2021-11-26

The Faser team detected neutrinos during the Large Hadron collision experiment for the first time

By yqqlm yqqlm

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e2fe38d76194fed - The Faser team detected neutrinos during the Large Hadron collision experiment for the first time

neutrinos are produced in stars, supernovae and quasars. Radioactive decay, cosmic rays and atoms in the earth’s atmosphere interact

in fact, in an instant, billions of neutrinos pass through our bodies. Popular, you can also call it “ghost particles”

The Faser team detected neutrinos during the Large Hadron collision experiment for the first time

research configuration figure – 1: metal plate structure of detector

for a long time, people have always thought that particle accelerators such as LHC can also produce neutrinos in the experimental process. Unfortunately, we have not been able to find a suitable instrument to detect

the good news is that the “correct instrument” was deployed and tested during the trial operation of the Faser project in 2018, which finally allowed scientists to discover six neutrino interactions

The Faser team detected neutrinos during the Large Hadron collision experiment for the first time(1)

study diagram – 2: μ Jonathan Feng, co-author of sub flux function

> research, said: “before this project, we have never seen signs of neutrinos on the particle collider. With this major breakthrough, we can have a deeper understanding of these elusive particles and their role in the universe in the future.”

during the experiment, the researchers deployed the Faser instrument to 408 meters (1575 feet) where the particle collision occurred, and carried out the recording work in a manner similar to film photography

The Faser team detected neutrinos during the Large Hadron collision experiment for the first time(2)

research diagram – 3: event projection

Faser detector body is composed of lead / tungsten metal partition, and there is a layer of emulsion in the middle. Some neutrinos will collide into the nuclei of dense metals, resulting in the production of other popular emulsion particles. p>

when the emulsion layer “develops” like film, the traces left by them can be observed. After verifying the effectiveness of this method, the Faser team now prepares a series of new experiments and uses a larger and more sensitive complete instrument

The Faser team detected neutrinos during the Large Hadron collision experiment for the first time(3)

research diagram – 4: Monte Carlo simulation distribution of BDT input variables in neutrino signal / neutral hadron background

it is reported that the weight of the complete detector named fasernu exceeds 1090 kg (2400 pounds), while the previous version of Faser is only 29 kg (64 pounds)

thanks to higher sensitivity, the research team can not only detect neutrinos more frequently, but also distinguish the three forms and even anti neutrinos when they enter

The Faser team detected neutrinos during the Large Hadron collision experiment for the first time(4)

research diagram – 5: charged hadrons/ μ David Casper, co-author of the BDT input variable

study on the interaction between nucleons, said: “the new detector is quite powerful and is located in the golden position of the European Center for Nuclear Research (CERN). We hope to carry out experiments in the next operation of LHC (opened in 2022)

if all goes well, fasernu is expected to record more than 10000 neutrino interactions – which also means detecting the most energetic neutrinos from man-made sources

The Faser team detected neutrinos during the Large Hadron collision experiment for the first time(5)

research diagram – 5: neutral vertex BDT output observation, fitting data, expected signal / background distribution (stacking)