An introduction to the CMS Experiment at CERN
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0:01 - 0:04Episode 1:
Why fundamental science is important -
0:04 - 0:06For millennia, we have looked up at the stars
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0:06 - 0:10and wondered about the nature of the Universe
and our place in it. -
0:10 - 0:13How big is the Universe?
How old is it? -
0:13 - 0:15What makes the stars shine?
-
0:19 - 0:23By performing fundamental research
to answer these questions -
0:23 - 0:26scientists have helped advance
our collective knowledge -
0:26 - 0:28bringing benefits to all of humanity.
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0:29 - 0:31But far from extinguishing our curiosity,
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0:32 - 0:34the answers we find lead to new questions.
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0:35 - 0:36What is the nature of gravity?
-
0:36 - 0:39Does the Universe only have
three dimensions of space, -
0:40 - 0:41or are there more to find?
-
0:41 - 0:44Why did all the anti-matter
produced in the Big Bang disappear, -
0:44 - 0:47leaving a Universe made of matter?
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0:47 - 0:48What is the origin of mass?
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0:51 - 0:54Here at CERN, physicists from all over the world
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0:54 - 0:57have come together to answer
some of these challenging questions. -
0:58 - 1:01To further our understanding
of the laws that govern the Universe, -
1:01 - 1:04we smash together particles at high energies
-
1:04 - 1:07and record what happens
with giant particle detectors -
1:07 - 1:11such as the Compact Muon Solenoid
(or CMS) experiment. -
1:11 - 1:13The Large Hadron Collider accelerates protons
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1:13 - 1:15to nearly the velocity of light
-
1:15 - 1:18before colliding them
inside the very heart of CMS. -
1:18 - 1:22The energy of the colliding protons
transforms into matter -
1:22 - 1:24spraying particles in every direction.
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1:24 - 1:27The CMS detector acts as a high-speed camera
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1:27 - 1:30recording collisions 40 million times a second
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1:30 - 1:31for further analysis.
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1:31 - 1:35The LHC is helping us
explore uncharted territory. -
1:38 - 1:43Episode 2:
Conception of LHC/CMS -
1:44 - 1:48The Large Hadron Collider
occupies a 27-kilometre underground ring, -
1:48 - 1:52located around 100 metres below
the Swiss-French border near Geneva. -
1:52 - 1:56It is the most powerful particle accelerator
ever built, -
1:56 - 2:01and is designed to collide protons together
up to 40 million times each second. -
2:01 - 2:04These collisions take place
at four points around the ring. -
2:04 - 2:08At each collision point
sits a large particle detector. -
2:08 - 2:13Each detector is built and operated
by different international collaborations. -
2:13 - 2:17CMS and ATLAS
are the two general-purpose detectors -
2:17 - 2:21designed to observe any signs of new physics
that nature might manifest. -
2:22 - 2:24CMS stands for Compact Muon Solenoid.
-
2:24 - 2:29It gets its name from the fact that,
at 15 metres high and 21 metres long, -
2:29 - 2:33it really is quite compact
for all the detector material it contains. -
2:34 - 2:37And it's designed to detect
particles known as muons very accurately; -
2:38 - 2:41and it has the most powerful
solenoid magnet ever made. -
2:41 - 2:44The detector weighs 14,000 tonnes,
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2:44 - 2:47and has around 75 million individual channels
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2:47 - 2:51for detecting and identifying assorted particles.
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2:51 - 2:55CMS is made of several layers,
like a cylindrical onion: -
2:55 - 2:58The innermost sub-detector is the silicon Tracker,
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2:58 - 3:01which registers the trajectories
of charged particles. -
3:01 - 3:04The next layers are
the Electromagnetic Calorimeter -
3:04 - 3:05and the Hadron Calorimeter
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3:05 - 3:09which collectively measure the energies
of electrons, photons -
3:09 - 3:11and composite particles called hadrons.
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3:12 - 3:14Then comes the solenoid magnet itself
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3:14 - 3:18and finally the muon detectors
that make up the outer layers. -
3:18 - 3:21Data from collision events
that are potentially interesting -
3:21 - 3:23are stored for further analysis,
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3:23 - 3:26and the uninteresting ones are discarded.
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3:26 - 3:32Analysis itself is performed around the globe,
using the Worldwide LHC Computing Grid -
3:32 - 3:35that connects thousands of computers
in many countries -
3:35 - 3:36into a single framework.
-
3:36 - 3:40CMS has published
over 300 scientific papers so far, -
3:41 - 3:47with 64 petabytes of data collected
and analysed until the beginning of 2013. -
3:49 - 3:53Episode 3:
Construction and operation of CMS -
3:55 - 3:59The CMS experimental site is located
in the French commune of Cessy, -
3:59 - 4:02about 10 km away from CERNâs main campus.
