ON PARASITIC CROSSINGS AND THEIR LIMITATIONS TO E+E− STORAGE RING COLLIDERS
ON PARASITIC CROSSINGS AND THEIR LIMITATIONS TO E+E− STORAGE RING COLLIDERS
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发表时间：
2004
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通讯作者：
J. Gao
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作者：
J. Gao
其中，提高存储环对撞机光度的有效方法之一是增加对撞束的数量。以双环对撞机为例，当相邻束团之间的距离是两个靠近相互作用点(IP)的小束团时，碰撞的束团不是被两个真空室隔开，而是在同一束管中传播，它们有机会在IP碰撞前后产生所谓的寄生交叉(PC)[1]-[9]，如图1所示。在PC处的长程非线性束流作用力将对IP束流相互作用的限制有额外的贡献。就PEP-II B-Factory而言，在BY-2模式和较大电流下运行，寄生交叉效应将是重要的甚至是主导的[10]。对于超级B工厂[11][12]来说，这种影响可能更重要。本文对激电点的寄生交叉及其与束流相互作用的综合效应进行了理论分析，并将其应用于运行在BY-2模式下的PEP-II低能环。
Among others, one of the efficient way to increase the luminosity of a storage ring collider is to increase the number of colliding bunches. Taking two ring collider for example, when the distance between the adjacent bunches are two small, near interaction point (IP), the colliding bunches instead of being separated by two vacuum chambers, they have to travel in the same beam pipe and they have chance to have so-called parasitic crossings (PC) [1]-[9] before and after making collision at IP as shown schematically in Fig. 1. The long rang nonlinear beam-beam forces at PCs will have extra contributions to the limitation from the beambeam interaction at IP. As far as PEP-II B-Factory is concerned, runing in by-2 mode and higher current, the parasitic crossing effect will be important even dominant [10]. As for Super-B factory [11][12] this effect could be more important. In this paper we make a theoretical analysis on the parasitic crossing and its combined effects together with beam-beam interaction at IP, and apply it to PEP-II low energy ring running in by-2 mode.