14. March 2024

Proton charge radius measurement at AMBER Proton charge radius measurement at AMBER

Group report at DPG 2024

Author: Martin Hoffmann and the GSI PRM group for the AMBER collaboration

DPG 2024
DPG 2024 © Deutsche Physikalische Gesellschaft
Download all images in original size The impression in connection with the service is free, while the image specified author is mentioned.


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.

Wird geladen