239 research outputs found

    The observation of long-range three-body Coloumb effects in the decay of 16Ne

    Get PDF
    The interaction of an E/AE/A=57.6-MeV 17^{17}Ne beam with a Be target was used to populate levels in 16^{16}Ne following neutron knockout reactions. The decay of 16^{16}Ne states into the three-body 14^{14}O+pp+pp continuum was observed in the High Resolution Array (HiRA). For the first time for a 2p emitter, correlations between the momenta of the three decay products were measured with sufficient resolution and statistics to allow for an unambiguous demonstration of their dependence on the long-range nature of the Coulomb interaction. Contrary to previous experiments, the intrinsic decay width of the 16^{16}Ne ground state was found to be narrow (Γ<60\Gamma<60~keV), consistent with theoretical estimates.Comment: 6 pages, 5 figure

    Observation of the gradual transition from one-dimensional to two-dimensional Anderson localization

    Full text link
    We study the gradual transition from one-dimensional to two-dimensional Anderson localization upon transformation of the dimensionality of disordered waveguide arrays. An effective transition from one- to two-dimensional system is achieved by increasing the number of rows forming the arrays. We observe that, for a given disorder level, Anderson localization becomes weaker with increasing number of rows, hence the effective dimension.Comment: 4 pages, 3 figures, to appear in Optics Letter

    Ground-state properties of H 5 from the He 6 (d, He 3) H 5 reaction

    Get PDF
    We have studied the ground state of the unbound, very neutron-rich isotope of hydrogen H5, using the He6(d,He3)H5 reaction in inverse kinematics at a bombarding energy of E(He6)=55A MeV. The present results suggest a ground-state resonance energy ER=2.4±0.3 MeV above the H3+2n threshold, with an intrinsic width of Γ=5.3±0.4 MeV in the H5 system. Both the resonance energy and width are higher than those reported in some, but not all previous studies of H5. The previously unreported He6(d,t)Heg.s.5 reaction is observed in the same measurement, providing a check on the understanding of the response of the apparatus. The data are compared to expectations from direct two-neutron and dineutron decay. The possibility of excited states of H5 populated in this reaction is discussed using different calculations of the He6→H5+p spectroscopic overlaps from shell-model and ab initio nuclear-structure calculations

    Chemical Fabrication Used to Produce Thin-Film Materials for High Power-to- Weight-Ratio Space Photovoltaic Arrays

    Get PDF
    The key to achieving high specific power (watts per kilogram) space solar arrays is the development of a high-efficiency, thin-film solar cell that can be fabricated directly on a flexible, lightweight, space-qualified durable substrate such as Kapton (DuPont) or other polyimide or suitable polymer film. Cell efficiencies approaching 20 percent at AM0 (air mass zero) are required. Current thin-film cell fabrication approaches are limited by either (1) the ultimate efficiency that can be achieved with the device material and structure or (2) the requirement for high-temperature deposition processes that are incompatible with all presently known flexible polyimide or other polymer substrate materials. Cell fabrication processes must be developed that will produce high-efficiency cells at temperatures below 400 degrees Celsius, and preferably below 300 degress Celsius to minimize the problems associated with the difference between the coefficients of thermal expansion of the substrate and thin-film solar cell and/or the decomposition of the substrate

    One-Dimensional Nanostructures and Devices of II–V Group Semiconductors

    Get PDF
    The II–V group semiconductors, with narrow band gaps, are important materials with many applications in infrared detectors, lasers, solar cells, ultrasonic multipliers, and Hall generators. Since the first report on trumpet-like Zn3P2nanowires, one-dimensional (1-D) nanostructures of II–V group semiconductors have attracted great research attention recently because these special 1-D nanostructures may find applications in fabricating new electronic and optoelectronic nanoscale devices. This article covers the 1-D II–V semiconducting nanostructures that have been synthesized till now, focusing on nanotubes, nanowires, nanobelts, and special nanostructures like heterostructured nanowires. Novel electronic and optoelectronic devices built on 1-D II–V semiconducting nanostructures will also be discussed, which include metal–insulator-semiconductor field-effect transistors, metal-semiconductor field-effect transistors, andp–nheterojunction photodiode. We intent to provide the readers a brief account of these exciting research activities

    Nanotechnology and the Treatment of HIV Infection

    Get PDF
    Suboptimal adherence, toxicity, drug resistance and viral reservoirs make the lifelong treatment of HIV infection challenging. The emerging field of nanotechnology may play an important role in addressing these challenges by creating drugs that possess pharmacological advantages arising out of unique phenomena that occur at the “nano” scale. At these dimensions, particles have physicochemical properties that are distinct from those of bulk materials or single molecules or atoms. In this review, basic concepts and terms in nanotechnology are defined, and examples are provided of how nanopharmaceuticals such as nanocrystals, nanocapsules, nanoparticles, solid lipid nanoparticles, nanocarriers, micelles, liposomes and dendrimers have been investigated as potential anti-HIV therapies. Such drugs may, for example, be used to optimize the pharmacological characteristics of known antiretrovirals, deliver anti-HIV nucleic acids into infected cells or achieve targeted delivery of antivirals to the immune system, brain or latent reservoirs. Also, nanopharmaceuticals themselves may possess anti-HIV activity. However several hurdles remain, including toxicity, unwanted biological interactions and the difficulty and cost of large-scale synthesis of nanopharmaceuticals
    corecore