Posts Tagged ‘LHC

CMS releases new batch of research data from LHC

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The CMS Collaboration at CERN has released more than 300 terabytes (TB) of high-quality open data. These include over 100 TB, or 2.5inverse femtobarns (fb−1), of data from proton collisions at 7 TeV, making up half the data collected at the LHC by the CMS detector in 2011. This follows a previous release from November 2014, which made available around 27 TB of research data collected in 2010.

Available on the CERN Open Data Portal — which is built in collaboration with members of CERN’s IT Department and Scientific Information Service— the collision data are released into the public domain under the CC0 waiver and come in types: The so-called “primary datasets” are in the same format used by the CMS Collaboration toperform research. The “derived datasets” on the other hand require a lot less computing power and can be readily analysed by university or high-school students, and CMS has provided a limited number of datasets in this format.

Notably, CMS is also providing the simulated data generated with the same software version that should be used to analyse the primary datasets. Simulations play a crucial role in particle-physics research and CMS is also making available the protocols for generating the simulations that are provided. The data release is accompanied by analysis tools and code examples tailored to the datasets. A virtual-machine image based on CernVM, which comes preloaded with the software environment needed to analyse the CMS data, can also be downloaded from the portal.CODP_VisualiseThese data are being made public in accordance with CMS’s commitment to long-term data preservation and as part of the collaboration’s open-data policy. “Members of the CMS Collaboration put in lots of effort and thousands of person-hours each of service work in order to operate the CMS detector and collect these research data for our analysis,” explains Kati Lassila-Perini, a CMS physicist who leads these data-preservation efforts. “However, once we’ve exhausted our exploration of the data, we see no reason not to make them available publicly. The benefits are numerous, from inspiring high-school students to the training of the particle physicists of tomorrow. And personally, as CMS’s data-preservation co-ordinator, this is a crucial part of ensuring the long-term availability of our research data.”

The scope of open LHC data has already been demonstrated with the previous release of research data. A group of theorists at MIT wanted to study the substructure of jets — showers of hadron clusters recorded in the CMS detector. Since CMS had not performed this particular research, the theorists got in touch with the CMS scientists for advice on how to proceed. This blossomed into a fruitful collaboration between the theorists and CMS revolving around CMS open data. “As scientists, we should take the release of data from publicly funded research very seriously,” says Salvatore Rappoccio, a CMS physicist who worked with the MIT theorists. “In addition to showing good stewardship of the funding we have received, it also provides a scientific benefit to our field as a whole. While it is a difficult and daunting task with much left to do, the release of CMS data is a giant step in the right direction.”

Further, a CMS physicist in Germany tasked two undergraduates with validating the CMS Open Data by re-producing key plots from some highly cited CMS papers that used data collected in 2010. Using openly available documentation about CMS’s analysis software and with some guidance from the physicist, the students were able to re-create plots that look nearly identical to those from CMS, showing what can be achieved with these data. “I was pleasantly surprised by how easy it was for the students to get started working with the CMS Open Data and how well the exercise worked,” says Achim Geiser, the physicist behind this project. Simplified example code from one of these analyses is available on the CERN Open Data Portal and more is on its way.

Prior to the launch of the CERN Open Data Portal with the first batch of research-quality data from CMS, the Collaboration had provided certain curated datasets for use in high-school workshops. These “masterclasses”, developed by QuarkNet and conducted under the aegis of the International Particle Physics Outreach Group, bring particle-physics data to thousands of high-school students each year. These educational datasets are also available on the CERN Open Data Portal, along with an “event display” for visualising the particle-collision events.

“We are very pleased that we can make all these data publicly available,” adds Kati. “We look forward to how they are utilised outside our collaboration, for research as well as for building educational tools.”


Written by physicsgg

April 23, 2016 at 5:31 pm

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LHC animation: The path of the protons

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This animation shows how the Large Hadron Collider (LHC) works.

The film begins with an aerial view of CERN near Geneva, with outlines of the accelerator complex, including the underground Large Hadron Collider (LHC), 27-km in circumference. The positions of the four largest LHC experiments, ALICE, ATLAS, CMS and LHCb are revealed before we see protons travelling around the LHC ring.

