Experimental Research for Complex Beam-Beam Effects under Asymmetric Collision with a Finite Angle

有限角度非对称碰撞下复杂束-束效应实验研究

• 批准号: 16540271
• 负责人: IEIRI Takao
• 金额: $ 2.3万
• 依托单位: High Energy Accelerator Research Organization (KEK)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16540271/
• 关键词: Beam-beam effects; Betatron tune shift; Electron cloud; Dynamic effects; ベータトロンチューン; ダイナミック効果

KEKB is an asymmetric electron/positron collider, which keeps the best luminosity in the world.The beam-beam effects were investigated with a gated-bunch method at KEKB. We obtained the following experimental results :(1)Collisions occur with a horizontal orbit offset to avoid the instability called "Egure" phenomena.(2)We found that the "Egure" phenomena are caused by a combination of the beam-beam and electron cloud effects under a finite crossing angle.(3)We obtained the experimental evidence of the dynamic beam-beam effects ; the emittance growth and the beta beat.We found new phenomena about a half-integer resonance. When a betatron tune more closely approached a half-integer, we observed a distortion just on a half-integer in the spectrum. The observed phenomena could be explained by supposing that some off-momentum particles in a bunch jumped into an unstable region in the half-integer resonance. A precise simulation including errors would be required to verify the phenomena.We found a fast ion effect related to collisions. It was observed that the vertical tune-spectrum of an electron bunch showed an asymmetrical distribution biased to a higher tune under normal colliding operations. The observations imply that the distortion in the spectrum is related to the field due to ions produced by colliding bunches placed forwards to a measured bunch. A tune-shift measurement supported the presence of ions.Based on these findings, we would like to promote more precise investigation about the beam dynamics of KEKB. The study would be useful and valuable for understanding beam dynamics in the ring accelerators.

KEKB是非对称正负电子对撞机，它保持了目前世界上最好的亮度，在KEKB上采用门控聚束方法研究了束-束效应。实验结果表明：（1）碰撞发生在水平轨道偏移的情况下，避免了被称为“Egure”现象的不稳定性。(2)We发现“Egure”现象是由有限交叉角下的束-束效应和电子云效应的组合引起的。(3)We获得了动态束-束效应、发射度增长和β拍频的实验证据，发现了半整数共振的新现象。当电子感应加速器的调谐更接近半整数时，我们观察到频谱中的半整数上的失真。观察到的现象可以解释为假设在一个束团中的一些非动量粒子在半整数共振跳到一个不稳定的区域。我们发现了与碰撞有关的快离子效应。结果表明，在正常碰撞条件下，电子束团的垂直调谐谱呈现出向高调谐方向偏置的非对称分布。观测结果表明，光谱中的失真与场有关，场是由放置在测量束前方的碰撞束产生的离子引起的。基于这些发现，我们希望能促进对KEKB束流动力学更精确的研究。这一研究对于理解环形加速器中的束流动力学具有重要意义。

项目成果

Dynamic Beam-Beam Effects measured at KEKB

KEKB 测量的动态梁-梁效应

• 发表时间: 2005
• 期刊: Proc. of the 2005 PAC, Knoxville, Tennessee, USA
• 作者: T.Ieiri;Y.Funakoshi;T.Kawamoto;M.Masuzawa;M.Tobiyama
• 通讯作者: M.Tobiyama

variations in Betatron Tune observed at KEKB, influenced by Magnetic-Field of KEK-PS

在 KEKB 观察到的 Betatron 调谐变化，受 KEK-PS 磁场的影响

• 发表时间: 2005
• 期刊: Proceedings of the 2nd Annual Meeting of Particle Accelerator Society of Japan 654
• 作者: T.Ieiri;Y.Funakoshi;T.Kawamoto;M.Masuzawa;M.Tobiyama;T.Ieiri
• 通讯作者: T.Ieiri

KEK-PS磁場によるKEKBベータトロンチューンの変動

由于 KEK-PS 磁场而导致 KEKB 电子感应加速器调谐的变化

• 发表时间: 2005
• 期刊: Proc.of the 2nd Annual Meeting of Particle Accelerator Society of Japan, Tosu, Saga
• 作者: T.Ieiri;K.Olde;Y.Ohnishi;H.Koiso;M.Suetake;M.Tobiyama;Y.Funakoshi;M.Yoshida
• 通讯作者: M.Yoshida

Measurement of Dynamic Beam-Beam Effects

动态梁-梁效应的测量

• 发表时间: 2005
• 期刊: Physical Review Special Topics - Accelerators and Beams 8
• 作者: T.Ieiri;Y.Funakoshi;T.Kawamoto;M.Masuzawa;M.Tobiyama
• 通讯作者: M.Tobiyama

Asymmetrical spectrum Observed at the KEKB High Energy Electron Ring

在 KEKB 高能电子环观察到的不对称光谱

• 发表时间: 2005
• 期刊: Proceedings of 2005 Particle Accelerator Cinference, Knoxville, Tennessee, USA
• 作者: T.Ieiri;Y.Ohnishi;M.Tobiyama
• 通讯作者: M.Tobiyama