Neutrino Detector - Sciencenerds

My hardcore science fans probably know about Super-Kamio Kande, or Super-K, as their friends call it. The 15-story high water tank buried 1,000 meters below a mountain in Japan has been instrumental in detecting and studying neutrinos, reshaping the standard model of particle physics while doing so. Now the Japanese government has approved Hyper-Kamiokande that it will be, he guessed, even bigger. So large that you can rewrite the standard model once again. Before arriving at the event of a change in particle physics that Hyper-K could detect in theory, let's first talk about what it is designed to detect. Hyper-K, like Super-K before, will look for neutrinos.

surface view of Neutrino detector

Neutrinos are incredibly elusive and difficult to detect because they rarely interact with anything. Billions and billions of ultralight and uncharged particles pass through us at almost the speed of light every second, and honestly, I've never noticed. But here is the beauty of the word "almost." Neutrinos almost never interact with another matter, which is another way of saying that sometimes they do! So, if you can get a lot of stuff and just look at it for a while, and I mean it, you should eventually see the telltale sign of a neutrino interaction. The revealing sign in question is something known as Cherenkov radiation. Cherenkov radiation occurs when a charged particle travels faster than the speed of light through a dielectric medium such as water. Think of it almost like a sonic boom, but instead of a conical air shock wave, the charged particle in motion generates a cone of blue light. If I paid close attention, he noticed that I said that Cherenkov's radiation is generated by charged particles, but neutrinos have no charge. However, neutrinos come in three types or "flavours"; electron, muon and tau.

On the rare occasion when a neutrino interacts with water, it will become one of these other subatomic particles based on its taste. The electrons, muons and tau particles charge and will briefly emit a Cherenkov light cone until they slow down below the speed of light in water. The end result that the sensors can detect is a faint flash of a blue ring of light. Super-K uses 50,000 metric tons of ultrapure water observed by 11,000 golden bulbs called Photo Multiplier Tubes that take that dim light and convert it into electric current. Thanks to its large size and sensitivity, it can detect neutrinos from the sun, our atmosphere or even from a particle accelerator on the other side of Honshu that shoots neutrinos from hundreds of kilometres away. 

In 1998, just two years after it started working, he observed that neutrinos oscillate, which means that they change between their three flavours while travelling. This discovery altered the standard model and earned a Japanese researcher the Nobel Prize. Super-K has accomplished a lot, so what could an even larger detector with more than five times the water and four times the photocopying tube achieve? How about explaining why things are here? Scientists believe that Hyper-K will be able to make more precise measurements that will reveal the different speeds of neutrinos and their antimatter counterparts, antineutrinos, run through their three flavours.

This difference could be the key to explaining why more matter was created than antimatter when the universe began, instead of being done in equal parts that were completely annihilated. And if physicists are very, very, very lucky, Hyper-K will observe the decomposition of a proton. At this time, the standard model says that it is impossible, but if Hyper-Kamiokande observes a decay of protons, then our understanding of the entire universe changes. It would mean that three of the four fundamental forces come from a single fundamental force when time began. It would be the final missing piece in the puzzle of the great unified theories that otherwise seem to fit so perfectly. Hyper-K should be able to see a proton decay if its half-life is 10 ^ 34 years. That's a 1 with 34 zeros later. Hopefully, it does, because if the ultra-huge hyper-K does not detect it, that means that the average life of a proton must be at least 10 times longer. But we are getting ahead, Hyper-Kisn has not yet been built.

Let them really build it, then lift a chair and look at 260,000 metric tons of water. Or as I call it, Tuesday. Fun fact: while Super-K used ultra-pure water for decades, in 2019, researchers added gadolinium to make it more sensitive to antineutrinos. To test water filtration with the new element, the scientists made two test benches with the acronym EGADS and GADZOOKS. because scientists can't resist cheesy acronyms.

~sciencefreak