Neon moderator for intense cold positron source

反氢是最简单的反物质原子，由一个正电子（相当于电子的反粒子）围绕一个反质子运行。近年来，欧洲核子研究中心通过将捕获的反质子与捕获的正电子结合来构建反氢原子。这项研究的目标是精确地研究反氢原子，并将它们的性质与普通氢原子的性质进行比较，从而将反物质的性质与物质的性质进行比较。由于物理学的基本对称性（CPT），可以预期这些性质将完全相同，因此比较将测试CPT对称性。所要求的资金是用于资助一种改进的收集正电子的方法。正电子是由钠-22放射源以非常高的能量产生的。慢化剂是通过使一小部分正电子在固体中热化来降低正电子的能量。目前我们使用的是一种很薄的钨晶体，但是如果我们使用固体氖慢化剂，我们实验中可用的正电子数量可以提高100倍。100的因数是由于固体氖的正电子调节效率提高了10倍，加上由此产生的更高密度允许更好地压缩正电子等离子体，这种压缩导致正电子传输到反质子被捕获的位置的效率提高了10倍。拨款建议是购买一个系统，这将使我们能够生产和维持一个坚实的霓虹灯慢化剂。这种慢化剂必须在低于24开尔文（-250摄氏度）的温度下建造和维持，并且需要在高真空设备内精确控制的超纯气体系统。

Neon Moderator for an intense positron source Antihydrogen is the simplest antimatter atom and consists of a positron (the antiparticle equivalent of an electron) orbiting about an antiproton. In recent years, antihydrogen atoms have been constructed at CERN by combining trapped antiprotons with trapped positrons. The goal of this research is to precisely study antihydrogen atoms and compare their properties to those of regular hydrogen, thus comparing the properties of antimatter to those of matter. Because of a fundamental symmetry of physics (CPT), it might be expected that the properties will be exactly identical and the comparison will therefore test CPT symmetry. The monies requested are to fund an improved method for collecting positrons. The positrons are produced at very high energy by a sodium-22 radioactive source. A moderator is used to lower their energy by having a small fraction of the positrons thermalize within a solid. Currently we are using a thin crystal of tungsten for this purpose, but the number of positrons available to our experiment could be improved by a factor of 100 if we were to use a solid neon moderator instead. The factor of 100 results from the 10 times higher positron moderation efficiency of solid neon combined with the fact that the resulting higher density allows for better compression of the positron plasma and this compression leads to a factor of 10 higher efficiency in transporting the positrons to the location where the antiprotons are trapped. The grant proposal is for the purchase of a system which will allow us to produce and sustain a solid neon moderator. This moderator must be constructed and maintained at temperatures below 24 Kelvin (-250 degrees Celsius) and require a precision-controlled ultrapure gas system within a high-vacuum apparatus.