ScholarWorks@성균관대학교

초록

We evaluated the uncertainty in the alpha-decay rates and fission barriers of the isotopes from Bi (Z = 83) to Fm (Z = 100) due to the difference in formalisms. The sensitivity of the r-process abundance to the alpha-decay rates and fission barriers of the considered heavy nuclei was investigated with the astrophysical site of the neutrino-driven high-entropy winds (HEWs). We estimated the alpha decay half-lives using seven semi empirical models and data adopted from the newly updated database (NUBASE2020). The fission barriers were deduced using Thomas-Fermi (TF) model, Lublin-Strasbourg Drop (LSD) approach, and micro-macroscopic method which were based on the finite range drop model (FRDM) mass model. We found that the uncertainties in the half-life and fission barrier estimates mostly range from a few factors to two orders of magnitude. The recent uncertainties in the alpha-decay rates and fission barriers of the heavy exotic nuclei lead to a large change in the r-process abundance, which is up to 2 orders of magnitude, for the nuclei beyond iron. At the low entropy S = 100 kB$k_B$/baryon, both alpha-decay rates and fission barriers emerge as significant impacts on the abundance, while their role becomes faint at the high entropy. The results of this study indicate that the alpha decay and fission of heavy nuclei still have a certain impact on the r-process calculation. Subsequently, more precise measurements for the alpha-decay half-lives and mass of the exotic heavy isotopes are necessary to reduce the uncertainty in the astrophysical calculation of the r-process.

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