Silicon Telescope Method Quantifies Weak e+e- Pair Branching Ratio in Low-Energy DD Fusion Under Background Constraints

The experiment deploys thin silicon detectors in telescope geometry to capture partial energy deposits from relativistic leptons while modeling cosmic-ray secondaries, terrestrial gammas constrained by NaI(Tl) data, and beam-induced neutrons. Long-duration runs in varied orientations and shielding establish run-to-run variability, translating into a systematic envelope applied to both singles and coincidence spectra. This yields the first background-limited branching-ratio value for the weak channel. The approach directly addresses overlap between continuum-like signals and natural radiation, a persistent barrier in surface-lab searches for rare nuclear processes.

Related work on low-energy fusion anomalies has repeatedly shown that apparent signals vanish under stricter background subtraction or improved statistics, as seen in historical claims around 3He and 4He branches. The current methodology improves on prior single-detector setups by enforcing multi-configuration validation, yet still operates at the edge of statistical power where small changes in cosmic-ray modeling can shift extracted limits by factors of two. Cross-checks against independent NaI(Tl) and neutron time-of-flight data provide necessary but not sufficient controls.

No replication campaign or underground measurement is described, leaving open whether the reported ratio survives deeper shielding or higher beam current. The framework is transferable to other weak-pair searches, but its ultimate utility depends on whether future runs achieve the factor-of-ten background reduction needed to move from upper limits to definitive observation.

Next steps include deployment at a shallow underground site and integration with active veto arrays to test the extracted ratio at the 10^-6 level within 18 months.