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News Article | April 19, 2017
Site: www.sciencemag.org

The aluminum hatches are the only clue to what lies beneath. Buried amid the corn and wheat fields of Fürstenfeldbruck, a sleepy monastery village 20 kilometers from Munich, Germany, is an inverted pyramid of concrete, steel pipes, and precision sensors, as deep as a three-story building. Last month, when lasers began coursing around the edges of the tetrahedron, Rotational Motions in Seismology (ROMY), as it is called, began its reign as the most sophisticated ring laser in the world, capable of sensing how Earth itself twists and turns. "It's a structure that has never been built before," says Heiner Igel, a seismologist at Ludwig Maximilian University in Munich and the principal investigator for the €2.5 million machine. "It's something so special." What makes it singular is the finesse needed to keep the lasers stable and to detect tiny changes in their wavelengths. In doing so, ROMY will measure minuscule changes in Earth's spin rate and spin axis. The speed and pace of those measurements promise to add an increment of precision to GPS navigation, and ROMY may even be able to detect a subtle effect predicted by Albert Einstein's theory of general relativity: the drag of the rotating planet on nearby spacetime, like a spoon turned in a pot of honey. ROMY also will be sensitive to the weak rotations that accompany earthquakes, long-ignored motions that contain clues to the interior structure of Earth. By showing the value of recording those motions, ROMY could pave the way for miniature sensors that could help oil and gas prospectors and even planetary scientists who want to listen for tremors on the moon and Mars. Ring lasers are exquisite rotation sensors thanks to an effect that French physicist Georges Sagnac demonstrated in 1913. He split light into two beams that traveled in opposite directions around the mirrored perimeter of a spinning tabletop. When he recombined the light, he saw interference "fringes"—dark and bright bands indicating that the light waves in the two beams were out of phase. The beam moving in the direction of the spin had traveled slightly farther than its counterpart, causing the phase shift. In the decades since, scientists put the Sagnac effect to work to track rotations. The principle underpins the laser and fiber optic gyroscopes that replaced finicky mechanical gyros in the 1970s and are now standard for navigation. The rotations they measure, like the turns and dives of a fighter jet, are fast and large. The idea of building a larger, more sensitive ring laser for geodesy—measuring Earth itself—didn't come around until the 1990s, when nearly perfect mirrors became available. One of the first such lasers was C-II, a ring laser in the shape of a square with 1-meter arms, built in New Zealand in the mid-1990s and housed in a disused World War II bunker, where temperatures are stable. Whereas Sagnac shone light into his experiment from an external source, the C-II's ring itself generated laser beams, its cavities filled with a lasing medium of neon and helium gas. As before, a rotation lengthened one light path, but the effect on C-II was to stretch the wavelength of the laser resonating along that path, like the coils in a stretched spring. For the beam running in the opposite direction, the path and wavelength were squeezed. When the beams were interfered, their slightly clashing wavelengths caused the optical equivalent of the pulsing beats that piano tuners try to eliminate as they strike a note and a tuning fork at the same time. "You have beats because you're out of tune," Igel says. The beat frequency is a direct measure of the rotation that causes it, and C-II was able to measure Earth's rotation rate to one part in a million. C-II also launched the career of Ulrich Schreiber, a laser physicist at the Technical University of Munich who led its design. Schreiber later worked on ring lasers in New Zealand, California, Germany, and Italy. "He is the lord of the rings," says Jacopo Belfi, a physicist at the National Institute for Nuclear Physics in Pisa, Italy, who works on GINGERino, a 3.6-meter square ring laser that is a forerunner to GINGER, a 6-meter, octahedral ring laser planned for Italy's Gran Sasso underground lab. Having won funding from the European Research Council, Igel offered Schreiber his biggest challenge: designing ROMY. With its 12-meter arms, ROMY is more sensitive than previous ring lasers, capable of sensing Earth's spin to better than one part per billion. And instead of one square ring, it has four triangular ones. Three of them are required to pin down rotations in any direction, and the fourth adds redundancy. Construction began in March 2016 and finished 6 months later. Last month, engineers achieved first light in all four rings at the same time—a sign that the geometry of the tetrahedron is precise enough to keep all the lasers resonating properly. "It's everything or nothing," Igel says. "Every time the red [laser] light is visible, people are screaming, really excited." The team is now working on interfering the lasers and measuring the Sagnac effect. They hope to present their first proof-of-principle measurements next week at a meeting of the European Geosciences Union in Vienna. Eventually, ROMY scientists will monitor changes in the length of the day and the position of the poles. Neither is as fixed as you might think, varying by milliseconds and centimeters each day. The sun and moon tug on the planet, while the drift of continents, changes in ocean currents, and the rebounding of the crust since the retreat of ice age glaciers all shift mass around, altering Earth's moment of inertia and therefore its spin. Even hurricanes and earthquakes can give a tiny nudge this way or that. Earth's little twitches have practical consequences. Precisely targeting a rocket, whether it is destined for Mars or geostationary orbit, requires taking them into account. And the data from GPS satellites—which businesses and consumers the world over use—would drift into irrelevance within weeks if their exact positions in relation to Earth's surface were not constantly corrected. Currently, the best measurements of those variables come from a system called very-long-baseline interferometry (VLBI), which