From Symmetry: “Smallest lab-made drop of liquid might cause strange particle behavior”

A new result from the CMS collaboration takes a step toward revealing the origin of the mysterious ridge effect.

May 07, 2013
Kelly Izlar

“The Large Hadron Collider is known for a list of impressive facts—it’s the world’s largest and most powerful particle collider; it accelerates particles to nearly the speed of light; its cryogenic system keeps it colder than outer space.

Now it’s under consideration for a new superlative: Scientists there might have created the most minuscule drop of liquid ever formed in a laboratory.

Photo: Michael Hoch / CERN

Last year physicists collided protons with heavier lead ions in the LHC. They found a small but noticeable correspondence between the trajectories of charged particles that sped away from collisions. Newly produced particles appeared to be synced, like a school of fish moving in unison. They dubbed this phenomenon the ‘ridge effect.’

The CMS experiment (pictured above) studied more proton–lead collisions early this year, and the result, made public this week, suggests that the particles are behaving the way they do in lead–lead collisions, where they are swept along by a drop of plasma. If this is true, the drop formed in proton–lead collisions would be the smallest drop of liquid ever formed in a laboratory.”

See the full article here.

Symmetry is a joint Fermilab/SLAC publication.

From CERN: Fabulous Photo and “CMS prepares for the future”

23 Apr 2013
Austin Ball, Achintya Rao

“While the Large Hadron Collider (LHC) takes a break for its first long shutdown, the CMS collaboration are busy maintaining and consolidating the detector to be sure to handle the collider’s improved performance from 2015 onwards.

The biggest priority for CMS is the tracker performance. The CMS tracking system forms the innermost subdetector and fits snugly round the LHC beampipe. It must withstand an onslaught of some 1010 particles a second and the aggressive field of mixed radiation that this produces.

Another major element is to improve the muon detectors with a fourth endcap layer to help discriminate between interesting muons and fake signatures or background. New shielding discs, 10 centimetres deep, are to be installed on either end of the detector. Each shielding disc is made of 12 iron sector-casings filled with a special concrete. The concrete, developed for this specific application by CERN’s civil engineers, is almost 50% denser than normal concrete – it is made using haematite (or ferric oxide) instead of the usual sand – and it is loaded with boron to absorb low-energy neutrons that would otherwise give rise to unwanted hits in the detector.”

See the full article here.

Meet CERN in a variety of places:

Cern Courier

THE FOUR MAJOR PROJECT COLLABORATIONS

ATLAS

ALICE

CMS

LHCb

LHC

Quantum Diaries

ScienceSprings is powered by MAINGEAR computers

From Fermilab- “Frontier Science Result: CMS CMS observes particle X”

Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

Friday, April 5, 2013
Jim Pivarski

“When the discovery of a new Higgs-like particle was announced last summer, it received a lot of well-deserved media attention. It is less widely known, however, that about a dozen new particles have been discovered in the past 10 years. Why all this lack of excitement? Unlike the Higgs boson, these other new particles are bound states of quarks: the same old particles in new combinations.

But they should not be so quickly dismissed. These new particles may be made of quarks, but most of them defy conventional explanations of how quarks fit together.

In the standard theory of quark interactions, quarks come in three types and can only bind together in ways that would result in an equal balance of these types. By analogy with the color wheel, they are called red, green and blue, and a particle like a proton is made of one red, one green and one blue quark, which mix to form white. Antiquarks are yellow, cyan and magenta. You can form a bound state from a yellow antiquark and a blue quark, for instance, since these colors are on opposite sides of the color wheel. See this Physics in a Nutshell for more.

A proton, composed of two up quarks and one down quark. (The color assignment of individual quarks is not important, only that all three colors be present.) (Wikipedia)

This is a nice demonstration of how you get white if you combine red, blue and green. You can try this yourself at home, or watch it demonstrated in a video online.

Up to 2003, the only combinations of quarks and antiquarks that had ever been seen were red-green-blue particles, yellow-cyan-magenta antiparticles, and quark-antiquark pairs. Since then, a growing number of bound states have been discovered that do not fit this scheme. The first of these, discovered by the Belle experiment in Japan, was the X(3872), named “X” because we do not know what it is, and “3872″ for its mass, measured in units of MeV.

