Around 85% of the matter in our Universe is a mystery. If this dark matter has never been observed, how do we know what it is, and how do scientists know where to start looking? This new animation, made in collaboration with TED-Ed, shows how the LHC is hoping to recreate these theoretical dark matter particles, and what this will tell us about our world.
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This account brings you hot items from public particle physics news sources, including CERN, SymmetryMagazine.org, and Interactions.org.
Expanding the search for dark matter
2017-08-22T17:28:41Z via NavierStokesApp To: Public
"Expanding the search for dark matter"
At a recent meeting, scientists shared ideas for searching for dark matter on the (relative) cheap.
Thirty-one years ago, scientists made their first attempt to find dark matter with a particle detector in a South Dakota mine.
Since then, researchers have uncovered enough clues to think dark matter makes up approximately 26.8 percent of all the matter and energy in the universe. They think it forms a sort of gravitational scaffolding for the galaxies and galaxy clusters our telescopes do reveal, shaping the structure of our universe while remaining unseen.
These conclusions are based on indirect evidence such as the behavior of galaxies and galaxy clusters. Direct detection experiments—ones designed to actually sense a dark matter particle pinging off the nucleus of an atom—have yet to find what they’re looking for. Nor has dark matter been seen at the Large Hadron Collider. That invisible, enigmatic material, that Greta Garbo of particle physics, still wants to be alone.
It could be that researchers are just looking in the wrong place. Much of the search for dark matter has focused on particles called WIMPs, weakly interacting massive particles. But interest in WIMP alternatives has been growing, prompting the development of a variety of small-scale research projects to investigate some of the most promising prospects.
In March more than 100 scientists met at the University of Maryland for “Cosmic Visions: New Ideas in Dark Matter,” a gathering to take the pulse of the post-WIMP dark matter landscape for the Department of Energy. That pulse was surprisingly strong. Organizers recently published a white paper detailing the results.
The conference came about partly because, “it seemed a good time to get everyone together to see what each experiment was doing, where they reinforced each other and where they did something new,” says Natalia Toro, a theorist at SLAC National Accelerator Laboratory and a member of the Cosmic Visions Scientific Advisory Committee. What she and many other participants didn’t expect, Toro says, was just how many good ideas would be presented.
Almost 50 experiments in various stages of development were presented during three days of talks, and a similar number of potential experiments were discussed.
Some of the experiments presented would be designed to look for dark matter particles that are lighter than traditional WIMPs, or for the new fundamental forces through which such particles could interact. Others would look for oscillating forces produced by dark matter particles trillions of times lighter than the electron. Still others would look for different dark matter candidates, such as primordial black holes.
The scientists at the workshop were surprised by how small and relatively inexpensive many of the experiments could be, says Philip Schuster, a particle theorist at SLAC National Accelerator Laboratory.
“‘Small’ and ‘inexpensive’ depend on what technology you’re using, of course,” Schuster says. DOE is prepared to provide funding to the tune of $10 million (still a fraction of the cost of a current WIMP experiment), and many of the experiments could cost in the $1 to $2 million range.
Several factors work together to lessen the cost. For example, advances in detector technology and quantum sensors have made technology cheaper. Then there are small detectors that can be placed at already-existing large facilities like the Heavy Photon Search, a dark-sector search at Jefferson Lab. “It’s basically a table-top detector, as opposed to CMS and ATLAS at the Large Hadron Collider, which took years to build and weigh as much as a battleship,” Schuster says.
Experimentalist Joe Incandela of the University of California, Santa Barbara and one of the coordinators of the Cosmic Visions effort, has a simple explanation for this current explosion of ideas. “There’s a good synergy between the technology and interest in dark matter,” he says.
Incandela says he is feeling the synergy himself. He is a former spokesperson for CMS, a battleship-class experiment in which he continues to play an active role while also developing the Light Dark Matter Experiment, which would use a high-resolution silicon-based calorimeter that he originally helped develop for CMS to search for an alternative to WIMPs.
“It occurred to me that this calorimeter technology could very useful for low-mass dark matter searches,” he says. “My hope is that, starting soon, and spanning roughly five years, the funding—and not very much is needed—will be available to support experiments that can cover a lot more of the landscape where dark matter may be hiding. It’s very exciting.”
Week 32 at the Pole
2017-08-18T17:28:38Z via NavierStokesApp To: Public
"Week 32 at the Pole"
It was a relatively quiet week at the Pole, with most of the action outside. IceCube winterover Martin captured a nice shot of the moon, with halo and moon dogs, over the Dark Sector. You can discern a faint glow along the horizon of an impending sunrise.http://icecube.wisc.edu/news/feed )
A jump in rates of knee arthritis, a brief history of eclipse science, and bands and beats in the atmosphere of brown dwarfs
2017-08-17T18:28:43Z via NavierStokesApp To: Public
"A jump in rates of knee arthritis, a brief history of eclipse science, and bands and beats in the atmosphere of brown dwarfs"
This week we hear stories on a big jump in U.S. rates of knee arthritis, some science hits and misses from past eclipse, and the link between a recently discovered thousand-year-old Viking fortress and your Bluetooth earbuds with Online News Editor David Grimm. Sarah Crespi talks to Daniel Apai about a long-term study of brown dwarfs and what patterns in the atmospheres of these not-quite-stars, not-quite-planets can tell us. Listen to previous podcasts. [Image: NASA/JPL-Caltech; Music: Jeffrey Cook]http://www.sciencemag.org/rss/podcast.xml )
TED-Ed: The hunt for dark matter
2017-08-17T15:28:39Z via NavierStokesApp To: Public
"TED-Ed: The hunt for dark matter"
QuarkNet takes on solar eclipse science
2017-08-16T18:29:14Z via NavierStokesApp To: Public
"QuarkNet takes on solar eclipse science"
High school students nationwide will study the effects of the solar eclipse on cosmic rays.
While most people are marveling at Monday’s eclipse, a group of researchers will be measuring its effects on cosmic rays—particles from space that reach collide with the earth’s atmosphere to produce muons, heavy cousins of the electron. But these researchers aren’t the usual PhD-holding suspects: They’re still in high school.
More than 25 groups of high school students and teachers nationwide will use small-scale detectors to find out whether the number of cosmic rays raining down on Earth changes during an eclipse. Although the eclipse event will last only three hours, this student experiment has been a months-long collaboration.
The cosmic ray detectors used for this experiment were provided as kits by QuarkNet, an outreach program that gives teachers and students opportunities to try their hands at high-energy physics research. Through QuarkNet, high school classrooms can participate in a whole range of physics activities, such as analyzing real data from the CMS experiment at CERN and creating their own experiments with detectors.
“Really active QuarkNet groups run detectors all year and measure all sorts of things that would sound crazy to a physicist,” says Mark Adams, QuarkNet’s cosmic ray studies coordinator. “It doesn’t really matter what the question is as long as it allows them to do science.”
And this year’s solar eclipse will give students a rare chance to answer a cosmic question: Is the sun a major producer of the cosmic rays that bombard Earth, or do they come from somewhere else?
