Measurement of the helicity asymmetry E for the reaction - The CBELSA/TAPS Collaboration

M. Gottschall; F. Afzal; A. V. Anisovich; D. Bayadilov; R. Beck; M. Bichow; K. Th. Brinkmann; V. Crede; M. Dieterle; F. Dietz; H. Dutz; H. Eberhardt; D. Elsner; R. Ewald; K. Fornet-Ponse; St. Friedrich; F. Frommberger; A. Gridnev; M. Grüner; E. Gutz; Ch. Hammann; J. Hannappel; J. Hartmann; W. Hillert; Ph. Hoffmeister; Ch. Honisch; T. Jude; S. Kammer; H. Kalinowsky; I. Keshelashvili; P. Klassen; F. Klein; E. Klempt; K. Koop; B. Krusche; M. Kube; M. Lang; I. Lopatin; P. Mahlberg; K. Makonyi; V. Metag; W. Meyer; J. Müller; J. Müllers; M. Nanova; V. Nikonov; R. Novotny; D. Piontek; G. Reicherz; T. Rostomyan; A. Sarantsev; Ch. Schmidt; H. Schmieden; T. Seifen; V. Sokhoyan; K. Spieker; A. Thiel; U. Thoma; M. Urban; H. van Pee; D. Walther; Ch. Wendel; D. Werthmüller; U. Wiedner; A. Wilson; A. Winnebeck; L. Witthauer; Y. Wunderlich

doi:10.1140/epja/s10050-020-00334-2

2024 Impact factor 2.8

Hadrons and Nuclei

Open Access

Eur. Phys. J. A (2021) 57: 40
https://doi.org/10.1140/epja/s10050-020-00334-2

Regular Article – Experimental Physics

Measurement of the helicity asymmetry E for the reaction $γ p \to π^{0} p$ $\gamma p\rightarrow \pi ^0 p$

The CBELSA/TAPS Collaboration

M. Gottschall¹, F. Afzal¹, A. V. Anisovich¹^,3, D. Bayadilov¹^,3, R. Beck¹, M. Bichow⁶, K. Th. Brinkmann⁴, V. Crede⁷, M. Dieterle⁵, F. Dietz⁴, H. Dutz², H. Eberhardt², D. Elsner², R. Ewald², K. Fornet-Ponse², St. Friedrich⁴, F. Frommberger², A. Gridnev³, M. Grüner¹, E. Gutz⁴, Ch. Hammann¹, J. Hannappel², J. Hartmann¹, W. Hillert², Ph. Hoffmeister¹, Ch. Honisch¹, T. Jude², S. Kammer², H. Kalinowsky¹, I. Keshelashvili⁵, P. Klassen¹, F. Klein², E. Klempt¹, K. Koop¹, B. Krusche⁵, M. Kube¹, M. Lang¹, I. Lopatin³, P. Mahlberg¹, K. Makonyi⁴, V. Metag⁴, W. Meyer⁶, J. Müller¹, J. Müllers¹, M. Nanova⁴, V. Nikonov¹^,3, R. Novotny⁴, D. Piontek¹, G. Reicherz⁶, T. Rostomyan⁵, A. Sarantsev¹^,3, Ch. Schmidt¹, H. Schmieden², T. Seifen¹, V. Sokhoyan¹, K. Spieker¹, A. Thiel¹, U. Thoma¹^bn, M. Urban¹, H. van Pee¹, D. Walther¹, Ch. Wendel¹, D. Werthmüller⁵, U. Wiedner⁶, A. Wilson¹^,7, A. Winnebeck¹, L. Witthauer⁵ and Y. Wunderlich¹

¹ Helmholtz–Institut für Strahlen– und Kernphysik, Universität Bonn, Bonn, Germany
² Physikalisches Institut, Universität Bonn, Bonn, Germany
³ Petersburg Nuclear Physics Institute, Gatchina, Russia
⁴ Physikalisches Institut, Universität Gießen, Gießen, Germany
⁵ Physikalisches Institut, Universität Basel, Basel, Switzerland
⁶ Institut für Experimentalphysik I, Ruhr–Universität Bochum, Bochum, Germany
⁷ Department of Physics, Florida State University, 32306, Tallahassee, FL, USA

^bn thoma@hiskp.uni-bonn.de

Received: 20 May 2019
Accepted: 28 November 2020
Published online: 28 January 2021

Abstract

A measurement of the double-polarization observable E for the reaction $γ p \to π^{0} p$ $\gamma p\rightarrow \pi ^0 p$ is reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility in Bonn using the Bonn frozen-spin butanol (C $_{4}$ $$_4$$ H $_{9}$ $$_9$$ OH) target, which provided longitudinally-polarized protons. Circularly-polarized photons were produced via bremsstrahlung of longitudinally-polarized electrons. The data cover the photon energy range from $E_{γ} = 600$ $E_\gamma =600$ to 2310 MeV and nearly the complete angular range. The results are compared to and have been included in recent partial wave analyses.

© The Author(s) 2021

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