Beam-beam effects and mitigation in a future proton-proton collider  

作　　者：Li-Jiao Wang Tanaji Sen Jing-Yu Tang Lin-Hao Zhang 

机构地区：[1]Institute of High Energy Physics,CAS,Yuquan Road 19B,Beijing 100049,China [2]University of Chinese Academy of Sciences,CAS,19A Yuquan Road,Beijing 100049,China [3]Spallation Neutron Source Science Center,Dongguan 523803,China [4]Fermi National Accelerator Laboratory,P.O.Box 500,Batavia,IL 60510,USA

出　　处：《Nuclear Science and Techniques》2022年第10期90-105,共16页核技术（英文）

基　　金：supported by the National Natural Science Foundation of China (Nos. 11575214, 11527811, and 11805218);the Fermi Research Alliance;LLC;under contract no. DE-AC02-07CH11359with the U.S. Department of Energy。

摘　　要：The beam-beam effects in a hadron collider with an unprecedented energy scale were studied.These effects are strongly related to the attainable luminosity of the collider.Long-range interactions were identified as the major factor limiting the dynamic aperture,which is strongly dependent on the crossing angle,β*,and bunch population.Different mitigation methods of the beam-beam effects were addressed,with a focus on the compensation of long-range interactions by electric curren wires.The CEPC-SPPC project is a two-stage large circular collider,with a first-stage circular electron-positron collider(CEPC)and a second-stage super proton-proton collider(SPPC).The design of the SPPC aims to achieve a center-of-mass energy of 75 TeV and peak luminosity of approximately 1×10^(35) cm^(-2)s^(-1).We studied the beam-beam effects in the SPPC and tested the effectiveness of the mitigation methods.We found that with compensation using electric current wires,the dynamic aperture is at an acceptable level.Moreover,considering the significant emittance damping in this future proton-proton collider the beam-beam effects and compensation are more complicated and are studied using long-term tracking.It was found that with a smaller emittance,the head-on interactions with a crossing angle become more prominent in reducing the beam stability,and combined head-on and long-range compensation is needed to improve the beam quality.When the reduction in population owing to burnoff was included,it was found that the coupling between the transverse and longitudinal planes at smaller emittance is the main driving source of the instabilities.Thus,crab cavities and emittance control are also necessary than just the compensation of the long-range interactions to improve the beam stability.This study serves as an example for studying the beam-beam effects in future proton-proton colliders.

关 键 词：Particle collider Beam-beam effects Luminosity Tune footprint Dynamic aperture 

分 类 号：O572.214[理学—粒子物理与原子核物理]