Got off the train after 9 hours, hundreds of kilometers away from where I started
Geneva is bustling, full of people playing out their life stories and buildings that are taller than I’ve gotten used to.
It’s technically the summer, but I haven’t felt the faintest touch of vacation,
and I find myself wondering how I end up here about 6 times every year.
I’m up to my neck in deadlines – got a paper to write, a project to plan, and a social backlog longer than Santa’s shopping list
and all I want to do is have a day – no, a week to myself
of doing absolutely nothing in my apartment
I’m really getting better at turning down projects, but I haven’t quite mastered the art of saying “no.”
and the squirrels, so alive in my head, have so much to say as I walk through the streets of this quaint but busy city
But I am not John Green, and this is not a Thoughts from Places video.
And all of those things are not important right now
because today, and for the rest of the week, I’ll be showing you a different side of Geneva
the wonderful world of particle physics and science in action.
Okay! So! Today we're at CERN and we're doing summer school
And our mission is to film a video using this 360 degree camera
So hopefully I'll have that on the channel for you later but, uh, let's see how it goes!
Exhibit narrator: Scientists from more than 100 nations are working at CERN, on the large hadron collider
the most powerful tool to study the first moments of the universe
The LHC is a circular machine of 27 km in circumference
That accelerates beams of protons to more than 99.99% of the speed of light
This is a map of the large hadron collider, where there are a total of 7 experiments.
We didn’t have a chance to cover all 7, so in this video, we’ll only look at ATLAS and LHCb.
We’ll take a peek at SM-18, where they test the magnets for the LHC
and ISOLDE, the radioactive ion beam facility
Unfortunately, we were unable to go down and see it ourselves because the experiment was running at the time
so I’m using footage from someone else’s video (link in the description)
ATLAS is a detector at the central point of the LHC
and it measures the collisions of bunches of particles that are accelerated to nearly the speed of light
When the particles collide, new particles are formed, and the subsystems of the ATLAS detector record their characteristics.
As you can imagine, when bunches of particles are thrown at each other,
they will collide and bounce off each other at different angles
The inner detector is designed to measure the paths of these collisions as accurately as possible
producing an image like this
The calorimeters, on the other hand, measure the energy of the particles
Their job is to stop the particles and measure the radiation that results from this stopping process
And further out than that, you have the resistive plate chambers and monitored drift tubes
which detect muons, particles similar to the electron, but much heavier
In looking at a select set of data from these collisions, researchers are able to simulate conditions that are very similar to that of the Big Bang
and can come closer to explaining the origin of our universe
exploring questions such as why our universe seems to be made of only matter,
what matter is made up of, and to what extent the standard model is correct
Next, we went to SM 18, CERN’s magnet testing facility
Magnets are used in the LHC to keep the particles on a particular trajectory
So, you are not only injecting the particle and then accelerating
But, as I said in the very beginning,
if you do not do any action on the particles, on the packets,
the packets [will go] straight forward
so you need to bend the trajectory
äh, the accelerator is a sort of Lega
and each piece has its own job to do
Now, the total number of pieces in the LHC is about 9000 (if only she had said "over"!)
To be honest, I was pretty tired and hungry at this point,
so I wandered around while the rest of the group listened to an explanation about the many sub-parts that make up the LHC
The next day, we went to the LHCb experiment
a collection of sub-detectors that looks at the subtle differences between
matter and anti-matter by looking at the forward beam of particles
The reason we're looking forwards is because we are looking at light objects
Light in terms of the energy of the large hadron collider
And the lighter an object is, the more likely it is to be created in collision along the direction of the beam
and the reason for that is simple kinematics
If you have two protons colliding, they can collide head on
and then you have the full kinematic energy available to create particles, to transform this energy into mass
But what is more likely to happen is that they are slightly offset
And then you get a kind of...inelastic collision, but there's always a refraction
and you have less energy available
But this less energy is still enough to create these particles
This is more likely to happen, but in this case,
you still have some remnant of the proton going forward
and they carry the particles with them
And that's why they tend to stay close to the beam
And if we want to catch them, it's best to just cover the forward region around the proton
More specifically – and I’m only going to give you the gist of it,
the LHCb experiment looks at CP violation
The C stands for charge conjugation, which is changing a particle into its anti-particle
So if we had an electron, say, it would turn into a positron, it’s antiparticle.
The P stands for parity transformation, which means a flipping of the sign of a particle’s spatial co-ordinates
So if our friend, the electron had an up spin to begin with, it would turn into an electron with a down spin
Putting C and P together, our down spin electron would come out an up spin positron
So if CP symmetry were perfect, equal amounts of matter and anti-matter
would have been created during the Big Bang, and our universe would be made out of nothing
But evidently, our universe is made entirely of matter, and this experiment aims to find out why
We're not looking for new particles that are not known in the standard model
We are tying to, we are studying particles that are well-known
But we are trying to find differences between theoretical predictions and experiments
As a side note, look at how cool it is that CP violation is built into the logo of this experiment!
And finally, we visited ISOLDE which stands for Isotope Separator On Line Detector
At this facility, nuclei are ionized, extracted, and separated into low energy beams
which are then delivered to several experiments
These experiments have applications in astrophysics, medicine, fundamental particle physics, and many other fields
We started out in the control room
At the moment we're not taking anything, but you can see "neutron time of flight"
Iso GPS, this is us,LHC might be there somewhere
Some machine development and the new beams they're testing for the LHC
and actually, the LCH takes very few protons
ISOLDE takes about 63% of CERN's protons
which is partly why we are here
because the source of protons is just across the road
Professor: Why do you need so many protons?
Uh because we keep hitting a target. So, we have a target that produces our beams
And basically, the more beam we hit onto the target, the more beam we get out the other side
This is just setting the position of the protons
the intensity of the protons, the energy of the protons
the mass that we're looking at at the moment
and then headed down into the experiment hall too look at the experimental setups
So here we are, kind of close to the source of beams
Behind all this concrete here, we have the electromagnets which separate the beam
And just behind that, we have a, I'll show you if we get a chance to go upstairs (we didn't!)
a target - so the protons are really about 25m in this direction, injected underneath the road for ISOLDE
And then here we start at the lowest energy that we can provide, so 30 kV, 60 kV
This is what we use for solid state physics, medical physics, things like this
and then other dedicated experiments all the way around
So this is the first experiment. You can see under all of these detectors, we have a football-sized space
And basically, inside this, they have a connected target
and basically what we do is collide a beam
[This is] a kind of general chamber where people put the detector that they want to use
then they can remove it and go home
Electronics have just been stood at the back in these cases
So this is a decay station - it's very, you might say, classical nuclear physics
But basically, inside this box, they have a kind of video tape
just going through the system
it passes here and there's a needle just in front of this point here
and then we collect on the tape, measuring properties
And here we have similar detectors to what we saw on the other setup
so basically 4 different (expensive!) germanium crystals
very, very pure; very, very expensive
We ended our tour by checking for our exposure to radiation, and luckily, we all got out uncontaminated
And that's pretty much it!
I hope you enjoys seeing a slice of what my summer school experience was like
even though I'm about 3 months late uploading this video...
In other news...I live in Japan now! so you'll be hearing about that in my future videos
And as always, thanks for watching!
[French] If you enjoyed this video, please give me a thumbs up and subscribe to my channel. Bye!
