Speaker
Description
Big Bang nucleosynthesis (BBN) theory predicts the primordial abundances of the light elements produced in the early universe. Among them, deuterium, the first nuclide produced by BBN, is also a key primordial material for subsequent reactions. With observed D abundance now at 1% precision, theoretical and nuclear data must match this accuracy. At the Shanghai Laser Electron Gamma Source (SLEGS), we measured the D($\gamma$,n)p photodisintegration reaction using a novel LCS quasi-monochromatic $\gamma$-ray source. Cross sections were determined for E$_\gamma$≈2.33--7.09 MeV, achieving ~2.2 times higher precision than previous measurements near the neutron separation threshold. Using dEFT and MCMC analysis, we re-evaluated p(n,$\gamma$)D cross sections, incorporating all available data. The new results are ~2.5--4.3 times more precise below 1 MeV, yielding a BBN-relevant reaction rate with 0.12% precision (~2.1--3.7 times improvement over prior evaluations). The impact on BBN nucleosynthesis has also been investigated.
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