The Compact Muon Solenoid (CMS) is a general purpose detector, designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting solenoid with 6-m-diameter by 12.5-m-length free bore, enclosed inside a 10,000-ton return yoke made of construction steel. The flux return yoke consists of five dodecagonal three-layered barrel wheels and four end-cap disks at each end comprised of steel blocks up to 620 mm thick, which serve as the absorber plates of the muon detection system. To measure the field in and around the steel, a system of 22 flux loops and 82 3-D Hall sensors is installed on the return yoke blocks. A TOSCA 3-D model of the CMS magnet is developed to describe the magnetic field everywhere outside the tracking volume that was measured with the field-mapping machine. The voltages induced in the flux loops by the magnetic flux changing during the CMS magnet standard ramps down are measured with six 16-bit DAQ modules. The off-line integration of the induced voltages reconstructs the magnetic flux density in the yoke steel blocks at the operational magnet current of 18.164 kA. The results of the flux loop measurements during three magnet ramps down are presented and discussed.
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机译：紧凑型μon螺线管（CMS）是通用探测器，设计用于在CERN大型强子对撞机（LHC）上以最高的亮度运行。它的独特功能包括直径为6 m x长度为12.5 m的4 T超导螺线管，该螺线管封闭在由结构钢制成的10,000吨的回程轭中。磁通返回轭由五个十二边形的三层圆筒轮和每个端部的四个端盖盘组成，每个端盖盘由厚度最大为620 mm的钢块组成，用作μ子检测系统的吸收板。为了测量钢中和周围的磁场，在回叉块上安装了由22个磁通回路和82个3-D霍尔传感器组成的系统。开发了CMS磁体的TOSCA 3-D模型，以描述在使用场映射仪测量的跟踪体积之外的任何地方的磁场。使用六个16位DAQ模块测量在CMS磁体标准斜坡下降期间由磁通量变化引起的磁通回路中感应的电压。感应电压的离线积分以18.164 kA的工作磁体电流重构了轭钢块中的磁通密度。给出并讨论了三个磁铁下降期间磁通回路的测量结果。
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