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4:02 - 4:08Excavation of the large underground cavern
that houses the CMS detector began in 1999. -
4:08 - 4:13During early digging on site,
the engineers came across something unexpected: -
4:13 - 4:18the ruins of a Roman villa
dating back to 309 and 315 AD -
4:18 - 4:20with broken coins and pottery.
-
4:20 - 4:22The second challenge was expected,
-
4:22 - 4:26the diggers would have to get past
an underground flow of water. -
4:26 - 4:29CERN engineers dealt with this
by freezing the water, -
4:29 - 4:31digging through it and applying concrete,
-
4:31 - 4:34as they prepared the 100-metre-deep shaft.
-
4:34 - 4:38Meanwhile, the CMS detector itself
was being constructed on the surface, -
4:38 - 4:41with parts sent to Cessy from all over the world.
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4:42 - 4:44CMS is designed in slices.
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4:45 - 4:47After construction,
each slice was lowered through the shaft -
4:48 - 4:49into the experimental cavern
-
4:49 - 4:51and then assembled on the floor.
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4:52 - 4:54The heaviest slice, weighing 2000 tonnes
-
4:54 - 4:57took around ten hours to be lowered
in a very delicate operation -
4:58 - 5:02In 2009, CMS recorded
its first collisions between protons, -
5:02 - 5:05and there were celebrations across the globe.
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5:05 - 5:10On 4 July 2012, CMS announced the discovery
of a new particle to the world, -
5:10 - 5:13now confirmed to be a Higgs boson.
-
5:14 - 5:17Physicists continue to search
for many new particles and phenomena -
5:17 - 5:21to resolve the many remaining
unanswered questions. -
5:23 - 5:28Episode 4:
What are the future challenges of CMS? -
5:29 - 5:33Discovering the Higgs boson in 2012
has helped cement our knowledge -
5:33 - 5:37of how fundamental particles
in the entire Universe gain mass. -
5:39 - 5:42This was the first step for the LHC
-
5:42 - 5:44and it will take years to study the properties
-
5:44 - 5:46of this newly discovered particle.
-
5:46 - 5:50The accelerator has been built
with a long-term exploration in mind. -
5:51 - 5:54Our best understanding
of all the particles in the Universe -
5:54 - 5:57and three of the four known forces
that govern them -
5:57 - 6:01is encoded in what is known as
the Standard Model of particle physics. -
6:01 - 6:05However, despite decades of correct prediction
after correct prediction -
6:05 - 6:10physicists know that the Standard Model
does not show us the whole picture. -
6:11 - 6:14Theorists have proposed several extensions
to the Standard Model, -
6:14 - 6:19many of which include predictions
that can be tested at the LHC and CMS. -
6:19 - 6:23These include searches for dark matter
and extra dimensions, -
6:23 - 6:25as well as explanations
of the matter-antimatter asymmetry -
6:26 - 6:27of our Universe.
-
6:27 - 6:31The LHC accelerator started a new run in 2015
-
6:32 - 6:36at the highest energy ever achieved
by a particle accelerator. -
6:37 - 6:40This new realm is expected
to provide a wealth of new data, -
6:40 - 6:43which CMS scientists
will eagerly analyse for years to come -
6:43 - 6:47in the hopes of unlocking more
of Natureâs most closely guarded secrets. -
6:47 - 6:50The Compact Muon Solenoid will operate
for at least another two decades, -
6:50 - 6:53undergoing a steady evolution over time.
-
6:53 - 6:55New sub-detectors are being manufactured,
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6:55 - 6:57existing ones are being upgraded.
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6:58 - 7:01A new scientific journey has just begun
-
7:01 - 7:06and we are really looking forward
to continuing this adventure, -
7:06 - 7:10looking at the deepest secret of nature.
- Title:
- An introduction to the CMS Experiment at CERN
- Description:
-
In this four-part video, we introduce you to the CMS detector at CERN's Large Hadron Collider, describing its construction and history as well as its physics goals.
Episode 1: Why Fundamental Science is Important – https://youtu.be/S99d9BQmGB0?t=1s
Episode 2: Conception of LHC/CMS – https://youtu.be/S99d9BQmGB0?t=1m37s
Episode 3: Construction and Operation of CMS – https://youtu.be/S99d9BQmGB0?t=3m47s
Episode 4: What are the Future Challenges of CMS? – https://youtu.be/S99d9BQmGB0?t=5m21s
The video is subtitled in several languages, so be sure to pick one that you prefer!
- Video Language:
- English
- Duration:
- 07:26
Yuan CHAO edited English subtitles for An introduction to the CMS Experiment at CERN |