Imagine being a scientist who has dedicated their entire life to discovering something
completely unique.
Well, that's exactly what happened to the scientists at CERN, the European Organization
for Nuclear Research.
In just nine months of starting the LHC Run 3 and its measurement campaign, the FASER
collaboration has revealed its first observation of collider neutrinos.
The excitement within the scientific community is palpable as the discovery is so enigmatic
that CERN scientists claim to have entered unchartered territory.
What are CERN scientists up to now?
What could this new discovery be?
Join us as we unravel the mysteries surrounding this incredible discovery made by CERN researchers
that is set to change everything we know.
Welcome to the world of particle physics, where mysteries and discoveries await!
The Large Hadron Collider (LHC) is a massive machine that is making incredible strides
in unraveling the secrets of the universe.
Located at CERN in Switzerland, this particle accelerator is the largest and most powerful
in the world, and it has already revealed fascinating information about particles that
make up the universe.
But the LHC isn't just about discovering new particles.
It's also about testing theoretical predictions in particle physics, particularly those related
to the "Standard Model."
Despite the Standard Model's success, it still leaves unanswered questions about dark matter,
dark energy, and other mysteries.
With the LHC back in action after three years of maintenance and upgrades, scientists are
poised to uncover even more secrets of the universe.
And that’s what they did with their latest discovery.
However, if you've ever come across a groundbreaking news story about subatomic particles, it's
very likely that it was discovered at CERN.
In January of 2022, the scientists at CERN made an announcement that shook the world
of particle physics: "evidence of X particles in the quark-gluon plasma produced in the
Large Hadron Collider."
This remarkable discovery meant that CERN had managed to recreate a scenario that has
not occurred naturally since the first few microseconds after the Big Bang.
In 2012, the discovery of the Higgs boson was the high point of the LHC's achievements.
Although often called the "God particle," it's not as miraculous as the name suggests.
The significance of the Higgs boson discovery was that it was the last prediction of the
Standard Model that needed to be proven.
Nevertheless, the LHC has made many other discoveries aside from the Higgs boson.
The CERN Courier reports that the LHC has uncovered about 60 previously unknown hadrons,
which are complex particles made up of various combinations of quarks.
However, despite these exciting discoveries, all of these particles remain within the confines
of the Standard Model, which has been the subject of much research and speculation by
scientists looking for alternative theories.
In 2021, there were tantalizing signs that a major breakthrough was on the horizon when
LHC data revealed activity patterns that deviated from the Standard Model.
These patterns were modest but distinct.
What's more, CERN is now planning to invest a staggering $23 billion in a new 100-kilometer-long
super collider, despite the Large Hadron Collider's already substantial energy consumption.
But it's hard to argue with the numerous breakthroughs that the LHC has already yielded.
For instance, the detection of elusive neutrinos, also known as ghost particles, stands out
as a remarkable achievement, thanks in no small part to the collaborative efforts of
CERN's Forward Search Experiments.
The scientific community was on the edge of their seats on March 22, 2023, when the LHC
experiments entered uncharted territory.
While neutrinos are abundantly produced in collisions at the LHC, they had never before
been detected.
However, the FASER collaboration changed the game by announcing their first observation
of collider neutrinos just nine months into LHC Run 3.
The announcement was made at the 2023 electroweak session of the Rencontres de Moriond, and
the collaboration observed muon neutrinos as well as electron neutrino candidate events.
FASER's co-spokesperson, Jamie Boyd, stated that the statistical significance of their
findings was 16 sigma, far surpassing the 5 sigma threshold for a discovery in particle
physics.
Furthermore, FASER also presented their results on searches for dark photons.
Despite a null result, the collaboration was able to set limits on previously unexplored
parameter space and exclude regions motivated by dark matter.
FASER is now looking to collect ten times more data in the coming years, allowing for
further searches and neutrino measurements.
FASER is one of the two new experiments situated at either end of the ATLAS cavern, with the
aim of detecting neutrinos generated in proton collisions in ATLAS.
At the same conference, the other experiment, SND@LHC, presented its initial results, demonstrating
eight muon neutrino candidate events.
"We're still working on assessing the systematic uncertainties of the background.
As a very preliminary finding, our observation can be claimed at the 5 sigma level," notes
SND spokesperson Giovanni De Lellis.
The SND detector was placed in the LHC tunnel right before the start of LHC Run 3.
