Alex Drlica-Wagner. Photo: Reidar Hahn, FermilabDiscovering dwarf galaxies, one sticky at a time

For Alex Drlica-Wagner, the most exciting day since joining DOE’s Fermi National Accelerator Laboratory as a postdoctoral fellow occurred earlier this year:  He and his collaborators on the Dark Energy Survey found new dwarf galaxy candidates, which could hold the key to understanding the invisible matter in our universe known as dark matter.

“Discovering things is the most exciting part of the job,” he says, “but it happens only once in a blue moon.”

Drlica-Wagner came to Fermilab in 2013, after doing research as a Stanford University graduate student at DOE’s SLAC National Accelerator Laboratory.

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LUX-ZEPLIN, a next-generation dark matter experiment, will search for signs of WIMPs – weakly interacting massive particles. It will be a few hundred times more sensitive than the current LUX experiment. (SLAC National Accelerator Laboratory)SLAC gears up for dark matter hunt with LUX-ZEPLIN

Researchers have come a step closer to building one of the world’s best dark matter detectors: DOE recently signed off on the conceptual design of the proposed LUX-ZEPLIN (LZ) experiment and gave the green light for the procurement of some of its components. DOE’s SLAC National Accelerator Laboratory, a key member of the LZ collaboration, is setting up a test stand for the detector prototype and a facility to purify liquid xenon, which will be the detector’s “eye” for dark matter.

If everything goes according to plan, LZ will be installed one mile underground in a cavern of the former Homestake gold mine in South Dakota. It promises to become the most sensitive tool for the direct detection of WIMPs – weakly interacting massive particles – that many researchers believe to be the fundamental components of dark matter. LZ will replace LUX, a dark matter experiment that holds the current record for looking for WIMPs of most possible masses.

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See also…

DOE Pulse
  • Number 443  |
  • July 13, 2015
  • X-Rays and electrons map catalytic reactions in real time

    Illustration of the micro-reactor showing the complementary imaging areas of the electron beams (blue) and x-rays (green), which combine to reveal a full portrait of the real-time reaction A new technique pioneered at Brookhaven Lab that combines electron microscopy and synchrotron x-rays reveals atomic-scale changes during catalytic reactions in real time and under real operating conditions. The work makes use of a newly developed micro-reactor the size of a mosquito to combine x-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM) at Brookhaven’s National Synchrotron Light Source (NSLS) and Center for Functional Nanomaterials (CFN), respectively. The results demonstrate a powerful operando technique—from the Latin for "in working condition"—that may revolutionize research on catalysts, batteries, fuel cells, and other major energy technologies.

    "We tracked the dynamic transformations of a working catalyst, including single atoms and larger structures, during an active reaction at room temperature," said CFN scientist Eric Stach. "This gives us unparalleled insight into nanoparticle structure and would be impossible to achieve without combining two complementary operando techniques."

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  • New findings to help predict risk and outcomes of anthrax attacks

    PNNL microbiologist Josh Powell looks at anthrax spores, which have developed into bacteria over the course of 12 hours. At low doses, researchers found growth of spores is lower in human lung cells than rabbits. Cultured human lung cells infected with a benign version of anthrax spores have yielded insights into how anthrax grows and spreads in exposed people. The study, published in the Journal of Applied Microbiology, will help provide credible data for human health related to anthrax exposure and help officials better understand risks related to a potential anthrax attack.

    The study also defined for the first time where the spores germinate and shows that the type of cell lines and methods of culturing affect the growth rates.

    "What we're learning will help inform the National Biological Threat Risk Assessment — a computer tool being developed by the Department of Homeland Security," said Tim Straub, a chemical and biological scientist at DOE's Pacific Northwest National Laboratory. "There is little data to estimate or predict the average number of spores needed to infect someone. By better understanding exposure thresholds, the ultimate goal is to be able to predict outcomes from terrorist incidents involving Bacillus anthracis."

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  • PPPL scientists propose  enhanced density limit  model

    Magnetic island geometry showing the asymmetry effect that is crucial in determining the mechanism for the density limit.  Reprinted with permission from Phys. Plasmas 22, 022514 (2015). Copyright 2015 AIP Publishing LLC. – David Gates. Researchers at DOE’s Princeton Plasma Physics Laboratory (PPPL) have developed a detailed model of the source of a puzzling limitation on fusion reactions. The findings, published in in Physics of Plasmas, complete and confirm previous PPPL research and could lead to steps to overcome the barrier if the model proves consistent with experimental data. “We used to have correlation,” said physicist David Gates, first author of the paper. “Now we believe we have causation.”

    At issue is a problem known as the “density limit” that keeps donut-shaped fusion facilities called tokamaks from operating at peak efficiency. This limit occurs when the superhot, charged plasma gas that fuels fusion reactions reaches a certain density and spirals apart in a flash of light, shutting down the reaction. Overcoming the limit could facilitate the development of fusion as a safe, clean and abundant source of energy for generating electricity.

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  • Sandia’s Z machine helps solve Saturn’s 2-billion-year age gap

    Results from Sandia National Laboratories’ Z machine provides hard data for an 85-year-old theory that could correct mistaken estimates of the planet Saturn’s age. (Image courtesy of NASA/JPL/Space Science Institute) Planets tend to cool as they get older, but Saturn is hotter than astrophysicists say it should be without some additional energy source.

    The unexplained heat has caused a two-billion-year discrepancy for computer models estimating Saturn’s age. “Models that correctly predict Jupiter to be 4.5 billion years old find Saturn to be only 2.5 billion years old,” says Thomas Mattsson, manager of the high-energy-density physics theory group at DOE's Sandia National Laboratories.

    Experiments at Sandia’s Z machine may help solve that problem when they verified an 80-year-old untested proposition that molecular hydrogen, normally an insulator, becomes metallic if squeezed by enough pressure. At that point, a lattice of hydrogen molecules would break up into individual hydrogen atoms, releasing free-floating electrons that could carry a current, physicists Eugene Wigner and Hilliard Huntington predicted in 1935.

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