Butsuri
Online ISSN : 2423-8872
Print ISSN : 0029-0181
ISSN-L : 0029-0181
Researches
Nuclear Experimental Approach Toward Solving the Cosmological Lithium Problem
Takahiro KawabataShigeru Kubono
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2018 Volume 73 Issue 1 Pages 27-32

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Abstract

The primordial abundances of the light elements produced in the Big Bang nucleosynthesis (BBN) provide important insights into the early universe. Accurate estimation of the primordial abundances is crucial to test the cosmological theories by comparing the predicted values with the observations. However, there remains a serious problem that the 7Li abundance does not agree with the standard BBN calculation. Since the BBN theory relies on nuclear reactions among the primordial light elements and their electroweak decays, nuclear experimental approaches toward solving the cosmological lithium problem are important.

Recently, we measured the cross sections of the 7Be (n, α)4He reaction at E=0.20–0.81 MeV close to the BBN energy window for the first time by measuring the time-reverse reaction. The obtained cross sections are significantly smaller than the theoretical estimation widely used in the BBN calculations. The present results suggest the 7Be (n, α)4He reaction rate is not large enough to solve the cosmological lithium problem.

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© 2018 The Physical Society of Japan
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