{"paper":{"title":"Observation of double radiative capture on pionic hydrogen","license":"","headline":"","cross_cats":[],"primary_cat":"nucl-ex","authors_text":"D. H. Wright, D. S. Armstrong, J. H. D. Clark, M. A. Kovash, M. D. Hasinoff, M. E. Christy, P. A. Zolnierczuk, S. Tripathi, T. P. Gorringe","submitted_at":"2002-04-25T21:32:16Z","abstract_excerpt":"We report the first observation of double radiative capture on pionic hydrogen. The experiment was conducted at the TRIUMF cyclotron using the RMC spectrometer, and detected $\\gamma$--ray coincidences following $\\pi^-$ stops in liquid hydrogen. We found the branching ratio for double radiative capture to be $(3.05 \\pm 0.27(stat.) \\pm 0.31(syst.)) \\times 10^{-5}$. The measured branching ratio and angle-energy distributions support the theoretical prediction of a dominant contribution from the $\\pi \\pi \\to \\gamma \\gamma$ annihilation mechanism."},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"nucl-ex/0204013","kind":"arxiv","version":4},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/nucl-ex/0204013/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"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"}