Precision measurement of the angular correlation coefficient a in neutron beta-decay

中子β衰变角相关系数的精密测量

• 批准号: 335549596
• 负责人: Professor Dr. Werner Heil
• 金额: --
• 依托单位: Institut für Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/335549596?language=en
• 关键词: Precision; measurement; angular; correlation; coefficient

In this proposal we ask for an expiry-financing of the aSPECT experiment. aSPECT has been funded in recent years via the DFG priority programme 1491 which expires end of 2016. In that period we were capable to perform a successful production run with the aSPECT spectrometer at ILL, Grenoble. We measured the electronantineutrino electron angular correlation coefficient a in ß decay of the free neutron via the recoil spectrum of the decay protons. A preliminary analysis of the data results in a relative uncertainty of ~ 0.7%. The total error bar is essentially determined by systematic errors which we want to investigate at the final analysis stage of our project in more detail. For that particle tracking simulations will be used for the recoil protons in the E und B field configurations of the aspect spectrometer. The final result will be published in peer reviewed journals. The present PDG value on a is known to 4%, relative. With our final result we will improve the accuracy on a significantly. Within the standard model of particle physics, a can be expressed as a function of lambda, the ratio of the weak axialvector and vector coupling constants. This value is an important input to calculate many semi-leptonic weak cross sections such as those relevant for big bang nucleosynthesis, stellar fusion and detection of neutrinos. It also enters the determination of the largest element of the CKM matrix which parameterizes mixing within the weak charged current interactions of quarks. On the other hand, a is sensitive to physics beyond the standard model as, e.g., scalar or tensor interactions. Our experiments will provide valuable input to global analyses of weak interaction parameters for applications and for tests of physics beyond the standard model.

在这项提案中，我们要求对方面实验进行到期融资。近年来，通过2016年底到期的DFG优先方案1491为这方面提供了资金。在此期间，我们能够在格勒诺布尔的伊尔使用Aspect光谱仪进行成功的生产运行。我们利用衰变质子的反冲能谱测量了自由中子的电子反中微子电子角相关系数a。对数据进行初步分析后，相对不确定度约为0.7%。总误差栏基本上是由系统误差决定的，我们希望在项目的最终分析阶段更详细地调查这一点。为此，粒子跟踪模拟将用于反冲质子在E和B场配置的角度光谱仪。最终结果将发表在同行评议的期刊上。目前已知的a上的PDG值相对为4%。有了我们的最终结果，我们将显着提高准确率。在粒子物理的标准模型中，a可以表示为波长的函数，即弱轴向量与向量耦合常数之比。这个值是计算许多半轻子弱截面的重要输入，例如那些与大爆炸核合成、恒星聚变和中微子探测有关的截面。它还涉及到确定CKM矩阵的最大元素，该矩阵将夸克弱带电电流相互作用中的混合参数化。另一方面，a对超出标准模型的物理非常敏感，例如，标量或张量相互作用。我们的实验将为弱相互作用参数的全局分析、应用和超越标准模型的物理测试提供有价值的输入。