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  • richardmitnick 7:50 am on September 11, 2014 Permalink | Reply
    Tags: , , Optics technology   

    From LLNL: “New energy record set for multilayer-coated mirrors” 

    Lawrence Livermore National Laboratory

    Anne M Stark, LLNL, (925) 422-9799, stark8@llnl.gov

    Multilayer-coated mirrors, if used as focusing optics in the soft gamma-ray photon energy range, can enable and advance a range of scientific and technological applications that would benefit from the large improvements in sensitivity and resolution that true imaging provides.

    In a paper published in a recent online edition of Optics Express, LLNL postdoc Nicolai Brejnholt and colleagues from LLNL, the Technical University of Denmark and the European Synchrotron Radiation Facility demonstrate for the first time that very short-period multilayer coatings deposited on super-polished substrates operate efficiently as reflective optics above 0.6 MeV, nearly a factor of two higher than the previous record at 384 keV, set last year by this same group (Physical Review Letters 101 027404, 2013).

    Regina Soufli, Marie-Anne Descalle, postdoc Nicolai Brejnholt (shown in photo) and LLNL colleagues and collaborators recently demonstrated that very short-period multilayer coatings deposited on super-polished substrates operate efficiently as reflective optics.

    Multilayer mirrors can be used for two broad classes of applications. First, they can be used in spectroscopy, to enhance or suppress certain photon. energies. The team is looking into how to use multilayers to examine spent nuclear fuel for non-proliferation missions.

    Second, multilayer mirrors can be used as focusing, imaging optics by applying multilayer coatings to curved substrates. “We have previously made hard X-ray optics for nuclear medicine and astrophysics applications, and we can now consider adapting the same fabrication techniques to work in the soft gamma-ray band,” said Michael Pivovaroff, LLNL co-author.

    The field of astrophysics would benefit the most from gamma-ray focusing optics, including the sub-disciplines of galactic and extragalactic astronomy, solar astronomy, cosmic-ray research and potentially observational cosmology. Gamma-ray optics also have shown promise for nuclear medicine and nuclear non-proliferation applications.

    “We have demonstrated the capability to make highly reflective multilayer thin films with ultra-short period thickness (1-2 nanometers) and stable, ultra-smooth interfaces between the layers, as needed for operation at these extremely high photon energies. We chose tungsten carbide/silicon carbide (WC/SiC) multilayers for this purpose,” said Regina Soufli, another LLNL co-author.

    “The measurements at 0.65 MeV showed we had to understand sub-nanometer variations across the 36-square-inch mirror to model the measured performance,” Brejnholt said.

    The team demonstrated that multilayer mirrors in the gamma-ray band operate efficiently and according to well-understood models. The team combined classical, wave interference models with a Monte-Carlo particle simulation code. The latter was used to account for incoherent scattering, a phenomenon that is negligible at lower photon energies but becomes significant in the soft gamma ray range. Incoherent scattering was observed and modeled on multilayer structures for the first time by the LLNL team.

    Other Livermore co-authors include Marie-Anne Descalle, principal investigator of the Laboratory Directed Research and Development (LDRD) project that funded this effort, Mónica Fernández-Perea, Jennifer Alameda, Tom McCarville and Sherry Baker.

    See the full article here.

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  • richardmitnick 5:54 pm on December 6, 2012 Permalink | Reply
    Tags: , , , , Optics technology, ,   

    From Brookhaven: “Growing Cutting-edge X-ray Optics” 

    Brookhaven Lab

    Scientists use a custom-designed machine and a reprogrammed Xbox controller to create atomically precise lenses

    December 6, 2012
    Justin Eure

    Unleashing some of the most promising energy technologies of tomorrow—from electric vehicle fuel cells to photovoltaics—hinges upon understanding tiny structures spanning just billionths of a meter. One way to explore this critical nanoscale world is by sending high-intensity x-ray beams through materials, similar to the way doctors capture images of internal bone structure using large x-ray devices. The challenge with fringe physics, however, is that focusing that penetrating power on just a single nanometer takes an entirely different caliber of lens.…”

    See how it is done-

    Is that cool, or what?

    “Using a massive, custom-built deposition device, Brookhaven Lab scientist Ray Conley and his team are able to grow special lenses one atomic layer at a time. As intense x-rays pass through these multilayer Laue lenses (MLL), the light diffracts and bends toward a single point. Creating these atomically precise optics is no small feat, and Conley continues to tweak the process of growing light-bending films and carving them into precise lenses.”

    See the full article here.

    The completed MLLs will be deployed on beamlines at Brookhaven Lab’s forthcoming National Synchrotron Light Source II, one of the world’s most advanced light sources, to reveal unparalleled details of nanomaterial structures.

    Brookhaven’s current light source — the National Synchrotron Light Source (NSLS) — is one of the world’s most widely used scientific facilities. Each year, 2,200 researchers from 400 universities, government laboratories, and companies use its bright beams of x-rays, ultraviolet light, and infrared light for research in such fields as biology, medicine, chemistry, environmental sciences, physics, and materials science. The scientific productivity of the NSLS user community is very high and has widespread impact, with more than 900 publications per year, many in premier scientific journals.

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

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