From Fermilab: “NOvA near-detector cavern construction completed, ready for research equipment”

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

Monday, May 20, 2013
Sarah Khan

“After breaking ground in May 2012, the NOvA near-detector cavern, situated 350 feet underground, is nearly complete—ahead of schedule, no less—and has been ready to accommodate NOvA research equipment since it received beneficial occupancy on May 10.

The lab originally planned for completion in mid-June this year, said FESS engineer Russ Alber. But construction subcontractor Kiewit Infrastructure Co. has been working ahead of schedule and is now ready to turn the cavern over to Fermilab scientists and engineers.

Kiewit is finishing the last steps to cavern construction, which include building a movable walkway that slides down the length of the cavern and entry doors to the cavern.

The empty space is now ready to start taking experiment equipment.

‘It’s exciting for us,’ Alber said. ‘This is not a typical building with typical construction techniques, so we’re glad to have completed this one ahead of schedule.’

Without all the clutter from building materials, the 75-foot-long cavern seems, well, cavernous.

But it won’t be empty for long. Scientists will soon install networking and computing components to process neutrino data once the detector is up and running, said near-detector project manager Ting Miao.

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.

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From Fermilab- “Frontier Science Result: CMS Seeing the invisible”

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

Friday, May 17, 2013
Don Lincoln

“The world of particle physics and cosmology is full of invisible phenomena like dark matter, neutrinos and that latest spiffy object predicted by the theory of the week. When you think about it, it’s really quite hard to measure some of the properties of these invisible particles. So scientists had to come up with some clever ways to determine things like the mass of something that cannot be detected directly. One such way involves careful accounting of the energy observed in the experiment.

When scientists were first studying beta decay, they expected the electron to be emitted with a single unique energy, as depicted in red. However, they measured instead a range of energies for the emitted electron, shown in yellow, all lower than the expected energy, which the electron would carry if neutrinos didn’t exist. In the lower right hand corner, we see a closeup of the spectrum near the expected energy. The dashed line is what we see if the neutrino has no mass, while the magenta curve is what we’d see if the neutrino had a small but non-zero mass. CMS scientists employed this technique to study top quark production to validate the method.

This technique has been used in the past. A type of radioactivity called beta decay occurs when a neutron in the nucleus of an atom converts to a proton and emits an electron. Following the principle of energy conservation, scientists predicted the electron to be emitted with a single energy, but measurements showed that the energy of the electron can have many different values. In fact, it turned out that the predicted value of the electron’s energy was actually the maximum it could be. The measured values were always lower.

In 1930 Wolfgang Pauli proposed a solution to this curious situation: Not only were a proton and an electron emitted in beta decay, but a neutrino was emitted as well. Neutrinos are particles that interact only via the weak nuclear force and are therefore very, very hard to detect. Clyde Cowan and Frederick Reines showed the idea to be correct in 1955 when the neutrino was detected.

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.

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From Symmetry: “What’s the next step in particle colliders”

“Already celebrated for bringing the world news of the Higgs boson, the Large Hadron Collider is only beginning its long journey of discoveries. Yet scientists are already planning the next big machine, the International Linear Collider [read Linear Collider, from the linear Collider Collaboaration], to study the LHC’s discoveries in more detail.

So what’s the difference between the LHC and the proposed ILC? Why do we need both?

LHC

Linear Collider.

For one thing, the ILC would accelerate particles along a straight line some 30 kilometers long while the LHC accelerates them along a circular path 27 kilometers in circumference. But that just skims the surface of their differences.

The two types of machine provide very different types of information because they collide different kinds of particles. The LHC collides protons, which themselves are made up of quarks and gluons. The ILC, in contrast, would collide electrons and positrons, point-like particles that have no known internal structure. Proton collisions are messy, allowing scientists to discover new particles and new processes, while linear-collider experiments are cleaner, allow scientists to explore these new particles and new processes without the complicated debris present at the LHC.

Not clear? Maybe this image helps. The protons in the LHC aren’t just single particles; they are each made of a list of ingredients (up quarks, a down quark and gluons)…That’s why the LHC produces the mind-boggling number of collisions that it does.

See the full scintillating article here.

Symmetry is a joint Fermilab/SLAC publication.

From Fermilab- “Frontier Science Result: CMS The Higgs boson’s big brother

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

Friday, May 3, 2013
Jim Pivarski

“Evidence is mounting that the particle discovered last year is the long-sought Higgs boson. When it was announced, no one seemed more cautious of claiming that than its discoverers. But now, as experimental uncertainties shrink, they can confidently say that the particle has no intrinsic spin, it is mirror-symmetric, and it couples to other particles in rough proportion to their masses. These are all properties that the boson predicted by the Higgs mechanism must satisfy.

A heavy variant of the Higgs boson would decay primarily into W bosons or Z bosons. This is a decay mode newly added to the search. No imaged credit.

One property that the theory does not predict well, however, is the mass of that boson. All predictions relied on assumptions about physics beyond the Standard Model, but generally they were in the few-hundred-GeV range. When the LHC experiments began their search, they cast as wide a net as possible and seem to have made a catch at the low end, 125 GeV.

