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 Fermilab- “From the Center for Particle Astrophysics Cosmic background: from quantum to cosmos”

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

Wednesday, May 15, 2013

Craig Hogan, director of the Center for Particle Astrophysics, wrote this column.

“The first great breakthrough of 20th-century physics came just as it dawned, in late 1900, when Max Planck derived from simple quantum principles an exact universal formula for the spectrum, or amount of light at each frequency, emitted by opaque matter.

A related breakthrough in cosmology came many decades later, when it was found that radiation with precisely Planck’s spectrum is found not only in the laboratory, but also coming from all directions in the sky. This simple fact carries a profound message about cosmic history: The entire universe is expanding from a state when matter everywhere was once hot, dense and opaque. The cosmic radiation is left over from the earliest moments of the cosmic expansion—the big bang.

In recent decades, measurements have shown that the cosmic radiation is not at exactly just one temperature, but varies by a tiny amount in different directions—a little colder here, a little hotter there. The early universe was not perfectly uniform, which is a good thing, because those tiny variations eventually led to the formation of galaxies and, of course, us.

Measurements of cosmic background radiation have advanced rapidly in the last year with new high-resolution detectors in Chile and at the South Pole and with the release in March of definitive all-sky data from the Planck satellite. Some of these results offer tantalizing hints of new physics beyond the Standard Model…Fermilab scientists invented many techniques of precision cosmology, helped create the Sloan Digital Sky Survey that defines the state of the art in precision measurement of cosmic structure with galaxies, and are about to start operating a still deeper cosmic mapping project, the Dark Energy Survey. Exciting choices lie ahead as we plan our participation in future experiments, perhaps including measurements of cosmic background radiation.”

See the full and very interesting 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: MINERvA Scouting the party: neutrinos and nuclei”

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

Friday, May 10, 2013
Philip Rodrigues

Neutrinos are notoriously difficult particles to study: For every 50 billion neutrinos that pass through the MINERvA detector at Fermilab, only about one will interact leaving a trace in our detector, producing particles that we can observe directly.

The likelihood of a neutrino undergoing a quasi-elastic interaction for different values of the momentum transferred to the proton or neutron (Q2) compared to several theoretical models. The data agree best with a model in which the neutrino can interact with multiple protons or neutrons at a time.

In spite of this, we are starting to use neutrinos to learn more about protons and neutrons and how they behave when they’re together inside an atomic nucleus. We already understand a lot about the nucleus: We know that it’s made of protons and neutrons, and we know the number of protons and the number of neutrons in the nucleus for every chemical element. But there is much we still don’t fully understand, especially about what those protons and neutrons are doing inside the nucleus.

We can study the protons’ and neutrons’ behavior in the nucleus the way we might study how people act at a party. Do the party-goers mingle according to the general spirit of the party, or do they break off into pairs? We could determine the party’s nature by sending in very shy folks and observing how quickly they leave and whether they leave through the same door they entered.

In a nucleus, does each proton and neutron react to just the average effect of the others, or do they occasionally pair up? One way to answer this question is to fire neutrinos at nuclei and measure the particles produced when neutrinos do interact with the nuclei of atoms in our detector. By studying those particles, we can try to infer the behavior of the protons and neutrons.”

The energy near the neutrino interaction point in neutrino quasi-elastic events. The data points, in black, are at higher energies on average than the prediction, in red, suggesting that the neutrino really is interacting with multiple protons or neutrons, which are kicked out of the nucleus.

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 Brookhaven: “Revolutionary Muon Experiment to Begin With 3,200-mile Move of 50-Foot-Wide Particle Storage Ring”

Brookhaven Lab

May 8, 2013

Massive device will travel from New York to Illinois by barge and truck this summer

Media contacts:
Andre Salles, Fermilab Office of Communication: 630-840-6733, asalles@fnal.gov.
Peter Genzer, Brookhaven Media & Communications Office: 631-344-3174, genzer@bnl.gov

“Scientists from 26 institutions around the world are planning a new experiment that could open the doors to new realms of particle physics. But first, they have to bring the core of this experiment, a complex electromagnet that spans 50 feet in diameter, from the U.S. Department of Energy’s Brookhaven National Laboratory in New York to the DOE’s Fermi National Accelerator Laboratory in Illinois.

The Muon g-2 storage ring, in its current location at Brookhaven National Laboratory. The ring, which will capture muons in a magnetic field, must be transported in one piece, and moved flat to avoid undue pressure on the superconducting cable inside. No image credit.

The experiment is called Muon g-2 (pronounced gee-minus-two), and will study the properties of muons, tiny subatomic particles that exist for only 2.2 millionths of a second. The core of the experiment is a machine built at Brookhaven in the 1990s, and the centerpiece of that machine is a circular electromagnet made of steel and aluminum, 50 feet wide, with superconducting cable inside.

‘It costs about 10 times less to move the magnet from Brookhaven to Illinois than it would to build a new one,’ said Lee Roberts of Boston University, spokesperson for the Muon g-2 experiment. “So that’s what we’re going to do. It’s an enormous effort from all sides, but it will be worth it.’

A model of the truck that will be used to transport the Muon g-2 ring, placed on a streetscape for scale. The truck will be escorted by police and other vehicles when it moves from Brookhaven National Laboratory in New York to a barge, and then from the barge to Fermi National Accelerator Laboratory in Illinois. Credit: Fermilab

While most of the machine can be disassembled and brought to Fermilab in trucks, the massive electromagnet must be transported in one piece. It also cannot tilt or twist more than a few degrees, or the complex wiring inside will be irreparably damaged. The Muon g-2 team has devised a plan to make the 3,200-mile journey that involves loading the ring onto a specially prepared barge and bringing it down the East Coast, around the tip of Florida and up the Mississippi River to Illinois.

