Speaker
Description
The radiative capture reaction 𝛼(d, 𝛾)6Li plays an important role in the early-Universe production of lithium and other light nuclei and has therefore been subject to extensive experimental and theoretical investigations. Its cross section was measured directly in the range of astrophysical relevance for the first time in 2014 by the LUNA collaboration [1], complementing two earlier attempts to determine it indirectly via Coulomb dissociation [2,3]. On the theoretical side, numerous estimates of the reaction cross section have been obtained using effective α+d descriptions of 6Li. Although the existing models describe well the binding energy and scattering properties of the α+d system, they predict substantially different short-range and asymptotic properties of the 6Li bound state wave function. Recently, the asymptotic normalization coefficient (ANC) of 6Li has been determined theoretically in an ab-initio study [4] yielding a value larger than that obtained from experimental phase shift analyses [5,6]. We present here a new set of α+d cluster effective descriptions of 6Li which enable us to systematically evaluate the influence of different short–range and asymptotic bound state properties on reaction observables. Using these potentials, we verify the peripheral nature of both the direct capture reaction 𝛼(d, 𝛾)6Li and the indirect dissociation process 208Pb(6Li, 𝛼d)208Pb. Furthermore, we confirm the relevance of higher-order effects and the nuclear-dominated character of the 208Pb(6Li, 𝛼d)208Pb reaction due to the N=Z nature of the clusters. Additionally, we study the relative magnitude of the E1 and E2 contributions to the radiative capture cross section, and how to adapt the effective α+d descriptions to fit experimental data.
[1] M. Anders et al. (LUNA Collaboration), Phys. Rev. Lett., 113, 042501 (2014).
[2] J. Kiener et al., Phys. Rev. C, 44, 2195 (1991).
[3] F. Hammache et al., Phys. Rev. C, 82, 065803 (2010).
[4] C. Hebborn et al., Phys. Rev. Lett., 129, 042503 (2022).
[5] L.D. Blokhintsev et al., Phys. Rev. C, 48, 2390 (1993).
[6] E. A. George et al., Phys. Rev. C, 59, 598 (1999).