The X(3872) and its companions might be the first examples of four-quark combinations, such as red-cyan-yellow-blue. These combinations are theoretically possible since they mix to form white, but they were not expected to be stable enough to be observed. The X(3872) in particular has a mass that is very close to the sum of two well-known bound states, D0 and D*0, so it might be a bound state of bound states. It has also been suggested that these new states are part-glueball hybrids.

In a recent experiment, CMS scientists observed the X(3872) with a strong signal and measured several of its properties with higher precision than ever before. Far from the glare of the spotlight, these scientists are working to solve one of nature’s underappreciated mysteries.”

In a large sample of proton-proton collisions resulting in muons and pions, a few thousand of them accumulate above the backgrounds with a mass of 3,872 MeV. This is the X(3872).

See the original article here.

Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

ScienceSprings is powered by MAINGEAR computers

From CERN: “CMS open for business”

March 27, 2013
Cian O’Luanaigh

“As CERN goes into its first long shutdown, it’s time open up the CMS detector and get inside for maintenance and repairs. Engineers and technicians started opening the CMS detector on 7 March, but moving the parts of this 14,000-tonne behemoth is no easy feat.

The open side of the CMS detector, looking upwards from the cavern floor (Image: Michael Hoch/CMS)

CMS has a barrel section made of five rings, with two endcaps each comprising three discs and, outside those discs, two 250-tonne forward hadron calorimeters (HF) [see diagram]. To open CMS, the HFs, which surround the beam pipe, are opened and lowered to the cavern floor, where they are floated on air pads into storage alcoves. Then the endcap discs are moved away from the barrel, starting with one end and then going to the other.

‘It took a couple of weeks of work to move the forward calorimeters and the first three discs apart,’ says detector physicist David Barney of CMS. ‘Then we went to the other end and started to move the other three discs.’

Barney has worked on one part of CMS, the electromagnetic calorimeter (ECAL) for nearly 20 years. The ECAL is mainly made of lead tungstate crystals that detect photons and electrons. But in the endcaps, an extra detector called the preshower sits in front of the crystals. The preshower is an array of silicon sensors that measure precisely the positions of incident high-energy electrons and photons.”

See the full article here.

Meet CERN in a variety of places:

Cern Courier

THE FOUR MAJOR PROJECT COLLABORATIONS

ATLAS

ALICE

CMS

LHCb

LHC

Quantum Diaries

ScienceSprings is powered by MAINGEAR computers

From US/LHC Blog at Quantum Diaries: “Shutdown? What shutdown?”

Ken Bloom

“The LHC has been shut down for about two months now, but that really hasn’t made anyone less busy. It is true that we don’t have to run the detector now, but the CMS operations crew is now busy taking it apart for various refurbishing and maintenance tasks. There is a detailed schedule for what needs to be done in the next two years, and it has to be observed pretty carefully; there is a lot of coordination required to make sure that the necessary parts of the detector are accessible as needed, and of course to make sure that everyone is working in a safe environment (always our top priority).

A lot of my effort on CMS goes into computing, and over in that sector things in many ways aren’t all that different from how they were during the run. We still have to keep the computing facilities operating all the time. Data analysis continues, and we continue to set records for the level of activity from physicists who are preparing measurements and searches for new phenomena. We are also in the midst of a major reprocessing of all the data that we recorded during 2012, making use of our best knowledge of the detector and how it responds to particle collisions. This started shortly after the LHC run finished, and will probably take another couple of months.

There is also some data that we are processing for the very first time. Knowing that we had a two-year shutdown ahead of us, we recorded extra events last year that we didn’t have the computing capacity to process in real time, but could save for later analysis during the shutdown. This ended up essentially doubling the number of events we recorded during the last few months of 2012, which gives us a lot to do. Fortunately, we caught a break on this — our friends at the San Diego Supercomputer Center offered us some time on their facility. We had to scramble a bit to figure out how to include it into the CMS computing system, but now things are happily churning away with 5000 processors in use.”

See Ken’s complete post here.

