A new paper in Physical Review X reports on experimental observations of a new D-D fusion reaction channel at very low energies. Importantly, this new channel helps to explain the lack of conventional branching ratios observed in many condensed matter nuclear science experiments. Our congratulations to Dr. Rakesh Dubey and his colleagues at Uniwersytet Szczeciński and the Maritime University of Szczecin.
Abstract:
The discovery of a new, 𝑒+𝑒− reaction channel in deuteron-deuteron (DD) fusion at very low energies might have major implications for understanding primordial and stellar nucleosynthesis, where electron-positron reaction channels are typically not considered. It could also enable research on metal hydride fusion, potentially paving the way for the design and construction of next-generation fusion energy sources. Following the first experimental indications of electron emission, we present here an extensive experimental study confirming emission of high-energy electrons from DD reaction at very low energy. A simultaneous use of Si charged particle detectors of different thicknesses and large-volume NaI(Tl) and HPGe detectors has allowed the determination of the branching ratios between emitted protons, neutrons, and 𝑒+𝑒− pairs for deuteron energies down to 5 keV. The high-energy positrons could be unambiguously detected by their bremsstrahlung spectra and annihilation radiation, supported by the geant4 Monte Carlo simulations. The theoretical calculations, based on a destructive interference between the threshold resonance and the known broad resonance in 4He, agree very well with experimentally observed increase of branching ratios for lowering projectile energies. The partial width of the threshold resonance for the internal 𝑒+𝑒− pair creation should be at least 10 times larger than that of the proton channel.