Compensation of the effects of a detector solenoid on the vertical beam orbit in a linear collider
Compensation of the effects of a detector solenoid on the vertical beam orbit in a linear collider
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线性对撞机中探测器螺线管对垂直光束轨道影响的补偿
DOI：
10.1103/physrevstab.8.041001
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发表时间：
2005
影响因子：
--
通讯作者：
A. Seryi
中科院分区：
文献类型：
--
作者：
B. Parker;A. Seryi
本文提出了一种通过相互作用区补偿垂直轨道变化的方法，该相互作用区是当束以交叉角进入直线对撞机探测器螺线管时产生的。这种补偿是必需的，因为垂直轨道的任何偏差会由于同步辐射而导致光束尺寸的退化，并且还因为非零的总垂直角会导致聚束的偏振矢量的旋转。为了保持亮度或保证了解相互作用点处的偏振，补偿是必要的。最有效的补偿是在探测器中加入一个特殊的偶极线圈（探测器集成偶极）进行局部补偿。这种补偿对ee-beam和ee-beam都是有效的，而且这种技术与用标准方法（使用斜四极杆）或用更有效的方法（使用弱反极化）进行的横向耦合补偿是兼容的。ILC相互作用区域（IR）的设计受到以下要求的约束：为入射光束提供强聚焦，为实验检测器提供可接受的背景环境，以及对出射光束的干净提取。ILC被指定为具有两个IR，其中至少一个IR将可能在水平面中使用小的（高达约20 mrad）交叉角，以便于提取出射的被干扰光束。交叉角允许单独的入射和出射光束线，可以独立优化。第二个红外线还必须能够适应碰撞，这需要一个稍大的交叉角，高达20 - 35 mrad。当水平半交叉角c大于x =-z时，为了保持IP处碰撞光束的重叠，需要采用螃蟹交叉技术。两个位于IP上游数米处的两个射频腔在两条光束线上引入了与聚束内的纵向位置相关的反冲，使得聚束旋转并在IP处完全重叠。水平交叉角意味着射束以一定角度穿过检测器的磁场，因此将被偏转到垂直平面中。垂直轨道的变化导致由于同步辐射（SR）的光束尺寸的退化，并且如果总垂直角非零，则还导致偏振矢量的旋转。本文讨论了这两种影响的背景下，NLC设计与c 10 mrad，并提出了可能的方法，以补偿垂直角在IP和最小化
This paper presents a method for compensating the vertical orbit change through the interaction region that arises when the beam enters the linear collider detector solenoid at a crossing angle. Such compensation is required because any deviation of the vertical orbit causes degradation of the beam size due to synchrotron radiation, and also because the nonzero total vertical angle causes rotation of the polarization vector of the bunch. Compensation is necessary to preserve the luminosity or to guarantee knowledge of the polarization at the interaction point. The most effective compensation is done locally with a special dipole coil arrangement incorporated into the detector (detector integrated dipole). The compensation is effective for both eeand eebeams, and the technique is compatible with transverse- coupling compensation either by the standard method, using skew quadrupoles, or by a more effective method using weak antisolenoids. The design of the ILC interaction region (IR) is constrained by the often conflicting requirements of providing strong focusing for the incoming beam, acceptable background environment for the experimental detector, and clean extraction of the outgoing beams. The ILC is specified to have two IRs, at least one of which will likely use a small (up to about 20 mrad) crossing angle in the horizontal plane to facilitate extraction of the outgoing disrupted beams. The crossing angle allows separate incoming and outgoing beam lines, which can be optimized independently. The second IR must additionally be able to accommodate �� collisions, which require a slightly larger crossing angle, up to 20 -35 mrad. When the horizontal half crossing anglec is larger thanx=� z, a crab-crossing technique is required in order to preserve the overlap of the beams in collision at the IP. Two rf cavities located several meters upstream of the IP on both beam lines introduce a kick correlated with longitudinal position within the bunch, so that the bunches rotate and fully overlap at the IP. The horizontal crossing angle means that the beam traverses the magnetic field of the detector at an angle and thus will be deflected into the vertical plane. The change in the vertical orbit causes degradation of the beam size due to synchrotron radiation (SR), and also causes rotation of the polarization vector if the total vertical angle is nonzero. This paper discusses both these effects in the context of the NLC design withc � 10 mrad and presents possible methods for compensating the vertical angle at the IP and minimizing