Beam-Helicity Asymmetries in Double-Pion Photoproduction off the Proton

Journal Article · Fri Jul 31 00:00:00 EDT 2009 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.103.052002· OSTI ID:21370606

Krambrich, D; Aguar, P; Ahrens, J; Arends, H J; Heid, E; Jahn, O; Martinez, M; Rost, M; Thomas, A; Walcher, Th ^[1]; Zehr, F; Boillat, B; Kotulla, M; Krusche, B; Pheron, F ^[2]; Fix, A ^[3]; Roca, L ^[4]; Annand, J R. M.; Codling, R; Downie, E J ^[5]

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1. Institut fuer Kernphysik, Johannes Gutenberg-Universitaet Mainz, Mainz (Germany)
2. Department of Physics, University of Basel, Basel (Switzerland)
3. Laboratory of Mathematical Physics, Tomsk Polytechnic University, 634034 Tomsk (Russian Federation)
4. Departamento de Fisica, Universidad de Murcia , Murcia (Spain)
5. Department of Physics and Astronomy, University of Glasgow, Glasgow (United Kingdom)

Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz in the three isospin channels gamma-vectorp->pi{sup +}pi{sup 0}n, gamma-vectorp->pi{sup 0}pi{sup 0}p, and gamma-vectorp->pi{sup +}pi{sup -}p. The circularly polarized photons, produced from bremsstrahlung of longitudinally polarized electrons, were tagged with the Glasgow magnetic spectrometer. Charged pions and the decay photons of pi{sup 0} mesons were detected in a 4pi electromagnetic calorimeter which combined the Crystal Ball detector with the TAPS detector. The precisely measured asymmetries are very sensitive to details of the production processes and are thus key observables in the modeling of the reaction dynamics.

• OSTI ID: 21370606
• Journal Information: Physical Review Letters, Vol. 103, Issue 5; Other Information: DOI: 10.1103/PhysRevLett.103.052002; (c) 2009 The American Physical Society; ISSN 0031-9007
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ASYMMETRY
BREMSSTRAHLUNG
CALORIMETERS
ELECTRONS
HELICITY
ISOSPIN
MAGNETIC SPECTROMETERS
PAIR PRODUCTION
PARTICLE DECAY
PHOTONS
PHOTOPRODUCTION
PIONS MINUS
PIONS NEUTRAL
PIONS PLUS
POLARIZED BEAMS
PROTON BEAMS
BASIC INTERACTIONS
BEAMS
BOSONS
DECAY
ELECTROMAGNETIC INTERACTIONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FERMIONS
HADRONS
INTERACTIONS
LEPTONS
MASSLESS PARTICLES
MEASURING INSTRUMENTS
MESONS
NUCLEON BEAMS
PARTICLE BEAMS
PARTICLE INTERACTIONS
PARTICLE PRODUCTION
PARTICLE PROPERTIES
PIONS
PSEUDOSCALAR MESONS
RADIATIONS
SPECTROMETERS