Ponente
Descripción
The solar r-process abundance distribution has a small but distinct local maximum at A~160, known as the rare-earth abundance peak (REP). The REP formation is sensitive to both astrophysical and nuclear parameters. There are several different hypothesizes in the literature to understand the synthesis of these isotopes, but experimental data (nuclear masses, $\beta$-decay parameters and nuclear structure information) are clearly necessary for fine-tuning the REP formation models [1,2] (and references therein).
In the last decade a large effort was devoted to measure masses, beta-decay half-lives and delayed neutron emission probabilities for neutron-rich unstable isotopes (see [3] for summary, further references therein), however, there is lack of such data for the lower mass lanthanides. On the one hand side, the most recent astrophysical sensitivity study [4] highlighted that the description of the peak formation in a hot scenario requires decay data on neutron-rich Xe-Ce isotopes not available at present. On the other hand side, in the most recent mass measurement carried out for the neutron-rich $^{148-153}$La isotopes an unexpected sudden increase in the two neutron separation was found [5]. This change in the S$_{2n}$ trend might be due to the the predicted onset of quadrupole deformation [6]. There is no information on the structure of the neutron-rich lanthanum isotopes with N $\geq$ 83 and therefore, we propose to study the level schemes in the mass region by measuring the $\beta$-delayed $\gamma$ emission of neutron-rich Xe, Cs and Ba isotopes.
Note, that the collected data might have a direct astrophysical relevance since recently lanthanide features in near-infrared spectra of kilonovae GW170817/AT2017gfo were found [7].
[1] A. Arcones et al., Phys. Rev. C 83 (2011) 045809.
[2] M. Mumpower et al., Phys. Rev. C 85 (2012) 045801.
[3] G. G. Kiss and Zs. Podolyak, Eur. Phys. J. 936 (2022) 107.
[4] Y. W. Hao et al., Phys. Rev. C Lett. 108 (2023) L062802.
[5] A. Jaries et al. Phys. Rev. Lett. 134 (2025) 042501.
[6] J. Dobaczewski et al., Phys. Rev. Lett. 60 (1988) 2254.
[7] N. Domoto et al., Astrophys. J. 939 (2022) 8.
