Precision Neutron Decay Measurements

精密中子衰变测量

• 批准号: 0855310
• 负责人: Fred Wietfeldt
• 金额: $ 36万
• 依托单位: Tulane University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2012-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0855310&HistoricalAwards=false
• 关键词: Precision; Neutron; Decay; Measurements

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The neutron is one of the building blocks of ordinary matter. However, when free from the confines of a stable atomic nucleus, the neutron is unstable and decays into a proton, electron, and antineutrino with an average lifetime of about 15 minutes. This decay is governed by the weak nuclear force, one of the four basic forces of nature. By carefully measuring the energies and directions of the emitted particles and the spin axis of the original neutron, subtle details of the fundamental nature of the weak force can be revealed. We pass beams of cold neutrons (moving less than 2000 m/s) through a variety of apparatus designed to make precise measurements of the neutron decay lifetime and angular correlations. We use these results to test the Standard Model of particle interactions and look for evidence of new physics. The neutron lifetime is used to calculated the abundances of light elements produced in the early universe from the big bang model.A number of graduate and undergraduate students, as well as postdoctoral researchers, participate in this research program. In addition to learning the science of neutron decay, they are educated broadly in the physics and methodology of research at neutron sources, which prepares them for a wide range of careers related to neutron science in academia and industry.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。中子是构成普通物质的基本元素之一。然而，当中子脱离稳定原子核的限制时，它就不稳定了，会衰变为质子、电子和反中微子，平均寿命约为15分钟。这种衰变是由弱核力控制的，弱核力是自然界四种基本力之一。通过仔细测量发射粒子的能量和方向以及原始中子的自旋轴，可以揭示弱力基本性质的微妙细节。我们将冷中子束（移动速度低于2000米/秒）通过各种设备，以精确测量中子衰变寿命和角相关性。我们用这些结果来测试粒子相互作用的标准模型，并寻找新物理学的证据。根据大爆炸模型，中子寿命被用来计算早期宇宙中产生的轻元素的丰度。一些研究生和本科生以及博士后研究人员参加了这个研究项目。除了学习中子衰变科学外，他们还接受了中子源物理学和研究方法方面的广泛教育，这为他们在学术界和工业界从事与中子科学相关的广泛职业做好了准备。