“We wanted to show that, if the rate of cosmic rays changes a lot during the eclipse, then the sun is a big source of cosmic rays,” Adams says. “We sort of know that the sun is not the main source, but it’s a really neat experiment. As far as we know, no one has ever done this with cosmic ray muons at the surface.”
Adams and QuarkNet teacher Nate Unterman will be leading a group of nine students and five adults to Missouri to the heart of the path of totality—where the moon will completely cover the sun—to take measurements of the event. Some QuarkNet groups will stay put, measuring what effect a partial eclipse might have on cosmic rays.
Most cosmic rays are likely high-energy particles from exploding stars deep in space, which are picked up via muons in QuarkNet detectors. But the likely result of the experiment—that cosmic rays don’t change their rate when the moon moves in front of the sun—doesn’t eclipse the excitement for the students in the collaboration.
“They’ve been working for months and months to develop the design for the measurements and the detectors,” Adams says. “That’s the great part—they’re not focused on what the answer is but the best way to find it.”
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Video: Dark Matter Hunt with LUX-ZEPLIN
2017-08-14T22:30:10Z via NavierStokesApp To: Public
"Video: Dark Matter Hunt with LUX-ZEPLIN"https://www6.slac.stanford.edu/taxonomy/term/805/feed )
Researchers at the Department of Energy’s SLAC National Accelerator Laboratory are on a quest to solve one of physics’ biggest mysteries: What exactly is dark matter – the invisible substance that accounts for 85 percent of all the matter in the universe but can’t be seen even with our most advanced scientific instruments?
ATLAS sees first direct evidence of light-by-light scattering at high energy
2017-08-14T21:29:49Z via NavierStokesApp To: Public
"ATLAS sees first direct evidence of light-by-light scattering at high energy"
ATLAS sees first direct evidence of light-by-light scattering at high energyPress UpdateDanielle Mon, 08/14/2017 - 10:573017
Geneva, 14 August 2017. Physicists from the ATLAS experiment at CERN have found the first direct evidence of high energy light-by-light scattering, a very rare process in which two photons – particles of light – interact and change direction. The result, published today in Nature Physics, confirms one of the oldest predictions of quantum electrodynamics (QED).
"This is a milestone result: the first direct evidence of light interacting with itself at high energy,” says Dan Tovey, ATLAS Physics Coordinator. “This phenomenon is impossible in classical theories of electromagnetism; hence this result provides a sensitive test of our understanding of QED, the quantum theory of electromagnetism."
Direct evidence for light-by-light scattering at high energy had proven elusive for decades – until the Large Hadron Collider’s second run began in 2015. As the accelerator collided lead ions at unprecedented collision rates, obtaining evidence for light-by-light scattering became a real possibility. “This measurement has been of great interest to the heavy-ion and high-energy physics communities for several years, as calculations from several groups showed that we might achieve a significant signal by studying lead-ion collisions in Run 2,” says Peter Steinberg, ATLAS Heavy Ion Physics Group Convener.
Heavy-ion collisions provide a uniquely clean environment to study light-by-light scattering. As bunches of lead ions are accelerated, an enormous flux of surrounding photons is generated. When ions meet at the centre of the ATLAS detector, very few collide, yet their surrounding photons can interact and scatter off one another. These interactions are known as ‘ultra-peripheral collisions’.
Studying more than 4 billion events taken in 2015, the ATLAS collaboration found 13 candidates for light-by-light scattering. This result has a significance of 4.4 standard deviations, allowing the ATLAS collaboration to report the first direct evidence of this phenomenon at high energy.
“Finding evidence of this rare signature required the development of a sensitive new ‘trigger’ for the ATLAS detector,” says Steinberg. “The resulting signature — two photons in an otherwise empty detector — is almost the diametric opposite of the tremendously complicated events typically expected from lead nuclei collisions. The new trigger’s success in selecting these events demonstrates the power and flexibility of the system, as well as the skill and expertise of the analysis and trigger groups who designed and developed it.”
ATLAS physicists will continue to study light-by-light scattering during the upcoming LHC heavy-ion run, scheduled for 2018. More data will further improve the precision of the result and may open a new window to studies of new physics. In addition, the study of ultra-peripheral collisions should play a greater role in the LHC heavy-ion programme, as collision rates further increase in Run 3 and beyond.
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ATLAS observes direct evidence of light-by-light scattering
2017-08-14T21:29:48Z via NavierStokesApp To: Public
"ATLAS observes direct evidence of light-by-light scattering"
Physicists from the ATLAS experiment at CERN have found the first direct evidence ofhigh energy light-by-light scattering, a very rare process in which two photons – particles of light – interact and change direction. The result, published today in Nature Physics, confirms one of the oldest predictions of quantum electrodynamics (QED).
"This is a milestone result: the first direct evidence of light interacting with itself at high energy,” says Dan Tovey(University of Sheffield), ATLAS Physics Coordinator. “This phenomenon is impossible in classical theories of electromagnetism; hence this result provides a sensitive test of our understanding of QED, the quantum theory of electromagnetism."
Direct evidence for light-by-light scattering at high energy had proven elusive for decades – until the Large Hadron Collider’s second run began in 2015. As the accelerator collided lead ions at unprecedented collision rates, obtaining evidence for light-by-light scattering became a real possibility. “This measurement has been of great interest to the heavy-ion and high-energy physics communities for several years, as calculations from several groups showed that we might achieve a significant signal by studying lead-ion collisions in Run 2,” says Peter Steinberg (Brookhaven National Laboratory), ATLAS Heavy Ion Physics Group Convener.
Heavy-ion collisions provide a uniquely clean environment tostudy light-by-light scattering. As bunches of lead ions are accelerated, an enormous flux of surrounding photons is generated. When ions meet at the centre of the ATLAS detector, very few collide, yet their surrounding photons can interact and scatter off one another. These interactions are known as ‘ultra-peripheral collisions’.
Studying more than 4 billion events taken in 2015, the ATLAS collaboration found 13 candidates for light-by-light scattering. This result has a significance of 4.4 standard deviations, allowing the ATLAS collaboration to report the first direct evidence of this phenomenon at high energy.
“Finding evidence of this rare signature required the development of a sensitive new ‘trigger’ for the ATLAS detector,” says Steinberg. “The resulting signature — two photons in an otherwise empty detector — is almost the diametric opposite of the tremendously complicated eventstypically expected from lead nuclei collisions. The new trigger’s success in selecting these events demonstrates the power and flexibility of the system, as well as the skill and expertise of the analysis and trigger groups who designed and developed it.”
ATLAS physicists will continue to study light-by-light scattering during the upcoming LHC heavy-ion run, scheduled for 2018. More data will further improve the precision of theresult and may open a new window to studies of new physics. In addition, the study of ultra-peripheral collisions should play a greater role in the LHC heavy-ion programme, as collision rates further increase in Run 3 and beyond.
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Three SLAC Scientists Receive DOE Early Career Research Grants
2017-08-10T23:30:43Z via NavierStokesApp To: Public
"Three SLAC Scientists Receive DOE Early Career Research Grants"https://www6.slac.stanford.edu/taxonomy/term/805/feed )Zeeshan Ahmed, Frederico Fiuza and Emilio Nanni will each receive about $2.5 million over five years to pursue cutting-edge research into cosmic inflation, plasma acceleration and using terahertz waves to accelerate particles.
