The Two-Photon Exchange Experiment at DESY

Author:

R. Alarcon, R. Beck, J. C. Bernauer, M. Broering, A. Christopher, E. W. Cline, S. Dhital, B. Dongwi, I. Fernando, M. Finger, M. Finger Jr., I. Friščić, T. Gautam, G. N. Grauvogel, D. K. Hasell, O. Hen, T. Horn, E. Ihloff, R. Johnston, J. Kelsey, M. Kohl, T. Kutz, I. Lavrukhin, S. Lee, W. Lorenzon, S. Lunkenheimer, F. Maas, R. G. Milner, P. Moran, J. Nazeer, T. Patel, M. Rathnayake, R. Raymond, R. P. Redwine, A. Schmidt, U. Schneekloth, D. Sokhan, M. Suresh, C. Vidal, Z. Yang

Keyword:

Nuclear Experiment, Nuclear Experiment (nucl-ex)

journal:

date:

2023-07-24 16:00:00

Abstract

We propose a new measurement of the ratio of positron-proton to electron-proton elastic scattering at DESY. The purpose is to determine the contributions beyond single-photon exchange, which are essential for the Quantum Electrodynamic (QED) description of the most fundamental process in hadronic physics. By utilizing a 20 cm long liquid hydrogen target in conjunction with the extracted beam from the DESY synchrotron, we can achieve an average luminosity of $2.12\times10^{35}$ cm$^{-2}\cdot$s$^{-1}\cdot$sr$^{-1}$ ($\approx200$ times the luminosity achieved by OLYMPUS). The proposed TPEX experiment entails a commissioning run at 2 GeV, followed by measurements at 3 GeV, thereby providing new data up to $Q^2=4.6$ (GeV/$c$)$^2$ (twice the range of current measurements). We present and discuss the proposed experimental setup, run plan, and expectations.

PDF: The Two-Photon Exchange Experiment at DESY.pdf