Tag Archives: large hadron collider

What is the Standard Model of Particle Physics?

By the mid-20th Century, physicists had begun to understand the fundamental structure of matter to such a degree that a theory was needed to encapsulate the Universe’s particles, the interactions between them and the forces that govern those interactions. That theory was the Standard Model of Particle Physics or just the Standard Model for short.

First devised in the 1970s, the Standard Model would be used to predict a wide variety of phenomena, meet various experimental challenges, before being confirmed by the discovery of the Higgs Boson in 2012. Yet, as successful and fruitful a theory as the Standard Model is, it can’t explain everything. Gravity still evades confinement within the Standard Model, and physicists have caught tantalizing glimpses of physics beyond the theory’s limits.

Before these glimpses can be confirmed and a new chapter in physics is opened, let’s take a trip through the particle zoo and discover the wonders of the Standard Model.

The Matter Particles

The everyday matter that surrounds us is comprised of building blocks called elementary particles. Of these building blocks, there are two main families; fermions and bosons.

Of the fermions, the two mains classes are leptons and quarks. Within each of these groups are six particles that group into three pairings that physicists call generations.

The first generation of leptons and quarks are made up of the lightest and most stable particles. These are the particles responsible for forming the elements of the Universe we are most familiar with–the stars, planets, moons, and us. The second and third generations are made up of increasingly more massive and less stable particles. The greater in mass these particles are, the quicker they decay into their lighter cousins.

Starting with the quarks is an easy way to introduce some of the qualities and values associated with the particles in the Standard Model. One thing you will notice is the interesting naming convention for these qualities. They reflect things we commonly encounter in the everyday macroscopic world such as flavour, colour and spin, but really shouldn’t be confused with those things.

So, let’s make quarks the first stop in our walk through the particle zoo.

Quarks

The six quarks that make this family of particles are known as up, down quarks, which make up the first generation of quarks, these second comprises of the more massive charm and strange quarks. And the third generation contains the most massive particles, known as the top and bottom quarks.

These are generally known as the ‘flavours’ of quarks, each of which has its own antiquark. Of course, I’ve primed you to realise that this name has nothing to do with how these quarks taste!

Of the four fundamental forces, quarks ‘feel’ electromagnetism, the strong and weak nuclear forces, and gravity, but the latter is too weak to have an effect on quarks’ tiny mass.

The strong nuclear force binds together quarks in nucleons, whilst the weak nuclear force can actually cause quarks to switch flavours something that we’ll look at further when we get to the force-carrying particles.

But these elementary particles don’t just come in flavours–they also come in ‘colours.’

It is this quality–again nothing to do with wavelengths of light, quarks are large enough to reflect light in such a way to have a conventional colour– that determines how quarks come together to form other, more massive, particles.

Incnis Mrsi/CC-by-SA 3.0

Quarks join up to make particles called baryons, the most common of which are the protons and neutrons that come together to form the elements and the matter we interact with on an everyday scale.

Protons are made up of one down quark and two up quarks, whilst neutrons are comprised of two down quarks and an up quark.

A diagram shows how quarks usually fit into our understanding of tiny particles.  (udaix/Shutterstock)

Considering these arrangements and the fact that each flavour of quark has its own charge it’s easy to see why the proton has a positive charge whilst the neutron is neutral. It should also be apparent that when the weak nuclear force causes an up quark to switch to a down quark it also charges the nucleon it is part of from a proton to a neutron.

There are a multitude of other exotic arrangements of quarks like mesons which consist of a quark and its antiquark, and tetra and pentaquarks made up of three and five quarks respectively.

Considering how quarks come together to form particles is important because despite being fundamental particles, quarks are found wandering the particle zoo on their own. They are always found in conglomerations.

There is another important quality of fundamental particles that need to be considered–and yes, just as with ‘flavour’ and ‘colour’ it has a slightly misleading name.–these particles also have ‘spin.’

This shouldn’t be considered as representing a particle constantly revolving. It’s more a description of how a particle reacts when it interacts with a magnetic field.

Quark, like all fermions, are 1/2 spin particles and are described as having ‘up’ or ‘down’ spin. Unlike the spin of a macroscopic object, say a football after it is kicked, the spin of fundamental particles doesn’t change.

Leptons

Like quarks, leptons are particles with 1/2 spin. They also come in six flavours and across three generations. But, unlike quarks, leptons are freely found wandering the particle zoo alone. The most famous lepton is possibly also the most famous fundamental particle. The electron–a generation I particle possessing a charge of –e.

Leptons can also be sub-divided into two groups; charged, which includes electrons and electron like muons, and chargeless leptons like the neutrinos. The charged leptons also possess a more considerable mass than their uncharged cousins. The reason that uncharged leptons have such smaller masses is not explained by the Standard Model of Particle Physics and doing so requires an extension to the model.

The lack of charge and practical lack of mass of neutrinos has led them to be labelled ‘ghost particles’ and means that 100s of thousands of them can stream through every square inch of your body every second without the slightest interaction with the matter that composes you.

Just like with quarks, each particle has its own anti-particle, including perhaps the most famous example of such symmetry–the antiparticle of the electron, the positron. One possible quirk to this symmetry is the possibility is that neutrinos are their own antiparticles.

Like quarks, leptons interact with gravity and the electromagnetic force, but unlike quarks leptons don’t feel the strong nuclear force.

Leptons obey the Pauli exclusion principle. This means that no two particles can share the same quantum numbers. This is key to the range of chemical elements that exist within the Universe as it forces electrons to occupy increasingly energetic shells around an atomic nucleus. The number of valance electrons in an element’s outer shell determines the chemical properties that the element will have.

The Pauli exclusion principle can be overwhelmed. A neutron star is protected from becoming black holes by this phenomenon, but when it exceeds a certain mass it can no longer rely on this to protect against complete gravitational collapse.

The Force Carriers

There are four fundamental forces in the Universe that we are currently aware of–the strong force, the weak force, the electromagnetic force, and the gravitational force. All of these forces work over different distances with different strengths. For instance, gravity is the weakest of the forces–even though there is actually a force explicitly called the ‘weak force’– but works over a potentially infinite distance. Meanwhile, the electromagnetic force also works over a long-range but is much more powerful than the force of gravity.

The strong and weak nuclear forces work over much shorter ranges; dominating the forces for sub-atomic particles. As the name implies, the strong force is the strongest of all the four forces, whilst the weak force is the weakest barring gravity.

We are certain that three of the four fundamental forces–electromagnetism, the strong and weak forces–are communicated by carrier particles called bosons. Particles exchange these bosons to communicate these forces.

Unlike leptons and quarks–collectively known as Fermions–Bosons have full integer spin. This means that they are not forced to obey the Pauli exclusion principle.

The electromagnetic force is carried by the most familiar of these particles–the photon. The strong force which ‘glues’ quarks together in protons and neutrons is communicated by gluons, and the weak force that influences particles to switch flavours is transmitted by W and Z bosons.

So what about gravity?

Put simply, the force that we are most familiar with and experience every moment of every day isn’t part of the Standard Model. Physicists think that this outsider force is also transmitted by a boson which they have given the provisional name the graviton. As of yet, however, there is no experimental sign of this hypothetical boson. Thus it can’t yet be seen in our particle zoo.

The exclusion of gravity isn’t a massive problem for particle physics, because the model deals with particles that are so small and the fact that gravity is so weak, the force doesn’t really have an effect on this sub-atomic world.

But what this omission does tell us, is that despite its importance and the fact that it has been experimentally verified to an impressive standard, and can now predict that outcome of a wide array of experiments, the Standard Model is by no means a complete description of the physical world.

That means we need extensions to this model to obtain that more accurate description. The problem is, no one can quite agree on what those extensions should look like.

Beyond the Standard Model

The force of gravity isn’t the only element of the Universe that physicists can’t squeeze into the Standard Model at the moment. Despite being a great description of sub-atomic particles, the theory can’t account for dark matter. As this mysterious form of matter that isn’t made up of baryons like protons and neutrons, accounts for around 85% of the mass in the known Universe, this isn’t an insignificant shortfall.

Likewise, the model can’t explain why matter dominates the Universe rather than antimatter. Processes that birth particles produce matter and antimatter in equal amounts. If the Universe had started with these balanced they would have likely met and annihilated each other before large scale structure had the oppotunity to form. That means there must be some reason beyond the Standard Model why the Universe initial favoured matter and allowed an imbalance.

The detection of the Higgs Boson by the CMS detetcor at the LHC was supposed to complete the Standard Model, but the particle isn’t exactly what the theory predicted (CERN)

Another potential issue with the Standard Model could result from the particle that was heralded as marking its completion: the Higgs Boson.