Coddled puppies don’t do as well in school, some trees make their own rain, and the Americas were probably first populated by ancient mariners
2017-08-10T18:30:36Z via NavierStokesApp To: Public
"Coddled puppies don’t do as well in school, some trees make their own rain, and the Americas were probably first populated by ancient mariners"
This week we hear stories on new satellite measurements that suggest the Amazon makes its own rain for part of the year, puppies raised with less smothering moms do better in guide dog school, and what DNA can tell us about ancient Greeks’ near mythical origins with Online News Editor David Grimm. Sarah Crespi talks to Lizzie Wade about coastal and underwater evidence of a watery route for the Americas’ first people. Listen to previous podcasts. [Image: Lizzie Wade; Music: Jeffrey Cook]http://www.sciencemag.org/rss/podcast.xml )
2017-08-10T18:30:36Z via NavierStokesApp To: Public
The new Fermilab Accelerator Science and Technology facility at Fermilab looks to the future of accelerator science.
Unlike most particle physics facilities, the new Fermilab Accelerator Science and Technology facility (FAST) wasn’t constructed to find new particles or explain basic physical phenomena. Instead, FAST is a kind of workshop—a space for testing novel ideas that can lead to improved accelerator, beamline and laser technologies.
Historically, accelerator research has taken place on machines that were already in use for experiments, making it difficult to try out new ideas. Tinkering with a physicist’s tools mid-search for the secrets of the universe usually isn’t a great idea. By contrast, FAST enables researchers to study pieces of future high-intensity and high-energy accelerator technology with ease.
“FAST is specifically aiming to create flexible machines that are easily reconfigurable and that can be accessed on very short notice,” says Alexander Valishev, head of department that manages FAST. “You can roll in one experiment and roll the other out in a matter of days, maybe months, without expensive construction and operation costs.”
This flexibility is part of what makes FAST a useful place for training up new accelerator scientists. If a student has an idea, or something they want to study, there’s plenty of room for experimentation.
“We want students to come and do their thesis research at FAST, and we already have a number of students working.” Valishev says. “We have already had a PhD awarded on the basis of work done at FAST, but we want more of that.”
Small ring, bright beam
FAST will eventually include three parts: an electron injector, a proton injector and a particle storage ring called the Integrable Optics Test Accelerator, or IOTA. Although it will be small compared to other rings—only 40 meters long, while Fermilab’s Main Injector has a circumference of 3 kilometers—IOTA will be the centerpiece of FAST after its completion in 2019. And it will have a unique feature: the ability to switch from being an electron accelerator to a proton accelerator and back again.
“The sole purpose of this synchrotron is to test accelerator technology and develop that tech to test ideas and theories to improve accelerators everywhere,” says Dan Broemmelsiek, a scientist in the IOTA/FAST department.
One aspect of accelerator technology FAST focuses on is creating higher-intensity or “brighter” particle beams.
Brighter beams pack a bigger particle punch. A high-intensity beam could send a detector twice as many particles as is usually possible. Such an experiment could be completed in half the time, shortening the data collection period by several years.
IOTA will test a new concept for accelerators called integrable optics, which is intended to create a more concentrated, stable beam, possibly producing higher intensity beams than ever before.
“If this IOTA thing works, I think it could be revolutionary,” says Jamie Santucci, an engineering physicist working on FAST. “It’s going to allow all kinds of existing accelerators to pack in way more beam. More beam, more data.”
Maximum energy milestone
Although the completion of IOTA is still a few years away, the electron injector will reach a milestone this summer: producing an electron beam with the energy of 300 million electronvolts (MeV).
“The electron injector for IOTA is a research vehicle in its own right,” Valishev says. It provides scientists a chance to test superconducting accelerators, a key piece of technology for future physics machines that can produce intense acceleration at relatively low power.
“At this point, we can measure things about the beam, chop it up or focus it,” Broemmelsiek says. “We can use cameras to do beam diagnostics, and there’s space here in the beamline to put experiments to test novel instrumentation concepts.”
The electron beam’s previous maximum energy of 50 MeV was achieved by passing the beam through two superconducting accelerator cavities and has already provided opportunities for research. The arrival of the 300 MeV beam this summer—achieved by sending the beam through another eight superconducting cavities—will open up new possibilities for accelerator research, with some experiments already planned to start as soon as the beam is online.
The third phase of FAST, once IOTA is complete, will be the construction of the proton injector.
“FAST is unique because we will specifically target creating high-intensity proton beams,” Valishev says.
This high-intensity proton beam research will directly translate to improving research into elusive particles called neutrinos, Fermilab’s current focus.
“In five to 10 years, you’ll be talking to a neutrino guy and they’ll go, ‘I don’t know what the accelerator guys did, but it’s fabulous. We’re getting more neutrinos per hour than we ever thought we would,’” Broemmelsiek says.
Creating new accelerator technology is often an overlooked area in particle physics, but the freedom to try out new ideas and discover how to build better machines for research is inherently rewarding for people who work at FAST.
“Our business is science, and we’re supposed to make science, and we work really hard to do that,” Broemmelsiek says. “But it’s also just plain ol’ fun.”
Hunting season at the LHC
2017-08-10T10:30:49Z via NavierStokesApp To: Public
"Hunting season at the LHC"
With the LHC now back smashing protons together at an energy of 13 TeV, what exotic beasts do physicists hope to find in this unfamiliar corner of the natural world?
Among the top priorities for the LHC experiments this year is the hunt for new particles suspected to lurk at the high-energy frontier: exotic beasts that do not fit within the Standard Model of particle physics and could lift the lid on an even deeper theory of nature’s basic workings.
Following the discovery of the Higgs boson five years ago, which was the final missing piece of the Standard Model of particle physics, physicists have good reason to expect that new particle species lie over the horizon. Among them is the mystery of what makes up dark matter, why the Standard Model particles of matter weigh what they do and come in three families of two, and, indeed, why the Higgs boson isn’t vastly heavier than it is – that is, why it isn't so heavy that it could have ended the evolution of the universe an instant after the Big Bang.
Casting the net wide
These outlandish prey are just a few of the known unknowns for physicists. To ensure that no corner of the new-physics landscape is left unturned, the LHC experiments also employ a model-independent approach to search for general features such as pairs of high-energy quarks and leptons or for unexplained sources of missing energy.
Their most elusive quarry might not light up their detectors at all, forcing the LHC exploration teams to adopt stealth approaches, such as making ultra-precise measurements of known Standard Model processes and seeing if they diverge from predictions. While physicists are hoping for a clear shot at any new particle species – a distinctive “bump” in the data that can only be explained by the presence of a new, heavy particle – they could be faced with a mere rustling in the undergrowth or other indirect signs that something is awry. This quest is not just the preserve of all of the LHC experiments, but also of numerous other experiments at CERN that are not linked to the LHC.
Either way, physicists exploring this uncharted territory of the high-energy frontier have to take extreme care not to get tricked by numerous Standard Model doppelgängers or be teased by inconclusive statistics. Even after an exotic new beast has been snared statistically and it seems that the LHC experiments have a discovery on their hands, so begins the task of identifying what the beast really is: a mere mutant or close relative of a species we already know? Or the first glimpse of a new subatomic kingdom?