uses radio dishes spaced across Earth to stare at quasars—brilliant beacons in the distant universe that occasionally flicker. By clocking when widely spaced dishes record a change in brightness, geodesists can calculate the planet's spin rate and its axis. But the system requires dozens of observatories to give up valuable astronomy time, and for the best timing comparisons, hard drives have to be shipped overnight from remote locales to supercomputer centers. It can take days to turn observations into a published measurement. ROMY will try to match the precision of VLBI—and outdo it in speed. In theory, ROMY could monitor Earth's spin rate and axis constantly, updating measurements in real time, says Lucia Plank, a geodesist at the University of Tasmania in Hobart, Australia, who helps provide the VLBI service. "The advantage of ROMY is you have an instantaneous result," Plank says, though she adds that the VLBI technique, being more stable, is unlikely to go away anytime soon. Whereas VLBI measures Earth's rotation with respect to markers billions of light-years away, ROMY measures it right at the surface—and the difference could be telling. That's because Einstein's frame-dragging effect, in which the gravity of Earth's rotating mass warps and twists nearby spacetime, should cause an infinitesimal shift in the rotation rate as measured close to Earth. It's the same test that was done, famously and expensively, by Gravity Probe B, a $750 million NASA mission that put gyroscopes on a satellite and measured the frame-dragging. Belfi says that doing it again, from the ground, is worthwhile. "In physics this is not a trivial result," says Belfi, who wants to use GINGER to do the test if ROMY cannot. Being so new, ROMY is plagued by experimental drift. The structure is still settling in the soft sediments of Fürstenfeldbruck. Unlike other ring lasers, which were fixed to blocks of Zerodur—a ceramic resistant to temperature changes—ROMY's steel tubes flex with the temperature swings of day and night. It also is prone to shifting after rains saturate the ground. Igel eventually wants to eliminate those drifts by putting small motors behind each of ROMY's mirrors to make tiny adjustments to the rings in real time. But he is keen to embrace one type of fast-moving "drift": earthquake shaking. In the past, seismologists have measured only translation—the displacement of the ground along any of the three cardinal axes. But seismic waves also drive tilt motions, which rotate points without shifting their positions. Traditional seismometers could not measure tilt motions, but theory suggested, reassuringly, that they are small enough to ignore. As Charles Richter, the seismologist who developed the famous magnitude scale for earthquakes, wrote in 1958, "such rotations are negligible." "But they are there," Igel says. Indeed, experiments in recent years have suggested that the motions can actually be large. Soft soils can amplify them to 10% or more of the magnitude of translational motions. Engineers have been designing buildings only for translational shaking, but they should take tilts into account as well, says John Evans, a seismologist with the U.S. Geological Survey in Santa Cruz, California. "It's best to know what [shaking] actually goes into a building to make its response within tolerable limits." Measurements of tilt also could pay dividends for earth science. Traditional seismometers can misclassify tilting as translational motion—a problem especially acute for ocean bottom sensors that sit on soft muds, Evans says. By measuring tilt directly, researchers could limit such "data contamination." Tilt measurements also might sharpen 3D models of the interiors of volcanoes, where swelling magmas create tremors with larger-than-normal rotations, Igel says. "If you do not take into account these tilt motions, your model might be wrong," he says. ROMY should help earth scientists explore this new seismological frontier—if only by showing that it exists. Soon after the team turned on its first triangular ring, it sensed rotations from the magnitude-6.6 Norcia earthquake in Italy last October. Eventually, scientists will want to get closer to the source. "You cannot move ROMY," says Frédéric Guattari, head of seismic rotation sensors at iXBlue, a navigation sensor company in Paris. "Now, we need a portable device." The answer from iXBlue is a compact sensor that relies not on lasers but on a fiber optic loop 5 kilometers long, wound into a coil just 20 centimeters across. The device sends photons in opposite directions through the loop, interferes them, and tracks phase shifts to detect rotations. Guattari has already placed prototypes astride the Stromboli volcano and in the Florence cathedral. At up to €50,000 each, the sensors will be much more expensive than a traditional seismometer, but Guattari says they will ultimately offer a cheaper way to map the subsurface. Typically, geoscientists search for oil and gas traps deep in Earth by laying out dozens or even hundreds of sensors in an array. The array listens for the echoes of seismic waves—generated by distant earthquakes or small explosions detonated nearby—as they bounce off subsurface structure. But by measuring rotation as well as translation, seismologists can get not only the displacement of earthquake waves but also their velocities, which are a powerful probe of subsurface structure. "You can do a lot more with this point measurement," Igel says. Technology from iXBlue might allow the oil and gas industry to get by with fewer sensors. It also could prove useful in situations when deploying even one sensor is challenging—such as on missions to other planets. Evans predicts that tilt sensors could flourish. "I think we're going to see slow adoption," he says. "In 20 years they could be standard." But Igel and Schreiber hope that it won't be just the small fry that proliferate—they also want ROMY to spawn offspring. With multiple large ring lasers scattered around the globe, geodetic measurements could be coordinated, calibrated, and checked against one another to create a richer and more precise picture of our planet's twists and turns. Plank, though loyal to VLBI, says she shares the hope that Germany's great ring won't reign alone. "The ultimate goal would be to have more of these around the globe."


