A5057861923- Astronomy and Astrophysical Research
- Astro and Planetary Science
- History and Developments in Astronomy
- Stellar, planetary, and galactic studies
- Space Science and Extraterrestrial Life
- Relativity and Gravitational Theory
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Planetary Science and Exploration
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Historical Astronomy and Related Studies
- Astrophysics and Star Formation Studies
- Astrophysics and Cosmic Phenomena
- Space exploration and regulation
- Geophysics and Gravity Measurements
- Space Exploration and Technology
- Historical and Architectural Studies
- Experimental and Theoretical Physics Studies
- Galaxies: Formation, Evolution, Phenomena
- Dark Matter and Cosmic Phenomena
- Advanced Fiber Laser Technologies
Technical University of Darmstadt
2017-2018
American Astronomical Society
2017-2018
Center for Astrophysics Harvard & Smithsonian
2017
Northwestern University
2017
Université de Haute-Alsace
2017
National Institute of Standards and Technology
2012-2015
University of Colorado Boulder
2012-2014
Hella (Germany)
2012
University of Rostock
2012
University of Göttingen
2012
We demonstrate a significant simplification of the scheme for few-cycle Optical Parametric Chirped Pulse Amplification (OPCPA) which results in elimination picosecond's master oscillator and electronic synchronization loops. A fraction broadband seed pulse centered at 760 nm from 70-MHz Ti:sapphire was frequency-shifted photonic crystal fiber to enable synchronized seeding Nd:YAG pump laser. The radiation 1064 is produced soliton regime makes it inherently more intense stable comparison with...
We demonstrate direct simultaneous seeding of a few-cycle optical parametric chirped pulse amplifier (OPCPA) in the 700-1000-nm spectral range, and Nd:YLF emitting 30-ps pulses at 1053 nm by use chirped-mirror 6-fs Ti:sapphire oscillator. This approach employing single master oscillator to drive two power amplifiers simplifies pump laser design is applied eliminate timing jitter between seed OPCPA chain. show that 10 mJ fundamental picosecond with intensity contrast excess 10/sup 4/ relative...
Photonic-crystal fibers are employed to demonstrate widely tunable frequency down-conversion of unamplified 6-fs Ti:sapphire laser pulses through the soliton self-frequency shift induced by Raman effect. Wavelength shifts as large 500 nm achieved for input few-cycle with broadband spectra centered at approximately 820 nm. The central wavelength redshifted output a photonic-crystal fiber is smoothly tuned from low-frequency edge in spectrum pulse up 1.35 microm varying energy fundamental mode fiber.
We study the collimation of relativistic hydrodynamic jets by pressure an ambient medium in limit where jet interior has lost causal contact with its surroundings. For a ultrarelativistic equation state and external that decreases as power spherical radius, p ∝ r−η, will lose when η > 2. However, outer layers gradually collimate towards axis long < 4, leading to formation shocked boundary layer. Assuming matching across shock front determines shape shock, we resulting structure two ways:...
Photonic-crystal fibers with special dispersion profiles are shown to provide a high efficiency of spectral transformation chirped sub-$6\text{\penalty1000-\hskip0pt}\mathrm{fs}$ Ti:sapphire laser pulses. With the wavelength zero group-velocity fiber lying within broad spectrum input few-cycle pulse, output spectra feature well-resolved peaks, indicative soliton self-frequency shift, four-wave mixing, and Cherenkov emission dispersive waves. We demonstrate that up 3% radiation energy at can...
—The sea cucumber fishery is important in several countries of the Western Indian Ocean (WIO) but generally not adequately managed. A regional MASMA programme (Marine Science for Management) granted by WIOMSA (Western Marine Sciences Association) providing data on reproduction some commercial species. In La Réunion, two target species are Actinopyga echinites and Holothuria leucospilota. These cucumbers very abundant fringing reefs were sampled monthly during 2005-2006. Data population...
