Posts Tagged ‘CERN

François Englert, The formula of the universe

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Nobel laureate François Englert at CERN last week. The equation on the blackboard describes the Brout-Englert-Higgs mechanism that gives particles mass (Image: Maximilien Brice)

Nobel laureate François Englert at CERN last week. The equation on the blackboard describes the Brout-Englert-Higgs mechanism that gives particles mass (Image: Maximilien Brice)

A Nobel laureate and a blackboard at CERN is all you need to explain the fundamental physics of the universe. At least, that’s what François Englert convinced us on his visit to CERN last week.
Englert shared the 2013 Nobel prize in physics with Peter Higgs “for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles”. In the video below, he explains how he and Higgs manipulated equations containing mathematical constructs called scalar fields to predict the existence of the Brout-Englert-Higgs field.

Nobel laureate François Englert explains the Brout-Englert-Higgs mechanism that gives particles mass, with the help of a blackboard (Video: CERN)

According to Englert, the equation describing this mechanism is built in two parts. One part consists of scalar fields; the other consists of constructs called gauge fields. Englert explains that a big problem in particle physics in the 1960s was to find a gauge field that had mass. Solving that problem – working out how a gauge field could have mass -would help to explain other problems in physics, such as how to mathematically describe short-range interactions inside the nuclei of atoms. But Englert says that you cannot easily just add mass to a gauge field “off-hand”. He needed another theoretical approach.
The key was to add a new part – a new scalar field – to the equation describing the mass mechanism. Part of this new scalar field could be mathematically simplified. What came out of the algebraic manipulation was a term that gave rise to “a condensate spread out all over the universe”. Then, the interaction between the condensate and another part of the equation could be generalized, says Englert, to give mass to elementary particles. Easy peasy!
“I know this is extremely abstract,” says a modest Englert of his explanation. “But if I have two minutes [to explain it], I can hardly do more!”


Written by physicsgg

March 2, 2014 at 11:21 am

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CERN Underground in 3D

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lhcA fifteen-minute stereoscopic 3D virtual tour of the CERN Large Hadron Collider (LHC) and its four main experiments – ATLAS, ALICE, CMS and LHCb. Filmed for and shown during the 2013 CERN Open Days

To enjoy the full 3D experience of this video, either use red/blue 3D glasses, or go to the “Settings” icon (in the shape of a cog) at the lower-right of the player and select one of the many 3D viewing options.

Written by physicsgg

January 4, 2014 at 11:12 am

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Atom smashing at CERN – what does it mean to us?

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Science has rarely seduced so many. CERN’s atom smashing Large Hadron Collider has had the world transfixed and probably, for the first time in history, turned a particle into a global celebrity. Last year scientists sent shockwaves around the world when they announced the discovery of the Higgs Boson. But that was only one, albeit important step, in a long quest.

To discuss what is going on at CERN, as well as other issues, I -talk’s Isabelle Kumar is joined by Fabiola Gianotti, one of the lead scientists at CERN.

euronews: “Fabiola Gianotti, thank you for joining us on I-talk. For our viewers who may need a reminder, in a nutshell, can you tell us what the Higgs Boson is?”

Fabiola Gianotti: “The Higgs Boson is a very special particle because it allows us to understand how other elementary particles, like the electron – that we all know because it’s part of our daily lives – acquire a mass. It seems that it might not be relevant to our everyday lives, that is is quite an abstract question, but in fact it is not. Because if the elementary particles, such as the electron itself and the quarks – which are the fundamental constituents of atoms – did not have mass, the world and the universe would not be what it is. The universe would not exist or perhaps it would exist in another form.”

euronews: “Right now we’re going to go to our first question which comes from Belgium.”

Pauline, Belgium: “Hello, I’d like to know why the discovery of the Higgs Boson particle is so important?”

euronews: “So, you’ve been chasing this Higgs Boson for years. Why is it so significant, particularly to the scientific world?”