News Article | February 15, 2017
Site: www.newscientist.com

A hint of matter and antimatter behaving differently to each other has been spotted in a new particle for the first time. If the find bears out, it could help explain the existence of all the matter in the universe, and why it was not snuffed out by antimatter long ago. Physicists think that the big bang should have produced equal amounts of matter and antimatter. But these contrasting particles annihilate each other in a puff of energy whenever they meet, so they should have destroyed each other long ago. The fact that there is enough matter in the universe today for us to exist and wonder why, means that some mechanism must have favoured matter over antimatter. “Today we have this complete imbalance between matter and antimatter. We have no evidence of antimatter in the universe,” says Nicola Neri of the National Institute for Nuclear Physics in Milan, Italy. “This is one of the main questions we’d like to answer.” One way the two could differ is by violating a rule about the way the laws of physics affect particles and antiparticles known as CP symmetry. Previously, experiments showed that CP symmetry is in fact violated in particles called mesons, which are made up of a quark and an antiquark. Those results garnered two Nobel prizes, one in 1980 and one in 2008. But it wasn’t enough. “The sources we’ve found so far are not sufficient to explain this huge imbalance,” Neri says. Now, Neri and his colleagues have checked another kind of particle: baryons, which are made of three quarks and no antiquarks. Neutrons and protons, the building blocks of matter, are baryons. They watched for differences in the decay of baryons and their antimatter counterparts made of three antiquarks, and they were lucky. The particles decayed in a way that seems to violate CP symmetry. “This is the first hint, a sign that something is going on there,” Neri says. During the first run of the Large Hadron Collider at CERN near Geneva, between 2011 and 2012, the large international team used the LHCb experiment to watch the decay of heavy baryons called lambda-b particles, which are about six times heavier than a neutron. They observed about 6500 instances of lambda-b particles decaying into a proton and three particles called pions, and about 1000 instances of a different decay that included particles called kaons as well. Theory suggested that there should be a lot of CP violation in these events, but because they needed the extreme energies of the LHC to be produced, they had never been seen before. “It was not anticipated that we could have such a large signal yield,” Neri says. “That was a nice surprise.” The kaon decay looked normal. But the pion version showed a deviation from the standard predictions to a statistical significance of 3.3 sigma, meaning random fluctuations would produce a similar signal less than once every 1000 times. Particle physicists consider that level of significance evidence that something strange is happening, but it’s not quite enough to declare discovery. That will have to wait for 5-sigma, when the odds of random fluctuations producing a similar signal are less than one in a million. But the LHC has been upgraded and collected more data since these measurements, and is still ramping up to its full potential. Neri expects to increase their data set by at least a factor of 10. And even if the signal goes away with more data, it’s still useful to be able to compare CP violation in baryons and mesons, Neri says. “We can do studies for the first time in baryon decays and make good comparisons with decays with similar quark transitions, and in that way get information on the underlying physics,” he says. “We are entering an era with LHCb where we can make precision measurements in CP violation in heavy baryons. You open a new series of measurements with this kind of result. That’s the excitement.” “It’s an important observation,” says David MacFarlane at the SLAC National Accelerator Laboratory in Menlo Park, California, who was on the team that measured CP violation in mesons. “The more systems we see CP violations in, the more chance we have to understand whether the standard model is correct, or whether there are other sources.”


News Article | February 15, 2017
Site: phys.org

The LUX-ZEPLIN (LZ) experiment, which will be built nearly a mile underground at the Sanford Underground Research Facility (SURF) in Lead, S.D., is considered one of the best bets yet to determine whether theorized dark matter particles known as WIMPs (weakly interacting massive particles) actually exist. There are other dark matter candidates, too, such as "axions" or "sterile neutrinos," which other experiments are better suited to root out or rule out. The fast-moving schedule for LZ will help the U.S. stay competitive with similar next-gen dark matter direct-detection experiments planned in Italy and China. On Feb. 9, the project passed a DOE review and approval stage known as Critical Decision 3 (CD-3), which accepts the final design and formally launches construction. "We will try to go as fast as we can to have everything completed by April 2020," said Murdock "Gil" Gilchriese, LZ project director and a physicist at the DOE's Lawrence Berkeley National Laboratory (Berkeley Lab), the lead lab for the project. "We got a very strong endorsement to go fast and to be first." The LZ collaboration now has about 220 participating scientists and engineers who represent 38 institutions around the globe. The nature of dark matter—which physicists describe as the invisible component or so-called "missing mass" in the universe that would explain the faster-than-expected spins of galaxies, and their motion in clusters observed across the universe—has eluded scientists since its existence was deduced through calculations by Swiss astronomer Fritz Zwicky in 1933. The quest to find out what dark matter is made of, or to learn whether it can be explained by tweaking the known laws of physics in new ways, is considered one of the most pressing questions in particle physics. Successive generations of experiments have evolved to provide extreme sensitivity in the search that will at least rule out some of the likely candidates and hiding spots for dark