Participants in Quantum Diaries:

Fermilab

Triumf

US/LHC Blog

CERN

Brookhaven Lab

KEK

ScienceSprings is powered by MAINGEAR computers

From Don Lincoln at Fermilab- “Frontier Science Result: CMS Contact!”

Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

Don Lincoln

“The quarks and leptons of the Standard Model are assumed to be point-like. Note that this doesn’t require that they have no size; it merely means that if we make the simplifying assumption that they have zero size, then we can make predictions that are in good agreement with measurements. The history of fundamental physics is littered with the corpses of physics models of particles once thought to have zero size, from atoms to the protons and neutrons in atomic nuclei. Each of them eventually was shown to have a measurable size and consequently to be made of yet smaller particles.

A proton, composed of two up quarks and one down quark. (The color assignment of individual quarks is not important, only that all three colors be present.) Wikipedia

The Standard Model of elementary particles, with gauge bosons in the fourth column.

For about 50 years, scientists have been poking at the quarks and leptons, trying to see if they are made of something smaller. However, the simple fact is that the success of the Standard Model has actually stymied our progress.

Physicists have theorized on what the building blocks that make up quarks and leptons might be, but because the data agrees so well with the point-like hypothesis, there is no universally agreed-upon theory describing the building blocks at the next-lower level. So physicists simply look at the quarks and leptons at higher and higher energy, which is equivalent to using a more and more powerful microscope. If we start to observe that there is a size at which the particles no longer act like point particles, we’ll have seen our first glimpse at the next-lower set of building blocks.”

See the full article here.

Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

ScienceSprings is powered by MAINGEAR computers

From CMS at CERN: “Colliding different particle species: the LHC’s proton-lead run”

2013-01-18
Achintya Rao

“The new year brings a new type of collision at the LHC: the accelerator will smash protons and lead nuclei together, allowing CMS and the other LHC experiments to study the cold nuclear matter we expect these collisions to produce. Although we caught a glimpse of these asymmetric proton-lead (pPb) collisions during a pilot run last September, the next four weeks will bring the first sustained pPb run and provide valuable data. Indeed the small data sample from 2012 already revealed interesting phenomena, and raised interest in this study.

A proton-lead collision at a centre-of-mass energy of 5 TeV per nucleon. In this side-on view, the proton beam enters from the right side of the image and leaves on the left; the lead beam travels in the opposite direction. The event was selected requiring a muon trigger, and the muon (red line) was reconstructed in the CSC detectors.

For this run, CMS will combine forces with TOTEM so as to cover a greater range of collision data. The two are essentially separate entities — independent experiments that use different analysis software — and they are fully complementary. CMS measures in the central region and TOTEM exclusively measures in the very forward region.

One arm of a TOTEM T2 detector during the installation in the interaction point

Julia Velkovska, … a co-convener of the HI [Heavy Ions] group , explains the motivations behind colliding these different particle species together: ‘Not only does it act as a straight reference for lead collisions, but it is an interesting physics system in its own right. In addition, there are a lot of things that we think we can address now that weren’t on the cards a few months ago: the ridge we observed in the pilot run raised a lot of new questions and new approaches on how to analyse the data have been proposed.’”

See the full article here.

And, now “And we have Stable Beams for the pPb run!” says CMS.

Provided by Symmetry Magazine

Meet CERN in a variety of places:

Cern Courier

ATLAS

ALICE

CMS

LHCb

LHC

Quantum Diaries

ScienceSprings is powered by MAINGEAR computers

From BBC: “The Hunt for the Higgs: A Horizon Special”

I was hunting around the BBC looking for something else when I came upon an excellent video originally broadcast in January 2012. While it is one year old, and while the question of the Higgs boson is probably very close to being answered*, still this video presents a valuable lesson.

Our host is Prof JIM AL-KHALILI, OBE, Professor of Theoretical Physics and Chair in the Public Engagement in Science at the University of Surrey.

Prof Jim Al-Khalili

The video is especially valuable because it ventures into the LHCb Collaboration at CERN’s incredible LHC.

In this section on the LHCb experiment, the subjects of Broken Symmetry and the theory, to date untested, of Supersymmetry are explored. These subjects were not at all present in the PBS Frontline piece The Atom Smashers (2008), nor the BBC video The Big Bang Machine(2008).