This particle is believed to emerge from the Higgs field and endow mass to most particles. But, the Standard Model isn’t the only theory that posits the existence of the Higgs Boson. The Higgs particle suggested by this theory is the simplest version. The particle that was measured by the CMS detector at the Large Hadron Collider (LHC) certainly conforms to the description given by the Standard Model, but it’s not a perfect fit.

That means that even as we create more Higgs Bosons at the LHC and continue learning more about the particle, the possibility of discovering that it conforms better to another theory remains.

One of the most well-supported extensions to the Standard Model is Supersymmetry (SUSY). This hypothesises a connection between fermions and bosons and suggests that all particles have a superpartner –or sparticle–with the same mass, and quantum numbers but a spin that differs by 1/2.

That means that each 1/2 lepton is a partner ‘slepton’ with a full integer spin–or more simply a boson. So, for the electron, SUSY posits the slepton with the same mass, charge, but with a spin of 1 rather than 1/2 called the selectron. For quarks, there are squarks, and so on.

SUSY could provide a dark matter candidate as the lightest particle suggested by the extension to the Standard Model would, if it existed, be a dead-ringer for dark matter.

Unfortunately, despite some tantalising hints at physics beyond the Standard Model of Particle Physics, experiments have thus far failed to turn up anything substantial. For SUSY specifically, sparticles that should be created in collisions at the LHC have thus far not been detected.

At least until the completion of high-luminosity upgrades at the LHC provide more collisions and thus a greater chance of spotting exotic phenomena, the Standard Model will remain our best, albeit incomplete, description of the sub-atomic world.

Sources and Further Reading

Manton. N., Mee. N., The Physical World, Oxford University Press, [2017].

Martin. B. R., Shaw. G., Particle Physics, Wiley, [1999].

Quark-Gluon Plasma that filled the early Universe investigated by ALICE

The secrets of the Quark-Gluon Plasma that filled the early universe are being unlocked by the ALICE collaboration at CERN with the first measurement of the flow of bottomonium particles.

Quark-Gluon Plasma that filled the early Universe investigated by ALICE (Author's Collection)

Quark-Gluon Plasma that filled the early Universe investigated by ALICE (Author’s Collection)

 

In a paper presented at the European Physical Society’s conference on high-energy physics, the ‘A Large Ion Collider Experiment’ (ALICE) collaboration has documented the first-ever measurement of the flow of a heavy meson particle — bottomonium.

The measurement of particles like bottomonium — a type of ‘upsilon’ particle — helps the researchers understand the Quark-Gluon Plasma (QGP) that filled the hot, dense early universe. 

By observing pairs of ‘heavy electrons’ — known as muons — produced by the decay of bottomonium, the team discovered bottomonium particles have small values of elliptic flow — a measure of how uniform energy and momentum is distributed across the particles when viewed from the beamline. 

This is quite unexpected as all other hadrons investigated thus far have exhibited significant elliptic flow. 

David Evans, a professor of high energy physics at the University of Birmingham, leads the UK participation in ALICE.

He says: “ Elliptical flow measurements in ALICE show that the Quark-Gluon Plasma flows like an almost perfect liquid, with the light quarks (up, down, strange, and charm) flowing with the system.”

“The fact that no significant elliptical flow is seen for the bottomonium suggests b-quarks are only produced in the initial collision of the lead ions, before the QGP is formed.”

The ALICE team’s results seem to support existing theories that bottonium and other upsilon particles split into their constituents during the early stages of their interactions with plasma.

This gives the researchers a better insight at the conditions in the early moments of the universe when it was filled with a plasma composed of free quarks and gluons. 

Evans continues: “This makes b-quarks (and particles made up of b-quarks) an ideal probe for studying the QGP as they experience the entire evolution of the system.”

Bottomonium particles — probing the Quark-Gluon Plasma at the dawn of the universe

Taking a trip through the ‘particle zoo’ to discover what these bottomonium particles actually are, helps us understand their role in the ALICE experiment. 

The six known types of quarks on the left and how they come together to form protons and neutrons on the right
The six known types of quarks on the left and how they come together to form protons and neutrons on the right

Bottonium is a heavy meson — particles which consist of a quark and its own antiparticle. In the case of bottomonium, a bottom (or beauty quark) — b quark — and its antiparticle counterpart.

These subatomic particles are extremely unstable, existing for short periods of time and only at high energies before decaying into other particles. When bottomonium decays it leaves behind a pair of ‘heavy electrons’ called muons. 

Bottomonium particles — which are formed in the LHC by the violent collision of heavy lead-lead ions — provide an excellent probe of the Quark-Gluon Plasma which filled the universe just a few millionths of a second after the big bang. 

Being produced so early in the collision event means bottomonium particles ‘experience’ the entire evolution of the plasma — from the moment it is produced to the moment it cools down and enters a state in which hadrons can form.

This extremely early stage in the universe’s evolution would have been the only time in history that quarks and gluons existed freely in plasma and not bound together in a state called ‘confinement’ in protons, neutrons and other hadrons.

These particles were only able to exist in this free state because of the incredible heat in the universe at this point. In our era, quarks and gluons are never observed as free particles.

Thus, it takes a tremendous amount of energy, to recreate these huge temperatures. At the moment, the Large Hadron Collider (LHC) is the only piece of apparatus on Earth capable of doing this, with collisions in the LHC able to generate temperatures a 100 thousand times hotter than the Sun. 

At these temperatures, protons and neutrons ‘melt’, freeing quarks and gluons from confinement, thus creating a Quark-Gluon Plasma and allowing them to form short-lived, unstable particles like bottonium. 

ALICE: Collision queen

The ALICE collaboration — consisting of over a 1000 scientists operating a 10-thousand-tonne, 16m tall detector buried 56m under the Alps — achieves this high-energy feat by slamming together beams of lead ions rather than the proton-proton collisions used in other LHC experiments. 

The decay of upsilon particles — another type of meson — into muon pairs as the result of a lead-lead collision. The red lines track the two muons the orange lines track the other particles produced (CERN)
The decay of upsilon particles — another type of meson — into muon pairs as the result of a lead-lead collision. The red lines track the two muons the orange lines track the other particles produced (CERN)

The benefit of colliding lead ions is that, as ALICE is looking to create Quark-Gluon Plasma, the more quarks available to it, the better the chance of observing something significant. 

A single proton and neutron each contain three quarks but as lead ions contain at least 56 protons and at least 204 neutrons this leaves the team with far more quarks to play with. 

ALICE then measures this plasma as it expands and cools, but it is still unable to measure the particles created directly— instead deducing the presence and properties of QGP from the signatures on pairs of muons it produced by decay. 

One of these signatures is the elliptic flow — the collective movement of the produced particles determined by several factors like particle type, mass, the angle at which the particles meet and the momentum they possess as they collide —  which is what the team measured. The flow is created by the expansion of hot plasma after the collision of the lead ions.

Upgrading ALICE: More collisions. More Quarks. More Results

Perhaps the most promising thing about ALICE’s mission to probe the early universe and its conditions is the fact that the forthcoming high-luminosity upgrade only promises to yield more data for researchers to investigate.

The ALICE Experiment is about to be revitalised (CERN)

The upgrade — which CERN hopes will be operational by 2021— aims to increase the luminosity of the LHC by a factor of 10. Luminosity, as described in reference to particle accelerators, is proportional to the number of collisions that occur. Thus increasing the luminosity also means increasing the number of collisions.

As an example of the usefulness of this upgrade, whereas the LHC produced 3 million Higgs boson particles in 2017, the High-Luminosity LHC is expected to produce 15 million per year.

In addition to the High-Luminosity upgrade — on which work began in 2018 — ALICE will also several other upgrades and improvements. As a result of these improvements, the ALICE team expect an overall gain of 100 times the current results.

Evans says: “With this huge increase in statistics and a new inner detector in ALICE, we will be able to measure particles made of b-quarks with much higher precision.”

As such, the experiment stands a very good chance of significantly improving our knowledge of the quark-gluon plasma and the conditions in the early universe, with these new bottomonium results pointing the way.

Evans concludes: “[The upgrades] allow us to probe the properties of the QGP in much more detail and hence learn more about the evolution of the early universe.”

At Last, Scientists Spot Higgs Boson Decaying into Fundamental Particles

Illustration of event in which Higgs boson decays into two botom-quarks (Blue cones), in association with a W boson decaying to a muon (red) and a neutrino. Credit ATLAS/CERN.

Six years after its groundbreaking discovery, two experiments at CERN report that they’ve observed the Higgs boson decaying in the way scientists predicted it would. The findings are important because they confirm the current theory that suggests the Higgs Boson, or ‘God particle’, plays a critical role in how fundamental particles gain their mass.

