1,430 research outputs found
Charting the TeV Milky Way: H.E.S.S. Galactic plane survey maps, catalog and source populations
Very-high-energy (VHE, E>100 GeV) gamma-rays provide a unique view of the
non-thermal universe, tracing the most violent and energetic phenomena at work
inside our Galaxy and beyond. The latest results of the H.E.S.S. Galactic Plane
Survey (HGPS) undertaken by the High Energy Stereoscopic System (H.E.S.S.), an
array of four imaging atmospheric Cherenkov telescopes located in Namibia, are
described here. The HGPS aims at the detection of cosmic accelerators with
environments suitable for the production of photons at the highest energies and
has led to the discovery of an unexpectedly large and diverse population of
over 60 sources of TeV gamma rays within its current range of l = 250 to 65
degrees in longitude and |b|<3.5 degrees in latitude. The data set of the HGPS
comprises 2800 hours of high-quality data, taken in the years 2004 to 2013. The
sensitivity for the detection of point-like sources, assuming a power-law
spectrum with a spectral index of 2.3 at a statistical significance of 5 sigma,
is now at the level of 2% Crab or better in the core HGPS region. The latest
maps of the inner Galaxy at TeV energies are shown alongside an introduction to
the first H.E.S.S. Galactic Plane Survey catalog. Finally, in addition to an
overview of the H.E.S.S. Galactic source population a few remarkable, recently
discovered sources will be highlighted.Comment: 8 pages, 6 figures, in Proceedings of the 48th Rencontres de Moriond
(2013), La Thuile (Italy
Bottle Fillers for the Natural Sciences Building
Proposed by Melissa Gast-Goodman, Administrative Coordinator, ICPS and Dr. Daniel Gleason, Director, ICPS. ($3,495.16
Application of a magnetic suspension balance to the oxidation study of the zirconium based alloys under high pressurewater vapour
International audienceThe fuel claddings in the Pressurised Water Reactor are corroded in water at high temperature and high pressure. The technical device ableto follow continuously the corrosion rate in conditions close to this medium does not yet exist. That is the reason why a high pressure thermogravimetric installation based on magnetic suspension has been designed to study in situ the oxidation kinetics of the zirconium based alloys under water vapour until 50 bars of pressure at 415°C. The accuracy of measurements is about 5•10–5 g under 2 bars, and 10–4 g under 50 bars. The reproducibility of measurements was verified and the deviation regarding post test weighing at room temperature is around 5•10–5 g what is clearly satisfying. Finally, the results presented in this work allow validating the high pressure thermogravimetric measurements obtained with this magnetic suspension device
Very-high-energy gamma radiation from supernova remnants as seen with H.E.S.S
Very-high-energy (VHE, E > 100 GeV) gamma radiation has already been detected
from several supernova remnants (SNRs). These objects, which are well-studied
in radio, optical and X-ray wavelengths, constitute one of the most intriguing
source classes in VHE astronomy. H.E.S.S., an array of four imaging atmospheric
Cherenkov telescopes in Namibia, has recorded an extensive dataset of VHE
gamma-ray observations covering the central region of the Milky Way, both from
pointed observations as well as from the Galactic Plane Survey conducted in the
inner region of the Galaxy. From radio observations, several hundred SNRs are
known in the Milky Way, but until now only few of them have been identified as
VHE gamma-ray emitters. Using the H.E.S.S. dataset and a large ensemble of
radio SNRs localized in the inner region of the Galaxy, the standard framework
that links the origin of cosmic rays to the gamma-ray visibility of SNRs can
now be tested. Here we present the ensemble of investigated SNRs and discuss
constraints on the parameter space used within a theoretical model of hadronic
VHE gamma-ray production.Comment: Proceeding of the 32nd ICRC, August 11-18 2011, Beijing, Chin
Rapid freeze-quench EPR spectroscopy: improved collection of frozen particles
Biological and Soft Matter Physic
Brief comments on Jackiw-Teitelboim gravity coupled to Liouville theory
Jackiw-Teitelboim gravity with non-vanishing cosmological constant coupled to
Liouville theory is considered as a non-critical string on dimensional flat
spacetime. It is discussed how the presence of cosmological constant yields
additional constraints on the parameter space of the theory, even when the
conformal anomaly is independent of the cosmological constant. Such constraints
agree with the necessary conditions for the tachyon field to be a primary
--prelogarithmic-- operator of the worldsheet conformal field theory. Thus, the
linearized tachyon field equation allows to impose the diagonal condition for
the interaction term. We analyze the neutralization of the Liouville mode
induced by the coupling to the Jackiw-Teitelboim Lagrangian. The free field
prescription leads to obtain explicit expressions for three-point correlation
functions for the case of vanishing cosmological constant in terms of a product
of Shapiro-Virasoro integrals. This is a consequence of the mentioned
neutralization effect.Comment: 14 pages, no figures. v2 References added. To be published in
Classical and Quantum Gravity. v3 typos correcte
Design of an Intelligent, Modular IGBT/SiC Inverter Platform up to 400 kW for Fast Realization of New Test-Bench Concepts
This paper presents an intelligent, modular two level, three phase inverter platform for up to 1200 V DC-link voltage and 400 kW continuous power at 10 kHz switching frequency. It features an integrated signal processing system and various sensors, which allow standalone as well as cross-linked operation. Customizable software of the signal processing system allows easy adaption to different applications such as Active-Front-End (AFE), DC/DC-converters, Dual-Active-Bridges or Drive Inverters. Focus of this paper is a design guideline for an inverter platform which fulfills requirements of various applications with regard to sensor setup, control, failure management and monitoring. Design goal of the platform is a fast setup of new testbench concepts for academic research and novel applications
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