of Nuclear Physics
Asia/Novosibirsk timezone

The PADME detector at LNF

24 Feb 2020, 17:20
Contributed Oral Colliders and detector integration Colliders and detector integration


Danilo Domenici (INFN - LNF)


The Positron Annihilation into Dark Matter Experiment (PADME) aims to search for the production of a dark photon in the process e + e → A 0 γ. It exploits the 550 MeV positron beam provided by the DAΦNE LINAC impinging on a thin target. The primary beam crosses a diamond target and if it does not interact it is bent by a magnet in between the end of the spectrometer and the calorime- ter, thus leaving the experiment undetected. If any kind of interaction causes the positron to lose more than 50 MeV of energy, the magnet bends it into the spectrometer acceptance, providing a veto signals against bremsstrahlung back- ground. In case of annihilation, the accompanying ordinary photon is detected by the electromagnetic calorimeter regardless of the A 0 decay products. A single kinematic variable characterizing the process, the missing mass, is computed using the formula: M2 miss = (P beam + P e − − P γ ) 2 Its distribution should peak at M A 2 0 for A 0 decays, at zero for the concurrent e + e → γγ process, and should be smooth for the remaining background. To measure such a reaction, the PADME apparatus has been built at the Frascati National Laboratory of INFN. It consists of a small scale detector composed of the following parts: • a diamond active target, to measure the position and the intensity of the beam in each single bunch; • a beam monitor system consisting of two different silicon-pixel detectors. The first one, located at the beam entrance, can be inserted in place of the target to tune beam parameters; the second, located on the beam exit trajectory, monitors the beam spot during the data taking; • a spectrometer, to measure the charged particles momenta in the range 50-400 MeV; • a dipole magnet, to deflect the primary positron beam out of the spec- trometer and the calorimeter and to allow momentum analysis; • a vacuum chamber, to minimize the unwanted interactions of primary and secondary particles; • a finely segmented, high resolution electromagnetic calorimeter, to measure 4-momenta and veto final state photons. Each element has specific requirements that are stringent and sometimes at the limit of present technology. A commissioning run has been performed between 2008 and 2019, and in Febru- ary 2020 the experiment is expected to take data for two months. The talk will give an overview of each detector component and a description of the chosen technical solutions implemented to accomplish the experiment needs. An insight of possible future upgrades will be given as well.

Primary author

Danilo Domenici (INFN - LNF)

Presentation Materials