Measurement of the beam-helicity asymmetry I<sup>⊙</sup> in the photoproduction of π<sup>0</sup>-pairs off the proton and off the neutron
- Oberle, M.
- Krusche, B.
- Ahrens, J.
- Annand, J.R.M.
- Arends, H.J.
- Bantawa, K.
- Bartolome, P.A.
- Beck, R.
- Bekrenev, V.
- Berghäuser, H.
- Braghieri, A.
- Branford, D.
- Briscoe, W.J.
- Brudvik, J.
- Cherepnya, S.
- Demissie, B.
- Dieterle, M.
- Downie, E.J.
- Drexler, P.
- Filʼkov, L.V.
- Fix, A.
- Glazier, D.I.
- Heid, E.
- Hornidge, D.
- Howdle, D.
- Huber, G.M.
- Jahn, O.
- Jaegle, I.
- Jude, T.C.
- Käser, A.
- Kashevarov, V.L.
- Keshelashvili, I.
- Kondratiev, R.
- Korolija, M.
- Kruglov, S.P.
- Kulbardis, A.
- Lisin, V.
- Livingston, K.
- MacGregor, I.J.D.
- Maghrbi, Y.
- Mancell, J.
- Manley, D.M.
- Marinides, Z.
- Martinez, M.
- McGeorge, J.C.
- McNicoll, E.
- Mekterovic, D.
- Metag, V.
- Micanovic, S.
- Middleton, D.G.
- Mushkarenkov, A.
- Nefkens, B.M.K.
- Nikolaev, A.
- Novotny, R.
- Ostrick, M.
- Oussena, B.
- Pedroni, P.
- Pheron, F.
- Polonski, A.
- Prakhov, S.N.
- Robinson, J.
- Rosner, G.
- Rostomyan, T.
- Schumann, S.
- Sikora, M.H.
- Sober, D.I.
- Starostin, A.
- Supek, I.
- Thiel, M.
- Thomas, A.
- Unverzagt, M.
- Watts, D.P.
- Werthmüller, D.
- Witthauer, L.
- Zehr, F.
DOIAbstract
Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of neutral pion pairs in the reactions s γp → pπ0π0 and γd → (n)pπ0π0, γd → (p)nπ0π0 off free protons and off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow magnetic spectrometer. Decay photons from the π<sup>0</sup> mesons, recoil protons, and recoil neutrons were detected in the 4π covering electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. After kinematic reconstruction of the final state, excellent agreement was found between the resu...
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