matter, or may lead to a discovery. LZ will be at least 50 times more sensitive to finding signals from dark matter particles than its predecessor, the Large Underground Xenon experiment (LUX), which was removed from SURF last year to make way for LZ. The new experiment will use 10 metric tons of ultra-purified liquid xenon, to tease out possible dark matter signals. Xenon, in its gas form, is one of the rarest elements in Earth's atmosphere. "The science is highly compelling, so it's being pursued by physicists all over the world," said Carter Hall, the spokesperson for the LZ collaboration and an associate professor of physics at the University of Maryland. "It's a friendly and healthy competition, with a major discovery possibly at stake." A planned upgrade to the current XENON1T experiment at National Institute for Nuclear Physics' Gran Sasso Laboratory (the XENONnT experiment) in Italy, and China's plans to advance the work on PandaX-II, are also slated to be leading-edge underground experiments that will use liquid xenon as the medium to seek out a dark matter signal. Both of these projects are expected to have a similar schedule and scale to LZ, though LZ participants are aiming to achieve a higher sensitivity to dark matter than these other contenders. Hall noted that while WIMPs are a primary target for LZ and its competitors, LZ's explorations into uncharted territory could lead to a variety of surprising discoveries. "People are developing all sorts of models to explain dark matter," he said. "LZ is optimized to observe a heavy WIMP, but it's sensitive to some less-conventional scenarios as well. It can also search for other exotic particles and rare processes." LZ is designed so that if a dark matter particle collides with a xenon atom, it will produce a prompt flash of light followed by a second flash of light when the electrons produced in the liquid xenon chamber drift to its top. The light pulses, picked up by a series of about 500 light-amplifying tubes lining the massive tank—over four times more than were installed in LUX—will carry the telltale fingerprint of the particles that created them. Daniel Akerib, Thomas Shutt, and Maria Elena Monzani are leading the LZ team at SLAC National Accelerator Laboratory. The SLAC effort includes a program to purify xenon for LZ by removing krypton, an element that is typically found in trace amounts with xenon after standard refinement processes. "We have already demonstrated the purification required for LZ and are now working on ways to further purify the xenon to extend the science reach of LZ," Akerib said. SLAC and Berkeley Lab collaborators are also developing and testing hand-woven wire grids that draw out electrical signals produced by particle interactions in the liquid xenon tank. Full-size prototypes will be operated later this year at a SLAC test platform. "These tests are important to ensure that the grids don't produce low-level electrical discharge when operated at high voltage, since the discharge could swamp a faint signal from dark matter," said Shutt. Hugh Lippincott, a Wilson Fellow at Fermi National Accelerator Laboratory (Fermilab) and the physics coordinator for the LZ collaboration, said, "Alongside the effort to get the detector built and taking data as fast as we can, we're also building up our simulation and data analysis tools so that we can understand what we'll see when the detector turns on. We want to be ready for physics as soon as the first flash of light appears in the xenon." Fermilab is responsible for implementing key parts of the critical system that handles, purifies, and cools the xenon. All of the components for LZ are painstakingly measured for naturally occurring radiation levels to account for possible false signals coming from the components themselves. A dust-filtering cleanroom is being prepared for LZ's assembly and a radon-reduction building is under construction at the South Dakota site—radon is a naturally occurring radioactive gas that could interfere with dark matter detection. These steps are necessary to remove background signals as much as possible. The vessels that will surround the liquid xenon, which are the responsibility of the U.K. participants of the collaboration, are now being assembled in Italy. They will be built with the world's most ultra-pure titanium to further reduce background noise. To ensure unwanted particles are not misread as dark matter signals, LZ's liquid xenon chamber will be surrounded by another liquid-filled tank and a separate array of photomultiplier tubes that can measure other particles and largely veto false signals. Brookhaven National Laboratory is handling the production of another very pure liquid, known as a scintillator fluid, that will go into this tank. The cleanrooms will be in place by June, Gilchriese said, and preparation of the cavern where LZ will be housed is underway at SURF. Onsite assembly and installation will begin in 2018, he added, and all of the xenon needed for the project has either already been delivered or is under contract. Xenon gas, which is costly to produce, is used in lighting, medical imaging and anesthesia, space-vehicle propulsion systems, and the electronics industry. "South Dakota is proud to host the LZ experiment at SURF and to contribute 80 percent of the xenon for LZ," said Mike Headley, executive director of the South Dakota Science and Technology Authority (SDSTA) that oversees SURF. "Our facility work is underway and we're on track to support LZ's timeline." UK scientists, who make up about one-quarter of the LZ collaboration, are contributing hardware for most subsystems. Henrique Araújo, from Imperial College London, said, "We are looking forward to seeing everything come together after a long period of design and planning." Kelly Hanzel, LZ project manager and a Berkeley Lab mechanical engineer, added, "We have an excellent collaboration and team of engineers who are dedicated to the science and success of the project." The latest approval milestone, she said, "is probably the most significant step so far," as it provides for the purchase of most of the major components in LZ's supporting systems. Explore further: Construction of world's most sensitive dark matter detector moves forward