Until recently, experiments have only explored neutrinos from different sources like space,
Earth, nuclear reactors, and fixed-target experiments.
Astrophysical neutrinos, such as the ones detected by IceCube at the South Pole, are
highly energetic, while solar and reactor neutrinos typically have lower energies.
Neutrinos from fixed-target experiments, like those from CERN's North and former West Areas,
have energies up to a few hundred gigaelectronvolts (GeV).
FASER and SND, on the other hand, will cover a much wider energy range, from a few hundred
GeV to several TeV, bridging the gap between fixed-target and astrophysical neutrinos.
But have you ever wondered why scientists are so excited about neutrinos?
These tiny, elusive particles are one of the greatest mysteries of the natural world, capable
of passing through matter as if it were not even there.
Despite their elusive nature, neutrinos are the most abundant particle in the universe,
with nearly 100 trillion of them passing harmlessly through your body every second.
The fact that they barely interact with other particles makes them incredibly difficult
to detect, but not impossible.
Although they have no charge, they do have mass, although it is extremely small - the
top limit of neutrino mass has been determined to be 0.8 electronvolts.
To put that in perspective, neutrinos are about 10,000 times less massive than electrons.
Even though neutrinos are extremely small, they play a big role in the universe, and
scientists are eager to learn more about them.
Neutrinos are unique particles that defy convention by not interacting with the strong nuclear
force.
Instead, they interact with the weak force, which is responsible for radioactive decay.
In fact, scientists use the weak force to produce neutrinos, as seen in the KATRIN experiment
that used tritium isotopes to determine the neutrino mass.
These elusive particles were formed in large numbers just after the Big Bang, and they
are still being produced today.
They can be generated in a variety of settings, from the nuclei of stars to particle accelerators
to atomic reactors.
Even supernovas and radioactive decay can produce these mysterious particles.
While they may be difficult to detect, scientists believe that neutrinos outnumber protons in
the universe by a billion times.
This is because neutrinos can pass through most matter without interacting with it, allowing
billions of them to pass through a single square centimeter of your body undetected.
It's as if they are invisible, passing through everything like a beam of light through a
clear glass.
Neutrinos are special particles that retain valuable information while traversing through
space, unlike other particles that can be altered by interactions with matter.
Studying neutrinos is a crucial step towards unraveling the mysteries of the universe.
Interestingly, neutrinos were discovered by scientists attempting to solve the enigma
of Beta Decay.
This phenomenon was puzzling because it appeared to violate two fundamental laws of physics:
the laws of energy conservation and momentum conservation.
The scientists realized that during Beta Decay, the end product seemed to have slightly less
energy, and a proton remained stationary instead of moving in the opposite direction as the
electron.
Back in 1930, Wolfgang Pauli came up with an idea for a particle that could carry energy
and momentum with it as it escaped the nucleus.
Unfortunately, he knew this particle couldn't be detected, and this left him with a sense
of despair.
If only he could see the remarkable results of the most recent experiment at CERN, where
scientists have finally managed to detect this elusive particle.
With this latest development scientists are now pondering whether neutrinos could be the
mysterious Dark Matter that has long puzzled the scientific community.
This substance is thought to be responsible for the extra gravitational force that keeps
galaxies and galaxy clusters together, but it remains elusive because it can't be seen
and only interacts with conventional matter through gravity, and even then, only very
weakly.
While neutrinos seem like promising candidates, there's a catch: they may not be large enough.
Despite being present everywhere in the universe, the three types of neutrinos that we know
of - electron, muon, and tau - have a maximum energy of 0.8eV, which is unlikely to account
for all of the Dark Matter.
FASER and SND have a lot to offer in the field of physics, including the study of high-energy
neutrinos from astrophysical sources.
These neutrinos are produced in cosmic-ray collisions with the atmosphere and have the
same production mechanism and energy level as the ones produced in the LHC.
However, atmospheric neutrinos can make it difficult to observe astrophysical neutrinos.
That's where FASER and SND come in - their measurements can provide a precise estimation
of the background created by atmospheric neutrinos, which will make it easier to observe astrophysical
neutrinos.
But that's not all!
These experiments will also measure the production rate of all three types of neutrinos.
By measuring the ratio of different types of neutrinos produced by the same type of
parent particle, they will be able to test the universality of their interaction mechanism.
This test will be a significant milestone in the neutrino sector and an important test
of the Standard Model.
Let us know what you think of these enigmatic particles in the comments section below.