The switch to a Linux based operating system is not as complicated and daunting as one may think. Over the years this process has been streamlined. The amount of technical knowledge that you need to have has also been lessened by critical pieces of automa...
However, we want to study them. One of the most important questions about them has been whether they have any mass at all of their own, or whether (like photons) they have no mass at all, and can only travel at the speed of light. This is important because massive particles turn out to be different from massless ones in some fairly fundamental ways, and the existence of extra massive particles -- even ones with tiny masses -- would affect our understanding of things like particle physics and the early universe.
It turns out that we can find out about these masses in a clever way. There are three kinds of neutrino, named the electron, muon, and tau neutrinos. Ordinary fusion reactions (like the ones in the Sun) only produce electron neutrinos, and they produce them in a very predictable fashion: two neutrinos per atom fusing. So if we had a way to measure how many neutrinos we were seeing on Earth, and compare it to how much light the Sun emits, we could measure if any are "missing."
Why missing? Because it turns out that electron neutrinos can turn into muon or tau neutrinos, only if they are massive. (This is one of the ways that massive and massless particles are different) The Sun only produces electron neutrinos; our detectors can only detect electron neutrinos. If we measured any difference, we would know for certain that neutrinos had mass.
But how do you measure neutrinos, if they see entire planets as being transparent? The answer is that "transparent" means that the odds of a neutrino being stopped by any particular piece of matter are very, very, small. So what you need is a whole lot of matter, and a whole lot of neutrinos, and being able to count every single time one of them hits.
How do you do that? You build a giant tank and fill it with a solution that contains atoms that are capable of catching a neutrino in a predictable way. On those extremely rare occasions that this happens, an electron gets shot off at very high speed, and as the electron tries to move through the solution, it creates a flash of light. (Technically: this is Cerenkov Radiation, the light produced when something tries to fly faster than the speed of light in a medium. Cerenkov radiation is to light what a sonic boom is to sound.)
You isolate this tank from absolutely anything else that could get into it -- which includes things like burying it in an old mineshaft, and purifying the solution so that there aren't any stray radioisotopes or anything into it.
You surround the tank with a lot of very sensitive light detectors.
You realize that you can't prevent everything that isn't a neutrino from getting in, so you figure out how to identify those other things by their distinctive light patterns.
And then you wait. The Sun fires about 2 million neutrinos through every square centimeter of your head every second; each will successfully strike an atom perhaps one time in 10^28. (Which means that one will actually interact with your body once in the lifetime of the universe or so)
How big a tank is "big enough?" The Super-Kamiokande detector, 1km under Japan, has a tank holding 50,000 tons of ultra-pure water, surrounded by over 11,000 photomultiplier tubes. The picture below shows the tank mostly drained for maintenance; that thing at the back is two people in a raft.
And over nearly two decades of work, the SuperK team managed to measure the Sun's neutrino flux, accurately enough and in enough different ways, to confirm a result that most physicists didn't expect: neutrinos indeed have mass. We still haven't been able to measure the mass -- we know that it's at least 40meV and at most about 200meV. (An eV is a unit of energy; it's roughly the energy that holds an electron into an atom. The mass of an electron is about 511keV, or about half a million eV; a proton, just under a billion eV. The neutrino mass is well under one eV)
So through building a tremendous tank of the purest water in the world, we have managed to see the faintest ghosts in all of nature.
Congratulations to Takaaki Kajita and Arthur B. McDonald, and to all of the hundreds of people who have worked on this problem in the past decades, for a well-deserved 2015 Nobel Prize in Physics.
- cyber consultant groupsoftware consultant, 2011 - present
- Green TechnologiesSoftware Consultant, 2006 - present
- Airshock Radio llc.System Administrator, 2011 - 2012
- Colorado University (*Denver)2005
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