News Article | February 15, 2017
Site: www.eurekalert.org

The race is on to build the most sensitive U.S.-based experiment designed to directly detect dark matter particles. Department of Energy officials have formally approved a key construction milestone that will propel the project toward its April 2020 goal for completion. The LUX-ZEPLIN (LZ) experiment, which will be built nearly a mile underground at the Sanford Underground Research Facility (SURF) in Lead, S.D., is considered one of the best bets yet to determine whether theorized dark matter particles known as WIMPs (weakly interacting massive particles) actually exist. There are other dark matter candidates, too, such as "axions" or "sterile neutrinos," which other experiments are better suited to root out or rule out. The fast-moving schedule for LZ will help the U.S. stay competitive with similar next-gen dark matter direct-detection experiments planned in Italy and China. On Feb. 9, the project passed a DOE review and approval stage known as Critical Decision 3 (CD-3), which accepts the final design and formally launches construction. "We will try to go as fast as we can to have everything completed by April 2020," said Murdock "Gil" Gilchriese, LZ project director and a physicist at the DOE's Lawrence Berkeley National Laboratory (Berkeley Lab), the lead lab for the project. "We got a very strong endorsement to go fast and to be first." The LZ collaboration now has about 220 participating scientists and engineers who represent 38 institutions around the globe. The nature of dark matter--which physicists describe as the invisible component or so-called "missing mass" in the universe that would explain the faster-than-expected spins of galaxies, and their motion in clusters observed across the universe--has eluded scientists since its existence was deduced through calculations by Swiss astronomer Fritz Zwicky in 1933. The quest to find out what dark matter is made of, or to learn whether it can be explained by tweaking the known laws of physics in new ways, is considered one of the most pressing questions in particle physics. Successive generations of experiments have evolved to provide extreme sensitivity in the search that will at least rule out some of the likely candidates and hiding spots for dark matter, or may lead to a discovery. LZ will be at least 50 times more sensitive to finding signals from dark matter particles than its predecessor, the Large Underground Xenon experiment (LUX), which was removed from SURF last year to make way for LZ. The new experiment will use 10 metric tons of ultra-purified liquid xenon, to tease out possible dark matter signals. Xenon, in its gas form, is one of the rarest elements in Earth's atmosphere. "The science is highly compelling, so it's being pursued by physicists all over the world," said Carter Hall, the spokesperson for the LZ collaboration and an associate professor of physics at the University of Maryland. "It's a friendly and healthy competition, with a major discovery possibly at stake." A planned upgrade to the current XENON1T experiment at National Institute for Nuclear Physics' Gran Sasso Laboratory (the XENONnT experiment) in Italy, and China's plans to advance the work on PandaX-II, are also slated to be leading-edge underground experiments that will use liquid xenon as the medium to seek out a dark matter signal. Both of these projects are expected to have a similar schedule and scale to LZ, though LZ participants are aiming to achieve a higher sensitivity to dark matter than these other contenders. Hall noted that while WIMPs are a primary target for LZ and its competitors, LZ's explorations into uncharted territory could lead to a variety of surprising discoveries. "People are developing all sorts of models to explain dark matter," he said. "LZ is optimized to observe a heavy WIMP, but it's sensitive to some less-conventional scenarios as well. It can also search for other exotic particles and rare processes." LZ is designed so that if a dark matter particle collides with a xenon atom, it will produce a prompt flash of light followed by a second flash of light when the electrons produced in the liquid xenon chamber drift to its top. The light pulses, picked up by a series of about 500 light-amplifying tubes lining the massive tank--over four times more than were installed in LUX--will carry the telltale fingerprint of the particles that created them. Daniel Akerib, Thomas Shutt, and Maria Elena Monzani are leading the LZ team at SLAC National Accelerator Laboratory. The SLAC effort includes a program to purify xenon for LZ by removing krypton, an element that is typically found in trace amounts with xenon after standard refinement processes. "We have already demonstrated the purification required for LZ and are now working on ways to further purify the xenon to extend the science reach of LZ," Akerib said. SLAC and Berkeley Lab collaborators are also developing and testing hand-woven wire grids that draw out electrical signals produced by particle interactions in the liquid xenon tank. Full-size prototypes will be operated later this year at a SLAC test platform. "These tests are important to ensure that the grids don't produce low-level electrical discharge when operated at high voltage, since the discharge could swamp a faint signal from dark matter," said Shutt. Hugh Lippincott, a Wilson Fellow at Fermi National Accelerator Laboratory (Fermilab) and the physics coordinator for the LZ collaboration, said, "Alongside the effort to get the detector built and taking data as fast as we can, we're also building up our simulation and data analysis tools so that we can understand what we'll see when the detector turns on. We want to be ready for physics as soon as the first flash of light appears in the xenon." Fermilab is responsible for implementing key parts of the critical system that handles, purifies, and cools the xenon. All of the components for LZ are painstakingly measured for naturally occurring radiation levels to account for possible false signals coming from the components themselves. A dust-filtering cleanroom is being prepared for LZ's assembly and a radon-reduction building is under construction at the South Dakota site--radon is a naturally occurring radioactive gas that could interfere with dark matter detection. These steps are necessary to remove background signals as much as possible. The vessels that will surround the liquid xenon, which are the responsibility of the U.K. participants of the collaboration, are now being assembled in Italy. They will be built with the world's most ultra-pure titanium to further reduce background noise. To ensure unwanted particles are not misread as dark matter signals, LZ's liquid xenon chamber will be surrounded by another liquid-filled tank and a separate array of photomultiplier tubes that can measure other particles and largely veto false signals. Brookhaven National Laboratory is handling the production of another very pure liquid, known as a scintillator fluid, that will go into this tank. The cleanrooms will be in place by June, Gilchriese said, and preparation of the cavern where LZ will be housed is underway at SURF. Onsite assembly and installation will begin in 2018, he added, and all of the xenon needed for the project has either already been delivered or is under contract. Xenon gas, which is costly to produce, is used in lighting, medical imaging and anesthesia, space-vehicle propulsion systems, and the electronics industry. "South Dakota is proud to host the LZ experiment at SURF and to contribute 80 percent of the xenon for LZ," said Mike Headley, executive director of the South Dakota Science and Technology Authority (SDSTA) that oversees SURF. "Our facility work is underway and we're on track to support LZ's timeline." UK scientists, who make up about one-quarter of the LZ collaboration, are contributing hardware for most subsystems. Henrique Araújo, from Imperial College London, said, "We are looking forward to seeing everything come together after a long period of design and planning." Kelly Hanzel, LZ project manager and a Berkeley Lab mechanical engineer, added, "We have an excellent collaboration and team of engineers who are dedicated to the science and success of the project." The latest approval milestone, she said, "is probably the most significant step so far," as it provides for the purchase of most of the major components in LZ's supporting systems. For more information about LZ and the LZ collaboration, visit: http://lz. . Major support for LZ comes from the DOE Office of Science's Office of High Energy Physics, South Dakota Science and Technology Authority, the UK's Science & Technology Facilities Council, and by collaboration members in South Korea and Portugal. Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel Prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit http://www. . DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at http://science. . The Sanford Underground Research Facility's mission is to enable compelling underground, interdisciplinary research in a safe work environment and to inspire our next generation through science, technology, engineering, and math education. For more information, please visit the Sanford Lab website at http://www. .