‘The transport of the ring from Brookhaven to Fermilab is a great example of the cooperation that exists between national laboratories,’ said James Siegrist, associate director of science for high-energy physics with the U.S. Department of Energy. “The Muon g-2 experiment is an important component of the future of particle physics in the United States.”

See the full article here.

I am just the blogger, it is not my business. It just seems to me if I had a job like this to plan I would have enlisted the aid of ESO, probably the most sophisticated movers of complex machinery anywhere in the world.

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

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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 Fermilab: “New dark matter detector begins search for invisible particles”

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

May 2, 2013
Science contacts:
Hugh Lippincott, Fermilab, 609-558-6313, hugh@fnal.gov .
Juan Collar, University of Chicago, 773-702-4253, collar@uchicago.edu

“Scientists this week heard their first pops in an experiment that searches for signs of dark matter in the form of tiny bubbles.

This is an image of the first particle interactions seen in the COUPP-60 detector, located half a mile underground at SNOLAB in Ontario, Canada. Photo: SNOLAB

Scientists will need further analysis to discern whether dark matter caused any of the COUPP-60 experiment’s first bubbles.

‘Our goal is to make the most sensitive detector to see signals of particles that we don’t understand,’ said Hugh Lippincott, a postdoc with the Department of Energy’s Fermi National Accelerator Laboratory who has spent much of the past several months leading the installation of the one-of-a-kind detector in a laboratory a mile and a half underground.

COUPP-60 is a dark-matter experiment funded by DOE’s Office of Science. Fermilab managed the assembly and installation of the experiment’s detector.

The COUPP-60 detector is a jar filled with purified water and CF3I—an ingredient found in fire extinguishers. The liquid in the detector is kept at a temperature and pressure slightly above the boiling point, but it requires an extra bit of energy to actually form a bubble. When a passing particle enters the detector and disturbs an atom in the clear liquid, it provides that energy.

Dark-matter particles, which scientists think rarely interact with other matter, should form individual bubbles in the COUPP-60 tank.

‘The events are so rare, we’re looking for a couple of events per year,’ Lippincott said.”

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: Dark Energy Survey Supernovae light the way to dark energy”

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

Friday, April 26, 2013
Brenna Flaugher

“The Dark Energy Survey (DES) collaboration has captured images of 176 star explosions, called supernovae, including 16 that occurred farther than 7 billion light-years away and when the universe was only about half as old as it is today. A new type of CCD detector contained in the Dark Energy Camera enabled identification of the distant supernovae, making DECam about 10 times more sensitive than other optical cameras to the long-wavelength (red and near-infrared) light coming from these very distant explosions. This improved sensitivity will allow the DES collaboration to find more supernovae from this period in the history of the universe than any other project.

Dark Energy Camera

To search for supernovae, the DES observers take images of the same patch of sky every four to seven days. Then they subtract the images from each other and search for differences. Computers and teams of people looked at thousands of sets of DECam images to find the 176 candidate supernovae. So far five of the candidates have been followed up, and all five were confirmed to be type 1a supernovae.”

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 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 Fermilab: “Dark-matter search results from CDMS II silicon detectors”

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

Monday, April 15, 2013
Dan Bauer

“Scientists around the world are working to understand the nature of dark matter, which accounts for most of the mass of the universe. The earth seems to be moving through a cloud of dark-matter particles that encompasses the visible parts of our galaxy. We should be able to sense this dark matter if we can deploy detectors that are sensitive to the ‘billiard ball’ scatter of a dark matter particle from an atomic nucleus inside these detectors.

Experimental upper limits (90 percent confidence level) for the WIMP-nucleon spin-independent cross section as a function of WIMP mass. The black dotted line is from the present analysis, and the blue solid line includes previous CDMS II silicon-detector data. Also shown are limits from the CDMS II germanium-detector standard and low-threshold analyses (dark and light dashed red), as well as limits from the XENON collaboration (dark and light dash-dotted green). The magenta oval shows a possible WIMP signal region proposed to explain data from CoGeNT. The light and dark blue regions indicate the 68 percent and 90 percent contours obtained if the present result were to be interpreted as a WIMP signal. The asterisk shows the maximum likelihood point under this interpretation.

The Cryogenic Dark Matter Search (CDMS) experiment was designed to do exactly that, using germanium and silicon detectors cooled to very low temperatures in order to detect the electric charge and heat liberated by single dark-matter particle collisions with nuclei and distinguish them from the messier interactions created by normal matter.

At the American Physical Society April meeting in Denver, the CDMS collaboration presented on Saturday its blind-analysis results from data taken with silicon detectors during CDMS II operation at the Soudan Underground Laboratory. Kevin McCarthy, a graduate student from MIT, presented the results, which were submitted to Physical Review Letters.

The blind analysis resulted in three candidate events. Although this number is higher than the expected background of roughly half an event, this is far from a discovery. Simulations of the known backgrounds indicate that a statistical fluctuation could produce three or more events about 5 percent of the time. In other words, if the experiment were done 100 times, five of them would show at least three events in the signal region even if dark-matter particles did not exist.”

See the full article here.

See further articles:
From SLAC
From Symmetry Mag
From BBC

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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