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  • richardmitnick 1:15 pm on May 25, 2017 Permalink | Reply
    Tags: , , , , , Grand Sasso National Laboratory, , , ,   

    From U Chicago: “World’s most sensitive dark matter detector releases first results” 

    U Chicago bloc

    University of Chicago

    May 18, 2017
    news@uchicago.edu
    (773) 702-8360
    News media only

    UChicago scientists part of international XENON collaboration

    1
    XENON1T installation in the underground hall of Laboratori Nazionali del Gran Sasso. The three story building on the right houses various auxiliary systems. The cryostat containing the LXeTPC is located inside the large water tank on the left. Photo by Roberto Corrieri and Patrick De Perio

    Gran Sasso LABORATORI NAZIONALI del GRAN SASSO, located in the Abruzzo region of central Italy

    2
    Scientists assembling the XENON1T time projection chamber. Photo by Enrico Sacchetti

    Scientists behind XENON1T, the largest dark matter experiment of its kind ever built, are encouraged by early results, describing them as the best so far in the search for dark matter.

    Dark matter is one of the basic constituents of the universe, five times more abundant than ordinary matter. Several astronomical measurements have corroborated the existence of dark matter, leading to an international effort to observe it directly. Scientists are trying to detect dark matter particle interacting with ordinary matter through the use of extremely sensitive detectors. Such interactions are so feeble that they have escaped direct detection to date, forcing scientists to build detectors that are more and more sensitive and have extremely low levels of radioactivity.

    On May 18, the XENON Collaboration released results from a first, 30-day run of XENON1T, showing the detector has a record low radioactivity level, many orders of magnitude below surrounding material on earth.

    “The care that we put into every single detail of the new detector is finally paying back,” said Luca Grandi, assistant professor in physics at the University of Chicago and member of the XENON Collaboration. “We have excellent discovery potential in the years to come because of the huge dimension of XENON1T and its incredibly low background. These early results already are allowing us to explore regions never explored before.”

    The XENON Collaboration consists of 135 researchers from the United States, Germany, Italy, Switzerland, Portugal, France, the Netherlands, Israel, Sweden and the United Arab Emirates, who hope to one day confirm dark matter’s existence and shed light on its mysterious properties.

    Located deep below a mountain in central Italy, XENON1T features a 3.2-ton xenon dual-phase time projection chamber. This central detector sits fully submersed in the middle of the water tank, in order to shield it from natural radioactivity in the cavern. A cryostat helps keep the xenon at a temperature of minus-95 degrees Celsius without freezing the surrounding water. The mountain above the laboratory further shields the detector, preventing it from being perturbed by cosmic rays.

    But shielding from the outer world is not enough, since all materials on Earth contain tiny traces of natural radioactivity. Thus extreme care was taken to find, select and process the materials making up the detector to achieve the lowest possible radioactive content. This allowed XENON1T to achieve record “silence” necessary to detect the very weak output of dark matter.

    A particle interaction in the one-ton central core of the time projection chamber leads to tiny flashes of light. Scientists record and study these flashes to infer the position and the energy of the interacting particle—and whether it might be dark matter.

    Despite the brief 30-day science run, the sensitivity of XENON1T has already overcome that of any other experiment in the field probing unexplored dark matter territory.

    “For the moment we do not see anything unexpected, so we set new constraints on dark matter properties,” Grandi said. “But XENON1T just started its exciting journey and since the end of the 30-day science run, we have been steadily accumulating new data.”

    UChicago central to international collaboration

    Grandi’s group is very active within XENON1T, and it is contributing to several aspects of the program. After its initial involvement in the preparation, assembly and early operations of the liquid xenon chamber, the group shifted its focus in the last several months to the development of the computing infrastructure and to data analysis.

    “Despite its low background, XENON1T is producing a large amount of data that needs to be continuously processed,” said Evan Shockley, a graduate student working with Grandi. “The raw data from the detector are directly transferred from Gran Sasso Laboratory to the University of Chicago, serving as the unique distribution point for the entire collaboration.”

