Analytical Estimation of the Beam-Beam Interaction Limited Dynamic Apertures and Lifetimes in e + e − Circular Colliders
Analytical Estimation of the Beam-Beam Interaction Limited Dynamic Apertures and Lifetimes in e + e − Circular Colliders
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发表时间：
2000
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通讯作者：
J. Gao
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作者：
J. Gao
从物理上讲，δ函数类似于梁-梁相互作用点（IP）处的非线性力，其作用是δ函数非线性多极之和。本文应用文献[1]中建立的一般理论，解析地研究了圆梁和扁梁的束-束相互作用限制动态孔径和相应的束寿命。建立了束-束受限的束寿命和束-束调谐偏移之间的关系，这清楚地表明了为什么在实验上，对于e +e−圆形对撞机，总是有最大的束-束调谐偏移，最大值为0.045，以及为什么可以使用圆形束来近似地加倍这个值。与一些机器参数的比较。最后，讨论了碰撞交叉角对光度降低的影响。
Physically speaking, the delta function like beam-beam nonlinear forces at interaction points (IPs) act as a sum of delta function nonlinear multipoles. By applying the general theory established in ref. [1], in this paper we investigate analytically the beam-beam interaction limited dynamic apertures and the corresponding beam lifetimes for both the round and the flat beams. Relations between the beam-beam limited beam lifetimes and the beam-beam tune shifts are established, which show clearly why experimentally one has always a maximum beam-beam tune shift, ξy,max, around 0.045 for e +e− circular colliders, and why one can use round beams to double this value approximately. Comparisons with some machine parameters are given. Finally, we discuss the mechanism of the luminosity reduction due to a definite collision crossing angle.