Division of Electronics, Detectors and Computing for Physics (DEDIP)

GEM detectors with streaming readout for the AMBER proton radius measurement 

Michael Lupberger

Bonn - HISKP

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The Apparatus for Meson and Baryon Experimental Research (AMBER) will be a fixed-target experiment at CERN's SPS in the context of the Physics Beyond Colliders initiative. In the approved phase I of the experiment, running also under the name NA66, three main topics will be covered:

1. a precision measurement of the proton charge radius using high-energy muon-proton elastic scattering

2. the measurement of pion valence and sea parton distribution functions

3. the measurement of the differential cross section for antiproton production, an important ingredient for Dark-Matter searches

The presentation will focus on the proton radius measurement and the implication for the GEM detectors.

The setup foresees a high-pressure TPC as active target, which identifies the recoil proton of the elastic muon-proton scattering. The muon kinematics is determined with a spectrometer, which partly uses the existing COMPASS detectors. Due to the higher beam rate and the need for a continuous readout to match the instantaneous muon track with delayed information of the recoil proton in the TPC, significant detector upgrades and novel developments are necessary. The muon reconstruction will rely on new large-area GEM detectors with self-triggering readout. Tests of prototype detectors and a possible candidate ASICs, the VMM, are performed in order to evaluate their performance.