The Higgs saga continues

The Standard Model is a kind of periodic table of the elements for particle physics. But instead of chemical elements, it lists the fundamental particles that make up the atoms that, in turn, make up chemical elements, along with any other particles that cannot be broken down into any smaller pieces. More than a quarter of the Nobel Prizes in physics of the last century were awarded for direct inputs to or direct results of the Standard Model. And in the last 50 years, every attempt to substantially rework the Standard Model — which could more accurately be called The Freaking Amazing Undefeated Model of Everything Ever — has failed.

Bearing with this track record, physicists working with the Large Hadron Collider (LHC) expected to see that about 60% of the time a Higgs boson will decay to a pair of bottom quarks, the second-heaviest of the six flavors of quarks.

“One of our main goals is to measure the Higgs decay rates, and the dominant Higgs decay is this bottom-quark channel. About 60 percent of Higgs bosons should decay into bottom quarks,” said Jason Nielsen, professor of physics at UC Santa Cruz and associate director of the Santa Cruz Institute for Particle Physics (SCIPP).

“If we measure all the predicted ways the Higgs can decay and they don’t sum up to 100 percent, it could mean there is something else coupling to the Higgs, like dark matter.”

But recording such an event is challenging to say the least. To produce Higgs bosons, two protons are accelerated and collided, fusing into two top quarks that ultimately recombine to form the God particle. Billions of collisions are required to record a single Higgs boson signal. Once it’s produced, the Higgs boson lasts only a mere 10-trillionths of a nanosecond before it decays into less massive particles. In 2011, when the boson was first confirmed, physicists identified it from its decay to a pair of photons, which theory predicts happens only 0.2% of the time. Other than bottom quarks and photons, Higgs bosons are supposed to decay into pairs of W bosons (21 percent), Z bosons (6 percent), tau leptons (2.6 percent), and other exotic particles in very low proportion.

Another reason why confirming the Higgs boson’s most common decay process is difficult is that there are many other ways of producing bottom quarks in proton-proton collisions. Sorting a Higgs-boson decay signal from the background “noise” associated with such processes can be daunting, if not impossible.

ATLAS and CMS, the two main physics experiments at CERN, were able to overcome these challenges by looking at collisions in which a Higgs boson was produced at the same time as a W or Z boson. Researchers call this class of collisions “associated production”. After they combined data from the first and second runs of the LHC, which involved collisions at energies of 7, 8, and 13 TeV, the researchers then applied complex analysis methods to the data, allowing them to single out the Higgs boson decay to a pair of bottom quarks with a significance that exceeds 5 standard deviations  — a one in 3.5 million chance that what the scientists were seeing was due to randomness. Finally, the rate of decay both teams measured was consistent with the Standard Model prediction.

“This observation is a milestone in the exploration of the Higgs boson. It shows that the ATLAS and CMS experiments have achieved deep understanding of their data and a control of backgrounds that surpasses expectations. ATLAS has now observed all couplings of the Higgs boson to the heavy quarks and leptons of the third generation as well as all major production modes,” said Karl Jakobs, spokesperson of the ATLAS collaboration.

In the future, researchers working at CERN plan on improving their method so they might study this decay mode with a much greater resolution and explore what other secrets the Higgs boson might be hiding.

Scientific reference: Observation of Higgs boson decay to bottom quarks. arXiv:1808.08242 [hep-ex] arxiv.org/abs/1808.08242.

What the proposed new particle accelerator's size could look like compared to the LHC. Credit: CERN.

Physicists dream up LHC 2.0: a new particle accelerator three times bigger than the current LHC

The new particle accelerator will allow physicists to smash particle beams together with a power equivalent to 10 million lightning strikes. Image credit: CERN

The new particle accelerator will allow physicists to smash particle beams together with a power equivalent to 10 million lightning strikes. Image credit: CERN

The Large Hadron Collider at the European particle physics laboratory CERN, near Geneva in Switzerland, is the most complex experimental facility ever built. Its 27-kilometre ring of superconducting magnets makes it the world’s largest and most powerful particle accelerator in the world. Since it first started up in 2008, the LHC has already made monumental contributions to physics. Without the LHC, it would’ve been impossible to confirm the existence of the now famous Higgs boson, the so-called ‘God particle’ thought to be responsible for lending things mass.

Surely, the future has many other scientific discoveries in store for the $4 billion scientific facility. But meanwhile, some of the world’s foremost physicists are already drafting plans for a new, improved LHC 2.0.

This week in Berlin, 500 scientists met to hammer out the new LHC or the Future Circular Collider (FCC), as they’ve named it. EuroCirCol, a four-year European-funded study, is responsible for tracing out the new particle accelerator. Some of the proposed upgrades so far include:

  • An 80-100 kilometre-long circuit (50-62 miles) instead of the LHC’s 27 kilometres (17 miles). That’s three times bigger.
  • It will be located so close to its predecessor on the France-Switzerland border that the two rings will literally overlap.
  • Double-strength magnets will help smash protons and other particles with a strength of up to 100 Tera electron Volts, which is equivalent to 10 million lightning strikes all firing at the same point and seven times more powerful than the LHC.
  • The number of Z bosons produced by FCC-ee (up to 1013),  is expected to be almost six orders of magnitude larger than the number of Z bosons collected at LEP (2×107), and up to four orders of magnitude larger than that envisioned with a linear collider (a few 109).

What the proposed new particle accelerator's size could look like compared to the LHC. Credit: CERN.

What the proposed new particle accelerator’s size could look like compared to the LHC. Credit: CERN.

The FCC will also likely require immense computing power and storage hardware. The LHC collides beams at 20 MHz and every collision is measured and is temporarily stored on hardware to be analyzed. Each recorded event is around 10 MB in size resulting in roughly 5 Zettabytes per year of data being processed. For comparison, the total permanently recorded data on Earth is 0.5 Zettabytes and the total amount of information analyzed by the entire planet is 10 Zettabytes per year.

“5% of the Universe is directly observable. The Standard Model of Particle Physics describes it precisely. What about the remaining 95%?,” a statement on the FCC website reads.

“Yet many questions about our Universe remain unanswered. Is there more matter in the Universe than what is visible? What is dark matter made of? What happened to antimatter after the Big Bang? Are there extra dimensions in the Universe and, if so, can we explore them? To get answers and find out more about our Universe, scientists have to carry out experiments in more powerful particle accelerators. The higher energy frontier will expand our horizons and may shed light to the missing pieces of the puzzle of Nature.”

The physicists reckon the upgrade that will smash particles at dazzling energies will help them find hidden particles that are possibly even heavier than the Hiss boson which LHC confirmed in 2012. On a more practical level, the FCC could lead to more radiation-resistant materials that can be used in nuclear reactors.

It took the LHC about 30 years to switch on since the first sketches on the drawing board in the 1980s to the last nut and bolt. The FCC team hopes to have a thorough plan worked out by next year but no one hopes to see it operational any sooner than 20 years from now.

Meanwhile, the LHC will be busy churning out particles and, in the process, advance our understanding of fundamental physics. Just earlier this year, it found five new subatomic particles. And the LHC is slated for an upgrade of its own when sometimes in the mid-2020s it will see new hardware meant to boost particle collision rate and accuracy. After the new upgrade is ready, it will change its name too into the High Luminosity Large Hadron Collider (HL-LHC).

Large Underground Xenon experiment fails to detect dark matter

After three years of scouring nearly a mile underground in a former gold mine in Lead, South Dakota as a part of the Large Underground Xenon (LUX) experiment, a team of scientists have announced that they have come up empty handed in their search for the elusive dark matter.

Image credit Pexels
Image credit Pexels

As of now, dark matter – which makes up approximately 27 percent of the mass and energy in the observable universe – has never been directly observed. Instead, its existence has been inferred from its gravitational effects and recent research has even connected the mysterious form of matter to the existence of black holes.

The LUX experiment is one of three looking for the unique matter – the second is taking place on the International Space Station, and the third is attempting to create it using the Large Hadron Collider, the world’s largest and most powerful particle accelerator that also discovered the Higgs boson particle.

The team examined more than 4,800 feet of Earth in their search in order to screen out background radiation. Using a large vat of liquid xenon, they attempted to create a flash of light when weakly interacting massive particles (WIMPs) bounced off of the super-cooling liquid.

Many scientists believe that WIMPs are the most viable dark matter candidates, although their failure to detect any in the LUX experiment means that they might have to consider alternative possibilities.

Hundreds of millions of dark matter particles are believed to pass through the Earth every second, but their weak nature makes them hard to detect.

