Gießen 2024 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 70: Hadron Structure and Spectroscopy IX

HK 70.1: Gruppenbericht

Donnerstag, 14. März 2024, 15:45–16:15, HBR 62: EG 18

Proton charge radius measurement at AMBER — •Martin Hoffmann¹ and the GSI PRM group² for the AMBER collaboration — ¹Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn — ²GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt

The AMBER collaboration plans to perform a new precision measurement of the proton electric form factor at low squared four-momentum transfers (Q²) by elastic scattering of high-energy muons off protons. This experiment features a high-intensity 100 GeV muon beam at the M2 beam line of CERN’s Super Proton Synchrotron, leading to reduced and different systematic uncertainties compared to low-energy lepton-proton elastic scattering experiments. A high-pressure hydrogen-filled Time Projection Chamber (TPC) serves as an active target and measures the energy transferred to the recoil proton. The muon trajectories and momenta are reconstructed by high-precision vertex detectors surrounding the TPC and a magnetic spectrometer. In this way, the measurement is over-constrained to cleanly select elastic scattering events.

In 2021, the core setup was studied under realistic beam conditions in a pilot run utilizing a prototype TPC and silicon strip detectors. Prototypes of the required tracking detectors and a free-running data acquisition were tested in 2022 and 2023. This talk will present ongoing analyses and an overview of further developments towards the main experiment.

Supported by EU.

Keywords: Proton; Radius; AMBER