Required precision of mass and half-life measurements for r-process nuclei planned at future radioactive-ion-beam facilities

¹ RIKEN, Hirosawa 2-1, Wako 351-0198, Japan
² Senior High School of Waseda University, Kami-Shakujii 3-31-1, Nerima-ku, Tokyo 177-0044, Japan
³ Advanced Research Institute for Science and Engineering, Waseda University, Okubo 3-4-1, Shinjuku-ku, Tokyo 169-8555, Japan
⁴ Institut d'Astronomie et d'Astrophysique, Université Libre de Bruxelles, CP 226, 1050 Bruxelles, Belgium

Abstract

In order to understand the r-process nucleosynthesis, we evaluate the precision required for mass and β-decay half-life measurements planned at future radioactive-ion-beam facilities. To satisfy a simple requirement that we put on nuclear model predictions, it is concluded that the detectors for the mass measurements must have a precision of 1σ < ~ 250 keV, and that the detectors for the half-life measurements demand a precision of 1σ < ~ 0.15 ms. The above two specifications are required at the neutron richness of A/Z = 3.0 at the N=82 shell closure and A/Z = 2.9 at the N=50 shell closure. For the doubly magic nuclide ⁷⁸Ni, a precision of 1σ < ~ 300 keV and 1σ < ~ 5 ms are required, respectively, for mass and half-life measurements. This analysis aims at providing a first rough guide for ongoing detector developments.