News Article | February 15, 2017
Site: www.sciencemag.org

On 20 February, dignitaries will descend on Virgo, Europe’s premier gravitational wave detector near Pisa, Italy, for a dedication ceremony to celebrate a 5-year, €24 million upgrade. But the pomp will belie nagging problems that are likely to keep Virgo from joining its U.S. counterpart, the Laser Interferometer Gravitational-Wave Observatory (LIGO), in a hunt for gravitational wave sources that was meant to start next month. What has hobbled the 3-kilometer-long observatory: glass threads just 0.4 millimeters thick, which have proved unexpectedly fragile. The delay, which could last a year, is “very frustrating for everyone,” says LIGO team member Bruce Allen, director of the Max Planck Institute for Gravitational Physics in Hannover, Germany. A year ago, LIGO confirmed a prediction made by Albert Einstein a century earlier: that violent cosmic events, like the merger of two black holes, would wrench the fabric of spacetime and emit ripples. But LIGO, with two instruments in Livingston, Louisiana, and Hanford, Washington, cannot pinpoint the sources of the waves, which would let astronomers train other telescopes on them. Triangulating on the sources requires a third detector: Virgo. The detectors all rely on optical devices called interferometers: two straight arms, several kilometers long, positioned at right angles. Inside each arm a laser beam bounces back and forth between mirrors at each end of a vacuum tube, resonating like sound in an organ pipe. The laser light is combined where the two arms meet so that the peak from one laser wave meets the trough of the other and they cancel each other out. But if something, such as a gravitational wave, stretches space and changes the length of the two arms by different amounts, the waves will no longer match up and the cancellation will be incomplete. Some light will pass through an exit known as the dark port and into a detector. The tiniest vibrations—earth tremors, the rumble of trains, even surf crashing on distant beaches—can swamp the signal of gravitational waves. So engineers must painstakingly isolate the detectors from noise. At Virgo, for example, the mirrors are suspended at the end of a chain of seven pendulums. For the upgrade, steel wires connecting the mirror to the weight above it were replaced with pure glass fibers to reduce thermal and mechanical noise. But a year ago, the glass threads began shattering, sometimes days or weeks after the 40-kilogram mirrors were suspended from them. After months of investigation, the team found the culprit: microscopic particles of debris from the pumps of the upgraded vacuum system. When these particles settled on the glass fibers they created microcracks, which widened over days and weeks until the fibers failed. “The fibers are very robust until something touches their surface,” says Giovanni Losurdo, Advanced Virgo project leader at Italy’s National Institute for Nuclear Physics in Pisa. During the investigation, the team temporarily replaced the glass fibers with steel wires—as in the original Virgo—and pressed ahead. But other problems compounded the delays. An examination of small steel triangles that act as vibration-damping springs revealed that 13 out of 350 were cracked or broken. Why remains a mystery, but the team replaced those that showed any sign of damage—40% of the total. Given the complexity of the detector, “it’s not surprising some things don’t work as expected,” says Virgo team member Benoit Mours of France’s National Institute of Nuclear and Particle Physics in Annecy. The Virgo team has now achieved “lock” in the two detector arms, meaning that light is stably resonating. They soon hope to bring in the central optics and combine the beams. Then they must hunt down and eliminate remaining sources of noise to see what level of sensitivity they can achieve with the steel wires still in place. For Virgo to make a useful contribution, it needs to be at least one-quarter as sensitive as LIGO. Researchers define sensitivity as the distance to which a detector could spot the merger of two neutron stars with masses 1.4 times the sun’s. LIGO’s Livingston detector can currently sense such an event out to about 80 megaparsecs (260 million light-years). In theory, with all of the upgrades but the mirrors still suspended with steel wires, Virgo should be able to reach 50 megaparsecs, Losurdo says. “As soon as Advanced Virgo reaches the sensitivity to join, we will start.” Frustratingly for the Virgo team, the steel wires are expected to have the most impact on sensitivity to gravitational waves with lower frequencies than neutron star mergers, such as those from the mergers of black holes. And black hole mergers are precisely the events that LIGO detected last year. The task of eliminating noise sources is sure to take several months, says Lisa Barsotti of the Massachusetts Institute of Technology in Cambridge, co-chair of the LIGO-Virgo Joint Run Planning Committee. That makes joining LIGO as planned in March a virtual impossibility. The current LIGO run, which began on 30 November 2016, was expected to continue for about 6 months, until late May 2017, but even that may be a stretch for Virgo. Barsotti says LIGO could extend its run by a month or two, “to give Virgo a chance to join.” Whether Virgo manages to take part in the current run, the team should be able to reinstall the glass fibers and root out other sources of noise by the spring of 2018, when LIGO will start a new observing run. Soon after, a fourth detector is poised to join the hunt: the Kamioka Gravitational Wave Detector, or KAGRA, near Hida City in Japan, which plans to begin operations in 2019. KAGRA’s arms will be underground, below 200 meters of rock, and its mirrors chilled to 20 K—two tricks that should reduce noise and boost sensitivity.


News Article | October 26, 2016
Site: www.nature.com

The SuperB factory, a particle accelerator to be built on the campus of the University of Rome Tor Vergata over the next six years, was officially launched on Friday. But the project faces uncertain funding and competition from a Japanese project. The accelerator will be what physicists call a B-factory, where electrons and their antiparticles, positrons, will race around two 1.3-kilometre-long rings, then collide and produce heavy B mesons. By studying the way these particles decay, physicists hope to fill some of the gaps in the standard model of physics, such as why there is more matter than antimatter in the Universe, and whether the exotic particles predicted by the theory of supersymmetry really exist. SuperB will produce 100 times more collision events each year than did the two B factories previously built: the BaBar experiment at the SLAC National Accelerator Laboratory in Menlo Park, California, which shut down in April 2008, and the ongoing Belle experiment at the KEKB accelerator in Tsukuba, Japan. This increased luminosity should allow researchers to study even the rarest of physical phenomena. Italy's National Institute for Nuclear Physics (INFN) is running the project. Under an agreement signed by the INFN and Tor Vergata on Friday, the two will set up an international laboratory to oversee the construction and operation of SuperB; the lab will be named after Italian physicist Nicola Cabibbo. Roberto Petronzio, who will soon give up his post as president of the INFN to become director general of the new laboratory, says that SuperB will complement the Large Hadron Collider (LHC) particle accelerator at CERN, Europe's high-energy physics laboratory near Geneva, Switzerland, by helping to build a theoretical model around the LHC's future discoveries. "Whereas the LHC uses high energies to produce as-yet-unknown particles, SuperB will look for the indirect effects of those particles on the ones we already know," says Petronzio. The Italian Institute of Technology in Genoa is expected to join the collaboration within a few months. It will build synchrotron laboratories, which will conduct microscopy using the high-energy radiation produced by the accelerator. However, more partners will be needed to ensure SuperB's success. The Italian Ministry for Research has promised to provide funds of €250 million (US$340 million), but the INFN estimates that the final price tag for the facility will be between €450 million and €600 million. Some assistance will come from the United States, which plans to provide reusable components from the BaBar detector, worth about €70 million; an agreement with Russia is currently under negotiation; and other European countries have expressed an interest in joining the project, says Petronzio. Further financial help from the United States is unlikely. In August 2010, an expert panel at the US Department of Energy suggested that the country should limit its participation in the Italian project to the recycled components already committed. The panel recommended that the United States should give direct financial support only to an upgrade of the Japanese Belle experiment, to be called Belle II, work on which will begin next year. Construction of SuperB is expected to begin next year and operations are scheduled to start in 2017 — a breakneck timetable brought on by the competition with Belle II. Although it will not reach SuperB's luminosity, the upgraded Japanese experiment is expected to start taking data in 2016. "We'll probably be one year late," says Petronzio. "We can catch up because we will see many more collisions, but we cannot afford to be later than that." Not everyone in the Italian physics community is happy with the project. When SuperB was being presented to the ministry for funding last December, Mario Calvetti, then director of INFN's Frascati National Laboratory, resigned in order to voice his opposition. "My reckoning is that SuperB will take 15 years to complete, and it will end up draining resources from the other INFN experiments," he says. INFN activities include many other large-scale experiments, such as neutrino and dark-matter research at the Gran Sasso Laboratories, the Virgo gravitational-wave observatory near Pisa and a strong involvement in the LHC. Fernando Ferroni, incoming president of the INFN, says that Calvetti is not alone in his doubts. "There is some opposition to the project, particularly from those working on other research lines," he says. "SuperB is a great, innovative project, but we will have to make sure that extra money and personnel for it do not come from the INFN's current budget."