Ranging from the bizarre to the mind-boggling, and in no particular order, below is a summary of some of the quantum creatures that are in the LHC experimentalists’ sights this year.
Week 31 at the Pole
2017-08-09T21:30:46Z via NavierStokesApp To: Public
"Week 31 at the Pole"
No, not yet—that’s the moon, not the sun. But so bright, one would be forgiven for mistaking it for the sun. Not only is this full moon bright, but it’s sporting a nice clear halo, too, providing an excellent backdrop for a shot of the IceCube Lab.http://icecube.wisc.edu/news/feed )
A new search for dark matter 6800 feet underground
2017-08-08T17:30:54Z via NavierStokesApp To: Public
"A new search for dark matter 6800 feet underground"
Prototype tests of the future SuperCDMS SNOLAB experiment are in full swing.
When an extraordinarily sensitive dark matter experiment goes online at one of the world’s deepest underground research labs, the chances are better than ever that it will find evidence for particles of dark matter—a substance that makes up 85 percent of all matter in the universe but whose constituents have never been detected.
The heart of the experiment, called SuperCDMS SNOLAB, will be one of the most sensitive detectors for hypothetical dark matter particles called WIMPs, short for “weakly interacting massive particles.” SuperCDMS SNOLAB is one of two next-generation experiments (the other one being an experiment called LZ) selected by the US Department of Energy and the National Science Foundation to take the search for WIMPs to the next level, beginning in the early 2020s.
“The experiment will allow us to enter completely unexplored territory,” says Richard Partridge, head of the SuperCDMS SNOLAB group at the Kavli Institute for Particle Astrophysics and Cosmology, a joint institute of Stanford University and SLAC National Accelerator Laboratory. “It’ll be the world’s most sensitive detector for WIMPs with relatively low mass, complementing LZ, which will look for heavier WIMPs.”
The experiment will operate deep underground at Canadian laboratory SNOLAB inside a nickel mine near the city of Sudbury, where 6800 feet of rock provide a natural shield from high-energy particles from space, called cosmic rays. This radiation would not only cause unwanted background in the detector; it would also create radioactive isotopes in the experiment’s silicon and germanium sensors, making them useless for the WIMP search. That’s also why the experiment will be assembled from major parts at its underground location.
A detector prototype is currently being tested at SLAC, which oversees the efforts of the SuperCDMS SNOLAB project.
Colder than the universe
The only reason we know dark matter exists is that its gravity pulls on regular matter, affecting how galaxies rotate and light propagates. But researchers believe that if WIMPs exist, they could occasionally bump into normal matter, and these collisions could be picked up by modern detectors.
SuperCDMS SNOLAB will use germanium and silicon crystals in the shape of oversized hockey pucks as sensors for these sporadic interactions. If a WIMP hits a germanium or silicon atom inside these crystals, two things will happen: The WIMP will deposit a small amount of energy, causing the crystal lattice to vibrate, and it’ll create pairs of electrons and electron deficiencies that move through the crystal and alter its electrical conductivity. The experiment will measure both responses.
“Detecting the vibrations is very challenging,” says KIPAC’s Paul Brink, who oversees the detector fabrication at Stanford. “Even the smallest amounts of heat cause lattice vibrations that would make it impossible to detect a WIMP signal. Therefore, we’ll cool the sensors to about one hundredth of a Kelvin, which is much colder than the average temperature of the universe.”
These chilly temperatures give the experiment its name: CDMS stands for “Cryogenic Dark Matter Search.” (The prefix “Super” indicates that the experiment is more sensitive than previous detector generations.)
The use of extremely cold temperatures will be paired with sophisticated electronics, such as transition-edge sensors that switch from a superconducting state of zero electrical resistance to a normal-conducting state when a small amount of energy is deposited in the crystal, as well as superconducting quantum interference devices, or SQUIDs, that measure these tiny changes in resistance.
The experiment will initially have four detector towers, each holding six crystals. For each crystal material—silicon and germanium—there will be two different detector types, called high-voltage (HV) and interleaved Z-sensitive ionization phonon (iZIP) detectors. Future upgrades can further boost the experiment’s sensitivity by increasing the number of towers to 31, corresponding to a total of 186 sensors.Matt CherryPaul BrinkPaul BrinkPaul BrinkPaul BrinkPaul BrinkPaul BrinkChris Smith/SLAC National Accelerator LaboratoryChris Smith/SLAC National Accelerator LaboratoryChris Smith/SLAC National Accelerator LaboratoryChris Smith/SLAC National Accelerator LaboratoryChris Smith/SLAC National Accelerator LaboratoryChris Smith/SLAC National Accelerator LaboratoryChris Smith/SLAC National Accelerator LaboratoryPaul BrinkPaul BrinkPaul BrinkMatt CherryMatt CherryPaul BrinkPaul Brink
Working hand in hand
The work under way at SLAC serves as a system test for the future SuperCDMS SNOLAB experiment. Researchers are testing the four different detector types, the way they are integrated into towers, their superconducting electrical connectors and the refrigerator unit that cools them down to a temperature of almost absolute zero.
“These tests are absolutely crucial to verify the design of these new detectors before they are integrated in the experiment underground at SNOLAB,” says Ken Fouts, project manager for SuperCDMS SNOLAB at SLAC. “They will prepare us for a critical DOE review next year, which will determine whether the project can move forward as planned.” DOE is expected to cover about half of the project costs, with the other half coming from NSF and a contribution from the Canadian Foundation for Innovation.
Important work is progressing at all partner labs of the SuperCDMS SNOLAB project. Fermi National Accelerator Laboratory is responsible for the cryogenics infrastructure and the detector shielding—both will enable searching for faint WIMP signals in an environment dominated by much stronger unwanted background signals. Pacific Northwest National Laboratory will lend its expertise in understanding background noise in highly sensitive precision experiments. A number of US universities are involved in various aspects of the project, including detector fabrication, tests, data analysis and simulation.
The project also benefits from international partnerships with institutions in Canada, France, the UK and India. The Canadian partners are leading the development of the experiment’s data acquisition and will provide the infrastructure at SNOLAB.
“Strong partnerships create a lot of synergy and make sure that we’ll get the best scientific value out of the project,” says Fermilab’s Dan Bauer, spokesperson of the SuperCDMS collaboration, which consists of 109 scientists from 22 institutions, including numerous universities. “Universities have lots of creative students and principal investigators, and their talents are combined with the expertise of scientists and engineers at the national labs, who are used to successfully manage and build large projects.”
SuperCDMS SNOLAB will be the fourth generation of experiments, following CDMS-I at Stanford, CDMS-II at the Soudan mine in Minnesota, and a first version of SuperCDMS at Soudan, which completed operations in 2015.
“Over the past 20 years we’ve been pushing the limits of our detectors to make them more and more sensitive for our search for dark matter particles,” says KIPAC’s Blas Cabrera, project director of SuperCDMS SNOLAB. “Understanding what constitutes dark matter is as fundamental and important today as it was when we started, because without dark matter none of the known structures in the universe would exist—no galaxies, no solar systems, no planets and no life itself.”
