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 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.”

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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.

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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.

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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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From DOE Pulse: “New particle detector records first 3-D tracks”

April 15, 2013
[Andre Salles, 630.840.3351,
media@fnal.gov]

“The NOvA particle detector, under construction in northern Minnesota, has begun recording its first three-dimensional images of particles. At its current size, the detector catches more than 1,000 cosmic rays per second. A webcam documents the progress of the construction of the humongous detector.

A cosmic-ray muon deposits a large shower of energy in the NOvA detector in Minnesota.

This summer, DOE’s Fermi National Accelerator Laboratory, located in Batavia, Ill., will start sending a beam of neutrinos every 1.3 seconds to the NOvA detector—500 miles straight through the Earth; no tunnel is necessary.

When complete in 2014, the full NOvA detector will be the most powerful neutrino detector in the United States. Made of PVC tubes that technicians will fill with scintillating liquid and outfit with light-sensitive electronics, the completed detector will weigh 14,000 tons. It will be the largest free-standing plastic structure in the world.

Scientists plan to use the NOvA experiment and Fermilab’s neutrino beam to discover the mass hierarchy of the three known types of neutrinos. Neutrinos are among the most abundant particles in the universe, but they have barely any mass and rarely interact with other matter particles. NOvA aims to discover which type of neutrino is the heaviest and which one is the lightest. The answer will shed light on the theoretical framework that scientists have proposed to describe neutrino interactions. Scientists suspect that neutrinos played a major role in the evolution of the universe. Neutrinos could help explain the imbalance of matter and antimatter in today’s universe, and scientists think there might be more types of neutrinos than the three known types.

‘The more we know about neutrinos, the more we know about the early universe and about how our world works at its most basic level,’ said NOvA co-spokesperson Gary Feldman of Harvard University.”

See the full article here.

DOE Pulse highlights work being done at the Department of Energy’s national laboratories. DOE’s laboratories house world-class facilities where more than 30,000 scientists and engineers perform cutting-edge research spanning DOE’s science, energy, National security and environmental quality missions. DOE Pulse is distributed twice each month.

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From Symmetry: “LHC passes ‘ping-pong ball’ test”

Physicists sent an ultra-clean, miniature ping-pong ball through part of the Large Hadron Collider beam pipe to test for hidden defects.

April 16, 2013
Ashley WennersHerron

“Sometimes the best solutions in high-energy physics research are surprisingly low-tech.

Physicists sent a carefully sterilized, slightly-smaller-than-regulation ping-pong ball through a 2-mile section of the Large Hadron Collider today. They were searching for possible defects in the connections between magnets that can arise as they change temperature.

The so-called radio-frequency ball, first developed in 2007, carried a small transmitter that allowed scientists to track its progress. It moved through simple suction, pinging every third of a mile.

‘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.’”

See the full article here.

Also, see this article from CERN.

Symmetry is a joint Fermilab/SLAC publication.

From CERN: “Opening the LHC – in pictures” Don’t Miss this one.

If you want to really see where your tax money is going, do not miss this article from CERN

12 Apr 2013.
Cian O’Luanaigh

This week technicians opened up the first interconnections between magnets on the Large Hadron Collider (LHC) to work on the accelerator components inside. Above, a technician prizes the thermal insulation plates from an interconnection between LHC magnets. Note the bicycles, which workers use to get around the LHC tunnel.

All images by Maximilien Brice for CERN.

There are two more terrific shots. Take a peak. The article is here.

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From Fermilab: “Pushing accelerator technology with PXIE”

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

Tuesday, April 9, 2013
Leah Hesla

“The Intensity Frontier program planned for Fermilab’s proposed Project X is an ambitious one, making extraordinary demands of its particle beams and thus of the machine that provides them. Project X teams aren’t shying away from the challenge. They’re tackling the machine head-on and from the front.

Engineering physicist Bruce Hanna works on the PXIE ion source test stand at Lawrence Berkeley National Laboratory. The ion source will arrive at Fermilab this month. Photo: Lionel Prost, AD

This month the Accelerator Sector will begin assembling the Project X Injector Experiment (PXIE), kicking off an R&D program to understand, integrate, test and hammer the dents out of this most complex subsystem in the Project X accelerator. PXIE focuses on the front-end injector of Project X, the section that prepares the beam for delivery to multiple physics experiments.

‘The unique aspects of Project X are pretty much enabled by the way the front end is configured,’ said Steve Holmes, project manager for Project X.

The injector takes up the first roughly 40 meters of the Project X 400-meter linear accelerator. In that short length reside the novel accelerator technologies that are most crucial for Project X.

‘There isn’t anything similar to PXIE in the world, so in some respect we are in uncharted waters,’ said Sergei Nagaitsev, project scientist for Project X.

In addition to those at Fermilab, researchers at Argonne, Berkeley, Oak Ridge and SLAC national laboratories and in the Project X India collaboration participate in PXIE, contributing R&D and the injector’s major components. The goal is to demonstrate by 2018 that the injector system works.

‘If you can prove you can produce, slice and dice the beam the way you like it, with the right beam quality, then you’re a lot more confident that the rest will go well downstream,’ Henderson said. ‘Relatively, the rest is a piece of cake.’

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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