Speaker
Hidetoshi Yamaguchi
(Center for Nuclear Study, University of Tokyo)
Description
Astrophysical reactions involving radioactive isotopes (RI) are of importance for the stellar energy generation and nucleosynthesis especially in explosive stellar environments, such as X-ray bursts, core-collapse supernovae, big-bang and supermassive metal-poor stars. In spite of the essential difficulties in the experimental evaluation of those reaction rates, there are several successful approaches to study them. The experiments at the low-energy RI beam separator CRIB (CNS Radioisotope Beam Separator), operated by Center for Nuclear Study (CNS), the University of Tokyo, are introduced as examples of such studies.
A striking method to study nuclear resonances in unstable nuclei is the proton/alpha resonant scattering with the thick target method in inverse kinematics. Many measurements have been performed at CRIB [1–4], mainly to study properties of resonances which may affect astrophysical reaction rates. With the measurement of 30S+alpha resonant scattering [4], we evaluated the 30S(alpha, p) reaction rate, which produces a considerable effect on the energy generation of X-ray bursts. The latest application of that method is the proton resonant scattering on an isomer-enriched 26Al RI beam, to study the destruction process of 26Al, which may reduce the production rate of cosmic 26Al gamma-rays.
Indirect measurements of relevant astrophysical reactions have also been performed at CRIB. The world's 1st Trojan-horse-method experiment with an RI beam was performed at CRIB by an international collaboration including the INFN-LNS group. Measuring quasi-free 18F(d, n alpha) reaction, the low-temperature 18F(p, alpha) reaction S-factor was experimentally determined for the 1rst time [5]. Another recent Trojan-horse measurement at CRIB was to determine 7Be(n, p) and (n, alpha) reaction rates, which can be relevant for the cosmological 7Li abundance problem. We have performed a measurement of those reactions with the 7Be beam at CRIB, covering the temperature range of the big-bang nucleosynthesis.
References
[1] H. Yamaguchi et al., Phys. Rev. C 87 (2013) 034306.
[2] J.J. He et al., Phys. Rev. C 88 (2013) 012801(R).
[3] H. Yamaguchi et al., Phys. Lett. B 766 (2017) 11.
[4] D. Kahl et al., Phys. Rev. C 97 (2018) 015802.
[5] S. Cherubini et al., Phys. Rev. C 92 (2015) 015805.
Primary author
Hidetoshi Yamaguchi
(Center for Nuclear Study, University of Tokyo)
Co-authors
Daid Kahl
(University of Edinburgh)
Hideki Shimizu
(Center for Nuclear Study, University of Tokyo)
Lei Yang
(Center for Nuclear Study, University of Tokyo)
Seiya Hayakawa
(Center for Nuclear Study, University of Tokyo)