Gianotti “The discovery is really crucial for our understanding of fundamental physics and also for the structural evolution of the universe. We now understand how it is possible for some particles to have a mass while others remain without mass. And this is very important to understand the basic fundamental shape of matter. If the elementary particles did not have the mass they have, then atoms wouldn’t exist. There would be no chemical elements, no chemistry, and the universe would be very different or perhaps wouldn’t exist at all.”

euronews: “Given that our audience is mostly non-scientific based, could you give us an everyday example of how Higgs Boson changes our lives?”

Gianotti “Well, we know that the universe, this room, everything around you; is permeated by the Higgs Boson field. If this was not the case, then we wouldn’t exist because the electrons and the quartz, which are the constituents of the atom of which we are made, would not stick together.”

euronews: “Which is why it’s called the ‘God’ particle…”

Gianotti “Well, this is not really a definition that scientists like; but clearly it’s a key particle. It’s a key particle in understanding our own existence, the evolution of the universe and perhaps its future.”

euronews: “Once again, in simple terms, the Large Hadron Collider is being revamped. What’s going on?”

Gianotti “After three years of extremely successful operation, the LHC is being shut down for two years so we’re going to start again in 2015 with higher energy and higher intensity of the colliding beams. This should allow us to make other very revolutionary discoveries and other important measurements.”

euronews: “We’re going to go to our next question which takes us to Portugal.”

Mafalda, Lisbon, Portugal: “I’d like to know what you think the next scientific discovery will be?”

euronews: “So, what do you think will be the next significant discovery?”

Gianotti: “It’s very difficult to tell. Actually, research means we don’t know what we’re going to find otherwise it would not be research. For a scientist, as I am, finding something totally unexpected is the best possible reward for our hard work.

“For me, the most exciting result to come from the LHC in the future would be the discovery of the particle which is the constituent of dark matter which accounts for about 20 percent of the energy matter contained in the universe. This would be a revolutionary discovery.”

euronews: “Why would that be revolutionary?”

Gianotti “Today, we only know five percent of the universe’s composition, meaning that only five percent of the universe is made from ordinary matter – the matter of which we are made – atoms. The rest, 95 percent, is made from a form of energy and matter that we don’t know; and for this reason also they are called dark energy and dark matter. 20 percent is made from dark matter, so – clearly, discovering the particle that will allow us to explain 20 percent of the universe will improve our knowledge from five percent to 25 percent, that is obviously revolutionary.”

euronews: “The work at CERN is very sci-fi, how important is creativity and fantasy to your work?”

Gianotti “Creativity and fantasy are very important in science. Science and research progress thanks to revolutionary ideas that allow us to make important steps forward. There is a lot of technology, and routine work, as there is in all jobs and activities. However in research, ideas, innovation and intuition are extremely important.”

euronews: “We are going to go to our last question which comes from France.”

Julie, France: “It seems as though science is quite fashionable at the moment, does this change the way you work at CERN?”

euronews: “So do you think science has become trendy?”

Gianotti “I think so and I am very pleased about it, because knowledge is mankind’s wealth – knowledge belongs to everyone. It is the duty and right of human beings, as clever beings, to develop our knowledge of the universe and of matter.”

euronews: “As the work that’s going on at CERN has become better known, there have been downsides, because CERN has faced legal action in terms of people being scared of what is going on there. People fear that the work is going to create some sort of black hole. What do you say to those people?”

Gianotti: “Well remember three years ago when the LHC started up operation and people were panicking and claiming that it would destroy the world? It didn’t happen. The reason is very simple, no accelerator on earth will ever achieve the same energy and intensity as the collisions of cosmic rays which surround us in outer space. These cosmic ray collisions have not destroyed earth, so there is nothing to fear at all.”

euronews: “Fabiola Gianotti many thanks for joining us on I-talk. Thats all for this edition. Do send us your comments and questions either on the I-talk website page or on euronews’ social media pages. From the European Parliament studios in Brussels, I’m Isabelle Kumar.”


