Fundamental symmetry tests with optically trapped radioactive neutral atoms

光学捕获放射性中性原子的基本对称性测试

• 批准号: 185806-2006
• 负责人: Behr, John
• 金额: $ 10.38万
• 依托单位: TRIUMF
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Project
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=392345
• 关键词: Fundamental; symmetry; tests; optically; trapped

We use laser trapping and cooling techniques to capture radioactive atoms and precisely test the Standard Model of the weak interaction. Confined in a 1 mm-sized cloud, the nuclei undergo beta decay, producing three products: a positron, a neutrino, and a daughter nucleus. The daughter moves slowly and would stop in a nm of material, but it freely escapes the trap. By detecting it in coincidence with the positron, we can measure the momentum and hence the angular distribution of neutrinos more directly than in previous experiments.   The known electroweak interaction is mediated by spin-1 vector bosons, the W+, W-, and Z0. These only produce left-handed neutrinos: parity (mirror symmetry) is maximally violated. We test these model features.   We have now published the best limits on scalar interactions coupling to the first generation of particles by measuring the beta-neutrino correlation in the pure Fermi decay of a spin-0 nucleus. We propose to improve these measurements by a factor of three. We published a missing-mass search for heavy neutrinos mixing with the electron neutrino, directly constraining admixture levels of interest to astrophysics.   We are learning to spin-polarize other nuclei and measure their polarization by atomic methods independent of their decays. When combined with beta-recoil coincidences, we can measure novel correlations. We have measured the neutrino asymmetry of 37K to 3% accuracy, which we intend to improve to 0.1%   The spin asymmetry of the direction of the daughter nuclei vanishes in pure Gamow-Teller decay. We can now uniquely measure this correlation with the atom trap, and since it vanishes many polarization systematics become unimportant. Our goal is to reach 0.1% accuracy to test hints of a nonzero tensor interaction reported by the PIBETA collaboration in radiative pion decays. This is the project of two M.Sc. students. We will soon graduate our 2nd Ph.D., to be followed by a 3rd, graduated an M.Sc. on a new type of trap, and average one undergrad at a time.

我们使用激光捕获和冷却技术来捕获放射性原子，并精确地测试弱相互作用的标准模型。在1毫米大小的云层中，原子核经历β衰变，产生三种产物：一个正电子、一个中微子和一个子核。女儿移动缓慢，会停在一纳米的物质中，但它自由地逃脱了陷阱。通过探测它与正电子的符合，我们可以比以前的实验更直接地测量中微子的动量，从而测量中微子的角分布。已知的电弱相互作用是由自旋为1的矢量玻色子、W+、W-和Z0介导的。它们只产生左手中微子：宇称(镜像对称性)被最大限度地破坏。我们测试这些模型功能。我们现在通过测量自旋为0的原子核的纯费米衰变中的β-中微子关联，发布了耦合到第一代粒子的标量相互作用的最佳极限。我们建议将这些测量结果提高三倍。我们发表了一项关于重中微子与电子中微子混合的缺失质量搜索，直接限制了天体物理学感兴趣的混合水平。*我们正在学习使其他原子核自旋极化，并通过原子方法测量它们的极化，而不是依赖于它们的衰变。当结合贝塔反冲重合时，我们可以测量新奇的相关性。我们测量了37K到3%精度的中微子不对称性，我们打算将其提高到0.1%，以至子核方向的自旋不对称性在纯Gamow-Teller衰变中消失。我们现在可以唯一地测量这种与原子陷阱的相关性，因为它消失了，所以许多极化系统学变得不重要了。我们的目标是达到0.1%的准确度来测试PIBETA合作报告的辐射介子衰变中的非零张量相互作用的暗示。这是两个理科硕士的项目。学生们。我们很快就会拿到第二个博士学位，然后是第三个，获得理学硕士学位。在一种新型的陷阱上，平均一次一个本科生。