Speaker
Description
The disagreement between abundances of observed $^{7}$Li in metal-poor halo stars and primordial $^{7}$Li as predicted by Big Bang Nucleosynthesis (BBN) theory is unsolved for decades. Before considering new physics beyond standard model, recent works tried to search for a nuclear physics solution. This includes studying the cross sections of relevant nuclear reactions, particularly those leading to the destruction of $^{7}$Be. The d + $^{7}$Be rate used in BBN calculations over the past thirty years was based on an estimate of a constant S-factor of 100 MeV-b. Thus the $^{7}$Be(d,p)$^{8}$Be reaction was considered as a potential candidate to solve the lithium abundance anomaly. The $^{7}$Be(d,$^{3}$He)$^{6}$Li reaction also needs to be studied in the context of the anomaly and there is only one measurement of this reaction.
We carried out an experiment at the HIE-ISOLDE radioactive ion beam facility at CERN to measure the $^{7}$Be(d,p)$^{8}$Be and $^{7}$Be(d,$^{3}$He)$^{6}$Li reactions in inverse kinematics using a 5 MeV/A $^{7}$Be beam on a CD$_2$ target. An array of double-sided silicon strip detectors covering $8^\circ -165^\circ$ in lab was utilised to detect the charged particles emitted from these reactions. The total cross sections of the (d,p) and (d,$^{3}$He) channels are obtained at a higher centre-of-mass energy than the required Gamow energies. We measured the higher excited states of $^{8}$Be up to 22 MeV for the first time in the $^{7}$Be(d,p)$^{8}$Be channel. The excitation functions of the reactions are calculated using TALYS by normalization to the present data and the S-factors are extrapolated to the Gamow energies. The experimental results in the context of the lithium anomaly will be presented.
| Length of presentation requested | Oral presentation: 17 min + 3 min questions |
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| Please select between one and three keywords related to your abstract | Nucleosynthesis |
| 2nd keyword (optional) | Nuclear physics - experimental |
