Nuclear physics of the dynamic origin of the elements

由于新的观测和大大增强的模拟能力，核天体物理学最近发现，许多元素的起源仍然是一个谜，可能是由于它们在恒星核生产场所的动态和暴力起源，而这种起源是无法用简单的方法解决的。在过去的几年里，这种动态的场景已经被确定来解释例如，在银河系的化学演化中，最贫金属的恒星的丰度，以及奇Z元素的起源。这些方案包括中间中子捕获过程（i-过程）的对流相互作用的H和He壳层在快速吸积的白色矮星或非常贫金属的大质量恒星，或对流反应核合成的合并的O-和C-燃烧壳层的大质量恒星。最近发现的引力波从中子星合并和相关的观察电磁对应的光可能从衰变不稳定的物种已经牢固地建立了快速中子俘获过程（r-过程）的动态核合成的作用。 这些动态核生产场所的重要性提出了改进不稳定物种核数据的必要性。放射性同位素的短寿命在过去严重限制了通过实验获得的关于核数据的信息，例如截面和核质量。现在，有了新的实验设施，如TRIUMF的ARIEL，FRIB和欧洲的其他设施，可以通过有针对性的高影响实验取得巨大进展，这些实验提供了关键的核数据，使天体物理学模拟能够区分恒星和恒星爆炸中元素动态起源的不同情景。 这个项目将结合联合收割机的天体物理学和核合成模拟能力的经验丰富的高级研究员谁将工作在四个项目，其中每一个侧重于一个不同的动态核合成环境。这些项目中的每一个都将由研究生进行，他们将在项目期间（三年）的一半时间用于这种模拟和建模工作，而另一半时间将专门用于相应领域的核物理实验。在上述每一个领域，一旦获得核数据，就将把这些数据纳入最新一代的天体物理模拟，并与观测结果进行对比，以最大限度地发挥核物理实验的影响。除了科学成果外，该项目的另一个主要目标是将天体物理学应用的核物理影响研究技能转移给新一代年轻的核物理研究人员。这种技能相对罕见，但涉及放射性束的加拿大和国际核天体物理学方案的影响关键取决于这类活动。

Thanks to new observations and greatly enhanced simulation capabilities, nuclear astrophysics has recently discovered that the puzzle still surrounding the origin of many elements is likely due to their dynamic and violent origin in stellar nuclear production sites that defy simple approaches. In the past few years such dynamic scenarios have been identified to explain e.g. the abundances of the most metal-poor stars, as well as the origin of odd-Z elements, in the galactic chemical evolution of the Milky Way. These scenarios include the intermediate neutron-capture process (i-process) in convective interactions of the H and He shells in rapidly accreting white dwarfs or very metal-poor massive stars, or the convective-reactive nucleosynthesis in the merger of the O- and C-burning shells in massive stars. The recent discovery of gravitational waves from neutron-star mergers and the associated observation of the electro-magnetic counterpart of the light likely from decaying unstable species has firmly established the role of dynamic nucleosynthesis for the rapid neutron-capture process (r-process). The importance of these dynamic nuclear production sites has put forth the need for improved nuclear data for unstable species. The short lifetime of radioactive isotopes has seriously limited in the past the experimentally available information on nuclear data, such as cross sections and nuclear masses. Now, with new experimental facilities such as ARIEL at TRIUMF, FRIB and other facilities in Europe huge progress can be made by targeted, high-impact experiments that provide critical nuclear data to enable astrophysics simulation to distinguish between different scenarios of the dynamic origin of the elements in stars and stellar explosions.    This project will combine the astrophysics and nucleosynthesis simulation capabilities of an experienced senior researcher who will work on four projects, each of which focusses on a different dynamic nucleosynthesis environment. Each of these projects will be carried out with graduate students who will spend one half of the period of the project (three years) on this simulation and modelling effort, while the other half will be dedicated to nuclear physics experiments in the corresponding area. In each of these areas nuclear data, as it becomes available, will be implemented into the latest generation of astrophysical simulation and confronted with observations to maximize the impact of the nuclear physics experiments. Other than the science outcome, another main goal of this project is to transfer the skill of nuclear physics impact studies for astrophysics applications to a new generation of young nuclear physics researchers. This skill is relatively rare, yet the impact of the Canadian and international nuclear astrophysics programs involving radioactive beams critically depends on this type of activity.