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  • richardmitnick 5:44 pm on May 2, 2016 Permalink | Reply
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    From Surf: “Notes from the underground – LUX celebrates 300 live days” 

    SURF logo
    Sanford Underground levels

    Sanford Underground Research facility

    Monday, May 2, 2016
    Constance Walter, Communications Director, SURF

    Amid streamers, a piñata and paper unicorns, LUX researchers celebrated the 300-live-day run of their dark matter detector.

    LUX Dark matter
    LUX Dark matter
    LUX Dark matter experiment
    Lux Dark Matter 2
    Lux Dark Matter 2

    “I would describe the mood as exciting, joyous and electric,” said Mark Hanhardt, Sanford Lab support scientist. Why unicorns? For LUX researchers, they symbolize thesearch for the elusive WIMP, or weakly interacting massive particle, the leading contender in the dark matter search.

    But don’t kid yourselves, in the search for dark matter, these researchers remain focused and motivated.

    LUX consists of one third-of-a-ton of liquid xenon inside a titanium vessel.

    Researchers hope to identify the very rare occasions when a dark matter particle collides with a xenon atom inside the detector. When that happens, the xenon atom will recoil and emit a tiny flash of light, which will be detected by sensitive light detectors.

    In October 2013, after a 90-live-day run, LUX announced it was the most sensitive dark matter detector in the world. “LUX was so much larger than existing detectors that within a few weeks of starting its first run in 2013, it had surpassed all previous direct detection experiments,” said Richard Gaitskell, co-spokesperson for LUX.
    And the trend continues. In December, LUX released a reanalysis of the 2013 data, which discussed new calibration techniques that allowed for even greater sensitivity. Those techniques, which included the use of tritiated methane, krypton-83 and a neutron generator, were used in the most recent run; however, results willnot be available before the end of 2016.

    The 300-day run began in November 2014 and the detector has been in WIMP search mode or calibration mode since. But it has not been without its challenges, Gaitskell said. “During any dark matter search, we must ensure the detector is taking data in a completely stable mode in which the operating conditions are clearly understood,” he said. “This means we monitor the detector health continually and occasionally we have to react to any apparent issues that have developed.”

    At regular intervals throughout the new run, calibrations were carried out for two weeks every four months to ensure a high level of accuracy in measuring responses to backgrounds and potential dark matter signals, he added.

    After 19 months, the run officially ended today at 1 p.m. “That’s a long time to to operate a detector without a significant break,” said Simon Fiorucci, LUX science operationsmanager. “But it was critical to demonstrate our ability to do so as we prepare to run LZ for more than three years.”

    Later this year, LUX will be decommissioned to make way for a new, much larger xenon detector, known as LUX-ZEPLIN, or LZ. This second generation dark matter detector will have a 10-ton liquid xenon target and be up to 100 times more sensitive.

    LUX Xenon experiment at SURF
    LUX Xenon experiment at SURF

    “The tremendous success of LUX paved the way for LZ,” said Murdock Gilchriese, LBNL (Lawrence Berkeley National Laboratory) operations manager for LUX and LZ project director. LZ will be located inside the same 72,000-gallon water tank that currently shields LUX.

    “Sanford Lab will continue to play a global role in the search for dark matter,” said Jaret Heise, science director at Sanford Lab. “We’re looking
    forward to working with the expanded collaboration, which will include 31 institutions and about 200 scientists.”

    In the meantime, LUX researchers are continuing their work, including testing several new calibration techniques that will be used in LZ. The team has come a long way and made significant progress. “We are all proud to have made it this far,” Fiorucci said.

    See the full article here .

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    About us.
    The Sanford Underground Research Facility in Lead, South Dakota, advances our understanding of the universe by providing laboratory space deep underground, where sensitive physics experiments can be shielded from cosmic radiation. Researchers at the Sanford Lab explore some of the most challenging questions facing 21st century physics, such as the origin of matter, the nature of dark matter and the properties of neutrinos. The facility also hosts experiments in other disciplines—including geology, biology and engineering.

    The Sanford Lab is located at the former Homestake gold mine, which was a physics landmark long before being converted into a dedicated science facility. Nuclear chemist Ray Davis earned a share of the Nobel Prize for Physics in 2002 for a solar neutrino experiment he installed 4,850 feet underground in the mine.

    Homestake closed in 2003, but the company donated the property to South Dakota in 2006 for use as an underground laboratory. That same year, philanthropist T. Denny Sanford donated $70 million to the project. The South Dakota Legislature also created the South Dakota Science and Technology Authority to operate the lab. The state Legislature has committed more than $40 million in state funds to the project, and South Dakota also obtained a $10 million Community Development Block Grant to help rehabilitate the facility.

    In 2007, after the National Science Foundation named Homestake as the preferred site for a proposed national Deep Underground Science and Engineering Laboratory (DUSEL), the South Dakota Science and Technology Authority (SDSTA) began reopening the former gold mine.

    In December 2010, the National Science Board decided not to fund further design of DUSEL. However, in 2011 the Department of Energy, through the Lawrence Berkeley National Laboratory, agreed to support ongoing science operations at Sanford Lab, while investigating how to use the underground research facility for other longer-term experiments. The SDSTA, which owns Sanford Lab, continues to operate the facility under that agreement with Berkeley Lab.

    The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s. In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The Majorana Demonstrator experiment, also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

    Another major experiment, the Long Baseline Neutrino Experiment (LBNE)—a collaboration with Fermi National Accelerator Laboratory (Fermilab) and Sanford Lab, is in the preliminary design stages. The project got a major boost last year when Congress approved and the president signed an Omnibus Appropriations bill that will fund LBNE operations through FY 2014. Called the “next frontier of particle physics,” LBNE will follow neutrinos as they travel 800 miles through the earth, from FermiLab in Batavia, Ill., to Sanford Lab.