If you use either the Opera browser or Firefox, there are excellent video download utilities for saving an .mp4 in at least 720p HD.

I hope that you will enjoy the video and might add it to your collection.

The BBC page for the video is here.

*On July 4, 2012 The General Director of CERN, Rolf-Dieter Heuer, announced that both the ATLAS and CMS collaborations had discovered a new particle with a degree of certainty [beyond five Σ (sigma)] which placed the find beyond doubt. The particle was a boson. But, there was not then and there is still not now certainty that the find was the Higgs boson. That has yet to be confirmed. This confirmation might wait until the completion of the International Linear Collider.

From CMS at CERN: “CMS observes melting of Upsilon particles in heavy-ion collisions”

“In 2011, CMS presented early evidence that Upsilon (Υ) particles produced in lead-lead collisions ‘melt’ as a consequence of interacting with the hot nuclear matter created in these heavy-ion interactions. CMS has since updated and extended this result using additional data collected in the 2011 heavy-ion run, and the observation now has a significance of greater than 5σ (or 5 standard deviations), the gold standard for claiming a discovery in high-energy physics.”

Candidate Υ decay to two muons observed in a lead-lead collision at the LHC. The two red lines (tracks) are the two muons, the mass of orange lines are tracks from other particles produced in the collision, whose energy is measured in the electromagnetic calorimeter (red cuboids) and the hadron calorimeter (blue cuboids)

Meet CERN in a variety of places:

Cern Courier

ATLAS

ALICE

CMS

LHCb

LHC

Quantum Diaries

ScienceSprings is powered by MAINGEAR computers

From Symmetry: “Scientists already planning for LHC long shutdown”

September 10, 2012 Re-posted 12.17.12 by Symmetry
Signe Brewster

Next year, scientific collaborations will take full advantage of the Large Hadron Collider’s time without beam.

“The Large Hadron Collider will go into a long shutdown early next year to allow scientists and technicians to prepare it for higher collision energy in 2015. It has been running at 7 TeV; scientists plan for it to reemerge at upward of 13 TeV. Beginning in February of 2013, highly coordinated teams will spend 20 months preparing its equipment for the change. Higher luminosity means more particle collisions, and the experiments will need more advanced equipment to keep up. With the detectors the most accessible they have been since their original construction, the four big LHC experiments will take the opportunity to perform upgrades and routine repairs. The collaborations already have plans for the new year.

ALICE

The ALICE experiment focuses on collisions of heavy ions to study the conditions present just after the big bang. The collisions produce a quark-gluon plasma, a hot soup in which quarks travel freely instead of being bound into particles. They also produce high-energy quarks and gluons that interact with the plasma and then fragment into jets of particles and gamma rays.

ALICE will install a new part to a system that records the energy of particles. The new Di-Jet Calorimeter will broaden the experiment’s ability to measure the energy of individual gamma rays. Scientists can study an individual gamma ray to infer the energy of the quark from which it was emitted. That way, they can study how the quark-gluon plasma affects the energy of the quark and resulting jet of particles.

ATLAS

ATLAS will add a fourth layer of pixels, known as the Insertable B-Layer, to its pixel detector. The increased number of pixels will enable measurements at a location closer to where particle collisions occur and allow scientists more accurately to identify jets of particles produced from bottom quarks.

Identifying these particles is important in the search for the Higgs boson, which, according to the Standard Model, frequently decays into bottom quarks. The ATLAS and CMS experiments discovered a Higgs-like particle this summer.

CMS

The LHC experiments cannot record data from every single collision that occurs, so they select or discard this information at a split second’s notice using automatic triggers. At higher luminosity, the experiments will deal with more collisions and therefore will need better trigger systems.

During the long shutdown, the CMS experiment plans to add a new layer to their muon detector, which will help them to decide which collisions are worth studying.

LHCb

LHCb’s most important project during the shutdown will be to replace a segment of beam pipe and its support structures. The new pipe will be able to withstand temperature changes and radiation better, and the lighter support structure will reduce background in the detector.

LHCb will also begin to prepare for the next planned shutdown, in 2018, when they will install an upgrade to their detector.

See the full article here.

Symmetry is a joint Fermilab/SLAC publication.