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.

在此提案中，我们要求对实验的到期。近年来通过DFG优先计划1491资助了该方面，该计划于2016年底到期。在此期间，我们能够通过Ill，Grenoble进行成功的生产运行。我们通过衰减质子的后坐力光谱测量了自由中子的电子角相关系数A的电子角相关系数A。对数据的初步分析导致相对不确定性约为0.7％。总误差线本质上是由系统的错误确定的，我们希望在项目的最终分析阶段进行更详细的范围。对于该粒子跟踪模拟，将用于方面光谱仪的E UND B场配置中的后坐力协议。最终结果将发表在同行评审的期刊上。当前A上的PDG值已知为4％，相对。通过我们的最终结果，我们将更明显地提高精度。在粒子物理的标准模型中，A可以表示为lambda的函数，弱轴向向量和矢量耦合常数的比率。该值是计算许多半左右弱横截面的重要输入，例如与大爆炸核合成，恒星融合和神经元检测相关的截面。它还进入了CKM矩阵的最大元素的确定，该矩阵的最大元素可以参数化在Quarks的弱电流电流相互作用中混合。另一方面，A除了标准模型之外对物理敏感，例如标量或张量相互作用。我们的实验将为应用程序和标准模型以外的物理测试的弱相互作用参数的全局分析提供宝贵的输入。