    Fermilab LBNE
    LBNE

     
  • richardmitnick 1:33 pm on December 29, 2015 Permalink | Reply
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    From LLNL: “New results from experimental facility deepen understanding of dark matter” 


    Lawrence Livermore National Laboratory

    Dec. 29, 2015
    Stephen Wampler
    wampler1@llnl.gov
    925-423-3107

    1
    Photomultiplier tubes can pick up the tiniest bursts of lights when a particle interacts with xenon atoms as part of the Large Underground Xenon (LUX) dark matter experiment at the Sanford Underground Research Facility (SURF). Photo courtesy of SURF.

    The Large Underground Xenon (LUX) dark matter experiment, which operates nearly a mile underground at the Sanford Underground Research Facility (SURF)in the Black Hills of South Dakota, has already proven itself to be the most sensitive dark matter detector in the world. Now, a new set of calibration techniques employed by LUX scientists has further improved its sensitivity.

    LUX researchers, including several from Lawrence Livermore National Laboratory’s (LLNL) Rare Event Detection Group, are looking for WIMPs, weakly interacting massive particles, which are among the leading candidates for dark matter.

    LLNL is one of the founding members of the LUX experiment, and LLNL researchers have participated in LUX and its predecessor experiment (XENON-10) since 2004.

    “It is vital that we continue to push the capabilities of our detector in the search for the elusive dark matter particles,” said Rick Gaitskell, professor of physics at Brown University and co-spokesperson for the LUX experiment. “We have improved the sensitivity of LUX by more than a factor of 20 for low-mass dark matter particles, significantly enhancing our ability to look for WIMPs.”

    The new research is described in a paper submitted to Physical Review Letters and posted to ArXiv. The work re-examines data collected during LUX’s first experimental run in 2013, and helps to rule out the possibility of dark matter detections at low-mass ranges where other experiments had previously reported potential detections.

    “The latest LUX science results are a re-analysis of data obtained over three months in 2013,” said LLNL principal investigator and physicist Adam Bernstein. “The first analysis of that data was published in 2014, and since then we have expanded our understanding of the detector response through a combination of low-energy nuclear recoil measurements, low-energy electron recoil measurements and an improved understanding of our background in the low-energy recoil regime where dark matter interactions are likely to appear.

    “This combination of improvements enabled us to increase our sensitivity to low-mass WIMPs by upward of two orders of magnitude. LUX is currently in a longer science run lasting 300 live days, scheduled for completion by this July,” Bernstein added.

    Dark matter is thought to be the dominant form of matter in the universe. Scientists are confident in its existence because its gravitational effects can be seen in the rotation of galaxies and in the way light bends as it travels through the universe. Because WIMPs are thought to interact with other matter only on very rare occasions, they have yet to be detected directly.

    “We have looked for dark matter particles during the experiment’s first three-month run, but are exploiting new calibration techniques that do a better job of pinning down how they would appear to our detector,” said Alastair Currie of Imperial College London. “These calibrations have deepened our understanding of the response of xenon to dark matter, and to backgrounds. This allows us to search, with improved confidence, for particles that we hadn’t previously known would be visible to LUX.”

    Bernstein and other LLNL researchers have taken part in initial science planning and experimental design for LUX. Physicist Peter Sorensen, formerly with LLNL and now at Lawrence Berkeley National Laboratory, spent many months with on-site assembly and commissioning, and has made key contributions to the study of the low-mass WIMP signal.

    Physicist Kareem Kazkaz, who works in the LLNL Rare Event Detection Group, created the LUXSim simulation framework, which has been used throughout the collaboration to understand detector response and increase the team’s understanding of signal backgrounds and how the liquid xenon medium responds to incident radiation.

    More recently, LLNL graduate scholar Brian Lenardo has served as the deputy science coordination manager and has been an integral member of the team studying the light and charge yield of nuclear recoils within the active volume. Joining LLNL in September, postdoctoral fellow Jingke Xu has organized a sub-group focused on events at the single electron quantum limit of detector sensitivity.

    LUX consists of a third of a ton of liquid xenon surrounded with sensitive light detectors. It is designed to identify the very rare occasions when a dark matter particle collides with a xenon atom inside the detector. When a collision happens, the xenon atom will recoil and emit a small burst of light, which is detected by LUX’s light sensors. The detector’s location at Sanford Lab beneath a mile of rock helps to shield it from cosmic rays and other radiation that would interfere with the dark matter signal.

    So far, LUX hasn’t detected a dark matter signal, but its exquisite sensitivity has allowed scientists to all but rule out dark matter particles over a wide range of masses that current theories allow. These new calibrations increase that sensitivity even further.

    One calibration technique used neutrons as stand-ins for dark matter particles. Bouncing neutrons off the xenon atoms allows scientists to quantify how the LUX detector responds to the recoil process.

    “It is like a giant game of pool with a neutron as the cue ball and the xenon atoms as the stripes and solids,” Gaitskell said. “We can track the neutron to deduce the details of the xenon recoil, and calibrate the response of LUX better than anything previously possible.”

    The nature of the interaction between neutrons and xenon atoms is thought to be very similar to the interaction between dark matter and xenon. “It’s just that dark matter particles interact very much more weakly — about a million-million-million-million times more weakly,” Gaitskell said.

    The neutron experiments help to calibrate the detector for interactions with the xenon nucleus. But LUX scientists also have calibrated the detector’s response to the deposition of small amounts of energy by struck atomic electrons. That’s done by injecting tritiated methane – a radioactive gas – into the detector.

