189 research outputs found
Structure analysis of two-dimensional nonlinear self-trapped photonic lattices in anisotropic photorefractive media
We generate experimentally different types of two-dimensional self-trapped
photonic lattices in a photorefractive medium and analyze the induced
refractive index change using two different methods. One method gives the first
experimental Fourier space analysis of both linear and nonlinear self-trapped
photonic lattices with periodic phase modulation using partially spatially
incoherent multi-band excitation of the lattice modes. The other method
utilizes the waveguiding properties of the lattice to achieve a real space
analysis of the induced refractive index change. The results of both methods
are compared.Comment: 4 pages, 3 figure
Nonlinear photonic lattices in anisotropic nonlocal self-focusing media
We analyze theoretically and generate experimentally two-dimensional
nonlinear periodic lattices in a photorefractive medium. We demonstrate that
the light-induced periodically modulated nonlinear refractive index is highly
anisotropic and nonlocal, and it depends on the lattice orientation relative to
the crystal axis. We discuss stability of such induced photonic structures and
their guiding properties.Comment: 3 pages, 3 figure
Reduced-symmetry two-dimensional solitons in photonic lattices
We demonstrate theoretically and experimentally a novel type of localized
beams supported by the combined effects of total internal and Bragg reflection
in nonlinear two-dimensional square periodic structures. Such localized states
exhibit strong anisotropy in their mobility properties, being highly mobile in
one direction and trapped in the other, making them promising candidates for
optical routing in nonlinear lattices.Comment: 5 pages, 4 figure
Fabrication and characterization of efficiency and radiation tolerance of 3D diamond detectors
Increased Sensitivity to Possible Muonium to Antimuonium Conversion
A new experimental search for muonium-antimuonium conversion was conducted at
the Paul Scherrer Institute, Villigen, Switzerland. The preliminary analysis
yielded one event fulfilling all required criteria at an expected background of
1.7(2) events due to accidental coincidences. An upper limit for the conversion
probability in 0.1 T magnetic field is extracted as (90%
CL).Comment: 2 figure
Approaching the Gamow Window with Stored Ions : Direct Measurement of Xe 124 (p,γ) in the ESR Storage Ring
© 2019 American Physical Society. All rights reserved.We report the first measurement of low-energy proton-capture cross sections of Xe124 in a heavy-ion storage ring. Xe12454+ ions of five different beam energies between 5.5 and 8 AMeV were stored to collide with a windowless hydrogen target. The Cs125 reaction products were directly detected. The interaction energies are located on the high energy tail of the Gamow window for hot, explosive scenarios such as supernovae and x-ray binaries. The results serve as an important test of predicted astrophysical reaction rates in this mass range. Good agreement in the prediction of the astrophysically important proton width at low energy is found, with only a 30% difference between measurement and theory. Larger deviations are found above the neutron emission threshold, where also neutron and γ widths significantly impact the cross sections. The newly established experimental method is a very powerful tool to investigate nuclear reactions on rare ion beams at low center-of-mass energies.Peer reviewedFinal Published versio
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