Resonance ionization mass spectrometry (RIMS) is a highly selective and sensitive method for trace analysis of radiotoxic elements in environmental, biological or technical samples. By multiple resonant laser excitation the element under investigation, an extremely high selectivity achieved. Additionally, isotope obtained by subsequent magnetic, time-of-flight quadrupole spectrometer which serves efficient background suppression as well. High sensitivity results from large optical cross...
In the light of global change, necessity to monitor atmospheric depositions that have relevant effects on ecosystems is ever increasing particularly for tropical sites. For this study, ionic were measured Central Sulawesi at remote sites with both a conventional bulk water collector system (BWS collector) and passive ion exchange resin (IER collector). The principle IER fix all depositions, i.e. anions cations, has certain advantages referring (1) post-deposition transformation processes,...
For ultratrace analysis of actinide Clements and studies their atomic propcrties with resonance ionization mass spectroscopy (RIMS), efficient stable sources beams are required.The thermodynamics idnetics the evaporation elements oxides from a variety metals were considered, including diffusion, desorption, associative desorption.On this basis various sandwich-type filaments studied.The most promising system was found to consist tantalum as backing material, an electrolytically deposited...
The balance between diffraction and index-step guiding in photonic-crystal fibers is controlled by modifying the fiber structure, leading to different wavelength dependences of effective mode area ${S}_{\mathrm{eff}}(\ensuremath{\lambda})$ providing a mechanism control nonlinear-optical phenomena. In optical with steep profile, guided light field tends become much less compact an increase radiation wavelength, slowing down Raman-induced soliton self-frequency shift ultrashort laser pulse. A...
We study the collimation of relativistic magnetohydrodynamic jets by pressure an ambient medium, in limit where jet interior loses causal contact with its surroundings. This follows up a hydrodynamic previous paper, adding effects toroidal magnetic field threading jet. As ultrarelativistic encounters medium profile radial scaling p ∝ r−η 2 < η 4, it surroundings and forms boundary layer large gradient. By constructing self-similar solutions to fluid equations within this layer, we examine...
We investigate the spectral properties of brightest gamma-ray flares blazars detected by Fermi Large Area Telescope. search for presence breaks and measure curvature on typical time-scales a few days. identify significant in fewer than half analysed flares, but their parameters do not show any discernible regularities, particular there is no indication absorption at fixed source-frame photon energy. More interestingly, we find that studied are characterized variability. Gamma-ray short...
Hot relativistic jets, passing through a background medium with pressure gradient p ∝ r−η where 2 < η ≤ 8/3, develop shocked boundary layer containing significant fraction of the jet power. In previous work, we developed self-similar description assuming isentropic flow, but found that such models respect global energy conservation only for special case = 8/3. Here, demonstrate 8/3 can be made self-consistent if relax assumption constant specific entropy. Instead, entropy must increase...
This paper describes research on forward and backward light reflection of road surfaces for typical vehicle-related illumination observation conditions. The aim is to improve luminance simulation in order include quality criteria headlamp distributions that correspond visual perception under night driving Measurements were performed full scale conditions instead the usual laboratory tests. Traffic safety requires tests dry wet experimental data can be described by coefficient-based models....
Because undergraduate participation in research is a longstanding and increasingly important aspect of the career path for future scientists, students can benefit from additional resources to introduce them culture process research. We suggest adoption web resource Astrobites as classroom tool increase preparation physics astronomy careers describe content development website, discuss previous university courses that have made use Astrobites, strategies using classroom.
A primary goal of many undergraduate- and graduate-level courses in the physical sciences is to prepare students engage scientific research, or for careers that leverage skillsets similar those used by research scientists. Even who may not intend pursue a career with these characteristics, exposure context applications modern can be valuable tool teaching learning. However, persistent barrier student participation familiarity technical language, format, academic researchers use communicate...
We suggest and experimentally verify a simple method for timing-jitter-free synchronization of the seed pump pulses in an optical parametric chirped-pulse amplifier. A fraction broadband pulse centered at 800 nm was frequency-shifted photonic crystal fiber to enable synchronized seeding picosecond Nd:YAG laser.