The Large Hadron Collider has been turned back on today (July 5) and is set
to smash particles together at never-before-seen energy levels.
The Large Hadron Collider (LHC) is the world's largest and most powerful
particle accelerator. Located at CERN near Geneva, Switzerland, the nearly
17-mile-long (27 kilometer) loop was fired up today after spending four
years offline for upgrades. With these fixes completed, scientists want to
use the gigantic accelerator to smash protons together at record-breaking
energies of up to 13.6 trillion electron volts (TeV) — an energy level that
should up the odds of the accelerator producing particles not yet observed
by science.
The upgrades to the accelerator's particle beams have done more than spike
their energy range; an increased level of compactness, making the beams
denser with particles, will increase the probability of a collision so much
that the accelerator is expected to capture more particle interactions in
its third run than it did in its previous two combined. During the two
previous stints, running from 2009 to 2013 and 2015 to 2018, the atom
smasher shored up physicists' understanding of how the basic building blocks
of matter interact — called the Standard Model — and led to the discovery of
the long-predicted Higgs boson, the elusive particle which gives all matter
its mass.
But, in spite of the accelerator's experiments, which produced 3,000
scientific papers on many minor discoveries and tantalizing hints of deeper
physics, scientists have yet to find conclusive evidence of new particles or
brand-new physics. After this upgrade, they're hoping that will change.
"We will measure the strengths of the Higgs boson interactions with matter
and force particles to unprecedented precision, and we will further our
searches for Higgs boson decays to dark matter particles as well as searches
for additional Higgs bosons," Andreas Hoecker, a spokesperson of the LHCs
ATLAS collaboration, an international project that includes physicists,
engineers, technicians, students and support staff, said in a statement.
Inside the LHC's 17-mile-long underground ring, protons zip around at near
light-speed before slamming into each other. The result? New and sometimes
exotic particles are formed. The faster those protons go, the more energy
they have. And the more energy they have, the more massive the particles
they can produce by smashing together. Atom smashers like the LHC detect
possible new particles by looking for telltale decay products, as the
heavier particles are generally short-lived and immediately break down into
lighter particles.
One of the LHC's goals is to further scrutinize the Standard Model, the
mathematical framework physicists use to describe all of the known
fundamental particles in the universe and the forces through which they
interact. Though the model has been around in its final form since the
mid-1970s, physicists are far from satisfied with it and are constantly
looking for new ways to test it and, if they're lucky, discover new physics
that will make it fail.
This is because the model, despite being the most comprehensive and accurate
one so far, has enormous gaps, making it totally incapable of explaining
where the force of gravity comes from, what dark matter is made up of, or
why there is so much more matter than antimatter in the universe.
While physicists want to use the upgraded accelerator to probe the rules of
the Standard Model and learn more about the Higgs boson, upgrades to the
LHC's four main detectors also leave it well positioned to search for
physics beyond what is already known. The LHCs main detectors — ATLAS and
CMS — have been upgraded to collect more than double the data they did
before in their new task of looking for particles that can persist across
two collisions; and the LHCb detector, which now collects 10 times more data
than it used to, will search for breaks in the fundamental symmetries of the
universe and for explanations why the cosmos has more matter than
antimatter.
Meanwhile, the ALICE detector will be put to work studying collisions of
high-energy ions, of which there will be a 50-fold increase in those
recorded compared to prior runs. Upon smashing together, the ions — atomic
nuclei given electrical charge by the removal of electrons from their
orbital shells — produce a primordial subatomic soup called quark-gluon
plasma, a state of matter which only existed during the first microsecond
after the Big Bang.
In addition to these research efforts, a slew of smaller groups will probe
at the roots of other physics mysteries with experiments that will study the
insides of protons; probe the behavior of cosmic rays; and search for the
long-theorized magnetic monopole, a hypothetical particle that is an
isolated magnet with only one magnetic pole. Added to these are two new
experiments, called FASER (Forward Search Experiment) and SND (Scattering
and Neutrino Detector), that were made possible by the installation of two
new detectors during the accelerator's recent shutdown. FASER will scan for
extremely light and weakly interacting particles, such as neutrinos and dark
matter, and SND will exclusively search for neutrinos, ghostly particles
which can travel through most matter without interacting with it.
One particle physicists are particularly excited to look for is the
long-sought-after axion, a bizarre hypothetical particle that doesn't emit,
absorb or reflect light, and is a key suspect for what dark matter is made
up of.
This third run of the LHC is slated to last for four years. After that time,
collisions will be halted once more for further upgrades that will push the
LHC to even greater levels of power. Once it has been upgraded and begins
running again in 2029, the High Luminosity LHC is expected to capture 10
times the data of the previous three runs combined.
Originally published on Live Science.
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Physics