Precision Muon Experiments

对基本粒子性质进行精确的实验测试，现在是一种行之有效的方法，可以超越我们目前的物理知识，寻找新的自然规律。这项提议的研究是为了进行两个实验，以精确测量一种叫做μ子的基本粒子，它与电子相似，但质量更大。费米国家加速器实验室（Fermi National Accelerator Laboratory）的一个名为g-2的实验将测量μ子的磁矩，精确度超过百万分之一，这将为粒子物理标准模型（Standard Model of particle physics）提供检验，该理论解释了构成宇宙中大部分可见物质的基本粒子的特性。另一个在瑞士保罗·谢勒研究所（PSI）进行的名为MuSun的实验将测量由介子和氘核（由一个质子和一个中子组成的原子核）组成的原子的寿命。这个实验将进一步了解热核氢燃烧的反应，它为太阳提供能量，并有助于理解中微子与物质的相互作用。μ子g-2实验将测量到十亿分之140的μ子异常磁矩，比之前在布鲁克海文国家实验室（BNL）进行的E821实验提高了四倍。该测量将解决E821的相同测量与标准模型预测之间长期存在的3个标准差差异。它代表了标准模型的一个关键测试，对标准模型之外的新粒子和相互作用具有广泛的敏感性。μ子g-2项目包括将μ子存储环从布鲁克海文国家实验室搬迁到费米实验室，以及新的探测器、电子设备和采集系统。PI和他的团队负责8gbyte /秒的热量计读出，使用基于多兆次浮点运算的gpu数据处理，并为数据采集系统构建分布式事件。MuSun实验将测量mu- d到n - n中微子双态捕获率，精度为1.5%。该测量解决了mu d捕获的早期测量之间长期存在的差异。它将为我们在pp热核融合、中微子实验的截面以及普通和双β衰变中发挥作用的两体弱轴流的知识提供五倍的改进。

Precise experimental tests of fundamental particle properties are now a well-established way to search for new laws of nature beyond our current physical knowledge. The proposed research is for two experiments to make precise measurements of an elementary particle called the muon, which is similar to the electron but with larger mass. One experiment at tha Fermi National Accelerator Laboratory, called g-2, will measure the magnetic moment of the muon to an accuracy of better than a part-per-million, which will provide a test of the Standard Model of particle physics, the theory that explains the properties of the elementary particles making up most of the visible matter in the Universe. The other experiment, called MuSun, at the Paul Scherrer Institute (PSI) in Switzerland will measure the lifetime of an atom comprised of a muon and a deuteron (a nucleus made from one proton and one neutron). This experiment will further the knowledge of the reaction of thermonuclear hydrogen burning which powers the sun, as well as helping to understand neutrino interactions with matter.The muon g-2 experiment will measure the muon anomalous magnetic moment to 140 parts-per-billion, a four-fold improvement over the previous experiment at Brookhaven National Laboratory (BNL), known as E821. The measurement will address the longstanding 3 standard deviation discrepancy between the same measurement from E821 and the Standard Model prediction. It represents a key test of the Standard Model and has broad sensitivity to new particles and interactions beyond the Standard Model. The muon g-2 project has involved the relocation of the muon storage ring from Brookhaven National Laboratory to Fermilab as well as new detector, electronics and acquisition systems. The PI and his group are responsible for the 8 GByte/sec calorimeter readout, using multi-teraflop GPU-based data processing, and distributed event building for the data acquisition system. The MuSun experiment will measure the mu- d to n n neutrino doublet capture rate to an accuracy of 1.5%. The measurement addresses a longstanding discrepancy among earlier measurements of mu d capture. It will provide a five-fold improvement in our knowledge of the two-body weak axial currents that plays a role in pp thermonuclear fusion, cross sections for neutrino experiments, and ordinary and double beta-decay.