Pony Adventures in Particle Physics: Twilight, Pinkie Pie and Rainbow Dash visit Sudbury, Ontario and shed light on neutrinos · 8:24pm Oct 9th, 2015
“Pinkie?”
“Yes Dashie?”
“Where are we?”
“In the dark.”
“Yes, but where?”
“I don’t know.”
“Twilight?”
Twilight lit up her horn, casting shadows onto the walls of a tunnel.
“We are in—or under—Greater Sudbury, a mining city in Ontario, Canada. Population 160,000. This region produces some ten percent of the world’s nickel. And it is the home of SNOLAB.”
“Snow lab? What is that, some sort of ice cave? But it feels pretty hot here.”
“It’s the site of the Sudbury Neutrino Observatory (SNO), one of the deepest underground laboratories in the world. This was where they solved the solar neutrino problem by showing that neutrinos can flip between different flavors. This year’s Nobel Prize in Physics was awarded to Takaaki Kajita and Arthur B. McDonald this week for this discovery. I thought it would be interesting to see the place where it was done, so I teleported us directly to the laboratory two kilometers underground. But maybe my positioning was a little off…” She looked along the tunnel. “This mine is bigger than I thought.”
“What are neutrinos?”
“They’re super-shy fundamental particles,” said Pinkie Pie in a conspiratorial voice. “And super-light-weight. They weigh less than—well just about everything except light—and light weights nothing at all, and neutrinos do weigh a bit. They’re made in the heart of the sun and in nuclear reactors. Most of them just zip straight through the Earth without even saying hello and we never see them. But if you look very carefully—if you have a great big gianormous megaton particle detector—you can sometimes catch them. The first experiment to see astronomical neutrinos was built in the 1960s using a big tank of cleaning fluid in a South Dakota gold mine. But they only saw a third as many as they should have. That was the start of a super exciting science mystery story!”
“That was the solar neutrino problem,” said Twilight, “which puzzled particle physicists for many years. They wondered if there was something wrong with the experiment.”
“Maybe they used the wrong brand of cleaning fluid,” suggested Pinkie.
“Or were the calculations of the rate of neutrinos from the sun wrong?”
“Or,” continued Pinkie, “were they even shyer than we thought? Maybe some of them were disguising themselves to elude detection. The Super-Kamiokande experiment in Japan saw a sign of what they were up to, and soon the game was up.”
“Super Cameo Candy,” said Rainbow, articulating the words slowly. You’re making these names up.”
“No,” said Twilight. “It was the upgraded model of the Kamioka Neutrino DEtector. Built in the Kamioka mine some 250km north-west of Tokyo.”
“Right…”
“They’re now building an even bigger one: Hyper-Kamiokande.”
“So what did they learn about neutrinos?”
“SuperK could see where the neutrinos were coming from. They looked for neutrinos produced when high energy cosmic rays slam into the top of the atmosphere. As neutrinos pass straight through the Earth, they could see them coming from all directions. But they saw more coming from above—which had just come a short way—than from below—where they had travelled through the whole planet—it seems that as they went through the Earth some of them disappeared! But actually they just put on a disguise! There are three flavors of neutrino: electron neutrinos, muon neutrinos, and tau neutrinos. When they travel long distance, they can flip from one flavor to another. A cleaning fluid detector can only see electron neutrinos. But if you want to do a full count, you gotta catch ‘em all!”
“That was what they did here in Sudbury between 1999 and 2006,” said Twilight. “They built a detector to count the rate of all flavors of neutrinos. And they showed that when you take account for all of them, they got the rate predicted. So there’s nothing wrong with the theory. Or the sun.”
“So if the experiment’s now over, what is there still to see?”
“There are other experiments here. They’re rebuilding the SNO experiment: the next phase is SNO+, which will count the low energy neutrinos and test other theories... If we can find where it is...”
Sheesh, as if neutrinos weren't hard enough to notice, they have to act like Everlasting Gobstoppers.
Hurrah for Sudbury, I was there this summer. Though I was at Science North, not SNOLAB.
'I'd like one neutrino and two banana in a cone please!'
So the question is.... y tho.
Why exactly do they change themselves.
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Because...
