Eur. Phys. J. A (2021) 57: 205
https://doi.org/10.1140/epja/s10050-021-00521-9

Regular Article - Experimental Physics

Single ${\pi }^0$ production off neutrons bound in deuteron with linearly polarized photons

¹ SUPA, School of Physics and Astronomy, University of Glasgow, G12 8QQ, Glasgow, UK
² SUPA, School of Physics and Astronomy, University of Edinburgh, EH9 3FD, Edinburgh, UK
³ Department of Physics, University of Regina, S4S 0A2, Regina, SK, Canada
⁴ Department of Physics, Institute for Nuclear Studies, The George Washington University, 20052, Washington, DC, USA
⁵ Institut für Physik, University of Basel, 4056, Basel, Switzerland
⁶ Institut für Kernphysik, Johannes Gutenberg-University Mainz, 55099, Mainz, Germany
⁷ Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, 53115, Bonn, Germany
⁸ INFN Sezione di Pavia, 27100, Pavia, Italy
⁹ Kent State University, 44242, Kent, OH, USA
¹⁰ JINR, 141980, Dubna, Russia
¹¹ University of Massachusetts, 01003, Amherst, MA, USA
¹² Institute for Nuclear Research, 125047, Moscow, Russia
¹³ Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem, Israel
¹⁴ Mount Allison University, E4L3B5, Sackville, NB, Canada
¹⁵ Department of Physics, University of York, Heslington, Y010 5DD, York, UK
¹⁶ Rudjer Boskovic Institute, 10000, Zagreb, Croatia
¹⁷ NRC “Kurchatov Institute”-ITEP, 117218, Moscow, Russia
¹⁸ Institut für Experimentalphysik, Ruhr-University of Bochum, 44801, Bochum, Germany

^c Derek.Glazier@glasgow.ac.uk

Received: 12 March 2021
Accepted: 10 June 2021
Published online: 26 June 2021

Abstract

The quasifree $\overrightarrow{\gamma }d\to {\pi }^{0}n(p)$ photon beam asymmetry, $\Sigma$, has been measured at photon energies, $E_{\gamma }$, from 390 to 610 MeV, corresponding to center of mass energy from 1.271 to 1.424 GeV, for the first time. The data were collected in the A2 hall of the MAMI electron beam facility with the Crystal Ball and TAPS calorimeters covering pion center-of-mass angles from 49${}^{\circ }$ to 148${}^{\circ }$. In this kinematic region, polarization observables are sensitive to contributions from the $\Delta (1232)$ and N(1440) resonances. The extracted values of $\Sigma$ have been compared to predictions based on partial-wave analyses (PWAs) of the existing pion photoproduction database. Our comparison includes the SAID, MAID and Bonn–Gatchina analyses; while a revised SAID fit, including the new $\Sigma$ measurements, has also been performed. In addition, isospin symmetry is examined as a way to predict ${\pi }^{0}n$ photoproduction observables, based on fits to published data in the channels ${\pi }^{0}p$, ${\pi }^{+}n$ and ${\pi }^{-}p$.