叠加电/磁“偶极矩比较器”晶格设计
Superimposed Electric/Magnetic "Dipole Moment Comparator" Lattice Design
摘要：
与“单粒子台式阱”相比，储存环“阱”的基本特征是$10^{10}$或更多粒子可以使它们的自旋在偏振光束中对准。这是一组足够大的偏振粒子，它们的偏振态可以在外部被检测到，并被反馈以允许外部对光束偏振态进行控制。可实现的自旋控制水平，虽然是经典的，而不是量子力学的，但可以与在低能陷阱中控制一个或少数极化粒子相媲美。出于研究时间反转不变性，特别是非零电偶极矩（EDM）的检测，本文描述了一个低能量存储环的设计，具有叠加的电和磁弯曲需要“冻结”的偏振光束的自旋。对于电子（任一符号）和质子，自旋可以用全电弯曲来冻结，但通常需要叠加的电/磁弯曲。由于在一个方向上的相长弯曲叠加意味着在另一个方向上的相消叠加，因此反循环光束必须在粒子类型或动量上不同，以便它们的轨道相同。对于全局冻结自旋操作，聚束极化相对于动量保持恒定，例如保持平行于循环束动量矢量。叠加的电和磁弯曲，全球冻结自旋条件可以满足超过连续（特定于粒子类型）的E/B比。当满足这个条件时，平面外的EDM引起的进动监测地积累，这对于产生可测量的大EDM信号是必需的。正如库普所解释的那样，如果允许极化围绕径向轴“像轮子一样滚动”，EDM信号仍然会积累。
英文摘要：
In contrast to a "single particle table-top trap", an essential feature of a storage ring "trap" is that $10^{10}$ or more particles can have their spins aligned in a polarized beam. This is a nunber of polarized particles large enough for the beam polarization to be detected externally, and fed back to permit external control of the beam polarization. The level of achievable spin control, though classical, not quantum mechanical, can be comparable to the control of one or a small number of polarized particles in a low energy trap. Motivated to investigate time reversal invariance, especially the detection of non-zero electric dipole moments (EDMs) this paper describes the design of a low energy storage ring having the superimposed electric and magnetic bending needed to "freeze" the spins of polarized beams. For electrons (of either sign) and protons the spins can be frozen with all-electric bending but, in general, superimposed electric/magnetic bending is required. Since constructive bending superposition in one direction implies destructive superposition in the other direction, counter-circulating beams must differ, either in particle type or momentum, in order for their orbits to be identical. For globally frozen spin operation the bunch polarizations remain constant relative to the momenta, for example remaining parallel to the circuating beam momentum vectors. With superimposed electric and magnetic bending, the globally frozen spin condition can be met over a continua (specific to particle type) of E/B ratios. When this condition is met, the out-of-plane, EDM-induced precession accumulates monitonically, which is obligatory for producing a measurably large EDM signal. As Koop has explained, the EDM signal will still accumulate if the polarization is allowed to "roll like a wheel" around a radial axis.
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