    “In a typical science run, most of what LUX sees are background electron recoil events,” said Carter Hall of the University of Maryland. “Tritiated methane is a convenient source of similar events, and we’ve now studied hundreds of thousands of its decays in LUX. This gives us confidence that we won’t mistake these garden variety events for dark matter.”

    Another radioactive gas, krypton, was injected to help scientists distinguish between signals produced by ambient radioactivity and a potential dark matter signal.

    “The krypton mixes uniformly in the liquid xenon and emits radiation with a known, specific energy, but then quickly decays away to a stable, nonradioactive Isotope, ” said Dan McKinsey, a University of California Berkeley physics professor and co-spokesperson for LUX, who also is an affiliate of Lawrence Berkeley National Laboratory. “By measuring the light and charge produced by these krypton events throughout the liquid xenon, we can flat-field the detector’s response, allowing better separation of dark matter events from natural radioactivity.”

    LUX improvements coupled to the advanced computer simulations at Lawrence Berkeley National Laboratory’s National Energy Research Scientific Computing Center and Brown University’s Center for Computation and Visualization have allowed scientists to test additional particle models of dark matter that can be excluded from the search. “And so the search continues,” McKinsey said.

    4
    Edison Cray XC30 at NERSC

    “LUX is once again in search mode at Sanford Lab. The latest run began in late 2014 and is expected to continue until June 2016. This run will represent an increase in exposure of more than four times compared to the previous 2013 run. We will be very excited to see if any dark matter particles have shown themselves in the new data.”

    The LUX scientific collaboration, which is supported by the DOE and National Science Foundation, includes 19 research universities and national laboratories in the United States, the United Kingdom and Portugal.

    “The global search for dark matter aims to answer one of the biggest questions about the makeup of our universe. We’re proud to support the LUX collaboration and congratulate them on achieving an even greater level of sensitivity,” said Mike Headley, executive director of the SDSTA.

    See the full article here .

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    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security
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  • richardmitnick 1:10 pm on December 14, 2015 Permalink | Reply
    Tags: , , , LUX Dark Matter Experiment   

    From LBL: “New Results from World’s Most Sensitive Dark Matter Detector” 

    Berkeley Logo

    Berkeley Lab

    December 14, 2015
    Glenn Roberts Jr. 510-486-5582

    Berkeley Lab Scientists Participate in Mile-deep Experiment in Former South Dakota Gold Mine

    The Large Underground Xenon (LUX) dark matter experiment, which operates nearly a mile underground at the Sanford Underground Research Facility (SURF) in the Black Hills of South Dakota, has already proven itself to be the most sensitive detector in the hunt for dark matter, the unseen stuff believed to account for most of the matter in the universe. Now, a new set of calibration techniques employed by LUX scientists has again dramatically improved the detector’s sensitivity.

    1
    A view inside the LUX detector. (Photo by Matthew Kapust/Sanford Underground Research Facility)

    Researchers with LUX are looking for WIMPs, or weakly interacting massive particles, which are among the leading candidates for dark matter. “We have improved the sensitivity of LUX by more than a factor of 20 for low-mass dark matter particles, significantly enhancing our ability to look for WIMPs,” said Rick Gaitskell, professor of physics at Brown University and co-spokesperson for the LUX experiment. “It is vital that we continue to push the capabilities of our detector in the search for the elusive dark matter particles,” Gaitskell said.

    LUX improvements, coupled to advanced computer simulations at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory’s (Berkeley Lab) National Energy Research Scientific Computing Center (NERSC) and Brown University’s Center for Computation and Visualization (CCV), have allowed scientists to test additional particle models of dark matter that now can be excluded from the search. NERSC also stores large volumes of LUX data—measured in trillions of bytes, or terabytes—and Berkeley Lab has a growing role in the LUX collaboration.

    Scientists are confident that dark matter exists because the effects of its gravity can be seen in the rotation of galaxies and in the way light bends as it travels through the universe. Because WIMPs are thought to interact with other matter only on very rare occasions, they have yet to be detected directly.

    2
    The LUX dark matter detector is seen here during the assembly process in a surface laboratory in South Dakota. (Photo by Matthew Kapust/Sanford Underground Research Facility)

    “We have looked for dark matter particles during the experiment’s first three-month run, but are exploiting new calibration techniques better pinning down how they would appear to our detector,” said Alastair Currie of Imperial College London, a LUX researcher.

    “These calibrations have deepened our understanding of the response of xenon to dark matter, and to backgrounds. This allows us to search, with improved confidence, for particles that we hadn’t previously known would be visible to LUX.”

    The new research is described in a paper submitted to Physical Review Letters. The work reexamines data collected during LUX’s first three-month run in 2013 and helps to rule out the possibility of dark matter detections at low-mass ranges where other experiments had previously reported potential detections.

    3
    A view of the LUX detector during installation. (Photo by Matthew Kapust/Sanford Underground Research Facility)

    LUX consists of one-third ton of liquid xenon surrounded with sensitive light detectors. It is designed to identify the very rare occasions when a dark matter particle collides with a xenon atom inside the detector. When a collision happens, a xenon atom will recoil and emit a tiny flash of light, which is detected by LUX’s light sensors. The detector’s location at Sanford Lab beneath a mile of rock helps to shield it from cosmic rays and other radiation that would interfere with a dark matter signal.

    So far LUX hasn’t detected a dark matter signal, but its exquisite sensitivity has allowed scientists to all but rule out vast mass ranges where dark matter particles might exist. These new calibrations increase that sensitivity even further.

    One calibration technique used neutrons as stand-ins for dark matter particles. Bouncing neutrons off the xenon atoms allows scientists to quantify how the LUX detector responds to the recoiling process.