    The framework, developed in collaboration with a group led by Robert Gardner, senior fellow at the Computation Institute, allows for the processing of data, both on local and remote resources belonging to the Open Science Grid. The involvement of UChicago’s Research Computing Center including Director Birali Runesha allows members of the collaboration all around the world to access processed data for high-level analyses.

    Grandi’s group also has been heavily involved in the analysis that led to this first result. Christopher Tunnell, a fellow at the Kavli Institute for Cosmological Physics, is one of the two XENON1T analysis coordinators and corresponding author of the result. Recently, UChicago hosted about 25 researchers for a month to perform the analyses that led to the first results.

    “It has been a large, concentrated effort and seeing XENON1T back on the front line makes me forget the never-ending days spent next to my colleagues to look at plots and distributions,“ Tunnell said. “There is no better thrill than leading the way in our knowledge of dark matter for the coming years.”

    See the full article here .

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    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 4:35 pm on September 2, 2016 Permalink | Reply
    Tags: , , Grand Sasso National Laboratory, Seach for neutrinoless double beta decay,   

    From Symmetry: “CUORE almost ready for first cool-down” 

    Symmetry Mag

    Symmetry

    09/02/16
    Ricarda Laasch

    1
    CUORE collaboration

    The refrigerator that will become the coldest cubic meter in the universe is fully loaded and ready to go.

    Deep within a mountain in Italy, scientists have finished the assembly of an experiment more than one decade in the making. The detector of CUORE, short for Cryogenic Underground Observatory for Rare Events, is ready to be cooled down to its operating temperature for the first time.

    Ettore Fiorini, the founder of the collaboration, proposed the use of low temperature detectors to search for rare events in 1984 and started creating the first prototypes with his group in Milano. What began as a personal project involving a tiny crystal and a small commercial cooler has grown to a collaboration of 165 scientists loading almost one ton of crystals and several tons of refrigerator and shields.

    The CUORE experiment is looking for a rare process that would be evidence that almost massless particles called neutrinos are their own antiparticles, something that would give scientists a clue as to how our universe came to be.

    Oliviero Cremonesi, current spokesperson of the CUORE collaboration, joined the quest in 1988 and helped write the first proposal for the experiment. At first, funding agencies in Italy and the United States approved a smaller version: Cuoricino.

    “We had five exciting years of measurements from 2003 to 2008 on this machine, but we knew that we wanted to go bigger. So we kept working on CUORE,” Cremonesi says.

    In 2005 the collaboration got approval for the big detector, which they called CUORE. That started them on a whole new journey involving growing crystals in China, bringing them to Italy by boat, and negotiating with archeologists for the right to use 2000-year-old Roman lead as shielding material.

    “I imagine climbing Mount Everest is a little bit like this,” says Lindley Winslow, a professor at the Massachusetts Institute of Technology and group leader of the MIT activities on CUORE. “We can already see the top, but this last part is the hardest. The excitement is high, but also the fear that something goes wrong.”

    The CUORE detector, assembled between 2012 and 2014, consists of 19 fragile copper towers that each host 52 tellurium oxide crystals connected by wires and sensors to measure their temperature.

    For this final stage, scientists built a custom refrigerator from extremely pure materials. They shielded and housed it inside of a mountain at Gran Sasso, Italy.

    Gran Sasso LABORATORI NAZIONALI del GRAN SASSO
    Gran Sasso LABORATORI NAZIONALI del GRAN SASSO, Italy

    At the end of July, scientists began moving the detector to its new home. After a brief pause to ensure the site had not been affected by the 6.2-magnitude earthquake that hit central Italy on August 24, they finished the job on August 26.

    The towers now reside in the largest refrigerator used for a scientific purpose. By the end of October, they will be cooled below 10 millikelvin (negative 460 Fahrenheit), colder than outer space.

