Search results for "Ultra"
showing 10 items of 4451 documents
Design of All-Normal Dispersion Microstructured Optical Fiber on Silica Platform for Generation of Pulse-Preserving Supercontinuum Under Excitation a…
2017
We investigated numerically the possibility of all normal dispersion fiber design for near-infrared supercontinuum generation based on a standard air-silica microstructure. The design procedure includes finding of target dispersion profile and subsequent finding of appropriate geometrical fiber design by inverse dispersion engineering. It was shown that the tailoring of dispersion profile could increase the spectral width of generated supercontinuum while maintaining perfect spectral flatness. Conditions necessary for wide and flat supercontinuum generation as well as restrictions imposed by chosen materials were discussed. As a result of design and optimization procedure, an air-silica des…
Spatial quantum noise interferometry in expanding ultracold atom clouds
2005
It is ten years since the exotic form of matter known as a Bose–Einstein condensate was first created. It was the birth of ultra-low-temperature physics, and practitioners gathered last month in Banff, Canada, to celebrate and discuss the latest news, as Karen Fox reports. And this week a new development that could have a major impact in the field is announced. In the 1950s, Hanbury Brown and Twiss showed that it is possible to measure angular sizes of astronomical radio sources from correlations of signal intensities in independent detectors. ‘HBT interferometry’ later became a key technique in quantum optics, and now it has been harnessed to identify a quantum phase of ultracold bosonic a…
Performance of a high repetition pulse rate laser system for in-gas-jet laser ionization studies with the Leuven laser ion source @ LISOL
2012
The Leuven Isotope Separator On-Line (LISOL) facility at the Cyclotron Research Center (CRC) Louvain-la-Neuve; The laser ionization efficiency of the Leuven gas cell-based laser ion source was investigated under on- and off-line conditions using two distinctly different laser setups: a low-repetition rate dye laser system and a high-repetition rate Ti:sapphire laser system. A systematic study of the ion signal dependence on repetition rate and laser pulse energy was performed in off-line tests using stable cobalt and copper isotopes. These studies also included in-gas-jet laser spectroscopy measurements on the hyperfine structure of 63Cu. A final run under on-line conditions in which the ra…
The squeezer ion guide
1992
Abstract The properties of an ordinary ion guide can be improved by inserting a grid between the nozzle and the skimmer. When positive ions are transported, an electric potential lower than +10 V is connected to the grid and one of the order of − 10 V to the skimmer. Efficient focusing is achieved between the nozzle and the grid by a combined action of the viscous helium flow field and the weak electric field. The focusing device is called a “squeezer”. It can be extended by adding more grids, a second skimmer, and differential pumping. Contrary to the first grid, the additional elements act more or less like electrostatic lenses in medium vacuum. With the squeezer ion guide, ions created i…
Ultra Trace Determination Scheme for26Al by High-Resolution Resonance Ionization Mass Spectrometry using a Pulsed Ti:Sapphire Laser
2008
We propose an ultra trace analysis approach for 26Al by high-resolution Resonance Ionization Mass Spectrometry (RIMS) using a pulsed narrow band-width Ti:Sapphire laser. For ensuring efficient ionization and high isotopic selectivity in RIMS of Al, we developed an injection seeded pulsed Ti:Sapphire laser with high repetition rate operation at up to 10 kHz. The laser produced an output power of 2 W and a spectral band-width of ~20 MHz with a repetition rate of 7 kHz. A first demonstration of its performance was done by detecting stable 27Al using RIMS.
Lateral distribution of muons in IceCube cosmic ray events
2013
In cosmic ray air showers, the muon lateral separation from the center of the shower is a measure of the transverse momentum that the muon parent acquired in the cosmic ray interaction. IceCube has observed cosmic ray interactions that produce muons laterally separated by up to 400 m from the shower core, a factor of 6 larger distance than previous measurements. These muons originate in high pT (>2 GeV/c) interactions from the incident cosmic ray, or high-energy secondary interactions. The separation distribution shows a transition to a power law at large values, indicating the presence of a hard pT component that can be described by perturbative quantum chromodynamics. However, the ra…
Ultrafast Dynamics of Magnetic Domain Structures Probed by Coherent Free-Electron Laser Light
2013
Synchrotron radiation news 26(6), 27 - 32 (2013). doi:10.1080/08940886.2013.850384
MeV ion beam lithography of biocompatible halogenated Parylenes using aperture masks
2015
Parylenes are poly(p-xylylene) polymers that are widely used as moisture barriers and in biomedicine because of their good biocompatibility. We have investigated MeV ion beam lithography using 16O+ ions for writing defined patterns in Parylene-C, which is evaluated as a coating material for the Cochlear Implant (CI) electrode array, a neuroprosthesis to treat some forms of deafness. Parylene-C and -F on silicon and glass substrates as well as 50 μm thick PTFE were irradiated to different fluences (1×1013-1×10161×1013-1×1016 1 MeV 16O+ ions cm−2) through aperture masks under high vacuum and a low pressure (<10−3 mbar) oxygen atmosphere. Biocompatibility of the irradiated and unirradiated …
Theoretical and experimental study of primary radiation defects in KNbO3 perovskite crystals
2000
Abstract The results of large-scale computer simulations of point defects – F-type electron centers and hole polarons bound to a potassium vacancy – in perovskite KNbO3 crystals are presented. One-site polarons and two-site (molecular) polarons are expected to coexist, both are characterized by close absorption energies around 1 eV. The transient absorption spectra and decay kinetics observed after ns-pulsed electron beam irradiation have been measured for different KNbO3 crystals. The relaxation kinetics of the optical density vary considerably for different impurity concentrations and sample stoichiometries. Experimental data are discussed in the light of the presented calculations.
Laser spectroscopy and β-decay asymmetry from on-line implanted nuclei
1985
The method of collinear laser spectroscopy is combined with s-radiation detected optical pumping by implanting the optically oriented atoms into a cubic crystal.