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

核天体物理学是研究元素是如何在各种恒星环境中产生的，以及这些环境是如何演变的。例如，恒星燃烧负责产生直到铁的元素，而中子俘获过程产生了大部分重元素。然而，铁上方重的、富含质子的原子核的起源是恒星核合成的最大谜团之一。最有可能产生这些同位素的情景是p过程：在超新星爆炸期间发生的光解反应及其逆反应(质子、α和中子捕获)的复杂网络。P-过程的一个由20,000个核反应组成的庞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，以便将这些反应的不确定性降至最低，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相关的质子和阿尔法俘获反应的截面，有助于理解恒星的p过程。这些反应以前从未被测量过，并已被两项独立的敏感性研究确定为p过程的关键。研究表明，在当前模型的不确定性范围内，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(赫克托)采用求和技术。将使用网络计算来验证测量的反应速率对p核最终丰度的影响，网络计算的结果将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，并将用于识别最能再现数据的模型输入。

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.