https://doi.org/10.1140/epja/i2009-10870-x
Regular Article - Experimental Physics
Measurement of
beam asymmetry in
photoproduction off the neutron in the second and third resonances region⋆
1
INFN - Sezione di Roma “Tor Vergata”, via della Ricerca Scientifica 1, I-00133, Roma, Italy
2
INFN - Sezione di Catania, via Santa Sofia 64, I-95123, Catania, Italy
3
INFN - Laboratori Nazionali di Frascati, via Enrico Fermi 40, I-00044, Frascati, Italy
4
INFN - Laboratori Nazionali del Sud, via Santa Sofia 64, I-95123, Catania, Italy
5
Institut National Polytechnique de Grenoble, LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, 53 Avenue des Martyrs, 38026, Grenoble, France
6
IPNO, Université de Paris-Sud 11, CNRS/IN2P3, 15 rue Georges Clémenceau, 91406, Orsay, France
7
INFN - Sezione di Torino, via P. Giuria, I-10125, Torino, Italy
8
INFN - Sezione di Roma, piazzale Aldo Moro 2, I-00185, Roma, Italy
9
Institute for Nuclear Research, 117312, Moscow, Russia
10
Dipartimento di Fisica, Università di Roma “Tor Vergata”, via della Ricerca Scientifica 1, I-00133, Roma, Italy
11
Dipartimento di Fisica e Astronomia, Università di Catania, via Santa Sofia 64, I-95123, Catania, Italy
12
Università di Torino, via P. Giuria, I-00125, Torino, Italy
13
Istituto Superiore di Sanità, viale Regina Elena 299, I-00161, Roma, Italy
14
Dipartimento di Fisica, Università di Messina, salita Sperone 31, I-98166, Messina, Italy
15
Laboratory of Mathematical Physics, Tomsk Polytechnic University, 634050, Tomsk, Russia
16
Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099, Mainz, Germany
17
Laboratory of Theoretical Physics, JINR Dubna, 141980, Moscow region, Russia
* e-mail: paolo.levisandri@lnf.infn.it
Received:
21
April
2009
Revised:
27
August
2009
Accepted:
3
September
2009
Published online:
4
October
2009
The beam asymmetry in the photoproduction of neutral pions from quasi-free nucleons in a deuteron target was measured for the first time between 0.60 and 1.50GeV, with the GRAAL polarized and tagged photon beam. The asymmetry values from the quasi-free proton were found equal to the ones extracted from a pure proton target. The asymmetries from quasi-free proton and quasi-free neutron were found equal up to 0.82GeV and substantially different at higher energies. The results are compared with recent partial-wave analyses.
PACS: 13.60.Le Meson production – / 13.88.+e Polarization in interactions and scattering – / 25.20.Lj Photoproduction reactions –
© SIF, Springer-Verlag Berlin Heidelberg, 2009