Slezakova M.,National Radiation Protection Institute, Czech Republic | Navratilova Rovenska K.,National Radiation Protection Institute, Czech Republic | Tomasek L.,National Radiation Protection Institute, Czech Republic | Holecek J.,National Institute for Nuclear
Radiation Protection Dosimetry | Year: 2013

In this paper, repeated measurements of radon progeny concentration in dwellings in the Czech Republic are described. Two distinct data sets are available: one based on present measurements in 170 selected dwellings in the Central Bohemian Pluton with a primary measurement carried out in the 1990s and the other based on 1920 annual measurements in 960 single-family houses in the Czech Republic in 1992 and repeatedly in 1993. The analysis of variance model with random effects is applied to data to evaluate the variability of measurements. The calculated variability attributable to repeated measurements is compared with results from other countries. In epidemiological studies, ignoring the variability of measurements may lead to biased estimates of risk of lung cancer. © The Author 2012. Published by Oxford University Press. All rights reserved.


News Article | November 18, 2015
Site: www.nature.com

Ocata buyout Astellas Pharma in Tokyo will pay US$379 million for Ocata Therapeutics of Marlborough, Massachusetts. Formerly called Advanced Cell Technology, Ocata has struggled financially but has continued to develop treatments in which human embryonic stem cells are coaxed into becoming retinal cells. The company has used the cells to treat two types of degenerative blindness in small-scale clinical trials. In the United States, limiting trials to a few participants would hamper speedy commercialization, but Japan has a fast-track approval system that allows commercialization of stem-cell treatments after studies on a small number of people. Olive aid The European Commission has announced a €7-million (US$7.5-million) call for proposals for research into Xylella fastidiosa, the aggressive plant pathogen that is destroying swathes of olive trees in the Puglia region of southern Italy. The call will focus on methods of detection and control. The outbreak, which has also reached some regions of France, is a major economic threat to the European Union, but has received little research funding so far. Italian regional and national governments have also promised €6 million for X. fastidiosa research. Chile budget boost Chile’s Congress was mulling a budget increase of 150 million pesos (US$210,000) for the nation’s research-funding agency as Nature went to press. The move followed street protests by researchers after the resignation of Francisco Brieva, director of the National Commission for Scientific and Technological Research. The body funds more than 3,000 researchers. See go.nature.com/pbwtp8 for more. Space junk splashes down safely A chunk of space debris re-entered Earth’s atmosphere on 13 November. The fragment was too small to hurt anyone but just the right size to help scientists to practise tracking an incoming asteroid. Researchers on a chartered jet filmed the debris, which may have fallen off a lunar spacecraft, as it disintegrated above the Indian Ocean near Sri Lanka. NASA astronomer Peter Jenniskens says the successful campaign proves that it is possible to gather data about an object targeting the planet, even with short notice. Paris talks go ahead International climate talks in Paris will go ahead despite the 13 November terrorist attacks that killed at least 129 people in the French capital. The climate conference will be held, with tightened security, because it is an “essential meeting for humanity”, French Prime Minister Manuel Valls said on 14 November. Some 40,000 participants will gather for the United Nations climate summit from 30 November to 11 December. Almost 120 government leaders will attend the meeting, which it is hoped will produce a global climate deal. Dark-matter hunt The world’s most sensitive detector for dark matter was inaugurated on 11 November at the Gran Sasso National Laboratory, run by Italy’s National Institute for Nuclear Physics. Dark matter is thought to make up 85% of matter in the Universe. The experiment, called XENON1T, will monitor 3.5 tonnes of liquid xenon, to try to detect the tiny amount of energy that is given off when dark matter interacts with atoms of ordinary matter. The collaboration involves 125 scientists, and the experiment is expected to start collecting data by the end of March 2016. Nuclear burial Finland’s government approved the construction of a deep underground facility to permanently store spent nuclear fuel on 12 November. Minister of economic affairs Olli Rehn said the move was a world first. The repository will dispose of up to 6,500 tonnes of uranium — high-level waste produced by nuclear-power facilities — by packing it into copper canisters and burying these in a clay buffer 400 metres underground. The local government has already given its go-ahead for the facility, which will be on Olkiluoto island off Finland’s west coast and is due to open around 2023. Reef protected Laws passed on 12 November in Queensland, Australia, will protect the Great Barrier Reef (pictured) from port development, the state’s development minister said. The laws ban disposal at sea of material dredged from ports in the region, and stop any new ports being developed in the reef World Heritage Area. They form part of commitments made by Australia to safeguard the reef after the United Nations Educational, Scientific and Cultural Organization considered categorizing the coral zone as ‘at risk’. Plans to dispose of dredging material near the reef have proved controversial in recent years, and conservation groups welcomed last week’s legislation. Pesticide risk The world’s most widely used herbicide, glyphosate, is unlikely to pose a cancer risk to humans, according to a report published on 12 November by the European Food Safety Authority (EFSA). In its report, the agency set limits on how much glyphosate a person may safely ingest in a short period of time. EFSA’s finding comes nearly eight months after the World Health Organization’s International Agency for Research on Cancer said that glyphosate probably does cause cancer in humans. See go.nature.com/mb8b4l for more. Space mining is go On 10 November the US Senate passed the Space Act of 2015, allowing US citizens the rights to any materials that they gather from asteroids or other space-based resources. However, space miners will also have to comply with the 1966 Outer Space Treaty, an international agreement that states: “outer space is not subject to national appropriation by claim of sovereignty”. The act also extends the use of the International Space Station from 2020 to at least 2024. Pipeline questions In a letter to transport minister Marc Garneau, Canadian Prime Minister Justin Trudeau on 13 November called for a moratorium on crude-oil-tanker traffic along the north coast of British Columbia. The move raises questions about a pipeline project by the Calgary-based energy-delivery firm Enbridge to carry oil from Alberta’s tar sands to the coast for shipment. Environmentalists said that a moratorium would effectively halt the pipeline, but Enbridge said that it still hopes to discuss the plan with the prime minister. Food rules For the first time, crop farmers in the United States will have to answer to the Food and Drug Administration (FDA) as part of an effort to prevent food-borne illness. A set of rules that the agency released on 13 November requires farmers to train their workers in proper hygiene, and to test crop-irrigation systems for pathogens, among other things. But the regulations are less stringent than a 2013 FDA proposal that farmers found too burdensome. Another of the rules creates a programme to allow auditors to assess imported food and the overseas facilities that produce it. The number of controversial fish aggregating devices (FADs) being used in the oceans is rising. Using data from tuna-fishing boats (see chart), a 6 November report from the Pew Charitable Trusts estimates that between 81,000 and 121,000 FADs were set adrift in 2013 — and their use is growing (see go.nature.com/ngeubv). These FADs are free-floating, so fish and other animals shelter underneath and become easier to catch. But researchers warn that the devices encourage overfishing, and kill vulnerable species. 8,690 The wind speed in kilometres per hour on HD 189733 b, a ‘hot Jupiter’ exoplanet 19.3 parsecs away from Earth — and the first weather data from a planet outside our Solar System. Source: Louden, T. & Wheatley, P. J. Preprint at http://arxiv.org/abs/1511.03689 (2015). 19–20 November The inaugural Meta-Research Innovation Center at Stanford (METRICS) conference convenes in California to discuss how biomedical scientists plan, conduct and communicate research. go.nature.com/narepc 23–27 November Ostend, Belgium, hosts the European Space Weather Week, a forum for space-weather forecasters and scientists. www.stce.be/esww12


