AWhat changed
De Sousa Borges and colleagues measured the positronium 1³S₁ → 2³S₁ interval with continuous-wave two-photon excitation and photoionization by the same laser. Coincidence detection of the released positron and two annihilation photons suppressed background; 1124 selected events from about 12 days supported a transition frequency of 1,233,607,224.1±6.0 MHz, or 4.9 parts per billion. They also developed an approximate semi-analytical line-shape model and compared its fitted centres with their Monte Carlo model and the measured spectrum.
Scientific scope
De Sousa Borges and colleagues measured the positronium 1³S₁ → 2³S₁ interval with continuous-wave two-photon excitation and photoionization by the same laser. Coincidence detection of the released positron and two annihilation photons suppressed background; 1124 selected events from about 12 days supported a transition frequency of 1,233,607,224.1±6.0 MHz, or 4.9 parts per billion. They also developed an approximate semi-analytical line-shape model and compared its fitted centres with their Monte Carlo model and the measured spectrum. The interval inference depends on the assumed positronium velocity and spatial distributions, line-shape simulation and laser-frequency calibration. A frequency comb was unavailable during data collection; wavemeter metrology dominated the uncertainty. Agreement between the two fits uses the same experiment and related model inputs and is not an independent replication. The semi-analytical expression uses perturbative depletion and fitted profile approximations, with visible deviations at high power and low speed. Some printed formula and correction conventions remain unresolved. This record describes the 2025 preprint; a later journal publication may differ. Sub-ppb or few-ppt precision remained prospective.
Evidence
The linked original works support the scoped statement and contribution attribution. WRS has not independently replayed experiments or reconstructed a full mathematical proof. The interval inference depends on the assumed positronium velocity and spatial distributions, line-shape simulation and laser-frequency calibration. A frequency comb was unavailable during data collection; wavemeter metrology dominated the uncertainty. Agreement between the two fits uses the same experiment and related model inputs and is not an independent replication. The semi-analytical expression uses perturbative depletion and fitted profile approximations, with visible deviations at high power and low speed. Some printed formula and correction conventions remain unresolved. This record describes the 2025 preprint; a later journal publication may differ. Sub-ppb or few-ppt precision remained prospective.
Contributors
- The named authors in the research record · SCIENCE: These 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.
Provisional WRS assessment, edition 2026-10-28.1. Independent expert calibration is pending. This grade does not certify correctness or assign ownership.
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