“Over 80 percent of our matter is in this dark matter form,” said Richard Gaitskell of Brown University and co-investigator of the study. “You and I are the flotsam and jetsam; dark matter is the sea. That’s why one doesn’t give up. We’ve got to figure out what this dark matter component is.”

Despite failing to find any dark matter, the team exceeded their technological goals for the project.

“We’re sort of proud that it worked so well and also disappointed that we didn’t see anything,” said Daniel McKinsey, a University of California, Berkeley physicist and one of two scientific spokesmen for the project.

The LHC is back – and it’s stronger than ever

After the Large Hadron Collider (LHC) took a 2 year hiatus to up its power, it’s finally back, and it’s stronger than ever – strong enough to uncover some of physics best kept secrets. Today, June 3, the LHC started delivering physics data for the first time in 27 months.

Image via CERN.

The LHC is the world’s largest and most powerful particle collider, the largest and most complex experimental facility ever built, and the largest single machine in the world. Now, they’re running their experiments at the unprecedented energy of 13 TeV, almost doubling what it did in its first run.

“With the LHC back in the collision-production mode, we celebrate the end of two months of beam commissioning,” said CERN Director of Accelerators and Technology Frédérick Bordry. “It is a great accomplishment and a rewarding moment for all of the teams involved in the work performed during the long shutdown of the LHC, in the powering tests and in the beam commissioning process. All these people have dedicated so much of their time to making this happen.”

The purpose of the LHC is an ambitious one – to provide crucial information concerning the basic laws governing the interactions and forces among the elementary objects, the deep structure of space and time, and in particular the interrelation between quantum mechanics and general relativity – quite a load. In particular, the LHC will either prove or disprove the Standard Model, the theory that classifies all subatomic particles. In order to do this, they need to smash particles at extremely high speeds – funny how modern physics works sometimes, isn’t it? In order to do this, they need huge quantities of energy, which is why they took the 2 year hiatus, to move from the initial setup to one that can provide more power.

“The first 3-year run of the LHC, which culminated with a major discovery in July 2012, was only the start of our journey. It is time for new physics!” said CERN Director General Rolf Heuer. “We have seen the first data beginning to flow. Let’s see what they will reveal to us about how our universe works.”

The first physics results from the LHC, involving 284 collisions which took place in the ALICE detector, were reported on 15 December 2009. Now, it’s time to go even further, and you could feel the wave of excitement across researchers involved in the project.

“The collisions we are seeing today indicate that the work we have done in the past two years to prepare and improve our detector has been successful and marks the beginning of a new era of exploration of the secrets of nature,” said CMS spokesperson Tiziano Camporesi. “We can hardly express our excitement within the collaboration: this is especially true for the youngest colleagues.”

“The successful restart of physics data-taking, with all systems in great shape to collect, process and analyse the new data quickly, is a testament to the commitment and immense hard work of very many people from across ATLAS during the long shutdown,” said ATLAS spokesperson Dave Charlton. “We are now starting to delve into the new data to see what nature has in store for us at these new unexplored energies.”

“All within the collaboration are tremendously excited that the new run has now begun,” said LHCb spokesperson Guy Wilkinson. “It will allow us to follow up on puzzles from our run-1 studies, and to probe with higher sensitivity the difference in behaviour between matter and antimatter.”

“Proton-proton collisions will provide essential reference data for the run with heavy-ion beams foreseen for the end of the year, in which the LHC will provide both higher energy and luminosity as compared to run 1,”said ALICE spokesperson Paolo Giubellino. “In addition, we plan to extend the exploration of the intriguing signals that have emerged from Run 1.”

We’ll keep you posted with developments from the LHC, which are set to come.

Aerial view of the LHC at CERN. Image: CERN

LHC back in business after two year hiatus: already breaks record

Two years ago, following the discovery of the Higgs boson – heralded as one of the greatest scientific achievements of this century – the Large Hadron Collider at CERN was shut down for much needed maintenance and upgrades. A few days ago, the massive particle accelerator was shifted into gear and powered up. The first test run wasn’t only successful, it set a new record by producing collision energies of around 13 trillion electron-volts. The highest speed that was previously  achieved was of only 6.5 TeV. More tests will be made throughout the remainder of this month and June.

Aerial view of the LHC at CERN. Image: CERN

Aerial view of the LHC at CERN. Image: CERN

“It doesn’t sound like very much, but if you have a mosquito buzzing around, the amount of energy it takes to keep that mosquito floating is about the energy of one of these collisions – except that you have this energy compressed down into the size that’s a million times smaller than the width of a human hair,” Greg Rakness,  one of the CMS experiment coordinators.

The aim of the LHC is to allow physicists to test the predictions of different theories of particle physics and high-energy physics like the Standard Model. During its two-year nap, the LHC was outfitted with new magnets and detectors. These are the most vulnerable parts to damage in the 17-mile long LHC particle accelerating ring. To avoid or at least minimize further damage in the future, technicians and researchers fitted an improved collimator shield. The collimator shield is basically a shield of metal that attracts protons that wander off course.

Once the LHC blasted particles at 13TeV, scientists found some particle with a distinct decay time. They think they may already have come across a new exotic particle. By all signs, it seems to be what’s called a Bs particle, a quark and an antiquark that bind to make something called a muoy.  Data taking and the start of the LHC’s second run is planned for early June.

CERN released some of the first images showing test results. They’re right below.

Protons collide at 13 TeV sending showers of particles through the ALICE detector (Image: ALICE)

Protons collide at 13 TeV sending showers of particles through the ALICE detector (Image: ALICE)

Protons collide at 13 TeV sending showers of particles through the CMS detector (Image: CMS)

Protons collide at 13 TeV sending showers of particles through the CMS detector (Image: CMS)

Protons collide at 13 TeV sending showers of particles through the ATLAS detector (Image: ATLAS)

\ Protons collide at 13 TeV sending showers of particles through the ATLAS detector (Image: ATLAS)

Protons collide at 13 TeV sending showers of particles through the LHCb detector (Image: LHCb)

Protons collide at 13 TeV sending showers of particles through the LHCb detector (Image: LHCb)

Protons collide at 13 TeV sending showers of particles through the TOTEM detector (Image: TOTEM)

Protons collide at 13 TeV sending showers of particles through the TOTEM detector (Image: TOTEM)

 

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Stephen Hawking: ‘God particle’ might destroy the Universe. But wait…

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Photo: Business Insider

I’m not sure what’s on with Stephen Hawking and his pessimistic view of the world. He’s been known for audacious, panic-inflicting claims like the world is going to be destroyed either by aliens or artificial intelligence, all if we don’t destroy ourselves in the meantime since humans only have 1,000 years left on this planet anyway, according to the eminent physicist. Now, it’s time for a new bold claim, one that newspapers were quick to grab onto and strap a doomsday headline.

For his new book, “Starmus”, Hawking relays some of his worries about the elusive God particle in the preface. The Professor wrote:

“The Higgs potential has the worrisome feature that it might become metastable at energies above 100bn gigaelectronvolts,” Hawking writes. “This could mean that the universe could undergo catastrophic vacuum decay, with a bubble of the true vacuum expanding at the speed of light.”

“This could happen at any time and we wouldn’t see it coming.”

 

The God particle, as the Higgs boson is sometimes called, is an elementary particle that is though to grant all fundamental particles mass. Despite being present everywhere and in every thing, these bosons were extremely hard to prove, but the resilience and painstaking efforts of physicists working at CERN eventually paid off when the elusive particle was confirmed to exist. This costeHawking $100 – money that he lost since he bet against the discovery of the Higgs boson.

[ALSO READ] Stephan Hawking: The Big Bang didn’t need god to happen

Ok, but now hold on there. Is Hawking actually putting gas on CERN conspiracy fires? Unlike most of the conspiracy theories that surround the Large Hadron Collider at CERN, ranging from such perils to society as birthing a black hole to building a stargate to awaken the Egyptian god Osiris, Hawiking is actually on to something. He never makes claims like these before doing his due diligence by computing. The only thing the newspapers missed is the 100bn gigaelectronvolts mark. A particle accelerator that can reach this kind of energy would have to be big enough to circle the whole planet. The Large Hadron Collider cost more than $15 billion to build and operate and it’s ‘only’ 17 miles in length.

In other news, the Stephen Hawking biopic, The Theory of Everything, will be out soon and judging from the trailer at least, it should be an interesting viewing. Anyone else excited about the movie?

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China plans to build world’s first super collider

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Photo from inside CERN’s particle accelerator. Photo: Martial Trezzini/epa/Corbis

A group of Chinese physicists, working with international collaborators, have announced their plans of building a  52-kilometre underground particle accelerator that would smash together electrons and positrons to unravel the fundamental building blocks of life. The project would offer means of probing these sort of fundamental questions that are unavailable to the Large Hadron Collider at CERN, an oval-shaped 26km underground tunnel where the famous Higgs boson was confirmed. Physicists say that the proposed US$3-billion machine is within technological grasp and could be ready by 2028. More importantly, however, the upcoming particle accelerator will become the first stepping stone for a much grander and ambitious project – a super collider.