Lasch P.,Robert Koch Institute | Drevinek M.,National Institute for Nuclear | Nattermann H.,Robert Koch Institute | Grunow R.,Robert Koch Institute | And 4 more authors.
Analytical Chemistry | Year: 2010

Yersinia are Gram-negative, rod-shaped facultative anaerobes, and some of them, Yersinia enterocolitica, Yersinia pseudotuberculosis, and Yersinia pestis, are pathogenic in humans. Rapid and accurate identification of Yersinia strains is essential for appropriate therapeutic management and timely intervention for infection control. In the past decade matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) in combination with computer-aided pattern recognition has evolved as a rapid, objective, and reliable technique for microbial identification. In this comprehensive study a total of 146 strains of all currently known Yersinia species complemented by 35 strains of other relevant genera of the Enterobacteriaceae family were investigated by MALDI-TOF MS and chemometrics. Bacterial sample preparation included microbial inactivation according to a recently developed mass spectrometry compatible inactivation protocol. The mass spectral profiles were evaluated by supervised feature selection methods to identify family-, genus-, and species-specific biomarker proteins and-for classification purposes-by pattern recognition techniques. Unsupervised hierarchical cluster analysis revealed a high degree of correlation between bacterial taxonomy and subproteome-based MALDI-TOF MS classification. Furthermore, classification analysis by supervised artificial neural networks allowed identification of strains of Y. pestis with an accuracy of 100%. In-depth analysis of proteomic data demonstrated the existence of Yersinia-specific biomarkers at m/z 4350 and 6046. In addition, we could also identify species-specific biomarkers of Y. enterocolitica at m/z 7262, 9238, and 9608. For Y. pseudotuberculosis a combination of biomarkers at m/z 6474, 7274, and 9268 turned out to be specific, while a peak combination at m/z 3065, 6637, and 9659 was characteristic for strains of Y. pestis. Bioinformatic approaches and tandem mass spectrometry were employed to reveal the molecular identity of biomarker ions. In this way, the Y. pestis-specific biomarker at m/z 3065 could be identified as a fragment of the plasmid-encoded plasminogen activator, one of the major virulence factors in plague infections. © 2010 American Chemical Society.


Otahal P.,National Institute for Nuclear | Burian I.,National Institute for Nuclear
Radiation Protection Dosimetry | Year: 2011

The knowledge of the behaviour of radioactive aerosol particles in the uranium mine atmosphere is very important due to the evaluation of the effective dose for uranium miners. During the research of the project SUJ200402-'Study of behaviour of natural long-lived radionuclides in the mine atmosphere', several measurement campaigns were performed in the last active Central Europe uranium mine Rozna I. The main purpose of this paper is characterisation the radionuclides which creating the main part of the airborne radioactivity in the uranium mine atmosphere. The present paper introduces results of the measurements of airborne radioactivity in stopes of the uranium mine Rozna I. The measurements were performed at the 21st floor at a depth of ~1100 m under the ground. In addition to the concentration of 222Rn, its progenies, long-lived radionuclides and also the concentration of aerosol particles were measured. © The Author 2011. Published by Oxford University Press. All rights reserved.

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