Ultracold Neutrons at TRIUMF

超冷中子（UCN）是一种缓慢移动的中子，可以储存在物质瓶、磁瓶和引力瓶中。一旦用这种方法对它们进行了限制，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（Masuda等人）的帮助下，我们在加拿大（在不列颠哥伦比亚省温哥华的TRIUMF）几乎完成了一个新的UCN来源。预计该源将提供世界上最高密度的UCN。我们将生产的UCN将用于将基础物理实验推进到前所未有的精度水平。****最初，我们专注于中子电偶极矩（nEDM）的测量，这主要是我们在这个实验的研发活动，需要NSERC的支持。nEDM的新测量将对涉及标准模型之外的新电荷宇称（CP）违反源的理论施加更严格的限制。据信，为了解释当今宇宙中物质对反物质（重子不对称）的优势，这些都是必需的。一般来说，它限制了许多可能不守恒CP的理论，例如超对称理论。一项新的测量也将进一步限制标准模型中一个长期存在的谜题，包括明显缺乏由强作用力引起的CP违逆。非零nEDM的发现显然将是一个重大发现，因为它可能会揭示如此广泛的理论。****我们在未来三年的活动将包括完成UCN在TRIUMF的设施，并完成关键的研究和开发，这将使未来世界领先的中子电偶极子实验成为可能

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 have nearly completed 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 in the world. The UCN we will produce will be used to advance fundamental physics experiments to unprecedented levels of precision.****Initially we are focused on a measurement of the neutron electric dipole moment (nEDM), and it is primarily our activities on R&D for this experiment which require support from NSERC. A new measurement of the nEDM will place even tighter constraints on theories involving new sources of Charge-Parity (CP) violation beyond the standard model. It is believed these are required in order to explain the predominance of matter over antimatter (baryon asymmetry) in the universe today. Quite generically, it constrains broad classes of theories which may not conserve CP, for example supersymmetry. A new measurement will also further constrain a long-standing mystery in the standard model, involving the appararent lack of CP violation arising from the strong force. A discovery of a non-zero nEDM would obviously be a major discovery, since it could potentially shed light on such a broad range of theories.****Our activities over the next three years will involve the completion of the UCN facility at TRIUMF, and the completion of key research and development that will enable a future world-leading neutron electric dipole moment experiment.**