Written by physicsgg

July 21, 2013 at 2:38 pm

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Forty years of neutral currents

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The first example of a single-electron neutral current. An incoming antineutrino knocks an electron forwards (towards the left), creating a characteristic electronic shower with electron–positron pairs (Image: Gargamelle/CERN)

The first example of a single-electron neutral current. An incoming antineutrino knocks an electron forwards (towards the left), creating a characteristic electronic shower with electron–positron pairs (Image: Gargamelle/CERN)

Forty years ago today, physicists working with the Gargamelle bubble chamber at CERN presented the first direct evidence of the weak neutral current. The result led to the discovery of the W and Z bosons, which carry the weak force – and ultimately to that of aHiggs boson announced last year.

Gargamelle was a bubble chamber at CERN designed to detect neutrinos. It was 4.8 metres long and 2 metres in diameter, weighed 1000 tonnes and held nearly 12 cubic metres of heavy-liquid freon (CF3Br).

In a seminar at CERN on 19 July 1973, Paul Musset of the Gargamelle collaboration presented the first direct evidence of the weak neutral current – a process predicted in the mid-1960s independently by Sheldon Glashow, Abdus Salam and Steven Weinberg – that required the existence of a neutral particle to carry the weak fundamental force. This particle, called the Z boson, and the associated weak neutral currents, were predicted by electroweak theory, according to which the weak force and the electromagnetic force are different versions of the same force.

The discovery involved the search for two types of events: one involved the interaction of a neutrino with an electron in the liquid, while in the other the neutrino scattered from a hadron (proton or neutron).  In the latter case, the signature of a neutral current event was an isolated vertex from which only hadrons were produced. By July 1973 the team had confirmed as many as 166 hadronic events, and one electron event. In both cases, the neutrino enters invisibly, interacts and then moves on, again invisibly.

Paul Musset presented the results of both hadronic and leptonic analyses at the seminar at CERN. The paper on the electron event had already been received by Physics Letters on 2 July (F J Hasert et al. 1973a); the paper on the hadronic events followed on 23 July (F J Hasert et al. 1973b). They were published together in the same issue of the journal on 3 September.

The discovery of weak neutral currents was a significant step toward the unification of electromagnetism and the weak force into the electroweak force.

In 1983, the UA1 and UA2 experiments at CERN confirmed the existence of the W and Z particles predicted by the theory of neutral currents.
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Written by physicsgg

July 19, 2013 at 3:17 pm

Posted in High Energy Physics

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Future LHC super-magnets pass muster

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Scientists in the US LHC Accelerator Research Program have successfully tested superconducting magnets needed to increase LHC collisions tenfold.

Courtesy of: Dan Cheng, Helene Felice

Courtesy of: Dan Cheng, Helene Felice

by Kelly Izlar

In the past four years, scientists at the Large Hadron Collider have accomplished unprecedented feats of physics, all with their particle accelerator working at half its design capacity.

The future is looking even brighter, literally.

Last week the US LHC Accelerator Research Program, or LARP, successfully tested a new type of magnet required to boost the power of the LHC—or the luminosity of its particle beams—by a factor of 10.

LARP is a collaboration among the US Department of Energy’s Brookhaven, Fermi, Lawrence Berkeley and SLAC national laboratories, working in partnership with CERN.

The improved magnets are one of the most critical components in a series of LHC upgrades that will be implemented over the next ten years. In the accelerator, magnets squeeze and focus beams of charged particles, directing them to a point of high-energy collision inside a detector. The new magnets, along with other upgrades, will allow the LHC to collect a larger amount of data at higher energies, making it possible to search for more massive potentially hidden particles than ever before.

Lucio Rossi, leader of the high luminosity project at CERN, says the improved LHC could illuminate unexplored corners of physics.

If you enter a dark room with only a candle, the room will be dim, and the candle will soon burn out, he says. But if you have a high-powered flashlight, not only can you see more of the room, but you also have enough time to get a good look around.

“Thanks to this magnet, we will have more collisions, more statistics and more rare events,” Rossi says. “If there is physics beyond the Standard Model, these magnets will shed light on it.”

Like the magnets that currently steer particles through the LHC, the new magnets are superconducting. A superconductor is a material that allows electric current to flow without resistance, creating a strong magnetic field.

