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old, it's already out of date.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
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But they have a lot of products.
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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.
So if you liked this, let
me know here in the comments
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