{"paper":{"title":"Measurement of the beam-helicity asymmetry $I^{\\odot}$ in the photoproduction of $\\pi^0$-pairs off the proton and off the neutron","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"nucl-ex","authors_text":"A. Braghieri, A. Fix, A. Kaeser, A. Kulbardis, A. Mushkarenkov, A. Nikolaev, A. Polonski, A. Starostin, A. Thomas, B. Demissie, B. Krusche, B.M.K. Nefkens, B. Oussena, D. Branford, D.G. Middleton, D. Hornidge, D. Howdle, D.I. Glazier, D.I. Sober, D. Mekterovic, D.M. Manley, D.P. Watts, D. Werthmueller, E. Heid, E.J. Downie, E. McNicoll, F. Pheron, F. Zehr, G.M. Huber, G. Rosner, H. Berghaeuser, H.J. Arends, I. Jaegle, I.J.D. MacGregor, I. Keshelashvili, I. Supek, J. Ahrens, J. Brudvik, J.C. McGeorge, J. Mancell, J.R.M. Annand, J. Robinson, K. Bantawa, K. Livingston, L.V. Fil'kov, L. Witthauer, M. Dieterle, M.H. Sikora, M. Korolija, M. Martinez, M. Oberle, M. Ostrick, M. Thiel, M. Unverzagt, O. Jahn, P.A. Bartolome, P. Drexler, P. Pedroni, R. Beck, R. Kondratiev, R. Novotny, S. Cherepnya, S. Micanovic, S.N. Prakhov, S.P. Kruglov, S. Schumann, T.C. Jude, T. Rostomyan, V. Bekrenev, V. Lisin, V.L. Kashevarov, V. Metag, W.J. Briscoe, Y. Maghrbi, Z. Marinides","submitted_at":"2013-04-06T17:49:07Z","abstract_excerpt":"Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of neutral pion pairs in the reactions $\\vec{\\gamma}p\\rightarrow p\\pi^0\\pi^0$ and $\\vec{\\gamma}d\\rightarrow (n)p\\pi^0\\pi^0$, $\\vec{\\gamma}d\\rightarrow (p)n\\pi^0\\pi^0$ 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 $\\pi^0$ mesons, recoil protons, and recoil ne"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1304.1919","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}