Ultracold Neutrons at TRIUMF

超冷中子（UCN）是一种缓慢移动的中子，可以储存在物质、磁性和引力瓶中。 一旦使用这种方法限制它们，就可以非常仔细地研究它们的性质，以寻找与基于粒子物理学标准模型的预期的偏差。 在日本合作者（增田等人）的帮助下，我们正在加拿大（在不列颠哥伦比亚省温哥华的TRIUMF）建立一个新的UCN源。 该源预计将提供世界上有史以来最高密度的UCN，我们生产的UCN将用于将一些非常有趣的物理实验推向前所未有的精度水平。 最初，我们专注于中子电偶极矩的测量，这主要是我们在这个实验上的活动，我们正在寻求NSERC的支持。 电偶极矩的测量已经严重限制了标准模型之外的电荷宇称（CP）破坏的新来源，这些来源被认为是解释当今宇宙中物质相对于反物质的优势（重子不对称性）所必需的。 如果在我们的新实验所能达到的实验精度水平上发现一个非零值，它可能意味着CP破坏的一个新来源，从而有助于解释宇宙的重子不对称性。 我们在未来三年的活动将包括在日本建造正在进行的实验设备，使用该设备在日本完成初始EDM实验，并将EDM实验送回TRIUMF进行安装。 通过在日本的实验学习，我们还将为TRIUMF的最佳实验开发新的想法，并准备TRIUMF的实验区。 这将在TRIUMF进行世界领先的实验。

Ultracold neutrons (UCN) are slow moving neutrons that can be stored in material, magnetic, and gravitational bottles. Once they've been confined using such methods, their properties can be studied very carefully to search for deviations from expectations based on the standard model of particle physics. We are building a new source of UCN in Canada (at TRIUMF, Vancouver, BC) with the help of collaborators from Japan (Masuda, et al). The source is projected to provide the highest density of UCN ever produced in the world, and the UCN we produce will be used to push some very interesting physics experiments to unprecedented levels of precision. Initially we are focused on a measurement of the neutron electric dipole moment, and it is primarily our activities on this experiment for which we are seeking NSERC support. Measurements of electric dipole moments already severely limit new sources of Charge-Parity (CP) violation beyond the standard model, sources which are believed to be required in order to explain the predominance of matter over antimatter (baryon asymmetry) in the universe today. If a non-zero value were discovered at the level of experimental precision within reach of our new experiment, it could signify a new source of CP violation, and hence help to explain the baryon asymmetry of the universe. Our activities over the next three years will involve the construction of equipment for ongoing experiments in Japan, the use of the equipment to complete initial EDM experiments in Japan, and the delivery of the EDM experiment back to TRIUMF for installation. As we learn through experiments in Japan, we will also develop new ideas for the best possible experiment at TRIUMF, and prepare the experimental area at TRIUMF. This will result in a world-leading experiment at TRIUMF.