Standard Model

That’s not the end of the story: Even if the 125-GeV boson gives mass to the fundamental particles, it may not be acting alone. Nothing in the theory forbids multiple Higgs bosons. In fact, many of the predictions for a low-mass Higgs were based on supersymmetric extensions of the Standard Model, and these extensions require at least five Higgs bosons. So while some physicists study the properties of the boson in hand, others scour the net for more.”

See the rest of the story in 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.

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From Symmetry: “SLAC’s historic ‘End Station A’ hosts electron beams again”

April 26, 2013
Mike Ross

A new facility opens for experiments this week in SLAC’s historic End Station A, where the first evidence for quarks was discovered.

Electrons are once again streaming into SLAC’s End Station A, setting the stage for a new facility in the huge, concrete hall where the first evidence for quarks was discovered.

It was there that a research team including SLAC and MIT physicists used SLAC’s electron beam to discover that protons in the atomic nucleus were composed of smaller entities called quarks. That research led to the 1990 Nobel Prize in Physics.

The new facility, called the End Station Test Beam, will host experiments that test detector parts and experiments that will aid in the design of a proposed international linear collider project.

ILC

The first experiment, which will be carried out by SLAC researchers as part of the commissioning process, is being installed this week. The first outside users are expected to arrive in about a month.

Researchers will use a new beamline fed by billion-particle bunches of high-energy electrons diverted from the laboratory’s Linac Coherent Light Source. LCLS uses the energetic electrons to create a powerful X-ray laser beam for research that reveals unprecedented detail on the atomic scale.”

See the full article here.

Symmetry is a joint Fermilab/SLAC publication.

From CERN and Symmetry Magazine: “LHCb experiment observes new matter-antimatter difference”

24 Apr 2013
No Writer Credit

A view of the LHCb underground area, looking upwards from the cavern floor (Image: Anna Pantelia/CERN)

“The LHCb collaboration at CERN today submitted a paper to Physical Review Letters on the first observation of matter-antimatter asymmetry in the decays of the particle known as the B0s. It is only the fourth subatomic particle known to exhibit such behaviour.

Matter and antimatter are thought to have existed in equal amounts at the beginning of the universe, but today the universe appears to be composed essentially of matter. By studying subtle differences in the behaviour of particle and antiparticles, experiments at the LHC are seeking to cast light on this dominance of matter over antimatter.

Now the LHCb experiment has observed a preference for matter over antimatter known as CP-violation in the decay of neutral B0s particles. The results are based on the analysis of data collected by the experiment in 2011. ‘The discovery of the asymmetric behaviour in the B0S particle comes with a significance of more than 5 sigma – a result that was only possible thanks to the large amount of data provided by the LHC and to the LHCb detector’s particle identification capabilities,’ says Pierluigi Campana, spokesperson of the LHCb collaboration . ‘Experiments elsewhere have not been in a position to accumulate a large enough number of B0s decays.’

Violation of the CP symmetry was first observed at Brookhaven Laboratory in the US in the 1960s in neutral particles called kaons. About 40 years later, experiments in Japan and the US found similar behaviour in another particle, the B0 meson. More recently, experiments at the so-called B factories and the LHCb experiment at CERN have found that the B+ meson also demonstrates CP violation.

All of these CP violation phenomena can be accounted for in the Standard Model, although some interesting discrepancies demand more detailed studies. ‘We also know that the total effects induced by Standard Model CP violation are too small to account for the matter-dominated universe,’ says Campana. ‘However, by studying these CP violation effects we are looking for the missing pieces of the puzzle, which provide stringent tests of the theory and are a sensitive probe for revealing the presence of physics beyond the Standard Model.’”

See the full CERN article here.

And now a different slant from Symmetry Magazine

Strange beauty particle decays boost matter

Photo: CERN via Symmetry Magazine

April 24, 2013
Kelly Izlar

“When the universe was less than a minute old, a tiny difference in the behavior of matter and antimatter led to the matter-dominated existence we experience today.

Today, particle physicists on CERN’s LHCb collaboration announced that, for the first time, they have observed particles called strange beauty mesons, or B0s, contributing to this imbalance.

Scientists found that in strange beauty particles, composed of beauty antiquarks bound with strange quarks, antimatter decays slightly more often than matter. This is called charge-parity, or CP, violation.

When B0s mesons decay to kaons and pions, physicists can determine if the new particles are matter or antimatter by looking at their relative charges. After comparing the number of matter particles with antimatter particles, they were able to confirm the findings.

‘It’s a simple idea, although getting there is quite complicated, says Tara Shears, a physicist on LHCb. ‘We’re looking at a very small discrepancy that reflects the nature of the universe.’

LHCb’s result has a statistical significance exceeding five sigma—the gold standard for declaring a discovery in particle physics.

‘We had about one thousand B0s candidates to measure,’ says Shears. ‘The results unambiguously support predictions that these particles violate CP.’

