Abstract We reveal that strongly enhanced generation of photon pairs with narrow frequency spectra and sharp angular correlations can be realised through spontaneous parametric down-conversion in metasurfaces. This is facilitated by creating meta-gratings nano-structuring nonlinear films sub-wavelength thickness to support the extended bound state continuum resonances, associated ultra-high Q -...

introduction spect projections are contaminated by scatter radiation, resulting in reduced image contrast and quantitative errors. backscatter constitutes a major part of the scatter contamination in lower energy windows. the current study is an evaluation of the effect of backscatter material on fwhm and image quality investigated by monte carlo simulation. materials and methods simind program...

This presentation summarizes the results on ultra-peripheral collisions obtained at RHIC. It also discusses some aspects of the corresponding electromagnetic interactions in pp and pp collisions. Ultra-peripheral nucleus-nucleus collisions are defined as collisions in which the distance between the nuclei is large enough that no purely hadronic interactions can occur. This roughly means impact ...

Following our successful analysis of VLBI observations of the 2Π 3 2 , J = 2 , F = 3− 3 and F = 2− 2 excited OH emission at 6035 and 6031 MHz in W3(OH), we have analyzed the same transitions in three other ultra-compact HII regions, M17, ON1, and W51. The restoring beams were in the range 6 to 30 milliarc sec. The F = 3−3 and 2−2 hyperfine transitions of OH were both mapped in ON1. Seven 6035 M...

Abstract The continuously increasing interest in flexible and integrated photonics requires new strategies for device manufacturing on arbitrary complex surfaces with smallest possible size, respectively. Terahertz (THz) technology can particularly benefit from this achievement to make compact systems emission, detection on-demand manipulation of THz radiation. Here, we present a novel fabricat...

The magnetospheres of neutron stars provide a valuable testing ground for as-yet unverified theoretical predictions of quantum electrodynamics (QED) in strong electromagnetic fields. Exhibiting magnetic field strengths well in excess of a TeraGauss, such compact astrophysical environments permit the action of exotic mechanisms that are forbidden by symmetries in field-free regions. Foremost amo...

I present ASCA observations of IRAS00317-2142, the most luminous (Lx ∼ 10 43 erg s0.1-2 keV) of the ’composite’ class of galaxies. This enigmatic class of objects presents narrow-emission line optical spectra classifying these galaxies as star-forming on the basis of the diagnostic emission line ratios; yet, the presence of weak Hα broad wings also suggests the presence of a weak or obscured AG...

We report evidence of photon emission in three experiments with hydrogen loading of Ni slabs, during the degassing phase, when hydrogen was introduced into the cell, and during thermal cycling. In the first experiment we obtained excess power of about 20 W, while in the second experiment photon emission was observed instead of power production. In the third experiment, a Ni sample in hydrogen u...

We present Chandra observations of nine high-redshift quasars (z = 2.7−5.9) discovered by the Sloan Digital Sky Survey with weak or undetectable high-ionization emission lines in their UV spectra (WLQs). Adding archival X-ray observations of six additional sources of this class has enabled us to place the strongest constraints yet on the X-ray properties of this remarkable class of AGNs. Althou...

Photonic crystal nanocavities, which have modal volumes of the order of a cubic wavelength in the material, are of great interest as flexible platforms for manipulating photons. Recent developments in ultra-high quality factor nanocavities with long photon lifetimes have encouraged us to develop an ultra-compact and flexible photon manipulation technology where photons are trapped in networks o...