Studies of the Structure of the Nucleon

该奖项授予罗格斯大学中能核物理小组，使教授。吉尔曼和兰瑟姆以及他们的研究生和本科生研究核子的结构。重点是质子的形状——质子的电荷是如何分布的。它包括对一个备受瞩目的难题的研究：当用两种粒子——电子和介子——测量质子的大小时，质子的大小是否相同。μ子是一种与电子具有相同特性但质量更大的粒子。除了该项目的直接科学目标外，这些实验还为本科生和研究生以及其他早期职业科学家提供了在现代科学实验的国际合作中工作的经验和培训，并提供了最先进的技术。这笔拨款将用于支持罗格斯大学中能实验核物理小组实验核物理研究项目的继续开展。这些活动的重点是MUSE，这是一种测量来自液氢目标的带正电荷和负电荷的电子和介子散射截面的方法，在瑞士保罗·谢勒研究所的PiM1束流线上进行。在此资助期间，该小组将继续收集生产数据并开始分析阶段。散射截面用于确定质子的形状因子，从中可以提取质子的电荷半径。该小组将比较带正电荷和带负电荷的粒子的散射，以确定双光子交换更正，并比较介子对电子的散射，以确定由两个粒子决定的质子半径是否相同。除了缪斯的新测量外，该小组将继续在较低水平上参与分析和发表先前运行的实验结果。该组织的广泛影响主要体现在对本科生、研究生和博士后的培训上。与该小组合作的学生和博士后除了继续从事基础物理研究外，还在各种领域从事职业，包括医学物理学，国家安全和金融系统。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。

This award to the Rutgers University Intermediate Energy Nuclear Physics group enables Profs. Gilman and Ransome and their graduate and undergraduate students to study the structure of the nucleon. The focus is on the shape of the proton - how the proton's charge is distributed. It includes the study of a high-profile puzzle: whether the proton size is the same when measured with two types of particles, electrons and muons. Muons are particles with the same characteristics as electrons but with more mass. In addition to the direct scientific goals of the project, the experiments provide undergraduate and graduate students and other early career scientists experience and training in working in international collaborations of modern scientific experiments, with state-of-the-art technology.This grant will support the continuation of the experimental nuclear physics research program of the intermediate energy experimental nuclear physics group at Rutgers University. The focus of the activities is MUSE, a measurement of the scattering cross sections of both positively and negatively charged electrons and muons from a liquid hydrogen target, performed at the PiM1 beam line of the Paul Scherrer Institute in Switzerland. During this grant period the group will continue taking production data and begin the analysis phase. The scattering cross sections are used to determine the proton form factors, from which the proton charge radius can be extracted. The group will compare scattering of positively and negatively charged particles to determine two-photon exchange corrections, and compare scattering of muons to electrons to determine if the proton radius is the same when determined by the two particles. In addition to the new measurements of MUSE, the group will continue to be involved at a lower level in the analysis and publication of results of experiments run previously. The broader impact of the group has been primarily in the training of undergraduates, graduates, and postdocs. Students and post-docs who have worked with the group have gone on to careers in a variety of areas, including medical physics, national security, and financial systems, in addition to continued work in fundamental physics research.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.