I apologize in advance for the second post involving neutrinos in as many weeks, but seeing as how they’re part of the mystery of the fundamental workings of the universe and directly tied to the types of research my day job conducts, I happen to know a lot about them. Probably more than the average person should. But then again, I’m not your average Cardinal/Vandal/Spartan/Hoosier/Buckeye.
Today’s fascinating neutrino discovery comes from the project dubbed MiniBooNE, short for the Mini Booster Neutrino Experiment. It’s a collaboration among some 60 researchers at several institutions, including the University of Michigan and Indiana University.
The project consists of 800 million tons of mineral oil in a light-tight sphere surrounded by 1280 photomultiplier tubes buried 20 feet under ground at the Fermi National Accelerator Laboratory, or Fermilab for short. The particle accelerator creates a beam of neutrinos and shoots it at the detector. When a neutrino interacts with the mineral oil, it creates a flash of light, which is picked up by the light sensitive tubes encompassing the sphere.
To understand why the hell they went to these extreme measures, you have to know a bit about neutrinos. They come in three different “flavors” or types, called electron, muon and tau. They’re created by astronomical phenomena like supernovae and neutron stars, as well as through the radioactive decay of atoms and particles. Because they are so small and barely ever interact with the physical world, we don’t notice that there are billions of them passing through us every single second of every single day.
As they make their long voyage through space not touching a single thing, they actually switch back and forth between the three types spontaneously. How many of each kind there are, how often they switch and how many types are all explained quite nicely mathematically in the Standard Model, our current best guess as to how the universe works at the most fundamental levels. I mean, come on, it has the word standard in its title.
However, 20 years ago, an experiment at Los Alamos National Laboratory called the Liquid Scintillator Neutrino Detector (LSND) detected something strange. After years of studying the number of oscillations between anti-neutrinos – the physical counterparts to the regular kind – it seemed as though there were more oscillations than there should be.
Now, science never counts on just one result. In order to be accepted, it must be verified. Thus, Fermilab set to work creating an experiment that could either confirm or deny these mysterious results. Several years ago, the first results came in and contradicted those from LSND. However, that project used a beam of neutrinos. Now, after switching to a beam of anti-neutrinos like the original experiment, the results appear to have been confirmed.
The results appear in a paper is “Event Excess in the MiniBooNE Search for ν̅ μ→ν̅ e Oscillations,” recently published in Physical Review Letters.
This is huge because it means there is new science out there that we have yet to uncover or understand. For years, it seemed as though the Standard Model was pretty well set, and it was just a matter of time before we were able to reveal all of the missing pieces that were predicted to be there, but had yet to be found. Results like these are the first steps towards debunking the most accepted form of how the universe works. Next thing you know, people may be hanging their hats on string theory or something else even more outrageous.
Or, there may just be a fourth type of neutrino that interacts with the physical world even less than it’s three cousins. That could work too.