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        "description": "The metastable fraction is a model-dependent estimate within the positronium beam, not a 10% conversion of incident positrons. It depends on transition locations, decay survival and detector efficiencies; the detected metastable rate was inferred to be about two atoms per second. Position-derived velocity distributions assume production geometry and approximate longitudinal energies. The broad microwave spectra are identification and apparatus diagnostics, rather than high-precision field-free intervals. Improved count rates, two-waveguide Ramsey fringes and FOSOF spectroscopy remained prospective in this paper.",
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      "statement": "# Production and characterization of an energy-tunable continuous metastable positronium beam\n\nNewson, Babij and Cassidy produced a continuous beam containing metastable 2³S₁ positronium through charge-exchange collisions between positrons and xenon. Two position-sensitive detectors measured the beam profiles, and microwave-induced 2³S₁ → 2³P₂ transitions reduced the surviving count rate, identifying the metastable component. With flight-decay and saturation corrections, the authors estimated a metastable fraction of up to about 10% of the positronium beam under their chosen conditions. The measured beam properties and a preliminary single-waveguide spectrum supported its proposed use in separated-field spectroscopy.\n\n## Scientific scope\n\nThe metastable fraction is a model-dependent estimate within the positronium beam, not a 10% conversion of incident positrons. It depends on transition locations, decay survival and detector efficiencies; the detected metastable rate was inferred to be about two atoms per second. Position-derived velocity distributions assume production geometry and approximate longitudinal energies. The broad microwave spectra are identification and apparatus diagnostics, rather than high-precision field-free intervals. Improved count rates, two-waveguide Ramsey fringes and FOSOF spectroscopy remained prospective in this paper.\n\n## Reading status\n\nThis is a source-linked WRS catalogue note. A full explanatory guide and independent scientific reconstruction have not been completed for this entry. Read the identified original work for its complete narrative and arguments.\n\n## People and systems\n\nD. M. Newson; T. J. Babij; D. B. Cassidy\n\nThese are the listed authors of the cited contribution sources. Paper authorship does not quantify individual effort. An incomplete list is explicitly marked; same names are not automatically merged.\n\n\n\n## Original sources\n\n- [An energy tunable continuous 2tripletS1 positronium beam (RSI94:083201)](https://discovery.ucl.ac.uk/id/eprint/10175970/1/083201_1_5.0167125.pdf)\n",
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