Astronomers propose building a neutrino detector out of the Pacific Ocean

Neutrinos are one of the vital elusive particles within the cosmos, second solely to ultra-mysterious dark matter. They’re made in appreciable amount — they take part within the weak nuclear force they usually’re answerable for nuclear fusion and decay. So any time one thing nuclear is going on, neutrinos are concerned.

For instance, the solar’s core is a big nuclear fusion response, so naturally, it is producing fairly just a few neutrinos. If you happen to maintain your thumb as much as the sun, roughly 60 billion neutrinos will move via your thumbnail each second, according to past studies.

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However neutrinos work together so not often with matter that regardless of the trillions upon trillions of them passing via your physique each second, in your total life, the full variety of neutrinos that can truly hit your physique is about … one.

Neutrinos are so ghostly and effervescent that, for many years, physicists assumed that these particles have been fully massless, touring via the universe on the speed of light. However after mountains of proof started to pile up, scientists found that neutrinos do have a tiny quantity of mass.

Precisely how a lot mass is a matter of lively scientific analysis. There are three sorts of neutrinos: the electron neutrino, the muon neutrino and the tau neutrino. Every of those “flavors” participates in several sorts of nuclear reactions, and frustratingly, all three neutrino varieties have the odd capacity to alter from one identification to a different as they journey. So, even when you do handle to see a neutrino and decide its kind, you solely know a fraction of what you want you knew.

Whispers in water

The mass of neutrinos has no rationalization within the Standard Model of particle physics, our present and greatest principle of basic interactions. So physicists would actually like to do two issues: measure the plenty of the three neutrino flavors and perceive the place these plenty come from. Which means they need to do plenty of experiments. 

Most neutrino detectors are fairly simple: You both arrange a tool to generate a ridiculous variety of the buggers in a laboratory, otherwise you construct a huge array to seize some that originate off Earth.

These experiments have made numerous progress and gotten greater with each technology. The Kamiokande experiment in Japan, for instance, famously detected the neutrinos coming from the supernova 1987A. However they wanted a vat of greater than 50,000 tons of water to do it.

Lately, the IceCube Neutrino Observatory in Antarctica has upped the ante. That observatory consists of a stable cubic kilometer (0.24 cubic mile) of ice on the South Pole, with dozens of Eiffel-Tower-sized strands of receivers sunk a kilometer (0.6 mile) into the floor. After a decade of labor, IceCube has discovered some of the most energetic neutrinos ever and made tentative steps towards discovering their origins. (Trace: It includes actually high-energy processes within the universe, like blazars.)

Why do each Kamiokande and IceCube use a lot water? A big chunk of just about something can function a neutrino detector, however pure water is right. When one of many trillions of passing neutrinos occurs to strike a random water molecule, it offers off a short flash of sunshine. The observatories comprise tons of of photoreceptors, and the purity of the water permits these detectors to pinpoint the course, angle and depth of the flash very precisely. (If the water had impurities, then it could be troublesome to reconstruct the place the flash got here from throughout the quantity.)

From there, they’ll reconstruct the unique course of the incoming neutrino and get a deal with on its power.

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The good Pacific neutrino patch

That is all nicely and good for regular, on a regular basis neutrinos. However essentially the most energetic neutrinos are terribly uncommon. These extraordinarily uncommon neutrinos are additionally essentially the most thrilling and attention-grabbing, nevertheless, as a result of they are often brought about solely by essentially the most gargantuanly {powerful} occasions in the universe.

Sadly, all the would possibly of IceCube, after a decade of remark, has been capable of seize a mere handful of those ultra-powerful neutrinos.

So we’re gonna want an even bigger boat … I imply, detector.

That is the thought behind the Pacific Ocean Neutrino Experiment (P-ONE), a brand new proposal described in a paper printed to the preprint server arXiv in November:  to show an enormous swath of the Pacific Ocean into nature’s personal neutrino detector.

As soon as once more, the idea is surprisingly easy: Discover a appropriate, lonely a part of the Pacific. Fairly simple. Assemble lengthy strands of photodetectors — and I imply lengthy, at the very least a kilometer lengthy. Sink these strands to the underside of the ocean, ideally to a depth of over a mile (2 km). Connect floats to them so that they stand upright within the water, like big mechanical kelp.

The P-ONE design presently includes seven 10-string clusters, with every string internet hosting 20 optical parts. That”s a grand complete of 1,400 photodetectors floating round an space of the Pacific a number of miles throughout, offering rather more protection than IceCube.

As soon as it is  up and working, you simply want to attend. Even neutrinos will strike some ocean water and provides off a bit flash, and the detectors will hint it.

After all, it is more durable than it sounds. The strands might be transferring consistently, waving backwards and forwards with the ocean itself. And the Pacific Ocean is … lower than pure, with salt and plankton and all method of fish excrement floating round. That may change the conduct of sunshine between the strands, making exact measurement troublesome.

Which means the experiment would require fixed calibration to regulate for all these variables and reliably hint neutrinos. The group behind P-ONE is on the case, nevertheless, and already has plans to construct a smaller, two-strand demo as a proof of idea.

After which, we will go neutrino searching.

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Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of “Ask a Spaceman” and “Space Radio,” and writer of “How to Die in Space.” Sutter contributed this text to Space.com’s Expert Voices: Op-Ed & Insights.

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