W. Esch
Max Planck Society
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Featured researches published by W. Esch.
Astronomy and Astrophysics | 2009
G. Siringo; E. Kreysa; A. Kovács; F. Schuller; A. Weiß; W. Esch; N. Jethava; Gundula Lundershausen; Angel Colin; R. Güsten; K. M. Menten; A. Beelen; Frank Bertoldi; Jeffrey W. Beeman; E. E. Haller
The Large APEX BOlometer CAmera, LABOCA, has been commissioned for operation as a new facility instrument at the Atacama Pathfinder Experiment 12 m submillimeter telescope. This new 295-bolometer total power camera, operating in the 870
Proceedings of SPIE | 2006
R. Güsten; R. S. Booth; Catherine J. Cesarsky; K. M. Menten; Claudio Agurto; M. Anciaux; Francisco Azagra; Victor Belitsky; A. Belloche; Per Bergman; C. De Breuck; C. Comito; Michael Dumke; C. Duran; W. Esch; J. Fluxa; Albert Greve; H. Hafok; W. Häupl; Leif Helldner; A. Henseler; Stefan Heyminck; L. E. B. Johansson; C. Kasemann; B. Klein; A. Korn; E. Kreysa; R. Kurz; Igor Lapkin; S. Leurini
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Astronomy and Astrophysics | 2001
L. A. Reichertz; B. Weferling; W. Esch; E. Kreysa
m atmospheric window, combined with the high efficiency of APEX and the excellent atmospheric transmission at the site, offers unprecedented capability in mapping submillimeter continuum emission for a wide range of astronomical purposes.
Review of Scientific Instruments | 2012
Torsten May; Vyatcheslav Zakosarenko; E. Kreysa; W. Esch; Solveig Anders; Hans-Peter Gemuend; Erik Heinz; Hans-Georg Meyer
APEX, the Atacama Pathfinder Experiment, has been successfully commissioned and is in operation now. This novel submillimeter telescope is located at 5107 m altitude on Llano de Chajnantor in the Chilean High Andes, on what is considered one of the worlds outstanding sites for submillimeter astronomy. The primary reflector with 12 m diameter has been carefully adjusted by means of holography. Its surface smoothness of 17-18 μm makes APEX suitable for observations up to 200 μm, through all atmospheric submm windows accessible from the ground.
Proceedings of SPIE | 2008
G. Siringo; E. Kreysa; A. Kovács; F. Schuller; A. Weiß; W. Esch; Hans-Peter Gemünd; N. Jethava; Gundula Lundershausen; Rolf Güsten; K. M. Menten; A. Beelen; Frank Bertoldi; Jeffrey W. Beeman; E. E. Haller; Angel Colin
Fastscanning is a new observing technique for millimeter and submillimeter astronomy from ground based telescopes. The atmosphere is eliminated by taking advantage of detector arrays. Instead of wobbling the secondary mirror with a fixed frequency of a few Hz to filter the atmospheric contribution, we sample the detector outputs at a much higher rate without a modulation by the secondary mirror. The atmospheric contribution is then removed later in the off line data reduction by correlation analysis between the detector pixels. In order to satisfy the AC requirement of the amplifiers in the absence of modulation, the telescope scans fast to convert the spatial frequencies of the sky into the detector frequency band. The acquired AC signals are then deconvolved with the corresponding filter function in order to reconstruct quasi-DC signals. This article describes the technique of this new method and shows simulations and preliminary test results.
Proceedings of SPIE | 2008
N. Jethava; E. Kreysa; G. Siringo; W. Esch; Hans-Peter Gemünd; K. M. Menten; Torsten May; Solveig Anders; L. Fritzsch; R. Boucher; V. Zakosarenko; H.-G. Meyer
The large array bolometer camera is scheduled to succeed its semiconducting predecessor at the Atacama pathfinder experiment. It shall be an array of 300 transition edge sensors operated at a temperature of about 0.25 K, provided by a (3)He evaporation cooler and a pulse tube refrigerator. The instrument will be read out by a superconducting quantum interference device time domain multiplexer. The design and realization of a suitable detector for this instrument is described. Based on sensitivity demands derived from the background limit, the thermal and electrical designs for a spider-web bolometer are deduced. The theoretical predictions are compared to experimental results. The pixel design yields a background-limited performance for background loads corresponding to blackbody sources between 77 K and 300 K and a partially effective anti-aliasing filter for the intended multiplexed readout.
