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"Ghost particles" detected in the Large Hadron Collider for first time
大型强子对撞机首次探测到"幽灵粒子"
Physicists have detected “ghost particles” in the Large Hadron Collider for the first time. An experiment called FASER picked up telltale signals of neutrinos being produced in particle collisions, which can help scientists better understand key physics. Neutrinos are elementary particles that are electrically neutral, extremely light and rarely interact with particles of matter. That makes them tricky to detect, even though they’re very common – in fact, there are billions of neutrinos streaming through your body right now. Because of this, they’re often described as ghost particles.
物理学家首次在大型强子对撞机中检测到"幽灵粒子"。一个名为FASER的实验捕捉到了粒子碰撞中产生的中微子的存在信号，这可以帮助科学家更好地理解关键的物理学特性。中微子是电中性的基本粒子，非常轻，而且很少与物质粒子相互作用。这使得它们很难被探测到，尽管它们非常常见，事实上，现在就有数十亿中微子流经你的身体。正因为如此，它们经常被描述为幽灵粒子。
Neutrinos are produced in stars, supernovae, quasars, radioactive decay and from cosmic rays interacting with atoms in the Earth’s atmosphere. It’s long been thought that particle accelerators like the LHC should be making them too, but without the right instruments they would just zip away undetected.
中微子产生于恒星、超新星、类星体、放射性衰变以及宇宙射线与地球大气中的原子相互作用。长期以来，人们一直认为像大型强子对撞机这样的粒子加速器也会产生中微子，但如果没有合适的仪器，它们就会自动消失而不被发现。
Located 480 m (1,575 ft) down the line from where the particle collisions occur, the FASER instrument works a little like film photography, the team says. The detector is made up of plates of lead and tungsten, separated by layers of an emulsion. Some of the neutrinos will strike the nuclei of atoms in the dense metals, which creates other particles that stream through the emulsion. The tracks they leave behind can then be seen when the emulsion layers are “developed” like film. And sure enough, six of these marks were spotted in the data.
该团队表示，FASER仪器位于距离粒子碰撞发生地480米（1575英尺）的下方，其工作方式有点像胶片摄影。探测器是由铅和钨板组成的，被一层层的乳剂分开。一些中微子撞击致密金属中的原子核，从而产生其他粒子，并流经乳剂。然后，当乳剂层像胶片一样被"冲洗（显影）"时，可以看到它们留下的痕迹。而且可以肯定的是，在数据中发现了六个这样的痕迹。
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