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A Super-Sensitive Dark Matter Detector Just Booted Up

The LUX-ZEPLIN (LZ) experiment team has announced the results from its first scientific run today; the experiment is the world’s most sensitive dark matter detector, and though it did not find any dark matter in this first round, the team confirmed that the experiment is working as expected.

今天,LUX-ZEPLIN (LZ)实验小组宣布了他们第一次科学实验的结果; 该实验器材是世界上最灵敏的暗物质探测器,虽然在第一轮实验中没有发现任何暗物质,但是该小组确认该实验仪器正如预期的那样工作。

The LZ experiment detector is made up nested tanks of liquid xenon, each 1.5 meters tall and 1.5 meters wide, buried under South Dakota. The idea is that a dark matter particle whizzing through space will eventually bounce off one of the xenon atoms, knocking loose electrons in a flash that is recorded by the experiment. The tank is buried about a mile below Earth’s surface to minimize the amount of background noise. Today’s announcement comes after 60 live days of data collection that spanned December 25 to May 12.

LZ 实验探测器由液体氙气嵌套罐组成,每个罐高1.5米,宽1.5米,埋在南达科他州。这个想法是,一个在太空中呼啸的暗物质粒子最终会从一个氙原子上反弹回来,在实验记录的闪光中撞击松散的电子。水箱被埋在地下一英里以减少背景噪音。今天的声明是在12月25日至5月12日的60天的数据收集活动之后宣布的。

“We’re looking for very, very low-energy recoils by the standards of particle physics. It’s a very, very rare process, if it’s visible at all,” said Hugh Lippincott, a physicist at UC Santa Barbara and a member of the LZ team, in a press conference today. “You can shoot a dark matter particle through 10 million light-years of lead and expect only one interaction at the end of that light-year.”

“按照粒子物理学的标准,我们正在寻找非常,非常低能量的后坐力。这是一个非常非常罕见的过程,如果可以看到的话。”圣塔芭芭拉加利福尼亚大学物理系物理学家、 LZ团队成员休•利平科特在今天的新闻发布会上表示。“你可以通过1000万光年的铅射出一个暗物质粒子,在那1000万光年结束时只有一次相互作用。”

Dark matter is the catch-all term for the unknown stuff that appears to make up about 27% of the universe. It hardly ever interacts with ordinary matter, hence its “darkness” to us. But we know it’s out there because, while never directly detected, it has gravitational effects that can be seen on cosmic scales. (NASA breaks down the concept pretty well here.)

暗物质是宇宙中27% 的未知物质的统称。它几乎从不与普通物质相互作用,因此对我们来说它是“黑暗的”。但我们知道它就在那里,因为虽然从未被直接探测到,但它具有可以在宇宙尺度上看到的引力效应。(美国国家航空航天局在这里很好地解释了这个概念。)

There are many candidates for dark matter. One is the WIMP, or a Weakly Interacting Massive Particle. Unlike other dark matter hypotheses like axions or dark photons, which are so small and diffuse that they may behave more like waves, WIMPs would have mass but hardly ever interact with ordinary matter. So to detect them, you need a device that pretty much mutes all other physics going on.