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Drs. E. Kreysa, G. V. Schultz, W.A. Sherwood and A. Winnberg from the Max-Planck-Institut für Radioastronomie (MPIfR) in Bonn have during the last two years simultaneously observed OH/IR sources atthe 100 m Effelsberg and the 1 m ESO... more
Drs. E. Kreysa, G. V. Schultz, W.A. Sherwood and A. Winnberg from the Max-Planck-Institut für Radioastronomie (MPIfR) in Bonn have during the last two years simultaneously observed OH/IR sources atthe 100 m Effelsberg and the 1 m ESO telescopes. G. V. Schultz reports about the results which open the door to further exciting investigations:
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In this paper a comparison between a rigorous electromagnetic model for transmission through a hexagonal array of circular waveguides in a series of thick, metallic screens and experimental measurements in the far infrared is made. It is... more
In this paper a comparison between a rigorous electromagnetic model for transmission through a hexagonal array of circular waveguides in a series of thick, metallic screens and experimental measurements in the far infrared is made. It is found that there is excellent agreement between theory and experiment when the frequency is below that where any diffracted orders propagate. The agreement
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ABSTRACT We present a new polarimeter for mm/submm wavelengths. Very low insertion losses and the possibility to tune its operating wavelength in a wide range make it a versatile instrument. It will be used with MPIfR bolometer arrays at... more
ABSTRACT We present a new polarimeter for mm/submm wavelengths. Very low insertion losses and the possibility to tune its operating wavelength in a wide range make it a versatile instrument. It will be used with MPIfR bolometer arrays at different wavelengths to produce high-resolution maps of polarization. .
ABSTRACT
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We have performed a sensitive (sigma~1.5mJy) systematic study of the 1.25mm emission of ~22 radio-quiet QSOs at z>4, with the IRAM 30m telescope equipped with bolometer arrays. Five radio-quiet QSOs at z>4 have been detected... more
We have performed a sensitive (sigma~1.5mJy) systematic study of the 1.25mm emission of ~22 radio-quiet QSOs at z>4, with the IRAM 30m telescope equipped with bolometer arrays. Five radio-quiet QSOs at z>4 have been detected at a 5-sigma level in addition to the initial detection of the z=4.7 QSO BR1202-0725 reported in McMahon et al. (1994MNRAS.267L...9M). The detected fluxes range
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ABSTRACT
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ABSTRACT 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... more
ABSTRACT 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. .
Formerly continuum observations of comets typically resulted in an intensity at a single frequency at the predicted position of the comet. The size of the cometary emission, the separation of the contribution of nucleus and halo, and the... more
Formerly continuum observations of comets typically resulted in an intensity at a single frequency at the predicted position of the comet. The size of the cometary emission, the separation of the contribution of nucleus and halo, and the estimate of the particle size in the halo could not be derived this way. In addition the comet intensity varied occasionally strongly
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ABSTRACT Cosmic Microwave Background observations became the tool to probe the the first events of cosmic history. After WMAP data releases, galactic and extragalactic foregrounds are perceived as the main limiting uncertainity for the... more
ABSTRACT Cosmic Microwave Background observations became the tool to probe the the first events of cosmic history. After WMAP data releases, galactic and extragalactic foregrounds are perceived as the main limiting uncertainity for the near-future search for the B-mode polarization inprints from the inflationary era, either through satellites or ground-based experiments like Brain at Dome-C. A combination of technology, scanning strategy and above all, accurate knowledge of polarized foregrounds will be necessary for an optimal mapping of B-mode CMB Polarization. In addition, the search for a better understanding of the galactic foregrounds will provide unprecedented knowledge on the Milky Way structure and star formation.
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We summarize the results of the Cosmic Microwave Background (CMB) working group of the ARENA project. The focus has been on precision measurements of CMB polarization (looking for the echoes of cosmological inflation) and high angular... more
We summarize the results of the Cosmic Microwave Background (CMB) working group of the ARENA project. The focus has been on precision measurements of CMB polarization (looking for the echoes of cosmological inflation) and high angular resolution CMB measurements (looking for Sunyaev Zeldovich effect in distant clusters of Galaxies, to probe the evolution of the Universe, Dark Matter and Dark Energy). For both projects the Dome C site represents the best choice worldwide.
