A Journey Through the Secrets of the Universe at CERN  Posted on August 12, 2017 by Barbara Weibel  Comment

Geneva held no fascination for me. It was just another Swiss
city with a pretty lake and exorbitant prices. But it offered
one thing that other
destinations in Switzerland
could not: tours of CERN, the
European Council for Nuclear Research, where
scientists and physicists are studying the basic constituents
of matter. For more than 50 years, they have been seeking
answers to the questions, “What is the universe made of?” and
“How did it start?”


Globe of Science and Innovation houses the permanent Universe of Particles exhibit, for those who are unable to book tours of CERN

Globe of Science and Innovation houses the permanent Universe
of Particles exhibit, for those who are unable to book tours
of CERN

I readily admit to being a science geek. I was only two years
old when CERN was founded in 1954 and during my elementary
school years, science textbooks spoke only of molecules, atoms,
electrons, protons, and neutrons. But I’d followed developments
in physics and read extensively about the subject over the
years, so I knew significant advancements had been made in the
field. Now I was beside myself with excitement at the prospect
of touring the world’s most prestigious particle physics
facility.


Full scale model of CERN's AMS detector, which has been deployed on an arm of the International Space Station

Full scale model of CERN’s AMS detector, which has been
deployed on an arm of the International Space Station

Those who are familiar with CERN often think of it in terms of
the Large Hadron Collider, the world’s largest and most
powerful particle accelerator. The LHC may be the best known
part of CERN, but is only one element of it. The complex
encompasses nine accelerators and seven different detectors,
which are mounted at intervals along the LHC tunnel and conduct
specific experiments. Additionally, experiments at other
accelerators and facilities on-site and off remain an important
part of the laboratory’s activities. The CLOUD experiment is
investigating a possible link between cosmic rays and cloud
formation, while the CAST experiment is looking for
hypothetical particles coming from collisions on the sun. Even
the International Space Station is being used to perform CERN
experiments. A detector – the only one not located at CERN –
has been deployed on an arm of the station to study particles
and the composition of the Universe in preparation for
colonizing Mars.


Diagram of the Large Hadron Collider on the floor of the magnet testing facility of CERN

Diagram of the Large Hadron Collider on the floor of the
magnet testing facility of CERN

The roughly circular tunnel that houses the LHC stretches from
the western suburbs of Geneva, Switzerland, to the Jura
mountains of France. It is 16.77 miles in circumference and
lies at an averages depth of 328 feet. The enormous size of the
tunnel was necessary in order to accelerate proton beams to
speeds that would force the protons to split into their
elemental parts when they collide. Since the energy density and
temperature of these collisions are similar to those that
existed a few moments after the Big Bang, the LHC allows
scientists to study conditions that were present at the
formation of the Universe.


Superconducting dipole magnets, traditional copper windings, and smaller magnets used to tweak the photon stream in the LHC at CERN

Superconducting dipole magnets, traditional copper windings,
and smaller magnets used to tweak the photon stream in the
LHC at CERN

I had chosen to take a tour of the facility where the dipole magnets are checked and
assembled, since the LHC would not be possible without them.
The tour began with a lecture that acquainted us with the
language of particle physics: electrons, quarks, leptons,
gluons, neutrinos, Higgs bosun particles, photons, and gluons.
There was no mention of atoms, much less molecules. My head was
swimming by the time we headed for the magnet facility.

Our guide led us to a section of the LHC tube, the top of which
had been cut off to expose its innards. Using it as a visual
aid, he explained the process in detail. First, electrons are
stripped from hydrogen atoms to obtain protons. These protons
are injected into a booster and two synchrotrons, each of which
increase the speed of the proton beams before they are
transferred to the Large Hadron Collider. Inside the LHC, half
the protons are sent down a tube in clockwise direction, while
the remainder are sent counter-clockwise in a parallel tube.


Highlight of tours of CERN include seeing actual sections of the Large Hadron Collider with a section of the exterior cut away to show the pipes through which the photon beams travel

Highlight of tours of CERN include seeing actual sections of
the Large Hadron Collider with a section of the exterior cut
away to show the pipes through which the photon beams travel

Protons have a positive charge, thus their natural tendency is
to repel one another. This is where the super-cooled dipole
magnets come into play. They align the beams vertically and
horizontally and focus them into a beam that is one-third the
thickness of a strand of hair. Unlike regular magnets, the ones
used in the LHC cannot be made of copper. The number of
windings required to produce the necessary energy would make
the magnets too large, and the heat generated would be too much
for the copper wires to bear. Instead, they are built of
niobium-titanium, which becomes superconducting at a
temperatures of -271 degrees Celsius. This extreme temperature
is achieved by pumping super-fluid helium into the magnet
systems. Once the magnets have stabilized the proton beams,
experiments begin. At intervals during the circulation, the
magnets bend the streams and force them to collide into one
another head on.


In 2009 engineers install the beam pipe in the CMS particle physics detector on the Large Hadron Collider. Photo courtesy of CERN.

In 2009 engineers install the beam pipe in the CMS particle
physics detector on the Large Hadron Collider. Photo courtesy
of CERN.

On July 6, 2017, ten days after my departure, CERN announced
that experiments with the Large Hadron Collider had allowed
them to observe a new particle containing two charm quarks and
one up quark. Physicists had long theorized about this particle
from the baryon family, but until recently had no definitive
proof that it existed. According to their press release:

“Nearly all the matter that we see around us is made of
baryons, which are common particles composed of three quarks,
the best-known being protons and neutrons. But there are six
types of existing quarks, and theoretically many different
potential combinations could form other kinds of baryons.
Baryons so far observed are all made of, at most, one heavy
quark.”

Giovanni Passaleva, spokesperson for the LHC collaboration
explains further. “Finding a doubly heavy-quark baryon is of
great interest as it will provide a unique tool to further
probe quantum chromodynamics, the theory that describes the
strong interaction, one of the four fundamental forces. Such
particles will thus help us improve the predictive power of our
theories.”


The Universe of Particles, one of the permanent exhibit available to those who are unable to book tours at CERN

The Universe of Particles, one of the permanent exhibit
available to those who are unable to book tours at CERN

Is your head spinning yet? Passaleva is referring to the Grand
Unified Theory or GUT, which studies the relationship between
the electromagnetic, weak, and strong interactions and attempts
to merge them into a single force. In theory, this would allow
them to scientifically describe nature and understand the
forces at work as far back as the Big Bang. But even the GUT
would only be a piece of the puzzle. Physicists would still
have to unify gravity with the other three interactions and
develop a theory of everything (TOE).

Less than a month later, CERN reported the first observation of
the “hyperfine structure of antihydrogen, the antimatter
counterpart of hydrogen,” which “could help understand any
differences between matter and antimatter.” My tour of CERN was
five weeks ago and my head is still spinning. By the time I
cycle off this planet, scientists probably won’t even be
talking about atoms anymore.

Author’s note: You can take free tours of CERN throughout
the year, however they fill up very fast, so it is best to book
as far in advance as possible. For more information on tours,
visit http://visit.cern/tours/guided-tours. Even if you are
unable to book a tour, it is worthwhile to visit the permanent
exhibitions, which need no reservations. The facility is easily
reached by public trolley from the center of Geneva.

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