World’s smallest neutrino detector finds big physics fingerprint
2017-08-07T19:31:30Z via NavierStokesApp To: Public
"World’s smallest neutrino detector finds big physics fingerprint"
World’s smallest neutrino detector finds big physics fingerprintPress ReleaseLauren Mon, 08/07/2017 - 13:582917
OAK RIDGE, Tenn., Aug. 3, 2017—After more than a year of operation at the Department of Energy’s (DOE’s) Oak Ridge National Laboratory (ORNL), the COHERENT experiment, using the world’s smallest neutrino detector, has found a big fingerprint of the elusive, electrically neutral particles that interact only weakly with matter.
The research, performed at ORNL’s Spallation Neutron Source (SNS) and published in the journal Science, provides compelling evidence for a neutrino interaction process predicted by theorists 43 years ago, but never seen.
“The one-of-a-kind particle physics experiment at Oak Ridge National Laboratory was the first to measure coherent scattering of low-energy neutrinos off nuclei,” said ORNL physicist Jason Newby, technical coordinator and one of 11 ORNL participants in COHERENT, a collaboration of 80 researchers from 19 institutions and 4 nations.
The SNS produces neutrons for scientific research and also generates a high flux of neutrinos as a byproduct. Placing the detector at SNS, a mere 65 feet (20 meters) from the neutrino source, vastly improved the chances of interactions and allowed the researchers to decrease the detector’s weight to just 32 pounds (14.5 kilograms). In comparison, most neutrino detectors weigh thousands of tons: although they are continuously exposed to solar, terrestrial, and atmospheric neutrinos, they need to be massive because the interaction odds are more than 100 times lower than at SNS.
The scientists are the first to detect and characterize coherent elastic scattering of neutrinos off nuclei. This long-sought confirmation, predicted in the particle physics Standard Model, measures the process with enough precision to establish constraints on alternative theoretical models.
Typically, neutrinos interact with individual protons or neutrons inside a nucleus. But in “coherent” scattering, an approaching neutrino “sees” the entire weak charge of the nucleus as a whole and interacts with all of it.
“The energy of the SNS neutrinos is almost perfectly tuned for this experiment—large enough to create a detectable signal, but small enough to take advantage of the coherence condition,” Newby said. “The only smoking gun of the interaction is a small amount of energy imparted to a single nucleus.”
That signal is as tough to spot as a bowling ball’s tiny recoil after a ping-pong ball hits it.
Physicist Juan Collar of the University of Chicago led the design of the detector used at SNS, a cesium iodide scintillator crystal doped with sodium to increase the prominence of light signals from neutrino interactions. After trying more sophisticated technologies, he went back to simple inorganic scintillators. “They are arguably the most pedestrian kind of radiation detector available, having been around for a century. Sodium-doped cesium iodide merges all of the properties required to work as a small, ‘handheld’ coherent neutrino detector,” he said. “Very often, less is more.”
Success depended on finding the right combination of neutrino detector and source. “The detector was designed with SNS in mind,” Collar said. “SNS is unique not only as a neutron source, but also as a neutrino source. It will provide us with opportunities for many more exciting sorties into neutrino physics.”
Because SNS produces pulsed neutron beams, the neutrinos are also pulsed, enabling easy separation of signal from background. That aspect makes data collection cleaner than at steady-state neutrino sources such as nuclear reactors.
Three neutrino flavors were seen by COHERENT—muon neutrinos that emerged instantaneously with the neutron beam and muon antineutrinos and electron neutrinos that came a few microseconds later. “The Standard Model predicts the energy and time signatures we saw,” Newby said. “Juan [Collar] wanted to make sure that he chose a detection mechanism with the timing resolution to distinguish the prompt from delayed signals.”
The calculable fingerprint of neutrino–nucleus interactions predicted by the Standard Model and seen by COHERENT is not just interesting to theorists. In nature, it also dominates neutrino dynamics during neutron star formation and supernovae explosions.
“When a massive star collapses and then explodes, the neutrinos dump vast energy into the stellar envelope,” said physicist Kate Scholberg of Duke University, COHERENT’s spokesperson. “Understanding the process feeds into understanding of how these dramatic events occur.”
Coherent elastic scattering is also relevant for detecting the enormous neutrino burst from a supernova. “When such an event occurs in the Milky Way, neutrinos of all flavors will bump into nuclei, and sensitive dark matter detectors may observe a burst of tiny recoils,” she said.
“COHERENT’s data will help with interpretation of measurements of neutrino properties by experiments worldwide,” Scholberg concluded. “We may also be able to use coherent scattering to better understand the structure of the nucleus.”
Though the cesium-iodide detector observed coherent scattering beyond any doubt, COHERENT researchers will conduct additional measurements with at least three detector technologies to observe coherent neutrino interactions at distinct rates, another signature of the process. These detectors will further expand knowledge of basic neutrino properties, such as their intrinsic magnetism.
The team included partners from the Russian Federation (Institute for Theoretical and Experimental Physics named by A.I. Alikhanov of National Research Centre “Kurchatov Institute”; National Research Nuclear University Moscow Engineering Physics Institute), USA (Indiana University, Triangle Universities Nuclear Laboratory, Duke University, University of Tennessee–Knoxville, North Carolina Central University, Sandia National Laboratories at Livermore, University of Chicago, Lawrence Berkeley National Laboratory, New Mexico State University, Los Alamos National Laboratory, University of Washington, Oak Ridge National Laboratory, North Carolina State University, Pacific Northwest National Laboratory, University of Florida), Canada (Laurentian University), Republic of Korea (Korea Advanced Institute of Science and Technology and Institute for Basic Science).
The title of the Science paper is “Observation of Coherent Elastic Neutrino-Nucleus Scattering.”
ORNL’s Laboratory Directed Research and Development (LDRD) Program funded local siting studies and installation to establish the experiment at the SNS. The U.S. National Science Foundation, the Kavli Institute for Cosmological Physics at the University of Chicago and an endowment from the Kavli Foundation and its founder Fred Kavli supported construction of the detector.
Additional support came from the DOE Office of Science, including an award from the office’s Early Career Research Program; National Nuclear Security Administration Office of Defense, Nuclear Nonproliferation Research, and Development; LDRD programs of Lawrence Berkeley and Sandia National Laboratories; Pacific Northwest National Laboratory via the National Consortium for Measurement and Signature Intelligence Research Program and Intelligence Community Postdoctoral Research Fellowship Program; Alfred P. Sloan Foundation; Consortium for Nonproliferation Enabling Capabilities; Institute for Basic Science (Korea); National Science Foundation (USA); Russian Foundation for Basic Research; Russian Science Foundation in the framework of MEPhI Academic Excellence Project; Triangle Universities Nuclear Laboratory; University of Washington Royalty Research Fund; and resources of the Spallation Neutron Source and the Oak Ridge Leadership Computing Facility, which are DOE Office of Science User Facilities at ORNL.
UT-Battelle manages ORNL for DOE’s Office of Science. The single largest supporter of basic research in the physical sciences in the United States, the Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit www.science.energy.gov.
