RUI: A High Precision Measurement of the Electron-Antineutrino Correlation Coefficient in Free Neutron Decay

RUI：自由中子衰变中电子-反中微子相关系数的高精度测量

• 批准号: 0970087
• 负责人: Alexander Komives
• 金额: $ 15.97万
• 依托单位: DePauw University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2014-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0970087&HistoricalAwards=false
• 关键词: RUI; Precision; Measurement; Electron; Antineutrino

The electroweak standard model describes two of the four fundamental forces present in the universe. By conducting experiments that probe with increasing sensitivity phenomena that can be described with this model, it is hoped discrepancies will appear that will lead to a more complete understanding of the weak interaction. This interaction is responsible for the decay, or transformation, of the neutron into a proton, electron and antineutrino. By studying the correlations between the properties of the neutron and its decay products, more precise tests of the electroweak standard model can be performed. One of these correlations, known as little "a," involves the direction of emission of the electron and antineutrino from the decay region. Other neutron decay correlations are known to within 1%, but little "a" is only known to 4%. After several years of planning and construction, the aCORN ("a" CORrelation in Neutron decay) collaboration is in the process of installing an apparatus on the fundamental physics beamline at the NIST (National Institute of Standards and Technology) Center for Neutron Research (NCNR). Production data will be collected the rest of this year (2010) and into the next that will result in a 2% measurement of little "a." The NCNR will then shutdown for a series of upgrades resulting in a higher neutron flux. During this period, improvements and modifications will be made to the aCORN apparatus based on performance for the 2% measurement to make a sub-1% measurement once the NCNR upgrades are complete. This grant will provide the support needed for DePauw University undergraduate students and the Principal Investigator to participate in the experiment during the 2% measurement, to determine the necessary modifications for a sub-1% measurement and to perform this measurement. The Principal Investigator has involved 20 undergraduates extensively in this experiment over the past several years. Of these 20, 12 first encountered this experiment during their freshman year and 9 became or already were physics majors. Of these 9, 3 have participated in other research programs via the NSF's REU (Research Experience for Undergraduates) program at major research universities and facilities such as Fermilab. Five of the 9 have also had further experiences working with the PI on experiments at Los Alamos National Laboratory and the Paul Scherrer Institut in Switzerland. By working on aCORN these students have been prepared to take on a wide variety of challenges ranging from other physics experiments to activities in other diverse fields such as biology, computer science and teaching.

电弱标准模型描述了宇宙中存在的四种基本力中的两种。通过进行实验，以越来越高的灵敏度探测可以用该模型描述的现象，希望能够出现差异，从而对弱相互作用有更全面的理解。这种相互作用导致中子衰变或转变为质子、电子和反中微子。通过研究中子性质与其衰变产物之间的相关性，可以对电弱标准模型进行更精确的测试。其中一种关联，被称为小“a”，涉及电子和反中微子从衰变区域发射的方向。已知其他中子衰变相关性在1%以内，但小“a”仅为4%。经过几年的规划和建设，aCORN（中子衰变的“关联”）合作项目正在美国国家标准与技术研究院中子研究中心（NCNR）的基础物理束线上安装一台设备。生产数据将在今年剩余时间（2010年）和明年收集，这将导致2%的小“a”测量。然后，NCNR将关闭，进行一系列升级，从而提高中子通量。在此期间，将根据2%测量的性能对aCORN设备进行改进和修改，以便在NCNR升级完成后进行低于1%的测量。这笔资金将为德堡大学的本科生和首席研究员在2%测量期间参与实验提供所需的支持，以确定对低于1%的测量进行必要的修改并执行该测量。在过去的几年里，首席研究员在这个实验中广泛地涉及了20名本科生。在这20人中，12人在大一的时候第一次接触到这个实验，9人成为或已经是物理专业的学生。在这9人中，有3人通过美国国家科学基金会的REU（本科生研究经验）项目在主要研究型大学和费米实验室等机构参加了其他研究项目。9人中有5人还在洛斯阿拉莫斯国家实验室和瑞士保罗·谢勒研究所与PI合作进行了进一步的实验。通过在aCORN工作，这些学生已经准备好接受各种各样的挑战，从其他物理实验到其他不同领域的活动，如生物学、计算机科学和教学。