{"paper":{"title":"Double pion photoproduction off nuclei - are there effects beyond final-state interaction?","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"nucl-ex","authors_text":"A. Braghieri, A. Fix, A. Knezevic, A. Kondratiev, A. Nikolaev, A. Polonski, A. Thomas, B. Boillat, B. Krusche, B.M.K. Nefkens, D. Branford, D. Hornidge, D.I. Glazier, D. Krambrich, D. Mekterovic, D.M. Manley, D.P. Watts, D. Sober, D. Werthmueller, E. Heid, E.J. Downie, F. Pheron, F. Zehr, G. Rosner, H.J. Arends, I. Jaegle, I.J.D. MacGregor, I. Keshelashvili, I. Supek, J. Ahrens, J. Brudvik, J.C. McGeorge, J.R.M. Annand, J.W. Price, K. Livingston, L.V. Fil'kov, M. Korolija, M. Kotulla, M. Lang, M. Martinez, M. Ostrick, M. Rost, M. Unverzagt, O. Jahn, P. Dexler, P. Pedroni, R. Beck, R. Codling, R. Gregor, R. Novotny, S. Cherepnya, S. Lugert, S.N. Prakhov, S. Schadmand, S. Schumann, S. Starostin, T. Rostomyan, V. Bekrenev, V. Lisin, V.L. Kashevarov, V. Metag, W.J. Briscoe, Y. Maghrbi","submitted_at":"2013-04-06T17:44:41Z","abstract_excerpt":"Photoproduction of $\\pi^{0}\\pi^{0}$ and $\\pi^{0}\\pi^{\\pm}$ pairs from nuclei has been measured over a wide mass range ($^2$H, $^{7}$Li, $^{12}$C, $^{40}$Ca, and $^{\\rm nat}$Pb) for photon energies from threshold to 600 MeV. The experiments were performed at the MAMI accelerator in Mainz, using the Glasgow photon tagging spectrometer and a 4$\\pi$ electromagnetic calorimeter consisting of the Crystal Ball and TAPS detectors. A shift of the pion-pion invariant mass spectra for heavy nuclei to small invariant masses has been observed for $\\pi^0$ pairs but also for the mixed-charge pairs. The preci"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1304.1918","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"}