The proton source is a simple bottle of hydrogen gas. An electric field is used to strip hydrogen atoms of their electrons to yield protons. Linac 2, the first accelerator in the chain, accelerates the protons to the energy of 50 MeV. The beam is then injected into the Proton Synchrotron Booster (PSB), which accelerates the protons to 1.4 GeV, followed by the Proton Synchrotron (PS), which pushes the beam to 25 GeV. Protons are then sent to the Super Proton Synchrotron (SPS) where they are accelerated to 450 GeV.

The protons are finally transferred to the two beam pipes of the LHC. The beam in one pipe circulates clockwise while the beam in the other pipe circulates anticlockwise, increasing in energy until they reach 6.5 TeV. Beams circulate for many hours inside the LHC beam pipes under normal operating conditions. The two beams are brought into collision inside four detectors – ALICE, ATLAS, CMS and LHCb – where the total energy at the collision point is equal to 13 TeV.

Collisions occur once every 25 nanoseconds, the trigger level 1 performs ultrafast event selection before data move to trigger levels 2 and 3 at the PC farm. Selected event data are then sent to the CERN data centre that performs initial data reconstruction and makes a copy of the data for long-term storage, while raw and reconstituted data are sent to the Computing Grid. The Worldwide LHC Computing Grid infrastructure includes two “Tier 0” sites, one at CERN and one in Budapest, Hungary, as well as further smaller computing sites located around the world.

As collision data increases, physicists build up enough statistics to test theoretical predictions, such as the prediction of a Higgs Boson, discovered in the data from the LHC’s first physics run (shown as a bump in the graphs in the animation). The LHC allows physicists to probe the nature of matter. The new higher collision energy of 13 TeV opens up new frontiers in particle physics.

Directors: Daniel Dominguez, Arzur Catel Torres
Music: F_Fact_-_State_of_Mind_(_psystep_vers._o­f_the_beach) by “Platinum Butterfly” CC BY 3.0

Written by physicsgg

June 3, 2015 at 4:28 pm

Posted in High Energy Physics

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Mysteries of matter at the LHC

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Two years ago, the Higgs Boson was discovered by the ATLAS and CMS experiments. But how precisely does it fill its role as the last missing piece in the Standard Model of particle physics?
The Large Hadron Collider will restart in 2015 with almost double the collision energy to test just that. But even then, this theory only accounts for 5% of the Universe, and does not include gravity.Can the LHC shed light on the origin of dark matter? Why is gravity so much weaker than the other forces? Dr Pippa Wells explains how the LHC will explore these mysteries of matter.
Pippa Wells was the Inner Detector System Project Leader on the ATLAS Experiment at CERN. ATLAS is one of two general-purpose detectors at the Large Hadron Collider (LHC). It investigates a wide range of physics, from the search for the Higgs boson to extra dimensions and particles that could make up dark matter.

Written by physicsgg

November 21, 2014 at 10:34 pm

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The LHC as a photon collider

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Quartic gauge coupling: A Feynman diagram showing how protons radiate photons that then interact and produce W bosons.

Quartic gauge coupling: A Feynman diagram showing how protons radiate photons that then interact and produce W bosons.

Yes, that’s correct: photon collider.

The Large Hadron Collider is known for smashing together protons. The energy from these collisions gets converted into matter, producing new particles that allow us to explore the nature of our Universe. The protons are not fired at one another individually; instead, they are circulated in bunches inside the LHC, each bunch containing some 100 billion (100,000,000,000) particles. When two bunches cross each other in the centre of CMS, a few of the protons — around 25 or so — will collide with one another. The rest of the protons continue flying through the LHC unimpeded until the next time two bunches cross.

Sometimes, something very different happens. As they fly through the LHC, the accelerating protons radiate photons, the quanta of light. If two protons going in opposite directions fly very close to one another within CMS, photons radiated from each can collide together and produce new particles, just as in proton collisions. The two parent protons remain completely intact but recoil as a result of this photon-photon interaction: they get slightly deflected from their original paths but continue circulating in the LHC. We can determine whether the photon interactions took place by identifying these deflected protons, thus effectively treating the LHC as a photon collider and adding a new probe to our toolkit for exploring fundamental physics. Read the rest of this entry »

Written by physicsgg

September 2, 2014 at 11:11 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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Nathan Seiberg: Where are we heading?

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Written by physicsgg

July 24, 2013 at 8:37 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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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.
– See more at:

Written by physicsgg

July 12, 2013 at 5:14 pm

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