Speaker
Description
It has been known that there is an outstanding discrepancy between theoretical predictions and astronomical observations of primordial lithium abundances, so called cosmological lithium problem (CLP). From the point of view of nuclear physics, 7Be(n,p)7Li and 7Be(alpha,n)4He are the most important reactions which act to decrease 7Li in Big Bang nucleosynthesis (BBN). There was still lacked information on cross sections of these reactions to further constrain BBN, such as the contribution of the exit channel to the first excited state of 7Li, in spite of several relevant experiments reported recently.
We measured the cross sections of the 7Be(n,p0)7Li, 7Be(n,p1)7Li* and 7Be(alpha,n)4He reaction channels by Trojan Horse method. An R-matrix analysis both to the present and the previous data improved uncertainty of the (n,p0) channel cross section, and the first-ever quantification of the (n,p1) contribution in the BBN energy range. The updated total reaction rate of (n,p0) + (n,p1) leads a reduction of the predicted 7Li abundance by about one-tenth. We expect this work to reduce the nuclear physics uncertainty, and to offer a closer standing point to the CLP solution.
[Reference]
Hayakawa et al., Astrophys. J. Lett. 915, L13 (2021).
DOI: 10.3847/2041-8213/ac061f
| Please select a main topic related to your abstract | Big Bang Cosmology and Primordial Nucleosynthesis |
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