    “It is like a giant game of pool with a neutron as the cue ball and the xenon atoms as the stripes and solids,” Gaitskell said. “We can track the neutron to deduce the details of the xenon recoil, and calibrate the response of LUX better than anything previously possible.”

    The nature of the interaction between neutrons and xenon atoms is thought to be very similar to the interaction between dark matter and xenon. “It’s just that dark matter particles interact very much more weakly—about a million-million-million-million times more weakly,” Gaitskell said.

    The neutron experiments help to calibrate the detector for interactions with the xenon nucleus. But LUX scientists have also calibrated the detector’s response to the deposition of small amounts of energy by struck atomic electrons. That’s done by injecting tritiated methane—a radioactive gas—into the detector.

    “In a typical science run, most of what LUX sees are background electron recoil events,” said Carter Hall a University of Maryland professor. “Tritiated methane is a convenient source of similar events, and we’ve now studied hundreds of thousands of its decays in LUX. This gives us confidence that we won’t mistake these garden-variety events for dark matter.”

    Another radioactive gas, krypton, was injected to help scientists distinguish between signals produced by ambient radioactivity and a potential dark matter signal.

    “The krypton mixes uniformly in the liquid xenon and emits radiation with a known, specific energy, but then quickly decays away to a stable, non-radioactive form,” said Dan McKinsey, a UC Berkeley physics professor and co-spokesperson for LUX who is also an affiliate with Berkeley Lab. By precisely measuring the light and charge produced by this interaction, researchers can effectively filter out background events from their search.

    “And so the search continues,” McKinsey said. “LUX is once again in dark matter detection mode at Sanford Lab. The latest run began in late 2014 and is expected to continue until June 2016. This run will represent an increase in exposure of more than four times compared to our previous 2013 run. We will be very excited to see if any dark matter particles have shown themselves in the new data.”

    McKinsey, formerly at Yale University, joined UC Berkeley and Berkeley Lab in July, accompanied by members of his research team.

    The Sanford Lab is a South Dakota-owned facility. Homestake Mining Co. donated its gold mine in Lead to the South Dakota Science and Technology Authority (SDSTA), which reopened the facility in 2007 with $40 million in funding from the South Dakota State Legislature and a $70 million donation from philanthropist T. Denny Sanford. The U.S. Department of Energy (DOE) supports Sanford Lab’s operations.

    Kevin Lesko, who oversees SURF operations and leads the Dark Matter Research Group at Berkeley Lab, said, “It’s good to see that the experiments installed in SURF continue to produce world-leading results.”

    The LUX scientific collaboration, which is supported by the DOE and National Science Foundation (NSF), includes 19 research universities and national laboratories in the United States, the United Kingdom and Portugal.

    “The global search for dark matter aims to answer one of the biggest questions about the makeup of our universe. We’re proud to support the LUX collaboration and congratulate them on achieving an even greater level of sensitivity,” said Mike Headley, Executive Director of the SDSTA.

    Planning for the next-generation dark matter experiment at Sanford Lab is already under way. In late 2016 LUX will be decommissioned to make way for a new, much larger xenon detector, known as the LUX-ZEPLIN (LZ) experiment.

    LZ project
    LZ schematic

    LZ would have a 10-ton liquid xenon target, which will fit inside the same 72,000-gallon tank of pure water used by LUX. Berkeley Lab scientists will have major leadership roles in the LZ collaboration.

    “The innovations of the LUX experiment form the foundation for the LZ experiment, which is planned to achieve over 100 times the sensitivity of LUX. The LZ experiment is so sensitive that it should begin to detect a type of neutrino originating in the Sun that even Ray Davis’ Nobel Prize-winning experiment at the Homestake mine was unable to detect,” according to Harry Nelson of UC Santa Barbara, spokesperson for LZ.

    LUX is supported by the DOE Office of Science. NERSC is a DOE Office of Science User Facility.

    A version of this release and additional materials are available on the Sanford Lab site.

    See the full article here .

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  • richardmitnick 12:55 pm on December 8, 2015 Permalink | Reply
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    From SURF: “4850 Feet Below: The Hunt for Dark Matter” 

    SURF logo

    Sanford Underground levels

    Sanford Underground Research facility

    Oct 5, 2015
    Deep in an abandoned gold mine in rural South Dakota, a team of physicists are hunting for astrophysical treasure. Their rare and elusive quarry is dark matter, a theoretical particle which has never been seen or directly detected. Yet its gravitational effect on distant galaxies hints at its existence and provides ample evidence to fuel the experiments and aspirations of scientists at the Sanford Underground Research Facility. Insulated by 4,850 feet of rock, the researchers have constructed the world’s most sensitive particle detector, known as the Large Underground Xenon Experiment, or “LUX.

    LUX Dark matter
    Lux Dark Matter 2
    LUX

    Their goal is to use this complex device to capture an epiphanous event: the interaction between dark matter and atoms inside a chilled tank of liquid xenon. If they’re successful, the researchers may not only solve some of the biggest mysteries in astrophysics but affirm their faith in the nature of dark matter.

    “4850 Feet Below” was produced with generous support from the John Templeton Foundation.

    See the full article here .

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    About us.
    The Sanford Underground Research Facility in Lead, South Dakota, advances our understanding of the universe by providing laboratory space deep underground, where sensitive physics experiments can be shielded from cosmic radiation. Researchers at the Sanford Lab explore some of the most challenging questions facing 21st century physics, such as the origin of matter, the nature of dark matter and the properties of neutrinos. The facility also hosts experiments in other disciplines—including geology, biology and engineering.

    The Sanford Lab is located at the former Homestake gold mine, which was a physics landmark long before being converted into a dedicated science facility. Nuclear chemist Ray Davis earned a share of the Nobel Prize for Physics in 2002 for a solar neutrino experiment he installed 4,850 feet underground in the mine.

