US-Germany Cooperative Research: The Crystal Ball at MAMI Project

0341791 Nefkens该奖项支持Bernard Nefkens和加州大学洛杉矶分校的学生与德国美因茨大学核物理研究所的Reinhard Beck合作。该奖项支持在德国美因茨的美因茨微加速器(Mami)进行的一项新的研究计划，该计划使用水晶球(CB)探测器，即TAPS光谱仪作为前端盖。其他设备包括格拉斯哥光子标记器、美因茨/波恩偏振靶和达芙妮线室。这一装置将使一个多方面的物理计划成为可能，包括测量与核子结构有关的几个基本量。核子结构模型不仅对态的质量和衰变分支比做出了具体的预测，而且对它们的磁矩也做出了具体的预测。美因茨的合作是测量D+(1232)和N+(1535)磁矩的独特地点。之前唯一类似的研究是1978年在洛斯阿拉莫斯对UD++(1232)进行的测量。这个程序的智力价值在于能够将基本量的测量，如D(1232)和N(1535)的磁矩与质子和中子的结构联系起来，这两个基本粒子加起来占已知宇宙可见质量的99%以上。加州大学洛杉矶分校的团队完全有资格参与这项工作，他们领导了一项国际合作，使用布鲁克海文AGS的水晶球探测器进行类似的介子和克子束研究。这家位于美因茨工厂的德国集团计划在未来五年内每年投入2000小时的束流时间来实现这一目标。这项研究的影响将远远超出本提案中所述的目标。除了培养几名从事原创研究项目的物理学博士生外，该项目还将为许多本科生和硕士研究生的教育做出贡献。水晶球项目的合作有着出色的多样性记录；使用该探测器获得博士学位的学生不仅包括一名女性，还包括来自孟加拉国、泰国、加拿大和俄罗斯的学生。通过参与这一计划，各成员机构将增强其实验室和数据分析能力，从而改善其研究和教育基础设施。

0341791NefkensThis award supports Bernard Nefkens and students from University of Californis-Los Angeles in a collaboration with Reinhard Beck of the Institute for Nuclear Physics at the University of Mainz, Germany. This award supports a new program of study being undertaken at the Mainz Microtron (MAMI) in Mainz, Germany with the Crystal Ball (CB) detector, the TAPS spectrometer as a forward endcap. Additional equipment includes the Glasgow photon tagger, the Mainz/Bonn polarized target, and the DAPHNE wire chamber. This apparatus will enable a multifaceted physics program involving the measurement of several fundamental quantities related to the structure of the nucleon. Nucleon structure models make specific predictions for not only the masses and decay branching ratios of the states, but also their magnetic moments. The collaboration in Mainz is uniquely situated to measure the magnetic moments of D+(1232) and N+(1535). The only similar previous study is a measurement of uD++(1232) performed at Los Alamos in 1978. The intellectual merit of this program lies in the ability to relate measurements of fundamental quantities such as the magnetic moments of the D(1232) and the N(1535) to the structure of the proton and the neutron, the two basic particles that together make up well over 99% of the visible mass of the known universe. The UCLA group is well qualified to participate in this endeavor, having led an international collaboration using the Crystal Ball detector at the Brookhaven AGS for similar studies with pion and kaon beams. The German group at the Mainz facility plans to devote 2000 hours of beam time per year to this effort over the next five years. The impact of this research will extend far beyond the goals stated in this proposal. In addition to training several physics Ph.D. students engaged in original research projects, this program will contribute to the education of many undergraduate and masters-level students. The Crystal Ball Collaboration has an excellent record of diversity; the students who earned their doctoral dissertations with this detector include not only a woman, but also students from Bangladesh, Thailand, Canada, and Russia. By participating in this program, the various member institutions will enhance their laboratory and data analysis capabilities, thus improving their research and educational infrastructure.