Multi-Probe Investigation of the Nucleon

质子、中子和电子是我们最熟悉的一切物质的基石。尽管科学家们正在努力理解它们的本质，但关于它们还有许多事情有待理解。2010年，对质子大小的测量得出的结果比预期的要小得多。这项测量与迄今为止所有其他质子大小的测量结果不一致，但要精确得多。从那时起，许多其他人试图用不同的方法重新测量质子大小，但分歧依然存在。这项由该奖项支持的研究旨在通过在Muon质子散射实验(MUSE)中首次同时测量质子上的Muon和电子散射来解决这一问题，也就是我们所熟知的“质子半径之谜”。通过这个实验，除了获得关于质子的知识外，博士后研究员、本科生和研究生还将获得现代探测技术以及模拟和重建软件的知识和经验，这些软件被用于许多应用，如工业或医学成像。他们还将参与世界上许多国家的研究人员的文化交流，发展他们的沟通、组织和领导技能。MUSE将在世界上首次通过弹性缪子散射测量质子半径，其精度可以解决4%的质子半径之谜。这项实验将在瑞士的保罗·谢勒研究所进行。在缪斯实验中同时测量质子的弹性e+/e-和u+/u-负散射，将有助于解决质子半径之谜：在穆斯介子氢的激发光谱中测得的质子电荷半径与在原子氢的激发光谱中测得的质子电荷半径之间的7西格玛差异。同时测量电子和µ子改善了系统的不确定度，并提供了对轻子普适性的测试。通过测量这两种电荷状态，可以直接测量和确定任何双光子效应，然后消除它们在Muon和电子散射中的作用。这个项目包括参与和领导的数据采集和分析缪斯通过支持的PI，研究生，本科生和博士后。该奖项反映了NSF的法定使命，通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为是值得支持的。

Protons, neutrons, and electrons are the building blocks of all matter with which we are most familiar. Despite the scientific efforts to comprehend their nature, there are many things about them that remain to be understood. In 2010, a measurement of the size of the proton gave a much smaller than expected result. This measurement disagreed with, but was much more precise than, all the other proton size measurements to date. Since that time, many other people have tried to re-measure the proton size using different approaches, but the discrepancy persists. The research supported by this award aims to resolve this issue, known as the "Proton Radius Puzzle" by making the first simultaneous measurement of muon and electron scattering on the proton in the Muon Proton Scattering Experiment (MUSE). Through this experiment, in addition to gaining knowledge about protons, the postdoctoral researcher, undergraduate, and graduate students will gain knowledge and experience of modern detection techniques, and simulation and reconstruction software, which are employed in many applications such as industrial or medical imaging. They will also participate in cultural exchanges with researchers from many countries worldwide, and develop their communication, organization, and leadership skills.MUSE will make the world's first measurement of the proton radius via elastic muon scattering at a precision which can address the 4% proton radius puzzle. The experiment will be performed at the Paul Scherer Institute in Switzerland. The simultaneous measurement of elastic e-plus / e-minus and mu-plus/mu-minus scattering on the proton in the MUSE experiment will allow resolution of the proton radius puzzle: the 7-sigma discrepancy between the charge radius of the proton measured in the excitation spectrum of muonic hydrogen and that measured in the excitation spectrum of the atomic hydrogen. Measuring with both electrons and muons simultaneously improves the systematic uncertainty, and provides a test of lepton universality. Measuring both charge states allows for the direct measurement and determination, and then cancellation, of any two-photon effects in both muon- and electron-scattering. This project involves participation in and leadership of data taking and analysis of MUSE through the support of the PI, a graduate student, undergraduate student, and a postdoc. It will result in precise, simultaneous elastic muon and electron scattering data.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.