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Using the Institut de Radio Astronomie Millimetrique (IRAM) 30-m telescope equipped with the Max-Planck-Institut fuer Radioastronomie (MPIfR) 7-channel bolometer array, we have mapped the lambda-1.3 mm continuum emission of NGC 891, an... more
Using the Institut de Radio Astronomie Millimetrique (IRAM) 30-m telescope equipped with the Max-Planck-Institut fuer Radioastronomie (MPIfR) 7-channel bolometer array, we have mapped the lambda-1.3 mm continuum emission of NGC 891, an edge-on Sb galaxy similar to the Milky Way. This emission is 7 times stronger along the major axis than the CO 2-1 line averaged over the 50 GHz bolometer passband, and 9 times stronger than the warm dust emission expected from the IRAS data. The lambda-1.3 mm dust emission correlates remarkably well with the CO emission and poorly with HI emission, at least up to +/- 7 kpc (150 sec) from the center. It arises mostly from cold dust (T less than or = 20 K) associated with molecular clouds. The H2 mass, calcuclated using Galactic values of the dust absorption cross section, is approximately 3 times smaller than the H2 mass derived from the CO luminosity and Strong et al's (1988) 'standard' Galactic CO to H2 conversion factor. It is about ...
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Infrared spectral energy distributions between 4.8 and 200 μm are presented for a subsample of 10 quasars and radio galaxies from the European Central Quasar Programme observed with the Infrared Space Observatory. For three of the... more
Infrared spectral energy distributions between 4.8 and 200 μm are presented for a subsample of 10 quasars and radio galaxies from the European Central Quasar Programme observed with the Infrared Space Observatory. For three of the sources, this represents the ...
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We report on the electrical conductivity sigma of a series of nominally uncompensated neutron-transmutation-doped isotopically enriched 70Ge:Ga samples with the Ga concentration [Ga] near Nc for the metal-insulator transition. sigma of... more
We report on the electrical conductivity sigma of a series of nominally uncompensated neutron-transmutation-doped isotopically enriched 70Ge:Ga samples with the Ga concentration [Ga] near Nc for the metal-insulator transition. sigma of all insulating samples obeys lnsigma~-\(T0/T\)1/2 with T0~\(Nc-[Ga]\)/Nc while the zero temperature conductivity sigma\(0\) of the metallic samples is sigma\(0\)~\{\([Ga]-Nc\)/Nc\}nu with the critical exponent nu~0.5. The values of Nc obtained
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ABSTRACT At the Max-Planck-Institut für Radioastronomie we built a 19-channel bolometer array for 150 GHz operating at 100 mK. We give an overview of how our new bolometer array is installed at mm/submm telescopes. With results obtained... more
ABSTRACT At the Max-Planck-Institut für Radioastronomie we built a 19-channel bolometer array for 150 GHz operating at 100 mK. We give an overview of how our new bolometer array is installed at mm/submm telescopes. With results obtained during observing runs at the 10 m HHT and the IRAM 30 m-telescope we illustrate the performance of the instrument. Measurements of the Sunyaev–Zel'dovich effect (SZE) at mm-wavelength towards distant clusters of galaxies allow us to determine the Hubble constant and the radial cluster velocities. In the diffraction limit of a 10 m telescope our instrument's beamwidth matches the size of many clusters of galaxies making it an ideal tool for observations of the SZE. As first measurements we observed the clusters CL0016+16 and A2218 and the blank sky as a control and we present preliminary results of the detection of the SZE.
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... AE Lange, E. Kreysa,~ SE McBride, and PL Richards ... In order to minimize the size of the blackbody required to fill the aperture of the detector optics, the exit to the blackbody is a Winston light concen-trator [14] with an... more
... AE Lange, E. Kreysa,~ SE McBride, and PL Richards ... In order to minimize the size of the blackbody required to fill the aperture of the detector optics, the exit to the blackbody is a Winston light concen-trator [14] with an acceptance of f/l.5. This whole struc-ture is separated from ...
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Continuum radiometers based on bolometers have a long tradition at the Max-Planck-Institut für Radioastronomie (MPIfR) in Bonn, Germany. Arrays of bolometers have been under development since the early 1990s. A small seven-element system,... more
Continuum radiometers based on bolometers have a long tradition at the Max-Planck-Institut für Radioastronomie (MPIfR) in Bonn, Germany. Arrays of bolometers have been under development since the early 1990s. A small seven-element system, operating at 300 mK, saw first light in 1992 at the IRAM 30-m telescope and has been used successfully by numerous observers at that facility since then.
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ABSTRACT 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... more
ABSTRACT 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 offline 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.
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We have performed a sensitive (sigma~1.5mJy) systematic study of the 1.25mm emission of ~22 radio-quiet QSOs at z>4, with the IRAM 30m telescope equipped with bolometer arrays. Five radio-quiet QSOs at z>4 have been detected... more
We have performed a sensitive (sigma~1.5mJy) systematic study of the 1.25mm emission of ~22 radio-quiet QSOs at z>4, with the IRAM 30m telescope equipped with bolometer arrays. Five radio-quiet QSOs at z>4 have been detected at a 5-sigma level in addition to the initial detection of the z=4.7 QSO BR1202-0725 reported in McMahon et al. (1994MNRAS.267L...9M). The detected fluxes range
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© European Southern Observatory Provided by the NASA Astrophysics Data System Astron. Astrophys. 272, L5-L8 (1993) Letter to the Editor Discovery of a cold and gravitationally unstable cloud R. Chini 1, E. KrUgel 1, CGT Haslam', E.... more
© European Southern Observatory Provided by the NASA Astrophysics Data System Astron. Astrophys. 272, L5-L8 (1993) Letter to the Editor Discovery of a cold and gravitationally unstable cloud R. Chini 1, E. KrUgel 1, CGT Haslam', E. Kreysa 1, R. Lemke 1, Bo ...
