Investigating the Nucleon with Electromagnetic Probes

用电磁探针研究核子

基本信息

批准号：
2012940
负责人：
Evangeline Downie
金额：
$ 55万
依托单位：
George Washington University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-08-15 至 2023-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2012940&HistoricalAwards=false
关键词：
Investigating Nucleon Electromagnetic Probes

项目摘要

Protons are one of the basic building blocks of matter and even 100 years after their discovery, they are still not fully understood. In fact, the precise radius of the proton is a puzzle and multiple measurements of this quantity do not all agree. A precise measurement of a proton’s radius is important because it determines the interaction with, and cross-section for scattering, other particles. The proton’s radius even affects the atomic spectroscopy of the hydrogen atom, which is tightly linked to the value of the Rydberg constant that has been so critical to the interpretation of all atomic spectra, because the electron and proton wave functions overlap and the radius is an important parameter in determining the amount of overlap. In 2010, a measurement of the radius of the proton was made using muonic hydrogen (hydrogen where the electron has been replaced by a muon). This proved to be the most precise experimental determination of the proton radius ever made, but was massively inconsistent with the accepted value for the proton radius at that time. This became known as the Proton Radius Puzzle (PRP). Since its inception, many physicists have tried to resolve the PRP, to no avail. MUSE (the MUon proton Scattering Experiment) will make the world’s first measurement of the proton radius via elastic muon scattering at a precision which can address this 4% radius discrepancy. The focus of this project is the supervision and maintenance of the data acquisition system which reads out the MUSE detector system; and the analysis of the resulting data to compare scattering cross sections, form factors, and radii, and to extract charge asymmetries. The MUSE experiment has been fully constructed and this project will support engineering runs to further calibrate and test the equipment, followed by 12 months of measurement. Measurements will take place in the Paul Scherer Institute PiM1 beam line, which affords a 3.3 MHz secondary beam with a mixture of pions, muons and electrons. The beam momenta will be approximately 117MeV/c, 160 MeV/c, and 210 MeV/c. These measurements will cover a Q2 range of 0.002 – 0.07 GeV2.In the course of the above described activities, undergraduate students, PhD students, and postdoctoral researchers will be trained in the development of modern electronics systems and modern data analysis techniques. The PI will present this work as part of her involvement in the National Organizing Committee Chair Line of the Conferences for Undergraduate Women in Physics.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.

质子是物质的基本组成部分之一，即使在其发现 100 年后，人们仍然没有完全了解质子的精确半径，而且对该数量的多次测量并不完全一致。质子半径的测量很重要，因为它决定了与其他粒子的相互作用以及散射的横截面。质子的半径甚至影响氢原子的原子光谱，而氢原子的原子光谱与里德伯的值紧密相关。这个常数对所有原子光谱的解释都至关重要，因为电子和质子波函数重叠，而半径是确定重叠量的重要参数。2010 年，人们使用质子半径进行了测量。 μ子氢（电子被μ子取代的氢）被证明是迄今为止对质子半径进行的最精确的实验测定，但与当时公认的质子半径值严重不一致。作为质子半径之谜（PRP）自诞生以来，许多物理学家都试图解决 PRP，但无济于事。解决这个 4% 的半径差异，该项目的重点是对读取 MUSE 探测器系统的数据采集系统进行监督和维护，并对结果数据进行分析以比较散射交叉。 MUSE 实验已经完全构建，该项目将支持工程运行以进一步校准和测试设备，随后将在保罗进行 12 个月的测量。 Scherer Institute PiM1 光束线，提供 3.3 MHz 的二次光束，其中包含π介子、μ介子和电子的混合物，光束动量约为 117MeV/c，160。 MeV/c 和 210 MeV/c。这些测量将覆盖 0.002 – 0.07 GeV2 的 Q2 范围。在上述活动过程中，本科生、博士生和博士后研究人员将接受现代电子学开发方面的培训。 PI 将展示这项工作，作为她参与物理学本科女性会议全国组委会主席系列的一部分。该奖项反映了 NSF 的法定使命，并具有通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

期刊论文数量（11）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Characterization of muon and electron beams in the Paul Scherrer Institute PiM1 channel for the MUSE experiment

Paul Scherrer 研究所 PiM1 通道中 MUSE 实验的 μ 子束和电子束表征

DOI：
10.1103/physrevc.105.055201
发表时间：
2022-05
期刊：
Physical Review C
影响因子：
3.1
作者：
Cline, E.;Lin, W.;Roy, P.;Reimer, P. E.;Mesick, K. E.;Akmal, A.;Alie, A.;Atac, H.;Atencio, A.;Ayerbe Gayoso, C.;et al
通讯作者：
et al

Extracting the spin polarizabilities of the proton by measurement of Compton double-polarization observables

通过测量康普顿双偏振可观测量提取质子的自旋极化率

DOI：
10.1103/physrevc.102.035205
发表时间：
2020-09
期刊：
Physical Review C
影响因子：
3.1
作者：
Paudyal, D.;Martel, P. P.;Huber, G. M.;Hornidge, D.;Abt, S.;Achenbach, P.;Adlarson, P.;Afzal, F.;Ahmed, Z.;Akondi, C. S.;et al
通讯作者：
et al

Cross section for γn→π0n measured at the Mainz A2 experiment

在美因茨 A2 实验中测量的 γn 至 0n 的横截面

DOI：
10.1103/physrevc.100.065205
发表时间：
2019-12
期刊：
Physical Review C
影响因子：
3.1
作者：
Briscoe, W. J.;Hadžimehmedović, M.;Kudryavtsev, A. E.;Kulikov, V. V.;Martemianov, M. A.;Strakovsky, I. I.;Švarc, A.;Tarasov, V. E.;Workman, R. L.;Abt, S.;et al
通讯作者：
et al

Experimental study of the $ \gamma p \rightarrow K^{0}\Sigma^{+}$, $ \gamma n \rightarrow K^{0} \Lambda$, and $ \gamma n \rightarrow K^{0} \Sigma^{0}$ reactions at the Mainz Microtron

$ gamma p ightarrow K^{0}Sigma^{ }$、$ gamma n ightarrow K^{0} Lambda$ 和 $ gamma n ightarrow K^{0} 的实验研究

DOI：
10.1140/epja/i2019-12924-x
发表时间：
2019-11
期刊：
The European Physical Journal A
影响因子：
0
作者：
Akondi, C. S.;Bantawa, K.;Manley, D. M.;Abt, S.;Achenbach, P.;Afzal, F.;Aguar;Ahmed, Z.;Annand, J. R.;Arends, H. J.;et al
通讯作者：
et al

Proton Compton Scattering from Linearly Polarized Gamma Rays

线性偏振伽马射线的质子康普顿散射

DOI：
10.1103/physrevlett.128.132502
发表时间：
2022-04
期刊：
Physical Review Letters
影响因子：
8.6
作者：
Li, X.;Ahmed, M. W.;Banu, A.;Bartram, C.;Crowe, B.;Downie, E. J.;Emamian, M.;Feldman, G.;Gao, H.;Godagama, D.;et al
通讯作者：
et al