In the 1960s, James Cronin and Val Fitch observed CP violation in neutral kaons. About 40 years later, another particle, the B0 meson, showed similar behavior in the BaBar and Belle detectors in the United States and Japan. Recently, these experiments and LHCb also observed CP violation effects in B+ meson decays.

However, the Standard Model predicts only a tiny portion of the amount of CP violation needed to explain the huge deficit of antimatter in the universe. While these results help scientists understand the mechanics of CP violation, the case of the missing antimatter remains unsolved.

“We expected a certain amount of CP violation to be found in the strange beauty system,” says Pierluigi Campana, the LHCb spokesperson. “But finding the missing fraction of CP violation in the early universe will be new physics, which the Standard Model can’t predict.”

Meet CERN in a variety of places:

Cern Courier

THE FOUR MAJOR PROJECT COLLABORATIONS

ATLAS

ALICE

CMS

LHCb

LHC

Quantum Diaries

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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

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From CERN: “Two-beam module to drive particle beams”

22 Apr 2013
Cian O’Luanaigh

“It may look like a steampunk locomotive, but this first prototype module for the Compact Linear Collider (CLIC) won’t be carrying any passengers. CLIC is a concept for a two-beam linear accelerator to collide electrons and positrons (antielectrons) head-on at energies up to several teraelectronvolts (TeV).

The first prototype module for the Compact Linear Collider is being tested at CERN (Image:Anna Pantelia/CERN)

The module above – the first of its kind – is being tested at CERN, with neither beam nor radiofrequency (RF) system. The CLIC two-beam module team is checking the feasibility of the engineering designs for the different technical systems, such as the RF structures, the support structures, the alignment, stabilization and vacuum.”

In the CLIC machine, energy is extracted from a low-energy, high-intensity electron beam to drive a parallel beam of particles The main linear accelerators (linacs) have a modular design based on 2-metre long two-beam modules, and will operate under ultra-high vacuum conditions required for beam physics.

CLIC

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

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From Fermilab- “Frontier Science Result- CMS The messy strong force”

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

Friday, April 19, 2013
Don Lincoln

“When scientists explain how interactions occur at colliders like the LHC, they often have to rely on approximate descriptions. For instance, in discussions of the production and decay of a Higgs boson, we often mention that its most likely decay mode is into two bottom quarks. We then draw a simple picture, with a Higgs boson decaying and two quarks flying away from the decay point. This picture is accurate to a point, but beyond that it’s far messier.

A simple description of a particular event might be how a Higgs boson (top) decays into a bottom quark-antiquark pair (middle). However the reality is much messier, involving a complex spray of particles. Today’s analysis is a study of the details of how a couple of quarks can turn into a much more complicated collection of particles. No image credit.

Like all quarks, bottom quarks carry color (the charge of the strong nuclear force) and feel a mutual interaction. Because of the way the strong force works, as the two quarks get farther apart, the force increases, leading to an increase in the energy stored in that force. This concentrated energy eventually results in something akin to a spark, and a gluon is emitted. Since the gluon also carries color, it too experiences a force between itself and the original quarks, and so the process repeats.”

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.

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From Fermilab- “Frontier Science Result: DZero Precise measure of matter preference

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

Thursday, April 18, 2013
Mike Cooke

“We live in a universe filled with matter, with no detectable pockets of antimatter, but don’t fully understand why. In the very early universe, matter and antimatter were created in equal abundance. As the universe cooled, the matter and antimatter annihilated each other, but left behind the small excess of matter that accounts for all of the stars, planets and galaxies in the universe today. This difference is thought to result from the slightly different ways the particles and antiparticles decayed. However, the decay rate difference predicted by the Standard Model is not nearly enough to account for the amount of matter in the universe. By precisely measuring processes that show a difference between matter and antimatter, physicists attempt to understand what caused the imbalance that led to the universe today.

Most matter and antimatter annihilated each other in the very early universe, but a small excess of matter remained to form the universe we live in today. To attempt to understand this imbalance, scientists measure particle decay processes that show a difference between matter and antimatter.

A recent result at DZero studied this asymmetry in the decay of a charged B meson, made of a bottom quark and an up quark, into a J/Ψ meson and a charged K meson, which involves the bottom quark decaying into a strange quark and two charm quarks. To reduce the uncertainty on the measurement, the analysis exploited the fact that the magnetic polarities of magnets in the DZero detector were systematically flipped during the decade of data collecting for Run II. Each possible source of bias in the measurement of asymmetry between matter and antimatter was carefully studied and accounted for.

The final result is the world’s most precise measurement of matter-antimatter asymmetry in charged B meson decays to a J/Ψ meson and a charged K meson. The measured asymmetry is consistent with the Standard Model. While it does not indicate the presence of new physics and explain the matter-antimatter asymmetry in the universe, it is an important step in exploring this mystery.”

See the full article here.

The final result is the world’s most precise measurement of matter-antimatter asymmetry in charged B meson decays to a J/Ψ meson and a charged K meson. The measured asymmetry is consistent with the Standard Model. While it does not indicate the presence of new physics and explain the matter-antimatter asymmetry in the universe, it is an important step in exploring this mystery.

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.

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