The super collider that never was

European and US teams have both shown interest in building their own super collider, but the huge amount of research needed before such a machine could be built means that the earliest date either can aim for is 2035. In fact, the US planned a building something like this in 1993 – the  Superconducting Super Collider (SSC)  or Desertron, as it was nicknamed, in Texas. Its planned ring circumference was 87.1 kilometres (54.1 mi) with an energy of 20 TeV per proton or 40 TeV collision energy. This would have made it eight times more powerful than the Large Hadron Collider at CERN, but Congress eventually canceled the project after it contested its utility and $2 billion had already been spent.

Now, China is inclined to make this giant leap which will put the country at the very forefront of particle physics, according to the announcement made by the country’s Institute of High Energy Physics. The country wants to  work towards a more immediate goal than a super collider by 2035, however, and in the meantime it plans on building an electron-positron collider, which should allow the Higgs boson to be studied with greater precision than at the much smaller Large Hadron Collider (LHC) at CERN.

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By examining in detail the interactions of the Higgs boson with other particles, the proposed Chinese collider should, for example, be able to detect whether the Higgs is a simple particle or something more exotic. This kind of data will help researchers tell whether the God particle – the fundamental particle thought to be responsible for granting mass to matter – fits within predictions made by the standard model of particle physics, or whether, for example, multiple types of Higgs boson exist.

For China, this is a huge leap forward and some are questioning whether the country wants to bite more than it can chew. China’s largest particle accelerator is only 240 meters long and only ten years ago China’s own physicists would have thought something like this out of reach. The country’s firm economic growth has changed all this and puts it in a position where it can commit to projects other countries can’t even dream of, including the US.

Used to isolation, China plans on building and operating the huge particle accelerator aided by international support, but officials said they don’t plan on waiting – if there isn’t any intention from the international community to help, they’re more than fine with working alone on this. Guido Tonelli, a particle physicist and former head of one of the two major experiments at CERN, says however that China will have to collaborate with the rest of the world if its project is to be a success because of its weakest point – manpower. While making remarkable advances, China’s particle physics community is yet to small to host and operate something as grand as a super collider. At CERN, for instance, physicists from all over the world are working there, including Europe, the US, Japan and, of course, China.

Realistically, only one super collider can be built in the world in the coming decades. As such, the world NEEDS to collaborate to make sure this project finds ist best home and leaders. Physics is not about politics.

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The LHC is gearing up for long-awaited restart

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Photo: LHC @ CERN

The Large Hadron Collider at the European Organization for Nuclear Research (CERN) is the most complex machinery devised by mankind. Here, scientists all over the world joined forces to recreate conditions similar those in the very first moments of the Universe, following the Big Bang. There’s a lot at stake here, and so far the LHC has delivered on some of its promises. In 2013, however, the massive particle accelerator had to be shutdown for maintenance. Today the long process leading to the LHC’s planned full operational restart in 2015 has begun.

LHC: restart

Getting the LHC back online isn’t like oiling up some old machinery then hitting the power button. It’s an incredibly complex system, with large volumes of intricate parts, each needing fine tuning and maintenance to work together as a whole.

“The accelerator complex has to start months before the LHC is back online because it’s going to need some serious TLC (in the form of recommissioning, debugging and tuning) following the shutdown,” LHC operation head Mike Lamont told Symmetry Magazine.

The 27-km long particle accelerator ring at CERN is world famous, but this isn’t where all the magic happens. In fact the facility is comprised of multiple, smaller accelerators all, however, indispensable.  Each of these accelerators ramp up particle energy in steady increments until they’re ready to hit the fan with big boys in the huge, main ring.

[ALSO READ] The LHC can be the world’s first time machine

One such component in this huge daisy-chain is “the source”. Here the reservoir of protons that are prompted to enormous energies first gather, as hydrogen atoms are stripped of this electrons, leaving only the protons behind to be inserted in the accelerator. This source was put back online last Friday. This week, engineers will gear up the  Linac2, the first particle accelerator that gives the “beam” of protons their first boost. Next, the Proton Synchrotron Booster, which has seen some significant improvements since the shutdown.

“When we get the beam going around the booster, it will be a very important moment,” said Paul Collier, the head of the beams department. “Among other things, we are making a complete upgrade of its control system, which is the nervous system of the machine.”

In all, it will take a couple of solid months of fine tuning and tests until each part of the chain is in proper order and the LHC can be put to good use once more. A key question might trouble some of you: what’s all of this for?

LHC: what is it good for?

The benefits coming from huge scientific projects like the LHC are indirect and most commonly overlooked by society. Unlike industrial technical projects, the LHC is mainly at its core a fundamental science project. It’s main mission is to answer important questions surrounding the Universe, so what it brings to the world is knowledge; knowledge that’s not sought after in the interest of making money or offering something practical to society in the short term, like a manufacturing factory or an R&D facility that researchers the next line of consumer products or better oil drills. This doesn’t mean there won’t be any practical, day-to-day benefits, far from it – it’s just that this isn’t an immediate goal for LHC.

[READ] LHC passes hardest test yet: ping-pong blazes through particle accelerator

“Why paying billions to search for a hypothetical particle while we need a cure for cancer?”. If you ask yourself “how does a modern computer CPU work?” you can trace it back to development of the semiconductor diode by German physicist K. F. Braun, in the end of the XIX century. He wasn’t trying to build a computer, not like the ones we see today; the kind you’re reading this article on. So while all of society’s machinery and gadgets are brought by technical innovation and design, ultimately all of this comes from basic and fundamental science.

The internet, GPS, satellites, all of these were introduced following great science projects like the moon race. New fundamental science, like quantum mechanics, had to be understood for all of these innovation to come to life. The same will surely be for the brain children that come off the LHC; the general public only needs to have faith, as those who have pledged the billions that were awarded for its construction and maintenance.

Either way, since it first accelerator its first protons in 2009, the LHC has already achieved more than many had bargained. In 2012, with much acclaim scientists announced the discovery of a new ‘boson’ – the Higgs boson. This is believed to be the elementary subparticle responsible for giving matter mass. It’s a fantastic, ground-breaking find, but of course this isn’t the only one of its kind. Here’s a list of all the hallmark discoveries made by the LHC thus far. Many of these aren’t known to the general public the way the Higgs boson was publicized, but are no less important.

 

 

Nanofabricated chips of fused silica just 3 millimeters long were used to accelerate electrons at a rate 10 times higher than conventional particle accelerator technology. (Brad Plummer/SLAC)

Particle accelerator on a chip demonstrated

Nanofabricated chips of fused silica just 3 millimeters long were used to accelerate electrons at a rate 10 times higher than conventional particle accelerator technology. (Brad Plummer/SLAC)

Nanofabricated chips of fused silica just 3 millimeters long were used to accelerate electrons at a rate 10 times higher than conventional particle accelerator technology. (Brad Plummer/SLAC)

A team of brilliant researchers at  the U.S. Department of Energy’s (DOE) SLAC National Accelerator Laboratory and Stanford University have demonstrated a working particle accelerator, used to accelerate particles like electrons or protons to extremely high energies and probe the Universe’s secrets, which is the size of a typical silicon chip. Typically, particle accelerators range from a few kilometers in length to 27 kilometers – the length of the Large Hadron Collider at CERN, the largest particle accelerator in the world.

The researchers liken their work to the pioneering research in electronics from the early ’50s when the transistor replaced huge vacuum tubes and scaled down computers from room-size to tabletop-size. Bring the particle accelerator to the researchers, instead of the researchers having to come to the particle accelerator. As fascinating and useful the idea is, so were the challenges the SLAC team had to overcome.

A tiny particle accelerator

Accelerators today work by using microwaves to boost the energy of electrons, in a two-phase process. In the first part, particles are accelerated near the speed of light. In the second phase, the particles stop gaining velocity, instead the acceleration increases their energy, not the speed – a highly tricky process.

The key to the accelerator chips is tiny, precisely spaced ridges, which cause the iridescence seen in this close-up photo. (Brad Plummer/SLAC)

The key to the accelerator chips is tiny, precisely spaced ridges, which cause the iridescence seen in this close-up photo. (Brad Plummer/SLAC)

The SLAC and Stanford team went on an alternate route and used high-precision lasers instead of microwaves, which allowed them to scale down their accelerators to the size of a typical chip. In the accelerator-on-a-chip experiment, electrons are accelerated near the speed of light just like in a conventional accelerator. Then comes the novel part: the near light-speed electrons are then focused through a tiny, half-micron channel (millionth of a meter) within a fused silica glass chip just half a millimeter long. The channel is patterned with precisely spaced nanoscale ridges, which when hit by infrared laser light  generates electrical fields that interact with the electrons in the channel to boost their energy.

