Ultracold Neutrons at TRIUMF: Bridging Grant Application for New Members

在日本合作者（Masuda等人）的帮助下，世界领先的超冷中子（UCN）新源正在加拿大（位于不列颠哥伦比亚省温哥华的TRIUMF）建造。我们生产的UCN将用于推动一些非常有趣的物理实验达到前所未有的精度水平。最初，我们专注于中子电偶极矩（EDM）的测量，这是我们在这个实验中的主要活动，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新的电荷宇称（CP）违反源，这些源被认为是解释当今宇宙中物质优于反物质（重子不对称）所必需的。如果在我们的新实验能够达到的实验精度水平上发现一个非零值，它可能意味着CP违背的新来源，从而有助于解释宇宙的重子不对称性。我们在未来两年的活动将包括完成实验中非常精确的磁强计的关键研发。我们正在开发双种Xe-129/Hg-199磁力仪。与传统的单种Hg-199磁强计相比，该方案有几个优点，最重要的是它可以对实验中预期的最大系统误差进行交叉检查。磁强计的研发需要先进的激光和原子物理技术方面的专业知识，由三个新的合作者提供，他们正在申请为期两年的过渡性资助。

A world-leading new source of ultracold neutrons (UCN) is being constructed in Canada (at TRIUMF, Vancouver, BC) with the help of collaborators from Japan (Masuda, et al). 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 (EDM), 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 two years will involve completing critical R&D on a very precise comagnetometer for the experiment. We are developing the dual-species Xe-129/Hg-199 comagnetometer. This solution has several advantages over the traditional single-species Hg-199 comagnetometer, the most important being that it offers a cross-check on the anticipated largest systematic error in the experiment. The comagnetometer R&D requires expertise in advanced laser and atomic physics techniques, offered by the three new collaborators that are requesting support via a bridging grant for two years.