    Homestake closed in 2003, but the company donated the property to South Dakota in 2006 for use as an underground laboratory. That same year, philanthropist T. Denny Sanford donated $70 million to the project. The South Dakota Legislature also created the South Dakota Science and Technology Authority to operate the lab. The state Legislature has committed more than $40 million in state funds to the project, and South Dakota also obtained a $10 million Community Development Block Grant to help rehabilitate the facility.

    In 2007, after the National Science Foundation named Homestake as the preferred site for a proposed national Deep Underground Science and Engineering Laboratory (DUSEL), the South Dakota Science and Technology Authority (SDSTA) began reopening the former gold mine.

    In December 2010, the National Science Board decided not to fund further design of DUSEL. However, in 2011 the Department of Energy, through the Lawrence Berkeley National Laboratory, agreed to support ongoing science operations at Sanford Lab, while investigating how to use the underground research facility for other longer-term experiments. The SDSTA, which owns Sanford Lab, continues to operate the facility under that agreement with Berkeley Lab.

    The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s. In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The Majorana Demonstrator experiment, also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

    Another major experiment, the Long Baseline Neutrino Experiment (LBNE) [being replaced by DUNE]—a collaboration with Fermi National Accelerator Laboratory (Fermilab) and Sanford Lab, is in the preliminary design stages. The project got a major boost last year when Congress approved and the president signed an Omnibus Appropriations bill that will fund LBNE operations through FY 2014. Called the “next frontier of particle physics,” LBNE [DUNE] will follow neutrinos as they travel 800 miles through the earth, from FermiLab in Batavia, Ill., to Sanford Lab.

    Fermilab LBNE
    LBNE

     
  • richardmitnick 12:23 pm on October 13, 2015 Permalink | Reply
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    From Symmetry: “Xenon, xenon everywhere” 

    Symmetry

    1
    Artwork by Sandbox Studio, Chicago with Ana Kova

    October 13, 2015
    Glenn Roberts Jr.

    It’s in the air we breathe, but it’s not so easy to get ahold of 10 metric tons of xenon in its liquid form.

    So, you want to buy some xenon to try to detect dark matter deep underground. Not a problem. There’s a market for that, with a few large-scale suppliers.

    Wait, what’s that you say? You need 10 metric tons of incredibly pure, liquid xenon for the LUX-ZEPLIN dark matter experiment? That’s a bit trickier.

    LUX Dark matter
    LUX-ZEPLIN dark matter experiment

    Looking for large amounts of xenon is a bit like searching for dark matter: It’s all around us, but it’s colorless, odorless and hard to separate from everything else. Xenon is in the air that we breathe, but it’s also one of the rarest elements on Earth.

    There is about 1 part xenon in every 11.5 million parts of air. The global industry that extracts liquid xenon produces a total of about 40 tons of xenon per year, so 10 tons is a very tall order.

    “Buying several tons per year won’t perturb the market too much,” says Thomas Shutt, a SLAC physicist who, along with physicist Daniel Akerib, left Case Western Reserve University in Ohio last year to join SLAC National Accelerator Laboratory. “If you buy 10 tons in a year that’s a quarter of the market.”

    Akerib and Shutt are heading up SLAC’s effort in the planned LUX-ZEPLIN, or LZ, experiment, one of the largest-scale efforts to find dark matter particles. Like its smaller predecessor experiment, called LUX (for Large Underground Xenon), LZ will be filled with supercooled liquid xenon.

    Xenon, like several other rare gases, can emit flashes of light and electrons when its atoms are hit by other particles. The LZ detector will sit 1 mile underground in a South Dakota mine [SURF], shielded from most other particles, and wait to see signals from dark matter particles.

    Sanford Underground Research Facility Interior
    Sanford Underground levels
    Sanford Underground Research Facility [SURF], in South Dakota

    “Xenon has really good stopping power,” Akerib says. Its liquid form is so dense that aluminum can float on it. It is particularly sensitive to passing particles.

    Xenon is used in more than just dark matter experiments. It is also in demand as a component in halogen lights such as the bluish headlights in some vehicles, in the bulbs for other specialized lighting such as flash lamps that drive lasers, and as a propellant for satellites and other spacecraft. It is also used in semiconductor manufacturing and medical imaging, and it has been used as an anesthetic.

    Xenon is a by-product of the steel-making process, which uses liquid oxygen to wash away contaminants on the surface of molten iron. Russia, South Africa and Saudi Arabia are among the major producers of xenon. Russia became a major player in this market during the era of the Soviet Union, when steel-making was largely centralized.

    Industrially produced xenon isn’t nearly pure enough for the exacting requirements of LZ, though.

    Shutt says extracting its own xenon from air was not an option. “If we had to start from scratch in refining xenon, it would be vastly more expensive,” he says.

    The LZ team plans to acquire xenon over the next 3 to 4 years.

    There is no expiration date on xenon, Shutt said; it just needs to be tightly contained so no venting occurs. “The xenon we use we can put back on the market or put to other scientific uses after the LZ experiment is complete,” he says. “It’s around forever.”

    To ensure that the dark matter detector is ultrasensitive, the LZ team is building a purification system at SLAC National Accelerator Laboratory to remove krypton, another rare gas that can get mixed in with liquid xenon. LUX started with xenon that had 100 parts of krypton per billion and purified it down to four parts per trillion, and LZ needs xenon purified to a standard of 0.015 parts krypton per trillion—a factor of 300 purer.

    Shutt jokes that, while LZ is all about particle physics, “we have become armchair chemical engineers” in the process of putting the experiment together.