Neutrinos are created as flavor eigenstates - i.e. as an electron neutrino, a muon neutrino, or a tau neutrino. Likewise when they are detected, we see them as one of these three flavors - when they interact it will produce an electron, a muon, or a tau depending on the flavor.
But they travel through space as mass eigenstates, labelled 1,2,3. A flavor eigenstate (such as an electron neutrino) is a mixture of the three mass eigenstates (1,2,3), and a mass eigenstate (such as 1) is a mixture of the three flavors (electron,muon,tau).
As the mass eigenstates all have a slightly different mass, they move at different rates, so the 1,2,3 mix you start with changes as it moves and the three components oscillate up and down as the phases progress. After a neutrino has travelled from the sun to the earth, the relative mix of 1,2,3 has changed, so when we detect it, there is a chance we may see it as a different flavor - the probability of seeing an electron, muon, or tau neutrino depends on the relative mix of the three eigenstates.
This is why the fact we see neutrino flavors oscillating means neutrinos must have mass, and we can use this to calculate the difference between the masses of the 1,2,3 eigenstates, but we don't know the absolute mass.
If you ever manage to get hold of the 4 dimentional rotating polytope screen saver, you can do this experiement.
Set rotation in X,Y,Z to zero, and then set rotation in WX, WY, WZ to low, prime relative values.
The shapes will then appear to not only rotate, but change shape constantly.
To me, WX, WY, WZ rotations are the variable parts of the neutrinos values, caused by rotation of a single spin vector particle in 4 spacial dimentions.
It helps that in 5 spaciotemporal Kaluza Klein theory, electric charge is due to motion along the 4th spacial axis. That is, turn a neutrino to an electron? Allow it to move along 4th spacial axis, which apparently prevents it rotation, as has electrons morphing to muons etc been measured or even theorised or shown to be impossible?
The big problem with this is that it would make black holes four spacial dimentional, which would lead to virtual singularities and dyson jet ejection effects. and black holes having no mass, only mass energy of their gravitational field. And no crossable event horizon. And being wormholes. And other horrible things that work just so good, but cant be had because of course we only live in flatland.
As a teacher, you will not like my new BlogPost:
Teenagers do not know that humans walked on Luna.
Warning:
The BlogPost is very depressing.
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It has gotten depressingly in vogue to say we never landed on the moon, despite it being perhaps the one thing that guarantees the USA's place in world history forever.
I think part of it is that the further from the event we get, especially without showing any signs of going back (as far as I know, we have nothing capable of sending humans to the moon at the moment, though I would assume if we really wanted to we could whip up another Saturn V) it gets harder and harder for the current generation of people to believe that we could have accomplished such a thing when our TVs had tiny black and white screens, and computers that took up entire rooms would melt if they tried to play a free phone app.
It's incredibly depressing, but perhaps if we could get people interested in NASA and space exploration again, maybe NASA would get the kind of funding it needs to really push the boundaries again. As is, well...
3456302 No kidding! Neil Armstrong on Luna should NEVER be forgotten! It's just too darned cute!
derpicdn.net/img/view/2012/6/20/12400.jpg
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You got it
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On reading the title of your link, I did wonder what the princess of the night would make of big apes treading on her spine.
Yes, it's depressing when you meet people who neither know nor care about such epic space flight achievements. But I've also met plenty of young people who are really excited about science and technology. Twenty years ago, far fewer people cared about particle physics than today.
Yesterday, I was so upset that I did not address the BlogPost at all. What strikes me about neutrinos is their extremely low rest mass:
We never detected any delay in when light and neutrinos arrive; but strangely however, neutrinos have rest mass. For fitting the observations, the Lawrence-Contraction must be in the millions. ¡The rest mass of neutrinos must be fantastically small!
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She is not a MoonHoaxer. At least MoonHoaxers know we landed on Luna, but are too stupid and crazy to accept it. She never heard about people walking on Luna. ⸘What do we teach children these days‽
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Next time I’m posting a writing prompt, I’m going to use “Luna has a human riding her”.
See if anyone writes something about it being their second time.
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Is it possible to know a neutrino's mass and flavour at the same time? Or are they subject to Heisenberg's uncertainty principle?