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Search Results: 1 - 10 of 325121 matches for " S. Funk "
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Space- and Ground-Based Gamma-Ray Astrophysics
S. Funk
Physics , 2015,
Abstract: In recent years, observational $\gamma$-ray astronomy has seen a remarkable range of exciting new results in the high-energy and very-high energy regimes. Coupled with extensive theoretical and phenomenological studies of non-thermal processes in the Universe these observations have provided a deep insight into a number of fundamental problems of high energy astrophysics and astroparticle physics. Although the main moti- vations of $\gamma$-ray astronomy remain unchanged, recent observational results have contributed significantly towards our understanding of many related phenomena. This article aims to review the most important results in the young and rapidly developing field of $\gamma$-ray astrophysics.
Simulation studies of the high-energy component of a future imaging Cherenkov telescope array
S. Funk,J. A. Hinton
Physics , 2009,
Abstract: The current generation of Imaging Atmospheric telescopes (IACTs) has demonstrated the power of the technique in an energy range between ~100 GeV up to several tens of TeV. At the high-energy end, these instruments are limited by photon statistics. Future arrays of IACTs such as CTA or AGIS are planned to push into the energy range beyond 100 TeV. Scientifically, this region is very promising, providing a probe of particles up to the 'knee' in the cosmic ray spectrum and access to an unexplored region in the spectra of nearby extragalactic sources. We present first results from our simulation studies of the high-energy part of a future IACT array and discuss the design parameters of such an array.
Monte-Carlo studies of the angular resolution of a future Cherenkov gamma-ray telescope
S. Funk,J. A. Hinton
Physics , 2009,
Abstract: The current generation of Imaging Atmospheric telescopes (IACTs) has demonstrated the power of this observational technique, providing high sensitivity and an angular resolution of $\sim0.1^{\circ}$ per event above an energy threshold of $\sim$100 GeV. Planned future arrays of IACTs such as AGIS or CTA are aiming at significantly improving the angular resolution. Preliminary results have shown that values down to $\sim 1'$ might be achievable. Here we present results of Monte-Carlo simulations that aim to exploring the limits of angular resolution for next generation IACTs and investigate how the resolution can be optimised by changes to array and telescope parameters such as the number of pixel in the camera, the field of view of the camera, the angular pixel size, the mirror size, and also the telescope separation.
Dynamics of the TrES-2 system
Florian Freistetter,áron Süli,Barbara Funk
Physics , 2009, DOI: 10.1002/asna.200811199
Abstract: The TrES-2 system harbors one planet which was discovered with the transit technique. In this work we investigate the dynamical behavior of possible additional, lower-mass planets. We identify the regions where such planets can move on stable orbits and show how they depend on the initial eccentricity and inclination. We find, that there are stable regions inside and outside the orbit of TrES-2b where additional, smaller planets can move. We also show that those planets can have a large orbital inclination which makes a detection with the transit technique very difficult.
A future very-high-energy view of our Galaxy
S. Funk,J. A. Hinton,G. Hermann,S. Digel
Physics , 2009, DOI: 10.1063/1.3076819
Abstract: The survey of the inner Galaxy with H.E.S.S. was remarkably successful in detecting a wide range of new very-high-energy gamma-ray sources. New TeV gamma-ray emitting source classes were established, although several of the sources remain unidentified, and progress has been made in understanding particle acceleration in astrophysical sources. In this work, we constructed a model of a population of such very-high-energy gamma-ray emitters and normalised the flux and size distribution of this population model to the H.E.S.S.-discovered sources. Extrapolating that population of objects to lower flux levels we investigate what a future array of imaging atmospheric telescopes (IACTs) such as AGIS or CTA might detect in a survey of the Inner Galaxy with an order of magnitude improvement in sensitivity. The sheer number of sources detected together with the improved resolving power will likely result in a huge improvement in our understanding of the populations of galactic gamma-ray sources. A deep survey of the inner Milky Way would also support studies of the interstellar diffuse gamma-ray emission in regions of high cosmic-ray density. In the final section of this paper we investigate the science potential for the Galactic Centre region for studying energy-dependent diffusion with such a future array.
Probing the momentum relaxation time of charge carriers in ultrathin semiconductor layers
S. Funk,G. Acuna,M. Handloser,R. Kersting
Physics , 2009, DOI: 10.1364/OE.17.017450
Abstract: We report on a terahertz time-domain technique for measuring the momentum relaxation time of charge carriers in ultrathin semiconductor layers. The phase sensitive modulation technique directly provides the relaxation time. Time-resolved THz experiments were performed on n-doped GaAs and show precise agreement with data obtained by electrical characterization. The technique is well suited for studying novel materials where parameters such as the charge carriers' effective mass or the carrier density are not known a priori.
