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Hernandez A.Saa.,Helmholtz Center for Heavy Ion Research | Spiller P.,Helmholtz Center for Heavy Ion Research | Ratzinger U.,IAP
IPAC 2011 - 2nd International Particle Accelerator Conference | Year: 2011

The SIS300 synchrotron, planned for the new Facility for Antiproton and Ion Research (FAIR) at GSI-Darmstadt, will become the first superconducting synchrotron worldwide using cos(θ) magnets for resonant slow extraction. A multi-objective optimization algorithm has been developed to design the nonlinear magnet scheme of the SIS300 lattice. The optimization algorithm aims to determine the gradients of the chromatic and harmonic sextupoles for the highest extraction efficiency. To this end, it makes use of the analytical descriptions of the slow extraction separatrices, of the resonance driving modes and of the chromaticity. The optimization algorithm also accounts for the sextupole errors on the dipole magnets, and it is used to compensate the persistent current decay which occurs in cos(θ) magnets during the slow extraction plateau. Tolerances on the magnet field errors have been established at the limits where the compensation is no longer valid. Copyright © 2011 by IPAC'11/EPS-AG.

Salvaterra R.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Haardt F.,University of Insubria | Haardt F.,National Institute of Nuclear Physics, Italy | Volonteri M.,IAP | Moretti A.,National institute for astrophysics
Astronomy and Astrophysics | Year: 2012

We place firm upper limits on the global accretion history of massive black holes at z > 5 from the recently measured unresolved fraction of the cosmic X-ray background. The maximum allowed unresolved intensity observed at 1.5 keV implies a maximum accreted-mass density onto massive black holes of ρ acc < 1.4 × 10 4 M Mpc -3 for z > 5. Considering the contribution of lower-z AGNs, the value reduces to ρ acc < 0.66 × 10 4 MMpc -3. The tension between the need for the efficient and rapid accretion required by the observation of massive black holes already in place at z > 7 and the strict upper limit on the accreted mass derived from the X-ray background may indicate that black holes are rare in high redshift galaxies or that accretion is only efficient for the black holes hosted by rare galaxies. © 2012 ESO.

Donges J.,German Electron Synchrotron | Rothkirch A.,German Electron Synchrotron | Wroblewski T.,German Electron Synchrotron | Bjeoumikhov A.,IfG | And 4 more authors.
Materials Science Forum | Year: 2014

Position resolved structural information from polycrystalline materials is usually obtained via micro beam techniques illuminating only a single spot of the specimen. Multiplexing in reciprocal space is achieved either by the use of an area detector or an energy dispersive device. Alternatively spatial information may be obtained simultaneously from a large part of the sample by using an array of parallel collimators between the sample and a position sensitive detector which suppresses crossfire of radiation scattered at different positions in the sample. With the introduction of an X-ray camera based on an energy resolving area detector (pnCCD) we could combine this with multiplexing in reciprocal space. © (2014) Trans Tech Publications, Switzerland.

Ghisellini G.,National institute for astrophysics | Haardt F.,University of Insubria | Haardt F.,National Institute of Nuclear Physics, Italy | Della Ceca R.,National institute for astrophysics | And 3 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2013

In powerful radio-quiet active galactic nuclei (AGN), the bulk of the population of black holes heavier than one billion solar masses form at a redshift ~ 1.5-2. Supermassive black holes in jetted radio-loud AGN seem to form earlier, at a redshift close to 4. The ratio of active radio-loud to radio-quiet AGN hosting heavy black holes is therefore a strong function of redshift. We report on some recent evidence supporting this conclusion, gathered from the Burst Alert Telescope (onboard Swift) and by the Large Area Telescope (onboard Fermi). We suggest that the more frequent occurrence of relativistic jets in the most massive black holes at high redshifts could be due to the average black hole spin being greater in the distant past, or else due to the jet helping a fast accretion rate (or some combination of the two scenarios). We emphasize that the large total accretion efficiency of rapidly spinning black holes inhibits a fast growth, unless a large fraction of the available gravitational energy of the accreted mass is not converted into radiation, but used to form and maintain a powerful jet. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Mancini C.,National institute for astrophysics | Forster Schreiber N.M.,Max Planck Institute for Extraterrestrial Physics | Renzini A.,National institute for astrophysics | Cresci G.,National institute for astrophysics | And 24 more authors.
Astrophysical Journal | Year: 2011

The zCOSMOS-SINFONI project is aimed at studying the physical and kinematical properties of a sample of massive z 1.4-2.5 star-forming galaxies, through SINFONI near-infrared integral field spectroscopy (IFS), combined with the multiwavelength information from the zCOSMOS (COSMOS) survey. The project is based on one hour of natural-seeing observations per target, and adaptive optics (AO) follow-up for a major part of the sample, which includes 30 galaxies selected from the zCOSMOS/VIMOS spectroscopic survey. This first paper presents the sample selection, and the global physical characterization of the target galaxies from multicolor photometry, i.e., star formation rate (SFR), stellar mass, age, etc. The Hα integrated properties, such as, flux, velocity dispersion, and size, are derived from the natural-seeing observations, while the follow-up AO observations will be presented in the next paper of this series. Our sample appears to be well representative of star-forming galaxies at z ∼ 2, covering a wide range in mass and SFR. The Hα integrated properties of the 25 Hα detected galaxies are similar to those of other IFS samples at the same redshifts. Good agreement is found among the SFRs derived from Hα luminosity and other diagnostic methods, provided the extinction affecting the Hα luminosity is about twice that affecting the continuum. A preliminary kinematic analysis, based on the maximum observed velocity difference across the source and on the integrated velocity dispersion, indicates that the sample splits nearly 50-50 into rotation-dominated and velocity-dispersion-dominated galaxies, in good agreement with previous surveys. © 2011. The American Astronomical Society. All rights reserved.