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Oak Ridge National Laboratory
An underground groundbreaking
2017-08-04T16:31:17Z via NavierStokesApp To: Public
"An underground groundbreaking"
A physics project kicks off construction a mile underground.
For many government officials, groundbreaking ceremonies are probably old hat—or old hardhat. But how many can say they’ve been to a groundbreaking that’s nearly a mile underground?
A group of dignitaries, including a governor and four members of Congress, now have those bragging rights. On July 21, they joined scientists and engineers 4850 feet beneath the surface at the Sanford Underground Research Facility to break ground on the Long-Baseline Neutrino Facility (LBNF).
LBNF will house massive, four-story-high detectors for the Deep Underground Neutrino Experiment (DUNE) to learn more about neutrinos—invisible, almost massless particles that may hold the key to how the universe works and why matter exists. Fourteen shovels full of dirt marked the beginning of construction for a project that could be, well, groundbreaking.
The Sanford Underground Research Facility in Lead, South Dakota resides in what was once the deepest gold mine in North America, which has been repurposed as a place for discovery of a different kind.
“A hundred years ago, we mined gold out of this hole in the ground. Now we’re going to mine knowledge,” said US Representative Kristi Noem of South Dakota in an address at the groundbreaking.
Transforming an old mine into a lab is more than just a creative way to reuse space. On the surface, cosmic rays from the sun constantly bombard us, causing cosmic noise in the sensitive detectors scientists use to look for rare particle interactions. But underground, shielded by nearly a mile of rock, there’s cosmic quiet. Cosmic rays are rare, making it easier for scientists to see what’s going on in their detectors without being clouded by interference.
It may be easier to analyze data collected underground, but entering the subterranean science facility can be a chore. Nearly 60 people took a trip underground to the groundbreaking site, requiring some careful elevator choreography.
Before venturing into the deep below, reporters and representatives alike donned safety glasses, hardhats and wearable flashlights. They received two brass tags engraved with their names—one to keep and another to hang on a corkboard—a process called “brassing in.” This helps keep track of who’s underground in case of emergency.
The first group piled into the open-top elevator, known as a cage, to begin the descent. As the cage glides through a mile of mountain, it’s easy to imagine what it must have been like to be a miner back when Sanford Lab was the Homestake Mine. What’s waiting below may have changed, but the method of getting there hasn’t: The winch lowering the cage at 500-feet-a-minute is 80 years old and still works perfectly.
The ride to the 4850-level takes about 10 minutes in the cramped cage—it fits 35, but even with 20 people it feels tight. Water drips in through the ceiling as the open elevator chugs along, occasionally passing open mouths in the rock face of drifts once mined for gold.
“When you go underground, you start to think ‘It has never rained in here. And there’s never been daylight,’” says Tim Meyer, Chief Operating Officer of Fermilab, who attended the groundbreaking. “When you start thinking about being a mile below the surface, it just seems weird, like you’re walking through a piece of Swiss cheese.”
Where the cage stops at the 4850-level would be the destination of most elevator occupants on a normal day, since the shaft ends near the entrance of clean research areas housing Sanford Lab experiments. But for the contingent traveling to the future site of LBNF/DUNE on the other end of the mine, the journey continued, this time in an open-car train. It’s almost like a theme-park ride as the motor (as it’s usually called by Sanford staff) clips along through a tunnel, but fortunately, no drops or loop-the-loops are involved.
“The same rails now used to transport visitors and scientists were once used by the Homestake miners to remove gold from the underground facility,” says Jim Siegrist, Associate Director of High Energy Physics at the Department of Energy. “During the ride, rock bolts and protective screens attached to the walls were visible by the light of the headlamp mounted on our hardhats.”
After a 15-minute ride, the motor reached its destination and it was business as usual for a groundbreaking ceremony: speeches, shovels and smiling for photos. A fresh coat of white paint (more than 100 gallons worth) covered the wall behind the officials, creating a scene that almost could have been on the surface.
“Celebrating the moment nearly a mile underground brought home the enormity of the task and the dedication required for such precise experiments,” says South Dakota Governor Dennis Daugaard. “I know construction will take some time, but it will be well worth the wait for the Sanford Underground Research Facility to play such a vital role in one of the most significant physics experiments of our time."
What’s the big deal?
The process to reach the groundbreaking site is much more arduous than reaching most symbolic ceremonies, so what would possess two senators, two representatives, a White House representative, a governor and delegates from three international science institutions (to mention a few of the VIPs) to make the trip? Only the beginning of something huge—literally.
“This milestone represents the start of construction of the largest mega-science project in the United States,” said Mike Headley, executive director of Sanford Lab.
The 14 shovelers at the groundbreaking made the first tiny dent in the excavation site for LBNF, which will require the extraction of more than 870,000 tons of rock to create huge caverns for the DUNE detectors. These detectors will catch neutrinos sent 800 miles through the earth from Fermi National Accelerator Laboratory in the hopes that they will tell us something more about these strange particles and the universe we live in.
“We have the opportunity to see truly world-changing discovery,” said US Representative Randy Hultgren of Illinois. “This is unique—this is the picture of incredible discovery and experimentation going into the future.”
First antiprotons in ELENA
2017-08-04T15:30:57Z via NavierStokesApp To: Public
"First antiprotons in ELENA"
On 2 August, the first 5.3 MeV antiproton beam coming from CERN’s Antiproton Decelerator (AD) circulated in the Extra Low ENergy Antiproton (ELENA) decelerating ring.
ELENA is the new decelerator for antimatter experiments. It has a circumference of just 30 meters and will be connected to the AD experiments to increase the number of antiprotons available to several antimatter experiments. The slower the antiprotons (i.e. the less energy they have), the easier it is for the AD’s antimatter experiments to study or manipulate them. However, the AD decelerator can reliably only slow antiprotons down to 5.3 MeV, the lowest possible energy for a machine of this size. ELENA will reduce this energy by 50 times, to just 0.1 MeV. In addition, the density of the beams will be improved. The number of antiprotons that can be trapped will be increased by a factor of 10 to 100. The new decelerator will also enable several experiments to receive antiproton beams simultaneously, opening up the possibility for additional experiments, such as GBAR.
This is not the first time that a beam has circulated in ELENA. The first tests began last November, but this is the first time that antiprotons, the particle type this machine has been conceived for, have been injected. The beam of antiprotons has been successfully injected and it has been observed circulating for a few milliseconds (that is, a few thousand turns of the machine).
The commissioning of the machine will continue over the next coming months with setting-up of several systems such as the radio-frequency cavity, which will be used to decelerate the bunches of antiprotons. At that point, the commissioning team will start changing the energy of the beams. At the same time, a series of general adjustments of the beam optics is as well foreseen.
As antiprotons are difficult to produce and they need to be shared among many experiments, progress in the commissioning of ELENA will also be made using protons and ions coming from a local H– ion and proton source.
