Speaker
Description
The neutron-rich $N\sim126$ region is important to r-process calculations and has been less explored by experiments. This region is unique for its strong competition between allowed and first-forbidden transitions [1], which complicates half-life predictions. Besides, the position of the third r-process abundance peak and production of actinides are sensitive to half-lives of $N=126$ isotones [2,3]. Measurements of more exotic nuclei are essential to verify theoretical models commonly used in r-process calculations.
We will present results from the BRIKEN experiment [4] at RIBF. Particle identification was confirmed by the BigRIPS separator and a silicon energy-loss telescope. On the first attempt by RIBF, half-lives and beta-delayed neutron-emission probabilities ($P_n$) of $N\sim126$ exotic isotopes—some never been measured before—were determined by the WAS3ABi beta-counting system [5] and the BRIKEN neutron counter [6]. Preliminary results of $Z\leq79$ isotopes will be discussed.
References
[1] Zs. Podolyák, EPJ Web of Conf. 260, 03005 (2022).
[2] T. Suzuki et al., Astrophys. J. 859(2), 133 (2018).
[3] E. Holmbeck et al., Astrophys. J. 870(1), 23 (2018).
[4] T. T. Yeung et al., arXiv:2401.06428 (2024). https://arxiv.org/abs/2401.06428
[5] S. Nishimura, Prog. Theor. Exp. Phys. 2012(1), 03C006 (2012).
[6] A. Tolosa-Delgado et al., Nucl. Instrum. Methods. Phys. Res. A 925-133 (2019).