This initial demonstration achieved an acceleration gradient, or amount of energy gained per length, of 300 million electronvolts per meter. That’s roughly 10 times the acceleration provided by the current SLAC linear accelerator. Using such a system, theoretically, you could match the accelerating power of the 2 mile-long SLAC accelerator with just 100 feet, and deliver a million more electron pulses per second. The researchers say the could scale it down even further.

“Our ultimate goal for this structure is 1 billion electronvolts per meter, and we’re already one-third of the way in our first experiment,” said Stanford Professor Robert Byer, the principal investigator for this research.

The nanoscale patterns of SLAC and Stanford's accelerator on a chip gleam in rainbow colors prior to being assembled and cut into their final forms. (Matt Beardsley/SLAC)

The nanoscale patterns of SLAC and Stanford’s accelerator on a chip gleam in rainbow colors prior to being assembled and cut into their final forms. (Matt Beardsley/SLAC)

New generations of smaller, less expensive devices for science, medicine

The demonstration proves that the system may be employed into powerful, yet compact particle accelerator as discussed. However, applications could go well beyond particle physics research. Laser accelerators could drive compact X-ray free-electron lasers, comparable to SLAC’s Linac Coherent Light Source, that are all-purpose tools for a wide range of research.

“It could also help enable compact accelerators and X-ray devices for security scanning, medical therapy and imaging, and research in biology and materials science,” said Joel England, the SLAC physicist who led the experiments.

This doesn’t mean, pocket-sized particle accelerator will start rolling in. Turning the accelerator on a chip into a full-fledged tabletop accelerator will require a more compact way to get the electrons up to speed before they enter the device.

“We still have a number of challenges before this technology becomes practical for real-world use, but eventually it would substantially reduce the size and cost of future high-energy particle colliders for exploring the world of fundamental particles and forces,” said Joel England.

The achievement was reported in the journal Nature. Find out more how the mini-particle accelerator works by watching the video below.

A three-dimensional view of a p-Pb collision that produced collective flow behavior. The green lines are the trajectories of the sub-atomic particles produced by the collision reconstructed by the CMS tracking system. The red and blue bars represent the energy measured by the instrument's two sets of calorimeters. (CMS Collaboration)

Smallest liquid droplets created at LHC are 100,000th the size of a hydrogen atom

Scientists closely working with the  Large Hadron Collider, the largest and most powerful particle accelerator in the world, have identified evidence of the minuscule droplets produced in the aftermath of high energy proton and lead ions collisions. If their calculations are right, then these are the smallest droplets of liquid ever encountered thus far, just three to five protons in size. That’s about one-100,000th the size of a hydrogen atom or one-100,000,000th the size of a virus. WOW!

“With this discovery, we seem to be seeing the very origin of collective behavior,” said  Julia Velkovska, professor of physics at Vanderbilt who serves as a co-convener of the heavy ion program of the CMS detector, the LHC instrument that made the unexpected discovery. “Regardless of the material that we are using, collisions have to be violent enough to produce about 50 sub-atomic particles before we begin to see collective, flow-like behavior.”

A three-dimensional view of a p-Pb collision that produced collective flow behavior. The green lines are the trajectories of the sub-atomic particles produced by the collision reconstructed by the CMS tracking system. The red and blue bars represent the energy measured by the instrument's two sets of calorimeters. (CMS Collaboration)

A three-dimensional view of a p-Pb collision that produced collective flow behavior. The green lines are the trajectories of the sub-atomic particles produced by the collision reconstructed by the CMS tracking system. The red and blue bars represent the energy measured by the instrument’s two sets of calorimeters. (CMS Collaboration)

These tiny droplets “flow” in a manner similar to the behavior of the quark-gluon plasma, a state of matter that is a mixture of the sub-atomic particles that makes up protons and neutrons and only exists at extreme temperatures and densities. Some scientists claim that at the very dawn of the Universe’s existence shortly after the big bang, this primordial cosmic goo was everywhere, because of much higher temperature and density conditions.

These interactions weren’t actually targeted for observation by the LHC researchers, though. Scientists were looking to check the validity of their lead-lead results, and scheduled a proton-lead ion collision for as a simply control run – they ended up with quark-gluon plasma in the process.

“The proton-lead collisions are something like shooting a bullet through an apple while lead-lead collisions are more like smashing two apples together: A lot more energy is released in the latter,” said Velkovska.

Indeed, last September LHC researchers found that in five percent of the  protons and lead nuclei collisions —those that were the most violent – evidence of collective behavior was encountered. In turn, this allowed for the formation of   liquid droplets about one tenth the size of those produced by the lead-lead or gold-gold collisions.  The data gathered then, however, wasn’t enough to discount the influence of particle jets. New experiments in January and February of this year resulted in hundreds of cases where the collisions produced more than 300 particles flowing together.

According to doctoral student Shengquan Tuo, who recently presented the new results at a workshop held in the European Centre for Theoretical Studies in Nuclear Physics and Related Areas in Trento, Italy, only two models were advanced to explain their observations at the workshop. Of the two, the plasma droplet model seems to fit the observations best.

The new observations are contained in a paper submitted by the CMS collaboration to the journal Physics Letters B and posted on the arXiv preprint server.

[source]

The Large Hadron Collider may have shut down, but physicists are using some unusual techniques to test it, including a ping-pong ball.

LHC passes ‘hardest’ test yet: ping-pong ball blazes through particle accelerator

The Large Hadron Collider may have shut down, but physicists are using some unusual techniques to test it, including a ping-pong ball.

The Large Hadron Collider may have shut down, but physicists are using some unusual techniques to test it, including a ping-pong ball.

How do you check a multi-billion dollar particle accelerator for defects or malfunctions? Sure, you could use various, equally expensive and sophisticated tools, but in some instances low tech comes in the aid of high tech, say a ping-pong ball. Wait, what ?! Yup, today researchers  sent a carefully sterilized, slightly-smaller-than-regulation ping-pong ball through a 2-mile section of the Large Hadron Collider. The LHC passed the ping-pong ball test flawlessly.

The ping-pong-ball is actually called a radio-frequency ball by scientists and holds a tiny transmitter inside. To blaze it through the particle accelerator,  simple force of suction is used, ping its position every third of a mile through its transmitter.

“The beam pipes are fragile,” says Vincent Baglin, the leader of the LHC beam vacuum section at CERN. “We always have to check and crosscheck to minimize any problems. This is a simple test that can prevent complicated issues.”

What they were actually looking to test are the connections between magnets, which are at risk of deterioration as temperature changes since they’re installed at room temperature, but need to operate below freezing when experiments are made. The LHC has 17 miles in circumference, but it’s not entirely circular; instead, it’s made out of eight straight sections, joined together by eight arcs.  More than 1600 magnets bend and focus the beams of particles that circle the collider at close to the speed of light. Interconnections, some of which resemble long, copper fingers, ensure that electricity flows from one magnet to the next.

This rather significant temperature difference causes these copper fingers to contract, typically by 40 millimeters, which isn’t necessarily a problem, but sometimes one or more of these fingers buckles and blocks particle beams. Since there are so many interconnections, if a problem arises, the researchers would have to start and shutdown the LHC repeatedly and find where the beam is blocked – a process which might take months. Instead, the scientists have opted for a more ingenious solution that only takes 15 minutes per section.  Rather than sending a beam through the pipe, they send the RF ball. How do they know if a connection is out of order? Simple, if the ball gets stuck, then we’ve got a problem.

For today’s test, the LHC passed without any issues, however it will pass through many such tests and others before its scheduled restart in 2015.

via Symmetry Mag

 

Elementary particles predicted by the Standard Model and discovered that make up the Universe. (C) AAAS

Higgs boson discovery confirmed after CERN scientists reviewed massive LHC data

The science of physics has entered a new era once with the discovery of the much sought-after Higgs boson in July 2012. The elementary particle thought to be responsible for granting matter its mass has been theorized for decades, but only with the deployment of the multi-billion Large Hadron Collider in Geneva could such a quest commence. Years of hard work, painstaking analysis, and a fine eye for detail have paid off eventually. Mixed emotions tried the team of researchers that headed the Higgs boson experiments after the monumental findings – what if they were wrong? Recently, an international panel of scientists has confirmed and cemented the discovery of the boson that has eluded physicists for all these years, after they reviewed massive amounts of data in the wake of the find.