Monte Carlo Studies of medium-size telescope designs for the Cherenkov Telescope Array
M. Wood,T. Jogler,J. Dumm,S. Funk
Physics , 2015, DOI: 10.1016/j.astropartphys.2015.04.008
Abstract: We present studies for optimizing the next generation of ground-based imaging atmospheric Cherenkov telescopes (IACTs). Results focus on mid-sized telescopes (MSTs) for CTA, detecting very high energy gamma rays in the energy range from a few hundred GeV to a few tens of TeV. We describe a novel, flexible detector Monte Carlo package, FAST (FAst Simulation for imaging air cherenkov Telescopes), that we use to simulate different array and telescope designs. The simulation is somewhat simplified to allow for efficient exploration over a large telescope design parameter space. We investigate a wide range of telescope performance parameters including optical resolution, camera pixel size, and light collection area. In order to ensure a comparison of the arrays at their maximum sensitivity, we analyze the simulations with the most sensitive techniques used in the field, such as maximum likelihood template reconstruction and boosted decision trees for background rejection. Choosing telescope design parameters representative of the proposed Davies-Cotton (DC) and Schwarzchild-Couder (SC) MST designs, we compare the performance of the arrays by examining the gamma-ray angular resolution and differential point-source sensitivity. We further investigate the array performance under a wide range of conditions, determining the impact of the number of telescopes, telescope separation, night sky background, and geomagnetic field. We find a 30-40% improvement in the gamma-ray angular resolution at all energies when comparing arrays with an equal number of SC and DC telescopes, significantly enhancing point-source sensitivity in the MST energy range. We attribute the increase in point-source sensitivity to the improved optical point-spread function and smaller pixel size of the SC telescope design.
Los efectos psíquicos actuales de la orientación mercantil
Funk,Rainer;
Revista chilena de neuro-psiquiatría , 2008, DOI: 10.4067/S0717-92272008000400008
Abstract: the reader gets first briefly acquainted with erich fromm's psychoanalytic approach and concept of human behavior. fromm tried to conceptualize this approach by using freud's dynamic understanding of character and by understanding behavior as determined by conscious and unconscious character traits. in the main part of the paper this approach is applied to the social character formation of the "marketing-orientation". today one can observe this character orientation either as a product-oriented or as a reality enacting marketing of one's own personality. in a third step the respective psycho dynamics are illustrated. finally, the psychic impact of this way to live is discussed: the progredient loss to bear ambivalences
Los efectos psíquicos actuales de la orientación mercantil The psychic impact of present-day marketing-orientation
Rainer Funk
Revista Chilena de Neuro-Psiquiatría , 2008,
Abstract: Al lector se le presenta primero una breve síntesis del concepto psicoanalítico de Erich Fromm y su comprensión de la conducta humana. Fromm trató de aplicar a su propia visión la concepción dinámica de carácter desarrollado por Freud y entendió que la conducta humana está determinada por rasgos caracterológicos conscientes e inconscientes. En la parte principal de este trabajo se utiliza este concepto para mostrar de que manera se forma el carácter social de orientación mercantil. Hoy en día se puede observar esta orientación caracterológica por un lado como marketing orientado al producto y por otro lado como marketing escenificador de realidades de la propia personalidad. En la tercera parte se ilustran las diferentes psicodinámicas de ambas orientaciones mercantiles. Finalmente se discute la pérdida creciente de la capacidad de ambivalencia como secuela psíquica de la forma de vivir orientada al marketing. The reader gets first briefly acquainted with Erich Fromm's psychoanalytic approach and concept of human behavior. Fromm tried to conceptualize this approach by using Freud's dynamic understanding of character and by understanding behavior as determined by conscious and unconscious character traits. In the main part of the paper this approach is applied to the social character formation of the "marketing-orientation". Today one can observe this character orientation either as a product-oriented or as a reality enacting marketing of one's own personality. In a third step the respective psycho dynamics are illustrated. Finally, the psychic impact of this way to live is discussed: the progredient loss to bear ambivalences
A Filosofia Humanista de Fromm como Ciência do Homem
Rainer Funk
Revista Espa?o Acadêmico , 2010,
Abstract: O conjunto da obra de Fromm revela que ele estudou Kant, Hegel, Nietzsche, Herbert Spencer, John Stuart Mill e William James, Heidegger, Sartre, Bloch e Habermas, mas nenhum deles marcou seu pensamento de verdade, e nem a filosofia de valores do seu mestre Rickert, em Heidelberg, reflete no seu pensamento. Fromm, porém, se vê profundamente ligado a pensadores como o filósofo judaico Maim nides, como a Cohen e Cassirer, Aristóteles, Espinoza e Marx, mais tarde também a Tomás de Aquino.
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