Speaker
Description
The abundances of the light elements are predicted by the Big Bang Nucleosynthesis (BBN) and can be spectroscopically determined by observing the low-metallicity stars. Usually, the measurements are in agreement with the BBN predictions. Particularly, the Li-7 measured abundance is 3-4 times lower than expected, discrepancy known as the “cosmological Li problem”. The reaction $^3$H(α,γ)$^7$Li contributes to the production of Li-7 in Universe and can be studied through its inverse reaction, according to the reciprocity theorem. The Li-7 photodisintegration has been measured by our team once in 2017 and then again in 2023 at the High Intensity γ-ray Source (HIγS) Laboratory of Duke University (USA), using a silicon detector array (SIDAR) to observe coincidences between alpha particles and tritons. In 2023, the reaction was measured for gamma-beam energies between 3.7 and 6 MeV.
The set-up and the results of the experimental campaign carried out at HIγS in 2023 will be presented. In addition, a new experiment conducted in 2026, enploying a similar set-up will be discussed. The latter focuses on the measurement of photonuclear reactions (γ,p) and (γ,α) on different targets as Sn-116 and Sn-120.