磁铁与冷却 Magnets and Cooling
沿着加速器组合的所有路径，大约有1万个50多种不同的磁铁，大多是用在加速器周围的“点阵磁铁”。
Along the path of the accelerator complex, there are more than 50 types almost ten thousand magnets, the majority are ‘lattice magnets’ used around the accelerators.
仅LHC就用到1600多个电磁铁。其中1232个8.3特斯拉15米长的偶极子用于弯曲粒子束，3992个5-7m长的四极子用于聚焦粒子束，更有一些六极、八极甚至十极磁铁用于修正路径上的小缺陷。*
In the LHC alone are more than sixteen hundred electromagnets. 1232 of which are 8.3 tesla 15m long dipoles for the bending, 392 5-7m long quadrupoles for focusing the beam and some sextupole, octupole and even decapole magnets for corrections of small imperfections along the path. *
在实验探测点(ATLAS, CMS, ALICE, LHCb)，这里插入式磁铁接管。由3个四极磁铁组成的内三态系统会使光束变窄12.5倍——从0.2毫米到16微米。
At the points of the detectors (ATLAS, CMS, ALICE, LHCb), the insertions magnets take over. Three quadrupoles are used to create the inner triplet system to make the beams 12.5 times narrower – from 0.2mm to 16μm. *
这些磁铁也会在探测器内用到，在粒子碰撞后可以确定它们的身份，并清除散落的粒子，以防止不相干的粒子接触LHC最敏感的组件。
These magnets also help after the collisions in the detectors to determine particle identities and clearing stray particles to prevent them from contacting LHC’s most sensitive components.
图为两段偶极磁铁组装链接之前的内部结构，所有蓝色管道内包含引导方向的电磁铁以及为他们降温的液态氦系统
The inner structure of the dipole magnets. All the blue cylinders contain the electromagnets that guide the beams and the liquid helium system that cools them
低温学是研究极低温度下的生产和效应的物理学。LHC作为地球上温度最低的地方之一，也是世界上最大的低温系统。
Cryogenics is the physics of production and effects of very low temperatures. The LHC, being one of the places with lowest temperature on Earth, is the largest cryogenic system in the world.
为了将36,000吨磁体保持在1.9K(比外太空还要冷)，这里的低温系统使用了4万个密封管道，40兆瓦电力和120吨氦气。氦气在这里作为超流体，任务就是以极低的温度包裹住所有磁铁，保证能在能量损失最低的情况下工作。
To keep 36,000 tonnes of magnets at 1.9K, which is even colder than outer space, the cryogenic system uses 40,000 leak-tight pipe seals, 40 MW of electricity and 120 tonnes of helium. Helium as a superfluid here, is tasked with covering all the magnets at extremely low temperatures, ensuring they can operate with minimal energy loss.
为了使质子保持在轨道上，需要11,850安培的电流才能使磁体运转，*使用超导铌钛已被证明是减少能量损失的最佳方法。
So that the protons can be kept on track, a current of 11,850 amps is required for the magnets to operate, * and the use of superconducting niobium-titanium has proven to be the best way of minimizing energy loss.
低温技术也涉及到探测器中，以保持重气体处于液态，例如用于量热计中氩或氪的探测工作。
Cryogenics technology is also involved in the detectors to keep heavy gases in liquid states, used in for example argon or krypton in the detection of particles in the calorimeters.
氦的超流体特性是它被选为最佳冷却剂的原因。在4.2K左右的大气压力下它会变成液体，2.17K以下变为超流体，并具有长距离的高导热系数。这是其他材料无法达到的。
It is helium’s superfluid properties why it is used as a coolant here. Allow components to be kept cool over long distances, it becomes liquid at around 4.2K in atmosphere pressure and turns to superfluid with high thermal conductivity below 2.17K.
图为6号点的4.5 K 冰箱压缩机单元，提供了18千瓦的制冷量，整个冷却系统中有八个这样的装置
The compressor unit of the 4.5 K refrigerator at Point 6. The unit provides 18 kW cooling capacity and there are eight of these units in the complete cooling system
正是这些最先进的技术
成就了整个CERN的实验们，
它们不容小觑！
It's these state-of-the-art technologies that
make up the entire CERN experiment,
and they're not to be underestimated!
图为2020年6月CERN第二次大型维护时，在PS安装最新磁铁的场景
The new PS septum magnet during installation in the injection line in June 2020 of CERN's Long Shutdown 2
图片和视频来自 CERN 官网
文中除*部分英文信息应用于CERN官网，
其余中英文内容为原创
Pictures and video from official website of CERN.
The * parts of English information was cited from official websites of CERN,
the rest of the Chinese and English content is original