Proceedings of SPIE | 2006
N. Jethava; E. Kreysa; G. Siringo; W. Esch; Hans-Peter Gemünd; Torsten May; Solveig Anders; L. Fritzsch; R. Boucher; V. Zakosarenko; H.-G. Meyer
A new facility instrument, the Large APEX Bolometer Camera (LABOCA), developed by the Max-Planck-Institut f&diaeru;r Radioastronomie (MPIfR, Bonn, Germany), has been commissioned in May 2007 for operation on the Atacama Pathfinder Experiment telescope (APEX), a 12 m submillimeter radio telescope located at 5100 m altitude on Llano de Chajnantor in northern Chile. For mapping, this 295-bolometer camera for the 870 micron atmospheric window operates in total power mode without wobbling the secondary mirror. One LABOCA beam is 19 arcsec FWHM and the field of view of the complete array covers 100 square arcmin. Combined with the high efficiency of APEX and the excellent atmospheric transmission at the site, LABOCA offers unprecedented capability in large scale mapping of submillimeter continuum emission. Details of design and operation are presented.
EXPERIMENTAL COSMOLOGY AT MILLIMETRE WAVELENGTHS: 2K1BC Workshop | 2002
L. A. Reichertz; B. Weferling; W. Esch; E. Kreysa
We present the experimental results and a bolometer model of the voltage-biased superconducting bolometer on the low stress silicon nitride (Si3N4) membrane, developed in collaboration between the Max-Planck-Institut fur Radioastronomie (MPIfR), Bonn and the Institute for Photonic Technology (IPHT), Jena, Germany. The superconducting thermistor, deposited on the low stress silicon nitride membrane, is a bilayer of gold-palladium and molybdenum and is designed for a transition temperature of 450 mK. Bolometers for the 1.2 mm atmospheric window were designed, built and tested. The thermal conductance of the bolometer is tuned by structuring the silicon nitride membrane into spider-like geometries. The incident radiation is absorbed by crossed dipoles made from gold-palladium alloy with a surface resistance of 10 Ω/square. Using the COSMOS finite element analysis package, the thermal conductance is obtained for the bolometers of different geometries. FEA simulations showed that the deposition of a gold ring around the absorbing area could increase the sensitivity of the bolometer. Therefore, a gold ring is deposited around the center absorbing patch of the silicon nitride membrane. For the bolometer with a gold ring, the measured NEP is 1.7 X (see manuscript for formula) Hz and the time constant is in the range between 1.4 and 2 ms.
Superconductor Science and Technology | 2011
V. Zakosarenko; M. Schulz; A. Krueger; E. Heinz; Solveig Anders; Katja Peiselt; Torsten May; E. Kreysa; G. Siringo; W. Esch; M. Starkloff; H.-G. Meyer
We present the experimental results of voltage-biased superconducting bolometers (VSB) on silicon nitride (Si3N4) membranes with niobium wiring developed in collaboration between the Institut fur Physikalische Hochtechnologie (IPHT), Jena, Germany and the Max-Planck-Institut fur Radioastronomie (MPIfR), Bonn, Germany. The bolometer current is measured with the superconducting quantum interference device (SQUID), and as expected, the current responsivity is proportional to the inverse of the bias voltage. The experiments were performed with bilayer gold-palladium molybdenum thermistor at 300 mK 3He cooled cryostat and the desired transition temperature of Tc = 450 mK is achieved. The strong negative electro-thermal feedback of the VSB maintains the constant bolometer temperature and reduces the response time from 4 ms to 100 μs. We have tested thermistors of various size and shape on a continuous membrane and achieved a noise equivalent power (NEP) of 3.5 × 10-16 W/√Hz. The measured NEP is relatively high due to the comparatively high background and high thermal conductance of the unstructured silicon nitride (Si3N4) membrane. We have fabricated 8-leg spider structured membranes in three different geometries and the relation between the geometry and the thermal conductance (G) is studied. Using the COSMOS finite element analysis tool, we have modeled the TES bolometers to determine the thermal conductance for different geometries and calculated the various parameters. Due to the demands of large number pixel bolometer camera we plan to implement multiplex readout with integrated SQUIDs in our design.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2000
L. A. Reichertz; W. Esch; Hans-Peter Gemünd; J Gromke; E. Kreysa
The use of a wobbling secondary mirror to suppress atmospheric noise restricts the scan velocity in mapping modes and has other disadvantages. The fastscanning observing technique allows observations with bolometer arrays from ground based telescopes without the need of a wobbling secondary mirror. Therefore mapping of large sky areas can be done in a shorter time than usual which is especially useful in surveys to search for new sources. We present here the basic principle of this method.