T2K presents hint of CP violation by neutrinos
2017-08-04T07:31:02Z via NavierStokesApp To: Public
"T2K presents hint of CP violation by neutrinos"
T2K presents hint of CP violation by neutrinosPress ReleaseDanielle Fri, 08/04/2017 - 01:052817
The international T2K Collaboration strengthened its previous hint that the symmetry between matter and antimatter may be violated for neutrino oscillation. A preliminary analysis of T2K's latest data rejects the hypothesis that neutrinos and antineutrinos oscillate with the same probability at 95% confidence (2σ) level. With nearly twice the neutrino data in 2017 compared to their 2016 results, T2K has performed a new analysis of neutrino and antineutrino data using a new event reconstruction algorithm for interactions in the far detector, Super-Kamiokande. Today's announcement was made by Prof Mark Hartz, of the University of Tokyo Kavli Institute for the Physics and Mathematics of the Universe (Japan) and TRIUMF (Canada), who presented the results at a colloquium at the High Energy Accelerator Research Organization (KEK) in Tsukuba, Japan. (https://kds.kek.jp/indico/event/25337/)
Why the universe is primarily comprised of matter today, instead of being comprised of equal parts matter and antimatter, is one of the most intriguing questions in all of science. One of the conditions required for the observed dominance of matter over antimatter to develop is the violation of Charge-Parity (CP) symmetry, which is the principle that the laws of physics should be the same if viewed upside-down in a mirror (Parity), with all matter exchanged with antimatter (Charge). If CP violation occurs in neutrinos, it will manifest itself as a difference in the oscillation probabilities of neutrinos and antineutrinos.
Whether the probability for electron neutrino appearance exceeds, or not, the electron antineutrino appearance probability depends on the value of the CP violating phase, δCP, introduced by Kobayashi and Maskawa. The CP violating phase can take any value from -180 to +180, and if it deviates from 0 and ±180 then CP violation occurs. It has been measured to be around 68 for quarks; T2K's goal is to measure the neutrino CP phase for the first time.
In the T2K experiment in Japan, a muon neutrino beam is produced at the Japan Proton Accelerator Research Complex (J-PARC) located in Tokai village, Ibaraki prefecture, on the east coast of Japan. The neutrino beam is created by directing 30 GeV protons from the J-PARC Main Ring (MR) accelerator onto a cylindrical target to produce an intense secondary particle beam that is focused and filtered by strong magnetic lenses called neutrino horns. The focused particle beam decays into a beam of muon neutrinos or antineutrinos, depending on the filtering done by the neutrino horns. The neutrino/antineutrino beam is monitored by a detector complex in Tokai, 280 m away from the neutrino target, and is aimed at the gigantic Super-Kamiokande underground detector in Kamioka, near the west coast of Japan, 295 kilometers (185 miles) away from Tokai. During their journey, a small fraction of these muon neutrinos will turn into electron neutrinos.
T2K's observed electron neutrino appearance rate is significantly higher than would be expected if CP symmetry were conserved. In contrast, the antineutrino data set, while still too small to make strong statements, shows a smaller electron antineutrino appearance rate than would be expected if CP symmetry were conserved. T2K observes 89 electron neutrinos while approximately 67 neutrinos are expected with no CP violation, and they observe 7 electron antineutrinos when approximately 9 are expected. When analyzed in a full framework of three neutrino and antineutrino flavors, and combined with measurements of electron antineutrino disappearance from reactor experiments, the T2K data exclude CP conservation at the 95% confidence (2σ) level. The 95% CL allowed region for the CP violating phase, δCP, is [-167; -34] ([-88; -68]) for the normal (inverted) hierarchy, with the best fit point being -105 (-79). The size of the expected T2K allowed region for this data set, using the constraint from the reactor experiments, is a 95% CL region spanning approximately [-200; +12] ([-156; -22]) for the normal (inverted) hierarchy, assuming a case of maximal CP violation.
This new data analysis includes use of an improved event reconstruction algorithm for neutrino and antineutrino interactions in Super-Kamiokande. With this new event reconstruction algorithm, the signal to background ratio of events used in the analysis is improved and the systematic errors associated with event reconstruction are reduced. Moreover, the new reconstruction algorithm allows the volume of the detector to be used more effectively for collecting neutrino interactions. This new CP violation result also includes the use of an additional selected sample of electron neutrino events at Super-Kamiokande. Taken together, the new reconstruction algorithm and the additional data sample amount to a data selection efficiency increase of 30%.
The T2K experiment is primarily supported by the Japanese Ministry for Culture, Sports, Science, and Technology (MEXT), and is jointly hosted by the High Energy Accelerator Research Organization (KEK) and the University of Tokyo's Institute for Cosmic Ray Research (ICRR). The T2K experiment was constructed and is operated by an international collaboration, which currently consists of nearly 500 scientists from 63 institutions in 11 countries [Canada, France, Germany, Italy, Japan, Poland, Russia, Spain, Switzerland, UK, and USA]. This observation is made possible by the efforts of J-PARC to deliver high-quality beam to T2K.
This 2017 result is based on a total data set of 2.25x1021 protons on target (POT), which is 28% of the POT exposure that T2K is set to receive. If there were no neutrino-antineutrino asymmetry, the chance of observing an asymmetry as large as what T2K observed, due to random statistical fluctuations, is about 1 in 20. To explore and solidify this intriguing hint the T2K collaboration need more neutrino and antineutrino data. The full T2K exposure of 7.8x1021 POT is expected to come by ~2021, thanks to planned upgrades to the J-PARC MR accelerator and the neutrino beamline. Moreover, T2K has proposed a run extension that will lead to a full exposure of 20x1021 POT, with 3σ sensitivity to CP violation observation (for certain values of oscillation parameters, including the current best-fit point) by ~2026, when the next generation experiments are expected to begin operations. An upgrade of the T2K near detector for the run extension is currently being designed, with a planned installation date of 2021. The T2K run extension has been given stage-1 status by the J-PARC Centre Directorate.
The search for CP symmetry violation with neutrinos and antineutrinos builds on T2K's 2013 discovery of electron neutrino appearance in a muon neutrino beam, which was the first statistically significant observation of the appearance of a neutrino flavour. This appearance is an example of neutrino oscillation, a purely quantum mechanical long-range interference phenomenon; neutrino oscillation proves conclusively that neutrinos have non-zero mass. T2K's 2013 electron neutrino appearance discovery resulted in a share of the 2016 Breakthrough Prize for Fundamental Physics being awarded to Koichiro Nishikawa and the entire T2K collaboration.
More details on the new T2K result, as well as prospects for future running of the experiment, can be found in the presentation file from the KEK seminar (https://kds.kek.jp/indico/event/25337/), and more information about the T2K experiment can be found on the T2K public website (http://t2k-experiment.org).
The proton beam extracted from the J-PARC Main Ring synchrotron are directed westward through the T2K primary beam line. At the target station the protons strike a 1) target composed of graphite rods and produce numerous positively charged π-mesons which are in turn focused towards the forward direction under the effect magnetic horns. The π-mesons then decay into muon and muon neutrino pairs during flight in a 100-m-long tunnel, called 2) the decay volume. 3) Neutrino detectors located 280 m downstream of the target can monitor these muon neutrinos. A comparison of the measurements with those observed at Super-Kamiokande facilitates detailed studies of neutrino oscillation.
