标题： “核热电偶”揭示了普遍r-过程核合成的起源 显示英文标题

标题： "Nuclear thermometers" reveal the origin of the universal r-process nucleosynthesis

摘要： 类似于基态和激发态上构建的巨大偶极共振表现出的相似行为支持了Brink-Axel假设的有效性，并将巨大偶极共振指定为光谱探针——或者“核热计”——来探索中子星合并过程中千新星喷发物冷却到通过快速中子俘获或r过程生产铁以外的重元素的过程。 在之前的研究中，我们发现在种子核素产生的典型温度（$1.0\gtrapprox T\gtrapprox0.7$ MeV）下，激发态上构建的巨大偶极共振能量略有增加，在持续的中子俘获之前。 这里提供了关键数据，支持在r过程发生的$T=0.51$ MeV（或$5.9\times 10^9$ K）处增强的对称能，这降低了Bethe-Weizsäcker半经验质量公式中的结合能，导致中子滴线的闭合。因此，通过限制r过程核合成的反应网络，为元素丰度的普遍性提供了起源。 远离基态的增强对称能进一步由核电偶极（{\sc E1}）极化率的壳模型计算所支持——它与对称能成反比——这是由于非对角线{\sc E1} 矩阵元产物的破坏性贡献的结果。 显示英文摘要

摘要： The resembling behaviour of giant dipole resonances built on ground and excited states supports the validity of the Brink-Axel hypothesis and assigns giant dipole resonances as spectroscopic probes -- or ``nuclear thermometers'' -- to explore the cooling of the kilonova ejecta in neutron-star mergers down to the production of heavy elements beyond iron through the rapid-neutron capture or r-process. In previous work, we found a slight energy increase in the giant dipole resonance built on excited states at the typical temperatures of $1.0\gtrapprox T\gtrapprox0.7$ MeV where seed nuclei are produced, before ongoing neutron capture. Crucial data are presented here supporting an enhanced symmetry energy at $T=0.51$ MeV (or $5.9\times 10^9$ K) -- where the r-process occurs -- that lowers the binding energy in the Bethe-Weizs\"acker semi-empirical mass formula and results in the close in of the neutron drip line. Ergo, providing an origin to the universality of elemental abundances by limiting the reaction network for r-process nucleosynthesis. An enhanced symmetry energy away from the ground state is further supported by shell-model calculations of the nuclear electric dipole ({\sc E1}) polarizability -- inversely proportional to the symmetry energy -- as a result of the destructive contribution of the products of off-diagonal {\sc E1} matrix elements.