Astroparticle Physics with a Trapped Electron

没有人知道宇宙中84%的物质是什么，APTE的目标就是找出答案。APTE将研究两种主要类型的暗物质：轴子和毫荷电粒子。轴子不仅解决了粒子物理学中一个长期存在的难题，而且如果它们的质量是0.001-1 meV，它们是一个很好的暗物质候选者。毫荷电粒子出现在标准模型之外的一些理论中，最近被认为是暗物质的组成部分，可以解释早期宇宙中氢的异常冷却。APTE将在一个全新的应用中使用低温潘宁陷阱中的电子：用于天体粒子物理学的量子传感器。被俘获电子的径向模式将被监测，以用于与毫荷电暗物质碰撞或从轴子衰变中吸收单个微波光子引起的跃迁。径向量子态的变化将使用强磁不均匀性被印在被困电子的轴向频率上，这与测量电子磁矩的原理相同。凭借我在BASE（世界上最灵敏的低温潘宁阱之一）中的经验，我将率先使用我自己发明的先进相敏测量协议。这些将被用来监测电子的轴向频率的相位跳变时发生的径向模式的变化。有了这个电子单光子计数器，我们将能够克服标准量子极限，它严重降低了我们研究质量大于0.04 meV的轴子的能力。APTE将首先搜索质量约为0.128 meV的暗物质轴子和质量至少为1 GeV、电荷为10^-1至10^-7 e的毫荷电暗物质粒子。这两种测量都是在一个目前没有数据和很少有人提出实验的领域探索重要的理论。这个开创性的项目将为未来的轴子搜索计划以及基础物理学的其他应用奠定基础。

No one knows what 84% of the matter in the universe is, and the goal of APTE is tofind out. APTE will investigate two leading types of dark matter: axions and millichargedparticles. Axions not only resolve a longstanding puzzle in particle physics, but if theirmass is 0.001-1 meV they are an excellent dark matter candidate. Millicharged particlesarise in some theories beyond the Standard Model and have recently been suggested as a com-ponent of dark matter that could explain the anomalous cooling of hydrogen in the early universe.APTE will use an electron in a cryogenic Penning trap in an entirely new application: aquantum sensor for astroparticle physics. The radial modes of the trapped electron will bemonitored for transitions caused by collisions with millicharged dark matter or the absorptionof single microwave photons from axion decays. Changes in radial quantum state will beimprinted onto the trapped electron's axial frequency using a strong magnetic inhomogeneity,the same principle as used to measure the electron magnetic moment. Drawing on myexperience in BASE, one of the world's most sensitive cryogenic Penning traps, I will pioneerthe use of advanced phase sensitive measurement protocols of my own invention. These willbe used to monitor the electron's axial frequency for phase jumps which occur when the radialmode changes. With this electron single photon counter we will be able to overcome the Stan-dard Quantum Limit which severely degrades our ability to investigate axion masses > 0.04 meV.APTE will perform a first search for dark matter axions with masses around 0.128 meVand millicharged dark matter particles with masses up to at least 1 GeV and charges 10^-1 to 10^-7 e. Both measurements probe important theories in a regime where there is currently nodata and few proposed experiments. This ground-breaking project will lay the foundations fora future program of axion searches, as well as other applications in fundamental physics.