Exploring the Origin of Heavy Elements: Nuclear Input for P-Process Nucleosynthesis

探索重元素的起源：P 过程核合成的核输入

• 批准号: 1614442
• 负责人: Anna Simon-Robertson
• 金额: $ 52万
• 依托单位: University of Notre Dame
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1614442&HistoricalAwards=false
• 关键词: Exploring; Origin; Heavy; Elements; Nuclear

Nuclear astrophysics is the study of how elements are created in various stellar environments and how such environments evolve. For example, stellar burning is responsible for the production of elements up to iron, and neutron capture processes create most of the heavy elements. However, the origin of heavy, proton-rich nuclei above iron is one of the greatest puzzles of stellar nucleosynthesis. The most likely scenario for creating these isotopes is the p-process: a complex network of photodisintegration reactions and their inverse (proton-, alpha- and neutron-capture) that occur during the explosion of a supernova. A vast network of 20,000 nuclear reactions for the p-process relies on models to provide input of nuclear properties and reaction rates for all the nuclei involved in the network. The goal of this project is to identify the reactions that are key for the p-process and to measure them directly, so as to minimize the uncertainty for those rates and provide constraints for the model predictions. This project will contribute to understanding of the stellar p-process by measuring cross sections for proton and alpha capture reactions of relevance for Pd-102, Cd-108, Cd-110, Te-120 and Te-122. Those reactions have not been measured before, and have been identified as key for the p-process by two independent sensitivity studies. Studies have shown that the variations of those rates within the current model uncertainties have a significant impact on the production of the p-nuclei. The project will utilize a newly purchased detector (HECTOR) to employ the γ-summing technique. The impact of the measured reaction rates on the final abundances of the p-nuclei will be verified using network calculations whose results will be compared with the solar abundances. Additionally, the measured cross sections will be compared with model predictions and will be used to identify the model inputs that best reproduce the data.

核天体物理学是研究元素如何在各种恒星环境中产生以及这些环境如何演变的科学。例如，恒星燃烧产生了铁等元素，而中子捕获过程产生了大多数重元素。然而，铁之上重的、富含质子的核的起源是恒星核合成的最大谜团之一。产生这些同位素最可能的情况是p过程：在超新星爆炸期间发生的光致衰变反应及其逆反应（质子，α和中子捕获）的复杂网络。p过程的20，000个核反应的巨大网络依赖于模型来提供网络中涉及的所有核的核性质和反应速率的输入。该项目的目标是确定对p-过程至关重要的反应，并直接测量它们，以便最大限度地减少这些速率的不确定性，并为模型预测提供约束。该项目将通过测量与Pd-102、Cd-108、Cd-110、Te-120和Te-122有关的质子和α俘获反应的横截面，促进对恒星p过程的理解。这些反应以前没有被测量过，并且已经被两项独立的敏感性研究确定为p过程的关键。研究表明，在当前模型不确定性范围内，这些速率的变化对p核的产生有重大影响。该项目将利用新购买的探测器（HECTOR）采用#947;求和技术。将使用网络计算来验证所测得的反应速率对p核最终丰度的影响，并将计算结果与太阳丰度进行比较。此外，测量的横截面将与模型预测进行比较，并将用于确定最佳重现数据的模型输入。