Does this image look familiar?
You may know it as an album cover for the famous post-punk band ‘The Strokes’, but
I’ve got a surprise for you.
It’s really a picture of charged subatomic particles inside a giant bubble chamber.
Yeah, you heard me right.
This artistic, iconic image is a visualization generated by one of the many interesting ways
we’ve tried to ‘see’ the subatomic particles in our world...which is harder than it sounds.
And that’s because subatomic particles can be...tricky.
Take neutrinos, for example.
They’re a fundamental particle of the universe, and they are quite literally everywhere around
us, all the time--you have neutrinos passing through you right now!
But the catch is they have no charge and a miniscule mass--some even say no mass at all.
This means they interact so little with the matter around them, we don’t notice them
zinging through the earth and our bodies at nearly the speed of light all day long.
And that’s also what makes them so hard to find, measure and understand!
How do you look at a thing that doesn’t interact with anything?
‘Very creatively’ is the answer.
Which brings us back to this album cover.
Like I mentioned, this dreamy image was generated by the equally dreamy-sounding bubble chamber.
The Gargamelle, for example, was a bubble chamber used at CERN in the 70’s, consisting
of a muon-neutrino beam and nearly 12 cubic meters of heavy-liquid freon.
Using Gargamelle, researchers could observe the charged particles set in motion by the
neutrinos...kind of like seeing the ‘shadow’ of the neutrino.
This is the reason the neutrino is sometimes referred to as the ghost particle--you can’t
see the neutrino itself, but you can see them knocking stuff around if you arrange things
properly.
Not only did this instrument help us ‘see’ neutrinos, but also provided crucial early
evidence that quarks exist, . And even though it was short-lived due to some cracks in its
structure, this particular bubble chamber played a pretty important role on the road
to our current understanding of particle physics.
That image is an actual picture of the real interaction.
It’s not a visualization generated abstractly from some other data, it’s the real picture
of the real thing in real time.
Since then we’ve moved on to some more sophisticated methods of neutrino detection, which you can
learn more about here.
But what about some more of the ones that just look cool?
Like liquid argon time projections, for example!
Remember how Gargamelle used heavy-liquid freon?
Well, after that we moved on to argon, which can be kept in its liquid phase more easily
than the rest of the noble gases.
In a liquid argon time projection chamber (TPCs), one charged particle produces 55,000
electrons with every centimeter it travels.
The way the electric and magnetic fields in a TPC are set up allows the electrons to travel
uniformly through the argon, and there are tons of them.
Both of these things mean that TPCs give really clean, crisp high-resolution details of neutrino
interactions and they’re able to capture lots of them simultaneously.
And last but not least, my favorite: Cherenkov radiation.
Which just looks like something out of a movie, honestly.
Nothing travels faster than the speed of light, right?
Well, that’s only true in a vacuum.
Here on earth, light actually travels a bit slower than its peak speed through transparent
media like water, for example.
When other subatomic particles, like electrons given off as radiation from a nuclear reactor,
travel through water faster than light does...it produces this radically cool blue glow.
Some of the neutrino observatories we use today incorporate what we call water Cherenkov
detectors.
Like the Sudbury Neutrino Observatory, a neutrino detection facility that happens to also be
the deepest clean room in the world at 2 kilometers below the earth’s surface!
In this detector, a neutrino passing through a special water tank sets a muon or an electron
in motion, producing Cherenkov radiation.
Scientists can see and reconstruct the moment that light begins, therefore essentially ‘seeing’
the moment the neutrino hit that muon or electron.
Sometimes science imitates art, I guess.
Which one is
your favorite?
Fun fact, that Strokes album is called ‘Is This It’, which kinda melds perfectly with
the whole concept behind the cover.
I can picture scientists standing around looking at each other asking themselves…’is this
it?
Is this the neutrino?’.
To keep up with all the developments on the quantum level, subscribe to Seeker, and check
out this video on quantum computing.
Thanks for watching.