The Higgs boson was first theorized in 1964 what of the need to fill in gaps in our understanding of the Universe. The particle was named for Peter Higgs, one of the physicists who proposed its existence, but it later became popularly known as the “God particle,” since its believed it grants all particles, and thus all matter, with size, shape, and mass.

“The preliminary results with the full 2012 data set are magnificent and to me it is clear that we are dealing with a Higgs boson, though we still have a long way to go to know what kind of Higgs boson it is,” said Joe Incandela, a physicist who heads one of the two main teams at CERN, each involving several thousand scientists.

Elementary particles predicted by the Standard Model and discovered that make up the Universe. (C) AAAS

Elementary particles predicted by the Standard Model and discovered make up the Universe. (C) AAAS

In order to confirm its existence and learn more about the subatomic particles, both the Atlas and CMS teams went through and analyzed more than two and a half more data than they had at their disposal when they first announced they had come across a particle that is very Higgs-like. The most important properties of a subatomic particle are considered to be it spin and parity.

“Now we’ve got more precise questions: is this particle a Higgs boson, and if so, is it one compatible with the Standard Model?” said Tony Weidberg, Oxford University physicist and a collaborator on the Atlas experiment.

At the  Moriond conference in Italy, scientists at CERN reported that their entire data sets from 2011 and 2012 strongly suggest that the new found particle’s spin is zero, making it the first elementary particle with such a property. Luckily, the finds are on par with Standard Model of Physics predictions so far. Another theory of physics however, called supersymmetry, predicts that in fact a number of various and different Higgs bosons exists.

“The preliminary results with the full 2012 data set are magnificent and to me it is clear that we are dealing with a Higgs boson, though we still have a long way to go to know what kind of Higgs boson it is,” said  Incandela.

This will require even more data and experiments to determine. Considering the LHC is slated for a two year shut down for maintenance, it might take a while.

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Higgs boson might be a twin particle, contradictory measurements suggest

The discovery of the Higgs boson is the most monumental find in physics of the year and possibility since the turn of the new century. Also known as the God particle, the Higgs boson is an elemental particle believed to be responsible for infusing all matter with mass. It’s been theorized for 50 years, but only after the technology was sufficiently advanced to prove or disprove its existence was the Higgs boson finally sealed this July, when the ATLAS team at CERN – the site of the Large Hadron Collider, the pinnacle of human science – finally found proof. Since then, however, more and more data has pilled up and a puzzling discrepancy in measurements is currently hinting towards two different Higgs masses. Perplexed scientists aren’t yet sure of these are simple statistical glitches or whether in fact, we can discuss the possibility of two different Higgs bosons.

To find the Higgs boson, physicists at CERN smashed protons at enormous energies, which caused a slew of particles to form and splatter like shrapnel. Among this shrapnel, sometimes the Higgs boson would surface – only in a few collisions out of millions or billions, though – before it would almost instantaneously decay into another particle. The Higgs can be detected in two way or two pathways: One channel decays into two characteristic photons while another creates four particles known as leptons. Each path offers a value of mass, however, the two are different. Although the discrepancy is just slight, nevertheless it shouldn’t be present at all.

The first pathway rends a mass of 123.5 GeV (giga-electron volts), the other at 126.5 GeV or 126 times the mass of a proton. Some physicists explain this peculiar phenomenon by inferring we’re simply dealing with two different Higgs bosons, each with a very similar mass, or that the difference in masses is due to a “systematic error”.

Higgs boson - twins

The blue plot shows 123.5 GeV signal, red shows 126.5 GeV signal. Source: CERN

“There turns out to be a slight tension between the two masses,” said physicist Beate Heinemann of the University of California, Berkeley, who works on ATLAS, one of the LHC’s Higgs-searching experiments. “They are compatible, just not super compatible.”

Like I said, earlier, you need billions of collisions to wind up with a few Higgs boson measurements. Heinemann said the four lepton channel has only analyzed about 10 Higgs bosons and the two-photon channel about 500 Higgs. Physicists need to see the same result over and over in thousands or even millions of particle events before they are sure it’s not just a statistical coincidence. “The most likely explanation is that it’s one particle,” said Heinemann. The Standard Model of Physics, the current framework used to describe all particle interactions, doesn’t rule out a pair of Higgs however. Any of the two scenarios are possible, then.

Scientists prepare a superconducting cavity for a test in Fermilab's Vertical Test Stand. (Courtesy Fermilab Visual Media Services)

Japan is lead candidate for hosting the next high energy particle smasher – the International Linear Collider

The Geneva based Large Hadron Collider has gobbled a lot of cash and resource in order to become operational, but through the constant fantastic results that has advanced particle physics understanding greatly, which couldn’t have been possible otherwise, it has definitely shown its value. The next generation of particle smasher is apparently destined for Japan, so far the only possible host for the planned  International Linear Collider (ILC). The collider will able to smash particles with enormous energy in order to break them apart and study their sub-particle constituents, complementing the more potent LHC.

Scientists prepare a superconducting cavity for a test in Fermilab's Vertical Test Stand. (Courtesy Fermilab Visual Media Services)

Scientists prepare a superconducting cavity for a test in Fermilab’s Vertical Test Stand. (Courtesy Fermilab Visual Media Services)

The current blueprint has the huge collider shaped as 31-kilometer-long track that will be capable of accelerating particles with energies of up to 500 gigaelectronvolts along its superconducting cavities before smashing them together for study. Heavy particles that offer glimpses into the very first moments after the Big Bang are then formed for very short periods of time before decaying.  The LHC, though it has a smaller runway of 27 kilometers, is capable of accelerating particles at a designed capacity of 14 terraelectronvolts – almost 30 times as much as the intended ILC.

The ILC however is intended to study other types of particle collisions. While the LHC collides  protons – comprised of multiple constitutive elements like quarks that splatter all over and disrupt accurate data reading – the ILC would use electrons and anti-electrons, which are fundamental particles and would give a much cleaner Higgs signal. This year, scientists at CERN confirmed the existence of the Higgs boson in a celebrated event for science. The ILC will further shape a better picture of the elusive particle, that would otherwise not be possible.

No easy task, but local support is strong

It’s enormously expensive, though, with a projected development cost of $7 billion to $8 billion. In an economic recession, these figures aren’t very encouraging. Even the final touches to the design of the ILC – which unlike the LHC will be deployed ground side with a large portion of the accelerator track set to be deployed in the mountainside, where heavy bore drilling will take place – were under danger of not being completed because of lack of funding. International support is thus indispensable for this project to kick start soon. Currently two sites have been proposed: one in the Tohoku region that was struck by the tsunami and the other in Kyushu, in the south of the country.

This begs a different question. Last year the country was plagued by a vicious tsunami that cost the lives of thousands and caused tens of billions in damage. Remarkably, the nation recovered phenomenally and handled the whole situation exemplary, however will the world’s governments agree on placing such an important and complex instrument in a country that’s subjected to a high risk of earthquakes and tsunamis? “Both sites would be excellent sites for an accelerator,” Barry Barish, the head of the global design effort for the ILC.

The country has never attempted a scientific global project of such magnitude, however government support is almost unanimous. Competitors aren’t really a reality, since the LHC is busy studying data that will keep them occupied for years and years ahead. The US might be the only other possible candidate. Its main particle physics program, the neutrino centered Fermilab in Batavia, Illinois, however is facing massive budget cuts.

“We need to have an expression of interest from other scientific communities around the world to persuade the government to go forward,” adds Yasuhiro Okada, a trustee at KEK, Japan’s particle-physics laboratory in Tsukuba.

If a global consensus can be reached within the next three years, construction could begin in Japan by the end of the decade. “It’s either Japan or it’s going to be on the shelf for a while,” Barish warns.

via Nature

A proton collides with a lead nucleus, sending a shower of particles through the CMS detector. (c) CERN

LHC finds new type of matter after proton-lead collision

A proton collides with a lead nucleus, sending a shower of particles through the CMS detector.  (c) CERN

A proton collides with a lead nucleus, sending a shower of particles through the CMS detector. (c) CERN

After the Large Hadron Collider‘s monumental find of the Higgs boson, the scientists in Geneva might have made new breakthrough finding. Scientists working with the  Compact Muon Solenoid, one of the two major-magnet particle detectors in the LHC, have discovered a new form of matter  known as color-glass condensate after studying proton-lead high speed collisions.

The Large Hadron Collider was designed to accelerate particles at near-light speed velocities and collide them at tremendous amounts of energy, in order for them to garner more mass. This allows for more “shrapnel” made out of sub-atomic particles to be discarded, in which scientists are extremely interested. By studying collision behavior between various kinds of particles, the scientists can recreate the conditions of the universe in the few micro-moments immediately following the Big Bang, and thus test out theories.