    Everything has to be this cold because the scientists are searching for minuscule temperature changes caused by an ultra-rare process. It is predicted to occur only once every trillion trillion years and is called neutrinoless double beta decay.

    During a normal beta decay, one atom changes from one chemical element into its daughter element and sends out one electron and one antineutrino. For the neutrinoless double beta decay, this would be different: The element would change into its granddaughter. Instead of one electron and one neutrino sharing the energy of the decay, only two electrons would leave, and an observer would see no neutrinos at all.

    This would only happen if neutrinos were their own antiparticles. In that case, the two neutrinos would cancel each other out, and it would seem like they never existed in the first place.

    If scientists measure this decay, it would change the current scientific thinking about the neutrino and give scientists clues about why there is so much more matter than anti-matter in the universe.

    “We are excited to start the cool-down, and if everything works according to plan, we can start measuring at the beginning of next year,” Winslow says.

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 5:14 pm on October 23, 2014 Permalink | Reply
    Tags: , , , Grand Sasso National Laboratory   

    From Symmetry: “Australia’s first dark matter experiment” 

    Symmetry

    October 23, 2014
    Glenn Roberts Jr.

    Physicists are hoping to hit pay dirt with a proposed experiment—the first of its kind in the Southern Hemisphere—that would search for traces of dark matter more than a half mile below ground in Victoria, Australia.

    The current plan, now being explored by an international team, is for two new, identical dark matter experiments to be installed and operated in parallel—one at an underground site at Grand Sasso National Laboratory in Italy, and the other at the Stawell Gold Mine in Australia.

    team

    “An experiment of this significance could ultimately lead to the discovery of dark matter,” says Elisabetta Barberio of the ARC Centre of Excellence for Particle Physics at the Terascale (CoEPP) and the University of Melbourne, who is Australian project leader for the proposed experiment.

    The experiment proposal was discussed during a two-day workshop on dark matter in September. Work could begin on the project as soon as 2015 if it gathers enough support. “We’re looking at logistics and funding sources,” Barberio says.

    The experiments would be modeled after the DAMA experiment at Gran Sasso, now called DAMA/LIBRA, which in 1998 found a possible sign of dark matter.

    DAMA/LIBRA looks for seasonal modulation, an ebb and flow in the amount of potential dark matter signals it sees depending on the time of year.

    If the Milky Way is surrounded by a halo of dark matter particles, then the sun is constantly moving through it, as is the Earth. The Earth’s rotation around the sun causes the two to spend half of the year moving in the same direction and the other half moving in opposite directions. During the six months in which the Earth and sun are cooperating, a dark matter detector on the Earth will move faster through the dark matter particles, giving it more opportunities to catch them.

    This seasonal difference appears in the data from DAMA/LIBRA, but no other experiment has been able to confirm this as a sign of dark matter.

    For one thing, the changes in the signal could be caused on other factors that change by the season.

    “There are environmental effects—different characteristics of the atmosphere—in winter and summer that are clearly reversed if you go from the Northern to the Southern hemisphere,” says Antonio Masiero, vice president for the Italian National Institute of Nuclear Physics (INFN) and a member of the Italian delegation collaborating on the proposal, which also includes Gran Sasso Director Stefano Ragazzi. If the results matched up at both sites at the same time of year, that would help to rule out such effects.

    The Australian mine hosting the proposed experiment could also house scientific experiments from different fields.

    “It wouldn’t be limited to particle physics and could include experiments involving biology, geosciences and engineering,” Barberio says. “These could include neutrino detection, nuclear astrophysics, geothermal energy extraction and carbon sequestration, and subsurface imaging and sensing.”

    Preliminary testing has begun at the mine site down to depths of about 880 meters, about 200 meters above the proposed experimental site. Regular mining operations are scheduled to cease at Stawell in the next few years.

    The ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO), the local government in the Victoria area, and the mine operators have joined forces with COEPP and INFN to support the proposal.

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.


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