MRI: Development of the SABRE Silicon Array for Branching Ratio Experiments

科学中最引人注目的两个问题是：元素是如何产生的，以及它们今天是如何继续合成的。了解元素的起源就能解释地球的起源。奇异的原子核通常是在天体物理学的爆炸炼金术的坩埚中产生的，这些新合成的原子核保留产生它们的带电粒子的概率决定了在这个过程中是否能形成更重的原子核。元素的起源最终与粒子发射和吸收之间的竞争联系在一起。该核磁共振发展奖将为SABRE（分支比实验硅阵列）的建设提供资金，SABRE将与圣母大学核科学实验室（NSL）独特的TriSol设备相结合，该新仪器将用于测量对爆炸核合成至关重要的原子核的粒子发射概率。在新星、超新星和x射线爆发等爆炸性环境中，质子和α诱导的反应主导着重元素核合成。美国国家科学实验室TriSol设施中的新SABRE阵列将使科学家能够测量小至10e−5的质子和α分支比。该光谱仪的主要特点是，它将允许实验人员选择特定的反应产物，在基本上不受背景影响的光谱中识别生成的原子核的各个状态。这种能力将使该小组能够测量如此低的分支比率，并对理解恒星温度下的捕获反应产生重大影响。一个典型的例子是15O(α, γ)19Ne反应，因为它在通过快速质子捕获过程触发重元素核合成方面具有关键作用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Two of the most compelling questions in science are: how were the elements created and how are they continuing to be synthesized today. Understanding the origins of the elements explains the origins of Earth. Exotic nuclei are often created in the astrophysical cauldrons of explosive alchemy, and the probabilities that these newly synthesized nuclei can retain the charged particles that created them determines whether heavier nuclei can be formed in the process. The origin of the elements is ultimately tied to this competition between particle emission and absorption. This MRI development award will provide funds to build SABRE (Silicon Array for Branching Ratio Experiments) that will be combined with the unique TriSol facility at the Notre Dame Nuclear Science Lab (NSL) – and that new instrumentation will be used to measure particle-emission probabilities for nuclei critical to explosive nucleosynthesis.Proton and alpha-induced reactions on exotic nuclei dominate the heavy-element nucleosynthesis in explosive environments such as novae, supernovae, and X-ray bursts. The new SABRE array in the TriSol facility at NSL will allow scientists to measure proton and α branching ratios as small as 10e−5. The key feature of this spectrometer is that it will allow experimenters to select specific reaction products that identify individual states of the resulting nucleus in a spectrum that is essentially background free. That capability is what will allow the group to measure such low branching ratios and have significant impacts on understanding capture reactions at stellar temperatures. A prime example is the 15O(α, γ)19Ne reaction because of its key importance in triggering heavy element nucleosynthesis via the rapid proton-capture process.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.