The resulting sub-atomic particles, usually fly about in all directions, but in some cases, a few in thousands, some of these particles fly away from each other with their respective directions correlated. This has been seen before in the case of proton-proton interactions, as well as other ion-heavy collisions like those between the nuclei of heavy metals like lead. Now, scientists working  with the Compact Muon Solenoid (CMS) team at the LHC found  the same effects in a sample of 2 million lead-proton collisions.

“Somehow they fly at the same direction even though it’s not clear how they can communicate their direction with one another. That has surprised many people, including us,” says MIT physics professor Gunther Roland, whose group led the analysis of the collision data along with Wei Li, a former MIT postdoc who is now an assistant professor at Rice University.

The data was taken after only four hour of operation at little more than half the  particle accelerator’s  full capacity. It has been theorized that proton-proton collisions may produce a liquid-like wave of gluons, known as color-glass condensate. The researchers believe that the same swarm of gluons might have also produced the same unusual collision pattern seen in proton-lead.  Why is this important? Well, for one these results were far from being expected. The researchers only introduced a proton-lead collision experiment in order to build control data for proton-proton collisions. Every bit of information that leads to a better understanding of how particles and sub-atomic particles interact is of great value, and this latest discovery makes no exception.

The LHC had only just begun colliding these two types of particles together in September, so the surprising results are doubly impressive. The scientists currently have planed another run of collisions within a few weeks to see if the findings are replicated.

The findings were reported in the journal Physical Review B

source: MIT News

What’s next for the Large Hadron Collider?

With the Higgs Boson being arguably found, what could be in store for the Large Hadron Collider? Many, many things. Steven Cherry for IEEE Spectrum’s “Techwise Conversations” discussed the matter with Rachel Courtland and professor Matt Strassler. Really interesting discussion, both for those with no physics knowledge, and for the particle aficionados.

quarks make protons

Hottest temperature on Earth reached after scientists create quark-gluon particle soup

quarks make protonsNot one, but two independent high-energy particle physics laboratories in New York (Relativistic Heavy Ion Collider – RHIC) and Geneva ( Large Hadron Collider – LHC) have managed to create quark-gluon plasma after smashing particles into another at very high speeds. The resulting plasma, which only lasted for a fraction of a moment,  is the hottest matter ever recorded – somewhere between 4 trillion and 6 trillion degrees Celsius.

“We now have created matter in a unique state, composed of quarks and gluons that have been liberated from inside protons and neutrons,” said Steven Vigdor, a physicist at Brookhaven National Laboratory, which hosts the RHIC.

Any proton or neutron, the building blocks of an atom, is made out of three quarks bound together by gluons, which are mass-less and hold the quarks together like a sort of glue. After colliding lead ions at extremely high velocities, a quark–gluon plasma was created, denser than a neutron star and the hottest man-made matter ever. This subatomic soup and unique state of matter is thought to have existed just moments after the Big Bang. Evidently, better understanding this incipient phase of the Universe would help unravel a number of secrets.

The ALICE heavy-ion experiment at CERN. (c) CERN

The ALICE heavy-ion experiment at CERN. (c) CERN

Scientists theorize that during a similar state to the one experimented by scientists at both RHIC and CERN, quarks and gluons would have combined to form protons and neutrons, which would have grouped with electrons a while later to form atoms. Eventually, this would latter on form cosmic dust, gas and lead to the birth of cosmic bodies like stars, galaxies and so on.

Concerning the exact temperature at which the matter was recorded, things aren’t exactly certain yet. One can imagine, keeping in mind the extremely fast decay time and record breaking temperature levels, that measuring such an experiment requires technology and innovation at the forefront of science. Spokesmen from ALICE,  a heavy-ion experiment and a lesser-known sibling to ATLAS (one of the teams which announced the Higgs boson discovery), say their data shows  an estimated 5.5 trillion degrees measured temperature or 100,000 times hotter than the center of the sun.  “It’s a very delicate measurement,” Paolo Giubellino, Alike spokesman says. “Give us a few weeks and it will be out.”

If you’re curious as to what’s the maximum possible temperature, well it is believed to be 1.416833(85) x 1032 Kelvin degrees, and at temperatures above it, the laws of physics just cease to exist

Brookhaven’s Relativistic Heavy Ion Collider (RHIC) have been studying the plasma from 2005, around the time when the first experiments were conducted. In terms of properties, they found that the plasma behaves like perfect, frictionless liquids. Meaning zero viscosity – no friction! This plasma is also extremely dense, with particles packed in more tightly than neutron stars.

“We do have now the tools in place to really experiment with it …and figure out precisely what kind of stuff this really is and why it has these extraordinary properties,” said Jurgen Schukraft, a physicist at the CERN physics lab in Geneva, home of the LHC.

Findings were published in Nature.

Transition Radiation Detector determines highest-energy particle velocities Silicon Trackers follow particle paths; how they bend reveals their charge Permanent Magnet is core component of AMS and makes particles curve Time-of-flight Counters determine lowest-energy particle velocities Star Trackers scan star fields to establish AMS's orientation in space Cerenkov Detector makes accurate velocity measurements of fast particles Electromagnetic Calorimeter measures energy of impacting particles Anti-coincidence Counter filters signal from unwanted side particles

ISS’s Alpha Magnetic Spectrometer is like an LHC in space – already boasting fantastic results

Alright, the analogy might not be the best. The Large Hadron Collider is a high energy particle accelerator, while the Alpha Magnetic Spectrometer is a state of the art particle detector, which traps high-energy charged particles called cosmic rays and analyzes them. You see, the AMS can practically perform the same functions as the LHC, only the high energy particles don’t need to be created – they’re harvested from nature, detecting high-energy particles “from the source”, which might eventually lead to tantalizing signs of dark energy or dark matter. In many respects, the AMS is better for science than the LHC, despite both are currently indisputable and dependent from one another.

The Alpha Magnetic Spectrometer, as a project, has been in the works for nearly two decades. After a number of delays, budget cuts and the likes, the seven-tonne giant was launched into space about Endeavour, the last shuttle mission, where it docked with the ISS as module some 18 months ago.

“It took more than 35 missions to build the International Space Station – very complicated space shuttle flights – to construct this incredible laboratory in space,” said Endeavour mission commander Mark Kelly told

“When we installed AMS, that was the last piece of the ISS, then the space station was complete. This is really the pinnacle of the science that ISS will do, in my opinion the most significant experiment we have on board.”

AMS – the pinnacle of space science

In fact the AMS was the last planned part of the International Space Station, making it fully complete after many years and resources invested. Last but not least, that is, as the AMS is the largest and most important experiment in space ever. Since it went into operation, the AMS has so far gathered some 18 billion “cosmic ray”; some of these might hold the key to unraveling the Universe’s mysteries.

Transition Radiation Detector determines highest-energy particle velocities  Silicon Trackers follow particle paths; how they bend reveals their charge  Permanent Magnet is core component of AMS and makes particles curve  Time-of-flight Counters determine lowest-energy particle velocities  Star Trackers scan star fields to establish AMS's orientation in space  Cerenkov Detector makes accurate velocity measurements of fast particles  Electromagnetic Calorimeter measures energy of impacting particles  Anti-coincidence Counter filters signal from unwanted side particles

Transition Radiation Detector determines highest-energy particle velocities
Silicon Trackers follow particle paths; how they bend reveals their charge
Permanent Magnet is core component of AMS and makes particles curve
Time-of-flight Counters determine lowest-energy particle velocities
Star Trackers scan star fields to establish AMS’s orientation in space
Cerenkov Detector makes accurate velocity measurements of fast particles
Electromagnetic Calorimeter measures energy of impacting particles
Anti-coincidence Counter filters signal from unwanted side particles

The team has already noted an excess of extremely high-energy positrons – the antimatter equivalent of electrons – and atomic nuclei at 9 teraelectronvolts (TeV) – higher even than the LHC can produce. The scientists involved in the project, however, aren’t too quick on publishing hasty results. The AMS collects hundreds of times per second, and a team of scientists at CERN is constantly monitoring particles 24/7 in shifts. So far, only a few percent of the data has been analyzed.

I have told my collaborators that in the next 40-50 years it is very unlikely people will be so foolish as to repeat this experiment, given the difficulty I ran into,” said Nobel laureate Sam Ting of the Massachusetts Institute of Technology (MIT) has led the project since its inception some 17 years ago.

“Therefore it’s extremely important when we publish a result, we publish it correctly, because otherwise you’ll certainly mislead physics and there’s no way to check us.”

Indeed, news from the AMS should be really interesting to follow in the coming years.

source: BBC