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... This agreement shows that the approximation by two modified Planck spectra should yieldreasonable mass estimates. ... This would explain the bipolar structure of the Homunculus nebula. The 210 K dust component outlines this nebula and... more
... This agreement shows that the approximation by two modified Planck spectra should yieldreasonable mass estimates. ... This would explain the bipolar structure of the Homunculus nebula. The 210 K dust component outlines this nebula and has - as already noted by White et al. ...
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The authors summarize three balloon flights of an experiment designed to search for anisotropy in the cosmic microwave background (CMB) on angular scales from 0.3 to 3 degrees. The instrument was a multiband, 3He-cooled bolometric... more
The authors summarize three balloon flights of an experiment designed to search for anisotropy in the cosmic microwave background (CMB) on angular scales from 0.3 to 3 degrees. The instrument was a multiband, 3He-cooled bolometric photometer installed on a pointed, low background telescope.
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With ESO and Onsala Space Observatory as partners, the Max-Planck-Institut für Radioastronomie (MPIfR) is building a submillimeter telescope of 12 m diameter (APEX), to be placed on the ALMA site (Chajnantor) in Chile. The telescope will... more
With ESO and Onsala Space Observatory as partners, the Max-Planck-Institut für Radioastronomie (MPIfR) is building a submillimeter telescope of 12 m diameter (APEX), to be placed on the ALMA site (Chajnantor) in Chile. The telescope will be a modified copy of that ALMA prototype antenna, which has been designed by Vertex. First light is foreseen for 2003. As a result
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Research Interests: Geology and Particle Size
ABSTRACT Cryogenic bolometers are among the most sensitive devices for the detection of electromagnetic radiation in the submillimeter wavelength range. Such radiation is of interest for astronomical observations as well as for security... more
ABSTRACT Cryogenic bolometers are among the most sensitive devices for the detection of electromagnetic radiation in the submillimeter wavelength range. Such radiation is of interest for astronomical observations as well as for security checks. We describe how we fabricate an array of these bolometers. Standard contact lithography is sufficient for these relatively coarse features. To increase the sensitivity, it is imperative to weaken the thermal link between the thermistors (the sensing devices) and the temperature bath. This is achieved by placing them on a silicon nitride membrane that is structured so that the thermistors are placed on a platform which is held only by a few beams. The fabrication process does not require sophisticated lithographic techniques, but special care to achieve the desired yield of 100 % intact bolometers in one array. We discuss bolometer basics and requirements for our applications, critical fabrication issues, and show results of complete systems built for a radio telescope and for security cameras.
Ever since the first proposal of the voltage-biased transition-edge bolometer the astrophysics community desired bolometer arrays with as many pixels as possible. With respect to the technical problem due to the need of lots of readout... more
Ever since the first proposal of the voltage-biased transition-edge bolometer the astrophysics community desired bolometer arrays with as many pixels as possible. With respect to the technical problem due to the need of lots of readout SQUID sensors only with multiplexing it is possible to go beyond a few hundred pixel. A technology which allows the manufacture of detector and readout on one chip would simplify this task substantially. Here we demonstrate the fabrication of a transition edge sensor based on a thermistor out of a molybdenum / gold-palladium bilayer. The alloy of gold-palladium (Au-Pd), which allows the tuning of molybdenum's critical temperature by one order of magnitude, is taken from our foundry process for SQUID manufacturing. Au-Pd can further be used for shunt resistances, absorber patterns and bond pads, and, therefore, it is a good choice for a combined technology. The thermistor is placed on a moderately patterned silicon nitride membrane in the shape of an 8-legged spider. The radiation band of interest is coupled via a conical feed horn to a simple grid of dipole-like antenna patterns. This removes the need for the poorly reproducible high-resistance absorption films for the matching of the free space impedance. The simple detector technology is compatible with the SQUID manufacturing. Hence, some of the SQUID layers can be merged with the corresponding detector layer, i.e. the thermistor wiring and the SQUID washer are made in a single niobium layer. The concept of feed horn coupling eases the design requirements, consequently the SQUID can be placed close to the detector, thereby allowing a simpler wiring to be used and in theory a better performance to be obtained.
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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),... more
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