The current LHC magnets are made of a metal alloy called niobium titanium. While they have performed remarkably well, there’s a limit to the amount of magnetic field they can sustain—and they’ve gone almost as far as they can go.

For the LHC to continue pushing the boundaries of high-energy physics, physicists plan to switch to magnets made out of niobium tin. Niobium tin has a greater tolerance to heat than niobium titanium, which means it has a larger window of superconductivity and can sustain a higher magnetic field longer.

However, there’s a catch; although niobium tin is a better superconducting material, it’s brittle and sensitive to strain.

“Think of a steel wire you would use for home repairs,” says Berkeley Lab’s GianLuca Sabbi, who directed the development of the new magnets. “You can bend it, and it won’t break. This is the case for niobium titanium, but niobium tin is more like glass.”

This presents some serious technical challenges because making a traditional superconducting magnet requires drawing the alloy into thin wires, gathering those wires into high current cables and then tightly winding them into an accelerator coil. If scientists took these steps, niobium tin would shatter.

US LHC Accelerator Research Program scientists get around this issue by following a clever recipe. First, they coil the “raw” ingredients of niobium tin—the metals that combine to create it—and then put the whole device into a special furnace for a high temperature heat treatment, which melds the components into a superconductor with the desired shape already intact.

At this point, it becomes sensitive to strain, so the scientists fill all the gaps and voids with an epoxy, which glues the brittle material together, providing the support the fragile wires need to withstand the harsh environment of the LHC.

The new technology has applications beyond high-energy physics. Plans are already in motion to incorporate these magnets into medical practices such as imaging and cancer treatment.

As the LHC continues to be streamlined, physicists hope to see further beyond the veil, piecing together the truth behind dark matter, dark energy, extra dimensions and other mysteries. At this scale of luminosity, previously undiscovered particles may even begin to appear.
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Written by physicsgg

July 12, 2013 at 5:14 pm

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Twenty years of a free, open web

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On 30 April 1993 CERN published a statement that made World Wide Web technology available on a royalty free basis, allowing the web to flourish

Screenshot of the original NeXT web browser in 1993

Screenshot of the original NeXT web browser in 1993

On 30 April 1993 CERN published a statement that made World Wide Web (“W3”, or simply “the web”) technology available on a royalty-free basis. By making the software required to run a web server freely available, along with a basic browser and a library of code, the web was allowed to flourish.

British physicist Tim Berners-Lee invented the web at CERN in 1989. The project, which Berners-Lee named “World Wide Web”, was originally conceived and developed to meet the demand for information sharing between physicists in universities and institutes around the world.

Other information retrieval systems that used the internet – such as WAIS and Gopher – were available at the time, but the web’s simplicity along with the fact that the technology was royalty free led to its rapid adoption and development.

“There is no sector of society that has not been transformed by the invention, in a physics laboratory, of the web”, says Rolf Heuer, CERN Director-General. “From research to business and education, the web has been reshaping the way we communicate, work, innovate and live. The web is a powerful example of the way that basic research benefits humankind.”

The first website at CERN – and in the world – was dedicated to the World Wide Web project itself and was hosted on Berners-Lee’s NeXT computer. The website described the basic features of the web; how to access other people’s documents and how to set up your own server. Although the NeXT machine – the original web server – is still at CERN, sadly the world’s first website is no longer online at its original address.

To mark the anniversary of the publication of the document that made web technology free for everyone to use, CERN is starting a project to restore the first website and to preserve the digital assets that are associated with the birth of the web. To learn more about the project and the first website, visit

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Written by physicsgg

April 30, 2013 at 10:39 am


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LHC upgrade to open up ‘new realm of particle physics’

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lhcEngineers have begun a major upgrade of the Large Hadron Collider (LHC).

Their work should double the energy of what’s already the most powerful particle accelerator in the world.

BBC News is the first to be allowed to see inside the LHC – on the French-Swiss border – to watch the work being carried out.

Scientists believe the upgrade will enable them to discover new particles which will lead to a more complete theory of how the Universe works.

A project leader with the LHC’s Atlas experiment, Dr Pippa Wells told BBC News that there was much more to come from the LHC.