    The current plan is to purify the xenon in 2018, and to run each batch through the purification process twice. The process is expected to take several months in total. LZ is scheduled to start running in 2019.

    See the full article here.

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 4:31 pm on August 4, 2014 Permalink | Reply
    Tags: , , LUX Dark Matter Experiment,   

    From Sanford Underground Research Facility: “DOE, NSF to fund LUX-ZEPLIN (LZ) experiment at Sanford Lab” 

    Sanford Underground Research facility

    Sanford Underground levels

    Sanford Underground Research facility
    August 4, 2014
    Constance Walter

    LUX-ZEPLIN (LZ), a second generation dark matter experiment, got a big boost when the Department of Energy and National Science Foundation selected it as one of three experiments that will be funded in the next-generation dark matter search. LZ will build on the Large Underground Xenon (LUX) experiment, which has been operating at the 4850 Level of the Sanford Underground Research Facility since 2012, and on the ZEPLIN dark matter program in the United Kingdom, which pioneered the use of these types of detectors underground.

    “We emerged from a very intense competition,” said Daniel McKinsey, professor of physics at Yale and a spokesperson for LUX. “We have the most sensitive detector in the world, with LUX. LZ will be hundreds of times more sensitive. It’s gratifying to see that our approach is being validated.”

    Construction on the supersized detector is scheduled to begin in 2016, with a commissioning date of 2018. Plans for LZ have been in the works for several years.

    “This is great news for the future of Dark Matter exploration and the Sanford Lab,” said Mike Headley, Executive Director of the South Dakota Science and Technology Authority. “The LZ experiment will play a key role in the future of the lab and we’re pleased that the DOE selected the experiment. It certainly will extend the state’s investment in this world-class facility.”

    Rick Gaitskell, Hazard Professor of Physics at Brown, is a founding member of LZ and also co-spokesperson for the LUX experiment.

    “The go-ahead from DOE and NSF is a major event,” Gaitskell said. “The LZ experiment will continue the liquid xenon direct dark matter search program at Sanford Lab, which we started with the operation of LUX in 2013. LUX will run until 2016 when we will replace it with LZ, which can provide a further improvement in sensitivity of two orders of magnitude due to its significant increase in size.”

    Even if LUX makes a dark matter detection before LZ is up and running, LZ will still be necessary to confirm the detection and fully characterize the nature of WIMPS, Gaitskell said.

    “This green light is a clear indication of the value the agencies see, not only in all the preparatory work that has gone into LZ, but also in the existing accomplishment of LUX and Sanford Lab these past few years,” said Simon Fiorucci, a research scientist at Brown who is the science coordinator for LUX and simulations coordinator for LZ. “LZ will be timed so that it is ready to start operations when LUX delivers its final results and reaches the limits of its technology. It will be a very natural transition.”

    Harry Nelson, professor of physics at the University of California, Santa Barbara and spokesperson for the LZ Collaboration, said, “We still have a lot of work to do. Basically, we got the green light to go the next green light, then the next green light.” Still, he continued, “Everyone is excited.”

    See the full article here.

    About us.
    The Sanford Underground Research Facility in Lead, South Dakota, advances our understanding of the universe by providing laboratory space deep underground, where sensitive physics experiments can be shielded from cosmic radiation. Researchers at the Sanford Lab explore some of the most challenging questions facing 21st century physics, such as the origin of matter, the nature of dark matter and the properties of neutrinos. The facility also hosts experiments in other disciplines—including geology, biology and engineering.

    The Sanford Lab is located at the former Homestake gold mine, which was a physics landmark long before being converted into a dedicated science facility. Nuclear chemist Ray Davis earned a share of the Nobel Prize for Physics in 2002 for a solar neutrino experiment he installed 4,850 feet underground in the mine.

    Homestake closed in 2003, but the company donated the property to South Dakota in 2006 for use as an underground laboratory. That same year, philanthropist T. Denny Sanford donated $70 million to the project. The South Dakota Legislature also created the South Dakota Science and Technology Authority to operate the lab. The state Legislature has committed more than $40 million in state funds to the project, and South Dakota also obtained a $10 million Community Development Block Grant to help rehabilitate the facility.

    In 2007, after the National Science Foundation named Homestake as the preferred site for a proposed national Deep Underground Science and Engineering Laboratory (DUSEL), the South Dakota Science and Technology Authority (SDSTA) began reopening the former gold mine.

    In December 2010, the National Science Board decided not to fund further design of DUSEL. However, in 2011 the Department of Energy, through the Lawrence Berkeley National Laboratory, agreed to support ongoing science operations at Sanford Lab, while investigating how to use the underground research facility for other longer-term experiments. The SDSTA, which owns Sanford Lab, continues to operate the facility under that agreement with Berkeley Lab.

    The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s. In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The Majorana Demonstrator experiment, also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

    Another major experiment, the Long Baseline Neutrino Experiment (LBNE)—a collaboration with Fermi National Accelerator Laboratory (Fermilab) and Sanford Lab, is in the preliminary design stages. The project got a major boost last year when Congress approved and the president signed an Omnibus Appropriations bill that will fund LBNE operations through FY 2014. Called the “next frontier of particle physics,” LBNE will follow neutrinos as they travel 800 miles through the earth, from FermiLab in Batavia, Ill., to Sanford Lab.

    Fermilab LBNE
    LBNE

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  • richardmitnick 4:53 am on April 12, 2014 Permalink | Reply
    Tags: , , , , , , LUX Dark Matter Experiment,   

    From BBC: “Dark matter hunt: LUX experiment reaches critical phase” 

    BBC

    8 April 2014
    Rebecca Morelle

    The quest to find the most mysterious particles in the Universe is entering a critical phase, scientists say.

