Ultracold Neutrons at TRIUMF: Bridging Grant Application for New Members

在来自日本的合作者（增田等人）的帮助下，加拿大正在建造一个世界领先的新型超冷中子源（UCN）（位于不列颠哥伦比亚省温哥华的TRIUMF）。 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，我们专注于测量中子电偶极矩（EDM），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。 我们在未来两年的活动将包括完成一个非常精确的实验comagnetometer的关键研发。 我们正在研制的双核素氚-129/汞-199彗星磁强计。 与传统的单物质Hg-199 comagnetometer相比，这种解决方案有几个优点，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。 Comagnetometer的研发需要先进的激光和原子物理技术的专业知识，由三个新的合作者提供，他们要求通过两年的桥接赠款提供支持。

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.