Vierinen J.,Massachusetts Institute of Technology | Chau J.L.,IAP | Pfeffer N.,IAP | Clahsen M.,IAP | Stober G.,IAP
Atmospheric Measurement Techniques | Year: 2016

The concept of a coded continuous wave specular meteor radar (SMR) is described. The radar uses a continuously transmitted pseudorandom phase-modulated waveform, which has several advantages compared to conventional pulsed SMRs. The coding avoids range and Doppler aliasing, which are in some cases problematic with pulsed radars. Continuous transmissions maximize pulse compression gain, allowing operation at lower peak power than a pulsed system. With continuous coding, the temporal and spectral resolution are not dependent on the transmit waveform and they can be fairly flexibly changed after performing a measurement. The low signal-to-noise ratio before pulse compression, combined with independent pseudorandom transmit waveforms, allows multiple geographically separated transmitters to be used in the same frequency band simultaneously without significantly interfering with each other. Because the same frequency band can be used by multiple transmitters, the same interferometric receiver antennas can be used to receive multiple transmitters at the same time. The principles of the signal processing are discussed, in addition to discussion of several practical ways to increase computation speed, and how to optimally detect meteor echoes. Measurements from a campaign performed with a coded continuous wave SMR are shown and compared with two standard pulsed SMR measurements. The type of meteor radar described in this paper would be suited for use in a large-scale multi-static network of meteor radar transmitters and receivers. Such a system would be useful for increasing the number of meteor detections to obtain improved meteor radar data products. © Author(s) 2016.

Prol-Ledesma R.M.,National Autonomous University of Mexico | Arango-Galvan C.,National Autonomous University of Mexico | Torres-Vera M.-A.,I.A.P.
Natural Resources Research | Year: 2016

Changes in legislation have opened the Mexican geothermal resources for exploitation to private companies; therefore the evaluation of the known geothermal areas has a high priority to plan further exploitation and possibly the expansion of the well fields. The calculation of the remaining productivity of geothermal fields currently in exploitation can be achieved with less uncertainty using the parameters obtained from production and injection wells, as well as the production efficiency of the installed plants. No information about previous volumetric evaluation is available for the fields presently being exploited, and there is the possibility that they may support an increase in their energy output or extend further their production life. The most widely used calculation technique is the USGS volumetric method that requires the knowledge of parameters that can be measured only after exploitation started. Heat in place-volumetric evaluation was undertaken for two fields in Mexico: Cerro Prieto and the Las Tres Vírgenes geothermal fields, using all information obtained by exploration surveys and exploitation drilling. The obtained values allow planning a possible expansion of the fields based on their estimated mean potential output that is 1397 MWe for Cerro Prieto and 48 MWe for Las Tres Vírgenes compared to the presently installed capacity of 580 MWe. © 2016 The Author(s)

Tornari V.,Foundation for Research and Technology Hellas | Bernikola E.,Foundation for Research and Technology Hellas | Tsigarida N.,Foundation for Research and Technology Hellas | Hatzigiannakis K.,Foundation for Research and Technology Hellas | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Environmental impact on artworks has always been a big issues for preservation of Cultural Heritage. Nowadays with the climate change it is experienced a slow but steady process of temperature increase affecting relative humidity which fluctuates while materials attempt to keep moisture balance. During repetitive equilibrium courses fatigue accumulates endangering the structural integrity prior to fracture. Assessing the risk imposed by the fluctuation allow preventive actions to take place and avoid interventive restoration action after fracture. A methodology is presented employing full-field interferometry by surface probing illumination based on direct realtime recording of surface images from delicate hygroscopic surfaces as they deform to dimensionally respond to relative humidity (RH) changes. The developed methodology aims to develop an early stage risk indicator tool to allow preventive measures directly through surface readings. The presented study1 aiming to experimentally highlight acclimatisation structural phenomena and to verify assumed standards in RH safety range based on the newly introduced concept of deformation threshold value is described and demonstrated with indicative results. © 2015 SPIE.

Maus J.,IAP | Schempp A.,IAP | Bechtold A.,NTG
Proceedings - 25th Linear Accelerator Conference, LINAC 2010 | Year: 2011

The IH-type RFQ for the MAFF project at the LMU in Munich was operated at a beam test stand at the IAP in Frankfurt. It is the second IH-RFQ after the HIS at GSI [1] and it has been designed to accelerate rare isotope beams (RIBs) with mass to charge ratios A/q up to 6.3 from 3 keV/u to 300 keV/u at an operating frequency of 101.28 MHz with an electrode voltage of 60 kV. Experimental results such as shunt impedance, energy spectrum and transmission will be presented and compared to simulations.

Maus J.,IAP | Jameson R.A.,IAP | Schempp A.,IAP
Proceedings - 25th Linear Accelerator Conference, LINAC 2010 | Year: 2011

For the development of high energy and high duty cycle RFQs accurate particle dynamic simulation tools are important for optimizing designs, especially in high current applications. To describe the external fields in RFQs as well as the internal space charge fields with image effect, the Poisson equation has to be solved taking the boundary conditions into account. In PteqHI a multigrid Poisson solver is used to solve the Poisson equation. This method will be described and compared to multipole expansion method to verify the answer of the Poisson solver.

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