Previously on Uno Dos of Trace.
There's really, really big questions
that the standard model does not answer.
We will increase five times the rate of collisions and 10 times
the recorded data.
Increasing the amount of data we're getting per second,
it taxes everything.
So you guys are like, here's some more beam.
And then they're like, oh, my god,
what are we gonna do with all this data?
That is exactly what's going on.
And so we're driven to try to find what's wrong.
It's a potential window to new physics, but we don't know.
We don't know so we have to measure it
as precisely as possible.
And for that, you need lots and lots and lots of data.
[THEME MUSIC]
The Large Hadron Collider is shut down
for upgrades and repairs.
During this LS2, or Long Shutdown 2,
the engineers, experts, postdocs, physicists,
and staff of CERN are busy building the High-Luminosity
LHC.
The HL-LHC is going to crank the LHC up to 11.
Five times more particle collisions, 10 times more data
about the subatomic particles that make up our universe,
10 times more fun.
But if they make all these collisions
and they don't have a way to capture that data,
then it's kind of a big fail.
So in part two of this mini-series
about the long shutdown, I got the chance
to dig into one of these major projects
to get an idea of just how much goes into detecting
one little particle.
This is the new small wheel.
The small wheel is the center of a five-story machine
called ATLAS, one of the detectors
that helped discover the Higgs boson back in 2012.
ATLAS is 45 meters long, 35 meters tall,
and weighs as much as the Eiffel Tower.
It sits in a cavern 100 meters below the border
of France and Switzerland.
This behemoth is engineered with micro precision
to detect fragments of the smallest bits of our universe.
And the small wheel sits right at the center of it.
But really, when you break it down
ATLAS is an overlapping set of smaller detectors
for fragments of atoms that are smashed together at the center.
And though it's only 11 years old, it's already out of date.
Small wheel needs to be replaced to cope
with the massive increase in collisions and data expected
out of the High-Luminosity LHC once it's been upgraded.
Like Queen Beyonce sang, "Partner, let me upgrade."
[MUSIC - BEYONCE, "UPGRADE U"]
Partner, let me upgrade you.
Upgrading a 10-meter section of a detector
so it can do its job 10 times better using only the space
left behind by the old detector-- that takes
a lot of design, which means going
to the office of Mechanical Engineer Konstantinos
Iakovidis.
Here you can see that around the small wheel,
there are other detectors that should be installed.
Yeah.
You see, and with this way, what we do,
we identify what is the envelope that we
have available for design something or install something.
So this is the envelope, right?
So we have to fit everything inside this space.
Yeah.
So this space is defined by the people working here,
the design office, and they give us the available space
that we have to install our things.
Things actually covers a lot here.
This big blue circle is just the skeleton
of the new small wheel.
Within this skeleton has to go power cables and boxes,
networking cables, cameras for alignment,
wires for detectors, not to mention the actual detectors
themselves.
It's a lot.
It's a very, very precise job.
The very delicate work is the electronics.
So we have also to install in certain places
and to the allowed space because all the allowed space
that we have comes from the other equipment that already
exists in the ATLAS detector.
This is one of the most exciting thing working for--
you have to apply everything from the computer
to the reality.
So to transfer everything and all the precision
because this was done by the engineers.
Konst likes the word "precision" because they can't be off,
even by a little bit.
Remember, this is supposed to detect the broken bits
of atoms, and they cannot miss even one particle.
There is nothing that can pass from inside there
without being detected.
So everything is with a precision of 100 microns.
So it's very, very complicated because we
have plenty of services, plenty of cables,
plenty of other detectors around the small wheel
that everything should close in such a way
that the particles does not pass from an empty space.
And we speak about particles, so it's very, very tiny.
100 microns.
That's like the thickness of a sheet of paper.
That's how precise they have to be for something this big.
And did I mention there are actually two of these?
But these skeletons still need to be filled
with the actual detectors.
The most common are called sTGC detectors for small strip
thin gap chambers.
But the new small wheel also has a new kind of detector
called micromegas detectors.
And like a lot of the stuff that I saw at CERN,
they were hand-built. Yeah, from scratch.
Micromegas is an acronym for micro mesh gaseous structure.
And this is Paolo Iengo.
He's the CERN physicist in charge of the new small wheel
micromegas.
Essentially, this is a gas detector.
So it is based on having a gas inside a gap that
is ionized as soon as charged particle traverse the gas.
It has two main components, always
defined by what happen in the gas.
From few electrons, you end up with the 10,000 more electrons
at the end.
And those 10,000 electrons give us
an electrical signal that is large enough to be detected.
Paolo is really smart, and this gets really complicated
really fast.
But I'll try and simplify it as much as I can.
It seems to me that there are charged layers of material that
can track and detect a particle, specifically a muon,
as they fly by.
If you want more detail than that, here we go.
Pretty much all fragments and particles are charged,
and since physicists know that, they design detectors
to take advantage of it.
In this case, the micromegas detector
is flooded with gas when it's running.
When a particle flies through, it
ionizes the gas, giving it a charge,
and that releases just a few electrons.
Not enough to detect though because the system
itself is using electricity.
You have to get above that signal to noise ratio.
So these few electrons have to be amplified.
The holes in the steel mesh are so
small that they let the electrons through,
and on the other side of these tiny pillars about
120 microns tall.
The pillars are electrified, so when those few extra electrons
show up from the ionized gas, "whee-zzhh-oo,"
the electrical field multiplies and they know right where
the particle was.
"Whee-zzhh-oo."
Technical term, by the way.