    An experiment located in the bottom of a gold mine in South Dakota, US, could offer the best chance yet of detecting dark matter.

    Scientists believe this substance makes up more than a quarter of the cosmos, yet no-one has ever seen it directly.

    Early results from this detector, which is called LUX, confirmed it was the most powerful experiment of its kind.

    LUX Dark matter

    In the coming weeks, it will begin a 300-day-long run that could provide the first direct evidence of these enigmatic particles.

    Spotting WIMPs

    Beneath the snow-covered Black Hills of South Dakota, a cage rattles and creaks as it begins to descend into the darkness.

    For more than 100 years, this was the daily commute for the Homestake miners searching for gold buried deep in the rocks.

    Today, the subterranean caverns and tunnels have been transformed into a high-tech physics laboratory.

    Scientists now make the 1.5km (1-mile) journey underground in an attempt to solve one of the biggest mysteries in science.

    “We’ve moved into the 21st Century, and we still do not know what most of the matter in the Universe is made of,” says Prof Rick Gaitskell, from Brown University in Rhode Island, one of the principle investigators on Large Underground Xenon (LUX) experiment.

    lux
    The LUX detector is located 3km underground – and could be our best hope yet of finding dark matter

    Scientists believe all of the matter we can see – planets, stars, dust and so on – only makes up a tiny fraction of what is actually out there.

    They say about 85% of the matter in the Universe is actually dark matter, so called because it cannot be seen directly and nobody really knows what it is.

    This has not stopped physicists coming up with ideas though. And the most widely supported theory is that dark matter takes the form of Weakly Interacting Massive Particles, or WIMPs.

    Prof Gaitskell explains: “If one considers the Big Bang, 14bn years ago, the Universe was very much hotter than it is today and created an enormous number of particles.

    “The hypothesis we are working with at the moment is that a WIMP was the relic left-over from the Big Bang, and in fact dominates over the regular material you and I are made of.”

    hills
    The Homestake gold mine, which has now been converted into a lab, is in the Black Hills of South Dakota

    The presence of dark matter was first inferred because of its effect on galaxies like our own.

    As these celestial systems rotate around their dense centre, all of the regular matter that they contain does not have enough mass to account for the gravity needed to hold everything together. Really, a spinning galaxy should fly apart.

    Instead, scientists believe that dark matter provides the extra mass, and therefore gravity, needed to hold a galaxy together.

    It is so pervasive throughout the Universe that researchers believe a vast number of WIMPs are streaming through the Earth every single second. Almost all pass through without a trace.

    However, on very rare occasions, it is thought that dark matter particles do bump into regular matter – and it is this weak interaction that scientists are hoping to see.

    The LUX detector is one of a number of physics experiments based in the Sanford Underground Research Facility that require a “cosmic quietness”.

    Prof Gaitskell says: “The purpose of the mile of rock above is to deal with cosmic rays. These are high-energy particles generated from outside our Solar System and also by the Sun itself, and these are very penetrating.

    “If we don’t put a mile of rock between us and space, we wouldn’t be able to do this experiment.”

    Inside a cavern in the mine, the detector is situated inside a stainless steel tank that is two storeys high.

    tank
    The detector is in housed in a tank that is filled with purified water

    This is filled with about 300,000 litres (70,000 gallons) of ultra-purified water, which means it is free from traces of naturally occurring radioactive elements that could also interfere with the results.

    “With LUX, we’ve worked extremely hard to make this the quietest verified place in the world,” says Prof Gaitskell.

    At the detector’s heart is 370kg (815lb) of liquid xenon. This element has the unusual, but very useful, property of throwing out a flash of light when particles bump into it.

    And detecting a series of these bright sparks could mean that dark matter has been found.

    The LUX detector was first turned on last year for a 90-day test run. No dark matter was seen, but the results concluded that it was the most sensitive experiment of its kind.

    Now, when the experiment is run for 300 days, Prof Gaitskell says these interactions might be detected once a month or every few months.

    The team would have to see a significant number of interactions – between five and 10 – to suggest that dark matter has really been glimpsed. The more that are seen, the more statistical confidence there will be.
    detect
    LUX uses light detectors called photomultiplier tubes to record any flashes of light

    However, LUX is not the only experiment setting its sights on dark matter.

    With the Large Hadron Collider, scientists are attempting to create dark matter as they smash particles together, and in space, telescopes are searching for the debris left behind as dark matter particles crash into each other.

    CERN LHC New
    LHC at CERN

    Mike Headley, director of the South Dakota Science and Technology Authority, which runs the Sanford laboratory, says a Nobel prize will very probably be in store for the scientists who first detect dark matter.

    He says: “There are a handful of experiments located at different underground laboratories around the world that want to be the first ones to stand up and say ‘we have discovered it’, and so it is very competitive.”

    Finding dark matter would transform our understanding of the Universe, and usher in a new era in fundamental physics.

    However, there is also a chance that it might not be spotted – and the theory of dark matter is wrong.

    Dr Jim Dobson, based at the UK’s University of Edinburgh and affiliated with University College London, says: “We are going into unknown territory. We really don’t know what we’re going to find.

    “If we search with this experiment and then the next experiment, LUX Zeppelin, which is this much, much bigger version of LUX – if we didn’t find anything then there would be a good chance it didn’t exist.

    He adds: “In some ways, showing that there was no dark matter would be a more interesting result than if there was. But, personally, I would rather we found some.”

    Prof Carlos Frenk, a cosmologist from Durham University, says that many scientists have gambled decades of research on finding dark matter.

    He adds: “If I was a betting man, I think LUX is the frontrunner. It has the sensitivity we need. Now, we just need the data.

