Ten facts about neutrinos

Friday again - facts again <3

You know the drill, say no more:

1. a neutrino is a en elementary particle
2. a neutrino is not a neutron - neutrons are made up of quarks, and are thus not elementary particles
3. there are three types of neutrinos: they're called electron neutrino, muon neutrino, and tau neutrino (they all also have an antiparticle)
4. the name neutrino actually means "little neutron", but I have to tell that story another time...;) (In short: Pauli proposed that there should be a particle called a neutron, before the actual neutron was discovered. Then, what we know today as a neutron was discovered before the neutrino, and by that time the term neutron was taken, and this particle became a neutrino).
5. neutrinos don't have any electric charge (so they are not at all affected by the electromagnetic force), and they're almost massless - but only almost...! They do have a tiny tiny tiny mass: the heaviest one is more than 4 million times lighter than the electron (the next lightest particle). Since they are so light, neutrinos move at a speed more than 80% of the speed of light at room temperature
6. neutrinos are created in radioactive decay (like beta-decay), nuclear reactions (like in a reactor when a heavy nucleus fission, or in the sun when light nuclei fuse), when cosmic rays hit atoms, and in supernovae. Most of the neutrinos here on Earth come from the nuclear reactions that take place in the Sun <3
7. every second, a trillion trillion neutrinos pass through your body, and since they do have (a tiiiiiny) mass, this means that there's a constant flow of matter through your body ALL THE TIME. Since their mass is so small, they don't add up to much mass - about 0.0000000000001 kg of neutrinos will pass through your body in a lifetime :D (If you add up the mass of all neutrinos that have passed through every single person who ever lived, over everyone's total lifetime, the sum is 0.15 kg)
8. neutrinos are extremely difficult to detect, so you need really huge detectors if you want to try... For example, the OPERA detector (a good neutrino detector) consists of 1000 tonnes of mass to try to catch a neutrino, but even if this detector was a block of lead a light-year in length, you'd only have a 50% chance of stopping a neutrino!
9. they are often called ghost particles, since they can actually change from being one kind to being another - an electron neutrino changing into being a muon neutrino changing into being a tau neutrino (this is weird: like if you went into a Mercedes and drove for a while, and then suddenly the car changed into being a BMW, and then when you arrived at your destination you were driving and Audi. W. E. I. R. D.)
10. in 2011 neutrinos were sort of detected to move faster than light - which shouldn't be possible. Of course it turned out to be an experimental mistake, and we are still very very certain that Einstein's theory of special relativity is true <3

Bonus facts: According to my colleague, Cecilie, neutrinos fabulous :D Happy Friday!