“The past two years have been the most exciting in my time as a particle physicist. People are absolutely fired up. They’ve made one new discovery (the Higgs) and they want to make more discoveries with the new high energies that the upgrade will give us. We could find a new realm of particle physics”.

I was taken by the technical coordinator for the upgrade project, Katy Foraz and Cern’s UK communications manager Stephanie Hills, to one of the many access points to the LHC’s underground tunnels….

How the Large Hadron Collider is being repaired

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April 2, 2013 at 1:29 pm

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Physicists unveil plans for ‘LEP3’ collider at CERN

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A group of physicists from Switzerland, Japan, Russia, US and the UK has proposed using the tunnel that currently houses the Large Hadron Collider (LHC) at the CERN particle-physics lab near Geneva for a dedicated machine to study the Higgs boson. The facility, dubbed LEP3, is named after CERN’s previous accelerator, the Large Electron–Positron Collider (LEP), which used to exist in the LHC tunnel before being shut down in 2000. In a preliminary study submitted to the European Strategy Preparatory Group, LEP3’s backers say that the machine could be constructed within the next 10 years.
The plans for LEP3 come just weeks after physicists working at CERN reported that they had discovered a new particle that bears a striking resemblance to a Higgs boson, as described by the Standard Model of particle physics. The ATLAS experiment measured its mass at around 125 GeV and the CMS experiment at 126 GeV.
LEP3 would operate at 240 GeV and comprise two separate accelerator rings that would smash electrons and positrons rather than protons and protons, as with the LHC. In their study, the 20 authors call the concept for LEP3 “highly interesting” and that it deserves more detailed study. “Now is the right moment to get this on the table,” says theorist John Ellis from Kings College London in the UK, who is an author of the preliminary study and hopes that it will trigger debate among physicists as to how to study the new boson in detail.
Tunnel vision
LEP3 is designed to be installed in the LHC tunnel and serve the two LHC’s general-purpose detectors – ATLAS and CMS. If LEP3 is to be built, it will have to fight off two rival proposals for a future collider to study the Higgs – the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). But Ellis says that one advantage of LEP3 is that the tunnel to house it is already built and the collider would use the existing infrastructure, such as cryogenics equipment, thus making LEP3 more cost-effective. LEP3 would also use conventional electromagnets to accelerate particles rather than the accelerating superconducting cavities that will be employed by the ILC.
Which collider is built to succeed the LHC will depend on what the LHC discovers in the next couple of years after it has run at its full design energy of 14 TeV. If it turns out that the LHC finds only the Higgs, then Ellis says there would be a strong case for LEP3. But if more particles are discovered by the LHC – such as supersymmteric particles – it would make sense to consider the other two proposals. “LEP3 could be a more secure option than the ILC if only a Higgs is discovered,” Ellis told “But, of course, it would be foolish to choose anything now, given that the LHC has not hit full energy yet.”
CERN plans to run the LHC into the 2030s after it has undergone a major upgrade in energy and luminosity in the coming decade. However, Ellis thinks that it may even be possible for the LHC and LEP3 to cohabit for a short time. “It would not be ideal, but it could be something to think about,” says Ellis. “If the LHC does not discover anything beyond the Higgs, then would you keep running it for years?”
“Little scope”
Yet some disagree that LEP3 represents the best way to study the Higgs, adding that a decision would have to be made between building LEP3 and running the high-luminosity upgrade to the LHC in the 2020s. “They both have an excellent physics case, but somehow LEP3 presents less chance of a huge breakthrough,” says one leading CERN researcher who prefers not to be named. “[The LHC upgrade] has precision measurements as well as discovery reach to offer.”
That view is shared by linear-collider director Lyn Evans, who told that he thinks it is unlikely that the proposal for LEP3 will get very far. “The first job is to fully exploit the LHC and all its upgrades,” says Evans, who led the construction of the LHC. “This is at least a 20 year programme of work, so I think that it is very unlikely that the LHC will be ripped out and replaced by a very modest machine with little scope apart from studying the Higgs.”
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August 9, 2012 at 7:39 pm

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