    “If they don’t [find it], it means the dark matter is not what we think it is. It would mean I have wasted my whole scientific career – everything I have done is based on the hypothesis that the Universe is made of dark matter. It would mean we had better look for something else.”

    See the full article here.


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  • richardmitnick 8:53 am on November 2, 2013 Permalink | Reply
    Tags: , , , LUX Dark Matter Experiment,   

    From Livermore Lab: “First results from LUX world’s most sensitive dark matter detector” 


    Lawrence Livermore National Laboratory

    10/31/2013
    Stephen P Wampler, LLNL, (925) 423-3107, wampler1@llnl.gov

    After its first run of more than three months, operating a mile underground in the Black Hills of South Dakota, a new experiment named LUX has proven itself the most sensitive dark matter detector in the world.

    device
    LUX researchers, seen here in a clean room on the surface at the Sanford Lab, work on the interior of the detector, before it is inserted into its titanium cryostat.

    cryo
    Photomultiplier tubes capable of detecting as little as a single photon of light line the top and bottom of the LUX dark matter detector. They will record the position and intensity of collisions between dark matter particles and xenon nuclei.

    “LUX is blazing the path to illuminate the nature of dark matter,” says Brown University physicist Rick Gaitskell, co-spokesperson for LUX with physicist Dan McKinsey of Yale University. LUX stands for Large Underground Xenon experiment.

    Gaitskell and McKinsey announced the LUX first-run results, on behalf of the collaboration, at a seminar Wednesday at the Sanford Underground Research Facility (Sanford Lab) in Lead, S.D. The Sanford Lab is a state-owned facility, and the U.S. Department of Energy (DOE) supports its operation. The LUX scientific collaboration, which is supported by the National Science Foundation and DOE, includes 17 research universities and national laboratories in the United States, the United Kingdom and Portugal.

    Three researchers from Lawrence Livermore National Laboratory — principal investigator Adam Bernstein and staff scientists Peter Sorensen and Kareem Kazkaz, all from the Lab’s Rare Event Detection Group in Physics Division — have been closely involved with the LUX project since its inception.

    Dark matter, so far observed only by its gravitational effects on galaxies and clusters of galaxies, is the predominant form of matter in the universe. Weakly interacting massive particles, or WIMPs — so-called because they rarely interact with ordinary matter except through gravity — are the leading theoretical candidates for dark matter. The mass of WIMPs is unknown, but theories and results from other experiments suggest a number of possibilities.

    LUX has a peak sensitivity at a WIMP mass of 33 GeV/c2 (see **below), with a sensitivity limit three times better than any previous experiment. LUX also has a sensitivity that is more than 20 times better than previous experiments for low-mass WIMPs, whose possible detection has been suggested by other experiments. Three candidate low-mass WIMP events recently reported in ultra-cold silicon detectors would have produced more than 1,600 events in LUX’s much larger detector, or one every 80 minutes in the recent run. No such signals were seen.

    “This is only the beginning for LUX,” McKinsey said. “Now that we understand the instrument and its backgrounds, we will continue to take data, testing for more and more elusive candidates for dark matter.”

    See the full article here.

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security
    Administration
    DOE Seal
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  • richardmitnick 7:20 pm on November 15, 2012 Permalink | Reply
    Tags: , , , LUX Dark Matter Experiment   

    From Livermore Lab: “LLNL scientists assist in building detector to search for elusive dark matter material” 


    Lawrence Livermore National Laboratory

    11/15/2012
    Anne M Stark

    “Lawrence Livermore National Laboratory researchers are making key contributions to a physics experiment that will look for one of nature’s most elusive particles, ‘dark matter,’ using a tank nearly a mile underground beneath the Black Hills of South Dakota.

    image
    Shown is a side view of the Lawrence Livermore National Laboratory-designed and built copper photomultiplier tube mounting structure, which is a key component of the Large
    Underground Xenon (LUX) detector, located at the Sanford Underground Research Facility in Lead, S.D. No image credit.

    The Large Underground Xenon (LUX) experiment located at the Sanford Underground Research Facility in Lead, S.D. is the most sensitive detector of its kind to look for dark matter. Thought to comprise more than 80 percent of the mass of the universe, scientists believe dark matter could hold the key to answering some of the most challenging questions facing physicists in the 21st century. So far, however, dark matter has eluded direct detection.

    LLNL researchers have been involved in the LUX experiment since 2008.

    ‘We at LLNL initially got involved in LUX because of the natural technological overlap with our own nonproliferation detector development programs,’ said Adam Bernstein, who leads the Advanced Detectors Group in LLNL’s Physics Division.

    ‘It’s very exciting to reflect that as a result, we are now part of a world-class team that stands an excellent chance of being the first to directly and unambiguously measure cosmological dark matter particle interactions in an earthly detector.'”

    LUX
    LUX

    sanford
    Sanford Underground Research Facility

    See the full article here.

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security Administration


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  • richardmitnick 12:23 pm on April 2, 2012 Permalink | Reply
    Tags: , LUX Dark Matter Experiment,   

    From Symmetry Magazine: “The LUX experiment takes the search for dark matter deep into a South Dakota gold mine.” 

    Almost a mile underground, in a new science facility in South Dakota, scientists of the LUX collaboration are building the world’s largest dark-matter search experiment.

    “This summer, researchers working in a former gold mine in South Dakota will slowly lower a titanium thermos the size of a phone booth into a large tank of purified water. The cylindrical thermos—nicknamed the can by its inventors—will hold ultra-pure liquid xenon and an array of photosensors, each capable of sensing a single photon of light.

    The can will be the core component of the Large Underground Xenon detector, or LUX, the most sensitive experiment yet to search for the elusive substance called dark matter.

    detect

    See the full article here. This could be a really big deal.

     
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