The world's largest underground neutrino detector affiliated with the Kamioka Observatory of the Institute for Cosmic Ray Research, the University of Tokyo. It is situated 1,000 m underground in the Kamioka Mine in Hida, Gifu Prefecture. Super-Kamiokande is observing neutrinos from outer space and conducting experiments to detect yet-to-be-discovered proton decays, in addition to detecting neutrinos from J-PARC. This detector contains about 11,200 photomultiplier tubes, which are installed on the inside wall of a cylindrical water tank (39.3 m in diameter and 41.4 m in height) filled with 50,000 tons of water, to detect faint Cherenkov light emanating from charged particles traveling faster than the speed of light in water.Media Contacts for Further Inquiries:
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High Energy Accelerator Research Organization
KEK was established in 1997 in a reorganization of the Institute of Nuclear Study, University of Tokyo (established in 1955), the National Laboratory for High Energy Physics (established in 1971), and the Meson Science Laboratory of the University of Tokyo (established in 1988).
Scientists at KEK use accelerators and perform research in high-energy physics to answer the most basic questions about the universe as a whole, and the matter and the life it contains.
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The biology of color, a database of industrial espionage, and a link between prions and diabetes
2017-08-03T18:30:19Z via NavierStokesApp To: Public
"The biology of color, a database of industrial espionage, and a link between prions and diabetes"
This week we hear stories on diagnosing Alzheimer’s disease in chimps, a potential new pathway to diabetes—through prions—and what a database of industrial espionage says about the economics of spying with Online News Editors David Grimm and Catherine Matacic. Sarah Crespi talks to Innes Cuthill about how the biology of color intersects with behavior, development, and vision. And Mary Soon Lee joins to share some of her chemistry haiku—one poem for each element in the periodic table. Listen to previous podcasts. [Image: Zoltan Tasi/Unsplash; Music: Jeffrey Cook]http://www.sciencemag.org/rss/podcast.xml )
Our clumpy cosmos
2017-08-03T15:30:15Z via NavierStokesApp To: Public
"Our clumpy cosmos"
The Dark Energy Survey reveals the most accurate measurement of dark matter structure in the universe.
Imagine planting a single seed and, with great precision, being able to predict the exact height of the tree that grows from it. Now imagine traveling to the future and snapping photographic proof that you were right.
If you think of the seed as the early universe, and the tree as the universe the way it looks now, you have an idea of what the Dark Energy Survey (DES) collaboration has just done. In a presentation today at the American Physical Society Division of Particles and Fields meeting at the US Department of Energy’s (DOE) Fermi National Accelerator Laboratory, DES scientists will unveil the most accurate measurement ever made of the present large-scale structure of the universe.
These measurements of the amount and “clumpiness” (or distribution) of dark matter in the present-day cosmos were made with a precision that, for the first time, rivals that of inferences from the early universe by the European Space Agency’s orbiting Planck observatory. The new DES result (the tree, in the above metaphor) is close to “forecasts” made from the Planck measurements of the distant past (the seed), allowing scientists to understand more about the ways the universe has evolved over 14 billion years.
“This result is beyond exciting,” says Scott Dodelson of Fermilab, one of the lead scientists on this result. “For the first time, we’re able to see the current structure of the universe with the same clarity that we can see its infancy, and we can follow the threads from one to the other, confirming many predictions along the way.”
Most notably, this result supports the theory that 26 percent of the universe is in the form of mysterious dark matter and that space is filled with an also-unseen dark energy, which is causing the accelerating expansion of the universe and makes up 70 percent.
Paradoxically, it is easier to measure the large-scale clumpiness of the universe in the distant past than it is to measure it today. In the first 400,000 years following the Big Bang, the universe was filled with a glowing gas, the light from which survives to this day. Planck’s map of this cosmic microwave background radiation gives us a snapshot of the universe at that very early time. Since then, the gravity of dark matter has pulled mass together and made the universe clumpier over time. But dark energy has been fighting back, pushing matter apart. Using the Planck map as a start, cosmologists can calculate precisely how this battle plays out over 14 billion years.
“The DES measurements, when compared with the Planck map, support the simplest version of the dark matter/dark energy theory,” says Joe Zuntz, of the University of Edinburgh, who worked on the analysis. “The moment we realized that our measurement matched the Planck result within 7 percent was thrilling for the entire collaboration.”
The primary instrument for DES is the 570-megapixel Dark Energy Camera, one of the most powerful in existence, able to capture digital images of light from galaxies eight billion light-years from Earth. The camera was built and tested at Fermilab, the lead laboratory on the Dark Energy Survey, and is mounted on the National Science Foundation’s 4-meter Blanco telescope, part of the Cerro Tololo Inter-American Observatory in Chile, a division of the National Optical Astronomy Observatory. The DES data are processed at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign.
Scientists on DES are using the camera to map an eighth of the sky in unprecedented detail over five years. The fifth year of observation will begin in August. The new results released today draw from data collected only during the survey’s first year, which covers 1/30th of the sky.
“It is amazing that the team has managed to achieve such precision from only the first year of their survey,” says National Science Foundation Program Director Nigel Sharp. “Now that their analysis techniques are developed and tested, we look forward with eager anticipation to breakthrough results as the survey continues.”
DES scientists used two methods to measure dark matter. First, they created maps of galaxy positions as tracers, and second, they precisely measured the shapes of 26 million galaxies to directly map the patterns of dark matter over billions of light-years using a technique called gravitational lensing.
To make these ultra-precise measurements, the DES team developed new ways to detect the tiny lensing distortions of galaxy images, an effect not even visible to the eye, enabling revolutionary advances in understanding these cosmic signals. In the process, they created the largest guide to spotting dark matter in the cosmos ever drawn (see image). The new dark matter map is 10 times the size of the one DES released in 2015 and will eventually be three times larger than it is now.
“It’s an enormous team effort and the culmination of years of focused work,” says Erin Sheldon, a physicist at the DOE’s Brookhaven National Laboratory, who co-developed the new method for detecting lensing distortions.
These results and others from the first year of the Dark Energy Survey will be released today online and announced during a talk by Daniel Gruen, NASA Einstein fellow at the Kavli Institute for Particle Astrophysics and Cosmology at DOE’s SLAC National Accelerator Laboratory, at 5 pm Central time. The talk is part of the APS Division of Particles and Fields meeting at Fermilab and will be streamed live.
The results will also be presented by Kavli fellow Elisabeth Krause of the Kavli Insitute for Particle Astrophysics and Cosmology at SLAC at the TeV Particle Astrophysics Conference in Columbus, Ohio, on Aug. 9; and by Michael Troxel, postdoctoral fellow at the Center for Cosmology and AstroParticle Physics at Ohio State University, at the International Symposium on Lepton Photon Interactions at High Energies in Guanzhou, China, on Aug. 10. All three of these speakers are coordinators of DES science working groups and made key contributions to the analysis.
“The Dark Energy Survey has already delivered some remarkable discoveries and measurements, and they have barely scratched the surface of their data,” says Fermilab Director Nigel Lockyer. “Today’s world-leading results point forward to the great strides DES will make toward understanding dark energy in the coming years.”
A version of this article was published by Fermilab.
Stephen Sekula shared this.