With this detector, we can detect particles
with an efficiency, which is close 100%.
And we can even track particles, which
means we can measure the impact point of the particle
with the precision which is of the order of 100 microns.
And this whole system is inside the center
of ATLAS, which also has giant toroid magnets surrounding
the whole system.
And they're so strong, they pull on those charged particles
causing them to bend, which is how
they make those beautiful pictures that you
see in the news.
The way we have to measure the energy of the particle
is not to measure how much energy it
lose during the trajectory but actually all
the muon spectrometer.
So this huge system of ATLAS is in a magnetic field.
And the particles are charged, so muons are charged.
And so they are bent by traveling
into a magnetic field.
So essentially what we measure is the bending of the particle.
And measuring the bending, we can
measure what we call the traverse momentum, which
is essentially the energy.
OK, so we got a lot of stuff going on.
Let's just take a sec and let that sink in.
(SIGHS) Not only are these detectors
engineered to the electron scale and then hand-built,
but also, the detectors are the largest micromegas
systems ever constructed.
Before this, the largest micromegas
was about the size of three dominoes medium pizzas.
And this one is going to be 1,200 square meters, almost as
large as a hockey rink.
If I think about the small detector prototypes
we were working with 10 years ago--
I'm talking about things like 10-by-10-centimeter squares.
Really, really small.
Now that we are really building, and it became a reality
to build such a huge detector based
on this type of technology-- this is really amazing.
Once they're assembled, the panels
will be installed into the new small wheel sections
along with the sTGC detectors.
Then the whole apparatus can be moved onto a truck,
into a shaft, above ATLAS and lowered into place
100 meters underground, which is where I got to go next.
I was so excited.
Here you see the detector.
It has several layers.
It looks like an onion.
Several layers and each layer has a very specific task
in the detection of the particles.
That's Rachel Maria Avramidou, detector physicist at CERN.
Sorry it's loud.
It turns out massive science projects aren't that quiet.
At this level is at the center.
We have two beams in opposite directions
that collide at the center of the detector.
The idea is that the energy is transformed into matter.
We have the production of new particles
which didn't exist before.
OK, you see that?
That's the old small wheel called the muon small wheel,
or muon spectrometer.
You can really see the layers we were talking about here.
For the muon spectrometer, we need different layers
because actually when we have the signal reduced,
we have points inside each cube.
And we need many of them in order
to have a good track reconstruction.
That's why we see several layers.
If all this coordination and construction works out,
there will be no way a subatomic particle could
escape that room undetected.
It will also be operating with 10 times more collisions
than before because remember, that's
why we're doing all this.
Because they're going to make so much more
physics than the High-Luminosity LHC
that the physics that they're going to physics
has to physics better.
That's not the only reason we're upgrading because eventually,
like any machine, it wears out, and they would
have had to update things.
See, ATLAS was completed in 2008 and has since
experienced thousands of billions of atomic collisions
at huge energies.
And parts wear out over time.
I guess one of the examples is we have this instrumentation
that's like a very thin wire.
It's 30 microns of carbon.
It's thinner than a hair, and actually, if you are around it
you could even breathe it.
You don't even see it.
We use this wire to go through the beam,
and then like this, we can measure basically
the transverse structure of it.
Protons are hitting this wire, and we
use it every day of operation for a lot of months
and for years and years.
And then if we bring these wire to an electronic microscope
and we look at it, we can see--
where the beam has been passing, we
see that there's atoms missing.
It's thinning.
Does that not blow your mind?
It's atoms shaving little pieces off
of this actual physical structure.
So cool.
So that is why we need the new small wheel.
It's a better camera to see the muons in this particle
accelerator.
It's just one small piece of a small piece of the small piece
of the giant High-Luminosity LHC upgrade going
on now at your local Terran particle accelerator.
We didn't talk about logistics, the actual design,
the sourcing of materials, conception phase of everything.
Someone had to think this up.
Someone was at a pub somewhere and thought, huh, what if we--
it's out there, and it's amazing.
Technology has improved so we're working
on improving our detectors and preparing for this higher
luminosity, preparing for the idea
that we're going to have many more collisions.
And that changes things.
It's a game changer.
Means that our detectors have to work even faster than before.
And by faster, we're talking about moving
from 40 million collisions per second to even more.
We're able to take a 100 megapixel camera that
can take photographs 40 million times a second
and go to even higher rates and be
able to improve the precision of the images that were taken.
And it's insane when you think about it,
but that's what we do.
And after all that, I bet you just have one really just
burning question, right?
Why is it blue?
Stick around because I asked.
Speaking of sticking around, I don't have this beard
for any specific reason.
It's more like I'm lazy, and beards, they grown on you.
But I do like a good shave.
Plus, you've got to take care of your skin.
Grooming, very important, so I like
to use face lotion and a nice sharp blade
when I do shave up the old neck-a-roo, which is
why I enjoy Dollar Shave Club.
They get it.
Right now, if you want to support Uno Dos of Trace
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I think the black pepper shampoo smells great and the lavender,
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OK, fam, the blue.
What's up with it?
All right, I think--
OK, I think that the color was not chosen
because of something special.
I think because of the old wheel color, which is blue,
we thought we have to continue with exactly the same color
to not be confused where we are in the ATLAS detector
because we have plenty of systems.
So we have to identify with the color.
It's a nice blue.
Yeah, could be lighter.
Or darker.
[LAUGHTER]
I guess.
Thanks for watching the second part of my CERN mini-series.
I do have more footage.
I could make a third part, but I didn't want to overwhelm you.
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