Isotopic equilibrium constants for very low-density and low-temperature nuclear matter

Abstract

Yields of equatorially emitted light isotopes, 1 ≤ Z ≤ 14, observed in ternary fission in the reaction 241 Pu(n th ,f) are employed to determine apparent chemical equilibrium constants for lowtemperature and low-density nuclear matter. The degree of equilibration and role of medium modifications are probed through a comparison of experimentally derived reaction quotients with equilibrium constants calculated using a relativistic mean-field model employing a universal medium modification correction for the attractive σ meson coupling. The results of these comparisons indicate that equilibrium is achieved for the lighter ternary fission isotopes. For the heavier isotopes experimental reaction quotients are well below calculated equilibrium constants. This is attributed to a dynamical limitation reflecting insufficient time for full equilibrium to develop. The role of medium effects leading to yield reductions is discussed as is the apparent enhancement of yields for 8 He and other very neutron rich exotic nuclei.

Light clusters in warm stellar matter: calibrating the cluster couplings

“…This cluster has been included in the analysis of the INDRA collaboration [41], which has recently published a new set of equilibrium constants [41] with a controlled bayesian determination of the system density during the expansion, including the possibility of in-medium modifications [42,43]. Note that this gRMF approach has been applied recently also to the description of yields of clusters produced at ternary fission [44].…”