Acquisition of a Spectrometer and Detectors for Precision Nuclear Physics Measurements of Neutron Beta Decay

购置光谱仪和探测器，用于中子 β 衰变的精密核物理测量

• 批准号: 0079767
• 负责人: Bradley Filippone
• 金额: $ 52.5万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-01 至 2003-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0079767&HistoricalAwards=false
• 关键词: Acquisition; Spectrometer; Detectors; Precision; Nuclear

A superconducting solenoidal spectrometer and state-of-the-art detectors for low energy electrons will be used for a series of high precisionmeasurements of neutron beta-decay using, for the first time, Ultra-Cold Neutrons (UCN). In particular the angular correlation (A) between the neutron spin direction and the electron momentum will be measured with a statistical precision of 0.2% and substantially smaller systematic errors. This represents nearly a factor of five improvement over the present best measurements in an experiment with significantly different and considerably smaller systematic uncertainties. High-precision measurements of the A-correlation in neutron beta-decay can be combined with measurements of the neutron and muon lifetimes toextract the u-quark/d-quark weak mixing also known as V_ud - a key component of the Cabibbo-Kobayashi-Maskawa (CKM) matrix. Improvedmeasurements of V_ud can provide access to physics beyond the Standard Model by testing the unitarity of this matrix.

超导螺线管谱仪和最先进的低能电子探测器将首次使用超冷中子（UCN）对中子β衰变进行一系列高精度测量。特别地，中子自旋方向和电子动量之间的角相关（A）将以0.2%的统计精度和小得多的系统误差测量。这代表了在具有显著不同和相当小的系统不确定性的实验中，与目前最佳测量相比，几乎提高了五倍。中子β衰变中A关联的高精度测量可以与中子和μ子寿命的测量相结合，以提取u夸克/d夸克弱混合，也称为V_ud -Cabibbo-Kobayashi-Maskawa（CKM）矩阵的关键组成部分。改进的V_ud测量可以通过检验这个矩阵的么正性来提供对标准模型之外的物理的访问。