Feasibility studies of the time-like proton electromagnetic form factor measurements with ANDA at FAIR

M. Sudoł; M. C. Mora Espí; E. Becheva; J. Boucher; T. Hennino; R. Kunne; D. Marchand; S. Ong; B. Ramstein; J. Van de Wiele; T. Zerguerras; F. Maas; B. Kopf; M. Pelizaeus; M. Steinke; J. Zhong; E. Tomasi-Gustafsson

doi:10.1140/epja/i2010-10960-8

2021 Impact factor 3.131

Hadrons and Nuclei

Open Access

Eur. Phys. J. A (2010) 44: 373-384
https://doi.org/10.1140/epja/i2010-10960-8

Regular Article - Experimental Physics

Feasibility studies of the time-like proton electromagnetic form factor measurements with ANDA at FAIR

M. Sudoł¹, M. C. Mora Espí², E. Becheva¹^,a, J. Boucher¹, T. Hennino¹, R. Kunne¹, D. Marchand¹, S. Ong¹, B. Ramstein¹, J. Van de Wiele¹, T. Zerguerras¹, F. Maas²^,3, B. Kopf⁴, M. Pelizaeus⁴, M. Steinke⁴, J. Zhong⁴ and E. Tomasi-Gustafsson⁵^,1^*

¹ Institut de Physique Nucléaire, CNRS/IN2P3 and Université Paris-Sud, Paris-Sud, France
² Institut fuer Kernphysik, Johannes Gutenberg Universitaet Mainz, 55099, Mainz, Germany
³ GSI Helmholtzzentrum fuer Schwerionenforschung, GmbH, 64291, Darmstadt, Germany
⁴ Ruhr Universitaet Bochum, 44801, Bochum, Germany
⁵ DSM, IRFU, SPhN, Saclay, 91191, Gif-sur-Yvette, France

^* e-mail: etomasi@cea.fr

Received: 25 July 2009
Revised: 12 March 2010
Accepted: 15 March 2010
Published online: 28 April 2010

Abstract

The possibility of measuring the proton electromagnetic form factors in the time-like region at FAIR with the ANDA detector is discussed. Detailed simulations on signal efficiency for the annihilation of + p into a lepton pair as well as for the most important background channels have been performed. It is shown that precise measurements of the differential cross-section of the reaction + p e ^- + e ⁺ can be obtained in a wide kinematical range. The determination of the ratio R of the moduli of the electric and magnetic proton form factors will be possible up to a value of momentum transfer squared of q ² ≃ 14 (GeV/c)^2 with absolute precision from 0.01 to 0.5 (for R ∼ 1 . The total + p e ^- + e ⁺ cross-section will be measured up to q ² ≃ 28 (GeV/c)^2. The results obtained from simulated events are compared to the existing data. Sensitivity to the two-photon exchange mechanism is also investigated.