Fundamental Physics of Trapped Atomic Tritium

这个研究项目的重点是在一个简单的室温装置中捕获和冷却原子氢。氢分子与惰性载气混合，在脉冲超音速光束的流动中膨胀。分子将在阀门的出口附近解离。依靠氢的磁矩，原子氢将被一系列定时脉冲电磁线圈停止。该原子线圈枪将针对氢的情况进行优化，并且将构建绝热线圈枪以实现与源的模式匹配。停止的原子将被限制在室温装置的磁阱中，并将使用243nm附近的双光子1S-2S跃迁进行检测。氢将被冷却到接近反冲温度的单光子冷却，在一个修饰的射频磁阱。氢原子是元素周期表中最简单的元素，但要控制它的平移运动却极具挑战性。由于缺乏可接近的循环过渡，激光冷却的标准方法是不可能的。这个研究项目将演示在一个简单的室温设备中捕获和冷却氢，使用已经成功应用于其他原子的新方法。这项工作更广泛的意义在于，它将在未来使原子氚的捕获和冷却成为可能。这是氢的一种放射性同位素，对它的研究可以为核物理学提供重要的数据。同样的技术也可以应用于反氢，这样的研究可以测试物质和反物质之间的基本对称性。

This research program focuses on trapping and cooling atomic hydrogen in a simple room-temperature apparatus. Molecular hydrogen is mixed with an inert carrier gas and expanded in the flow of a pulsed supersonic beam. The molecules will be dissociated near the output of the valve. Atomic hydrogen will be stopped with a timed series of pulsed electromagnetic coils, relying on the magnetic moment of hydrogen. This atomic coilgun will be optimized for the case of hydrogen, and an adiabatic coilgun will be constructed in order to enable mode matching to the source. The stopped atoms will be confined in a magnetic trap in a room temperature apparatus, and will be detected using the two-photon 1S-2S transition near 243 nm. Hydrogen will be cooled to near the recoil temperature by single-photon cooling, in a dressed RF magnetic trap. Atomic hydrogen is the simplest element in the periodic table, yet it has proven extremely challenging to control its translational motion. The standard method of laser cooling has not been possible, due to the lack of an accessible cycling transition. This research program will demonstrate trapping and cooling of hydrogen in a simple room temperature apparatus, using new methods that were successfully applied to other atoms. The broader significance of this work is that it will enable in the future the trapping and cooling of atomic tritium. This is a radioactive isotope of hydrogen, and its study can provide important data for nuclear physics. The same techniques can also be applied to anti-hydrogen, and such studies can test basic symmetries between matter and anti-matter.