Speaker
Description
Nuclear fission plays an important role in various phenomena such as the
-process nucleosynthesis. Spontaneous fission is an important subject for developing a microscopic theory of large-amplitude collective motions. The nuclear energy density functional (EDF) theory can be one such microscopic theory that provides a microscopic description of fission dynamics [1]. Recent EDF-based works on spontaneous fission employ the semiclassical WKB approximation for many-body quantum tunneling [2]. In those works, the collective potential energy has been calculated using a constrained EDF method, while the collective inertia has been calculated with the so-called cranking formula. It is known that the cranking formula ignores dynamical residual effects, and then the cranking formula significantly deviates from the correct inertia.
We have developed a framework to evaluate collective inertia within the local quasiparticle random-phase approximation (QRPA) with the Skyrme EDF [3]. This framework correctly includes the dynamical residual effects on the collective inertia that the former EDF-based works have ignored. We applied the local QRPA to calculate the collective inertia along a spontaneous fission path in actinide nuclei [3,4].
In this contribution, we will show the results of the collective inertia
along the fission path in actinide nuclei and the importance of the dynamical residual effects on the collective inertia. We take the triaxiality into account as a collective variable as well as an axially quadrupole moment, and determine the fission path in the two-dimensional collective space. Then, we will discuss the impact of the correct evaluation of the collective inertia on the fission path and fission half-life in spontaneous fission. We will further discuss the isotope dependence of the collective inertia and fission half-life in Fm isotopes.
[1] N. Schunck and L.M. Robledo, Rep. Prog. Phys. \textbf{79}, 116301 (2016).
[2] J. Sadhukhan et al., Phys. Rev. C \textbf{88}, 064314 (2013).
[3] K. Washiyama, N. Hinohara, and T. Nakatsukasa, Phys. Rev. C \textbf{103}, 014306 (2021).
[4] K. Washiyama, EPJ Web of Conferences \textbf{306}, 01026 (2024).