Eur. Phys. J. A (2005) 26: 399-419
https://doi.org/10.1140/epja/i2005-10191-2

Original Article

Measurement of πphotoproduction on the proton from 550 to 1500 MeV at GRAAL

¹ Dipartimento di Fisica ed Astronomia, Università di Catania, via Santa Sofia 64, I-95123, Catania, Italy
² Dipartimento di Fisica, Università di Roma “Tor Vergata”, via della Ricerca Scientifica 1, I-00133, Roma, Italy
³ Dipartimento di Fisica Sperimentale, Università di Torino, via P. Giuria, I-00125, Torino, Italy
⁴ Laboratori Nazionali di Frascati, INFN, via E. Fermi 40, I-00044, Frascati (Roma), Italy
⁵ Laboratori Nazionali del Sud, INFN, via Santa Sofia 44, I-95123, Catania, Italy
⁶ Sezione di Catania, INFN, via Santa Sofia 64, I-95123, Catania, Italy
⁷ Sezione di Genova, INFN, via Dodecanneso 33, I-16146, Genova, Italy
⁸ Sezione di Roma I, INFN, piazzale Aldo Moro 2, I-00185, Roma, Italy
⁹ Sezione di Roma II, INFN, via della Ricerca Scientifica 1, I-00133, Roma, Italy
¹⁰ Sezione di Torino, INFN, I-10125, Torino, Italy
¹¹ Instituto Superiore di Sanità, viale Regina Elena 299, I-00161, Roma, Italy
¹² Laboratoire de Physique Subatomique et de Cosmologie, IN2P3, F-38026, Grenoble, France
¹³ Institute for Nuclear Research, 117312, Moscow, Russia

^* e-mail: lleres@lpsc.in2p3.fr

Received: 27 June 2005
Accepted: 5 January 2006
Published online: 23 January 2006

Abstract

Neutral pion photoproduction has been measured from 550 to 1500 MeV with the GRAAL facility, located at the ESRF in Grenoble. Differential cross-section and beam asymmetry have been measured over a wide angular range. These high-precision data improve significantly the database for the beam asymmetry in the second and third resonance regions covering for the first time the energy domain 1100-1500 MeV. New partial-wave analyses including these data are presented for which the beam asymmetry brings crucial constraints.