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.

弱电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，探索可以用这个模型描述的灵敏度越来越高的现象，希望会出现差异，从而导致对弱相互作用的更完整的理解。这种相互作用是中子衰变或转变为质子、电子和反中微子的原因。通过研究中子及其衰变产物的性质之间的关联，可以对弱电标准模型进行更精确的测试。其中一个被称为“a”的关联关系涉及衰变区电子和反中微子的发射方向。已知的其他中子衰变关联性在1%以内，但很少有人知道“a”只有4%。经过几年的规划和建设，橡子(中子衰变中的关联)合作正在NIST(国家标准和技术)中子研究中心(NCNR)的基础物理光束线上安装设备。生产数据将在今年(2010年)的剩余时间内收集，并进入下一年，这将导致2%的小幅“a”测量。然后，NCNR将关闭以进行一系列升级，从而产生更高的中子通量。在此期间，将根据2%测量的性能对橡子仪器进行改进和修改，以便在NCNR升级完成后进行低于1%的测量。这笔资金将为DePauw大学本科生和首席研究员提供所需的支持，让他们在2%的测量期间参与实验，确定对低于1%的测量进行必要的修改，并执行此测量。在过去的几年里，首席调查员让20名本科生广泛参与了这项实验。在这20人中，12人在大一时第一次遇到这个实验，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NSF在主要研究型大学和设施(如费米实验室)的REU(本科生研究体验)计划参与了其他研究计划。9人中有5人还在洛斯阿拉莫斯国家实验室和瑞士保罗·谢勒研究所的实验中与PI有进一步的合作经验。通过研究橡子，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、计算机科学和教学。