Max Planck Institute for Astronomy - Annual Report 2005

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106 IV. Instrumental Development IV.11 Pacs – Far-Infrared Camera and Spectrometer for the hErschEL Space Telescope Within a consortium of 15 European institutes, MPIA is participating – with a share of 15 percent – in the development of the Pacs instrument, a camera and spectrometer for wavelengths of 60 to 210 µm. The most important contributions from Heidelberg are the focal plane chopper, the characterization of the large Ge:Ga-spectrometer-cameras and their – 270 °C cold readout electronics, the investigation and avoidance of radiation damages to these components, and the calibration of the instrument before and during flight. Already in June 2005, MPIA was able to deliver the focal plane chopper – as one of the consortium's first contributions to the Pacs flight model – to MPE Garching, which is responsible for the overall instrument. The chopper manufactured by C. ZEiss is a derivative of a prototype designed and tested at MPIA. It is of excellent quality and surpasses many of the technical requirements. In the summer of 2005, construction of the flight spare unit of the chopper was started, which promises an even better performance. During the characterizations of the 16 3 25 Pixel-Ge: Ga-cameras for the flight model unexpectedly numerous Fig. IV.11.1: Seven detector rows with 16 pixels each of a camera for the Pacs spectrometer unit. The light funnels in front of the Ge:Ga pixels are visible. The two cameras each have 25 of such modules. At MPIA, these detector modules are characterized in detail with respect to their sensitivity, noise, dark current etc. at temperatures below – 270 °C. Fig. IV.11.2: PhD student Jutta Stegmaier prepares a test of detector modules (as in Fig. IV.11.1) to be conducted in the liquid helium cryostat of MPIA. failures occurred. MPIA participated in a series of experiments lasting several months to explain the malfunctions. For this we had to move the extensive test facilities of MPIA to the manufacturer of the cameras. Finally, two main causes for the high failure rates were determined: 1. destruction of electronic amplifier and readout stages by electrostatic discharges and 2. bad bonding of the thin steel connecting leads; steel is used because of its low thermal conductivity. To avoid the electrostatic problems the handling of the components had to be regulated very carefully at the institutes and firms involved (air humidity, groundings, protection circuits …). With the new procedures the success rate of the detector/readout electronic tests rose steeply. So by the end of the year most of the camera modules were fully characterized and could be delivered to the manufacturer astEq for the assembly of the cameras. Because of the unexpectedly time-consuming tests with the Ge:Ga-spectrometer-cameras, the radiation tests with gamma-ray sources to simulate an optimal operation at the Lagrangian Point L2 were delayed. After the work for the actual instrument is drawing to a close at MPIA, the tests and development of the ground observatory are reaching the critical stage. Scientists from Heidelberg were involved in the cold tests of the Pacs qualification model and in the integrated module tests of all three hErschEL instruments. For this, test procedures were designed and an extended data analysis was carried out. Naturally, the focus of the contributions from Heidelberg was on detectors, chopper, and calibration. Because the development of subsystems and their mutual interfaces from the 15 institutes of the Pacs consortium are still not quite perfected, all these tests took noticeably more time than originally planned. Moreover, MPIA is contributing to the design of the scientific observing templates for future users of the hErschEL Observatory and has taken on a leading role in the development of the interactive data analysis for Pacs.
The launch date of the hErschEL Far-Infrared Space Telescope has been postponed by almost one year to the spring of 2008 owing to several technical difficulties encountered in fabricating the largest-yet space observatory. The novel 3.5m primary mirror – made of silicon carbide – showed large focus variations when it was cooled down to – 200 °C, and the three scientific instruments needed more time to optimize their extremely sensitive detector systems. (Dietrich Lemke, Stephan Birkmann, Helmut Dannerbauer, Ulrich Grözinger, Thomas Henning, Ralph Hofferbert, Ulrich Klaas, Jürgen Schreiber, Jutta Stegmaier, Manfred Stickel) IV.12 Pia – A Mainframe Computer for the MPIA Since September 2005, 264 processors and an efficient network at the Supercomputer Center in Garching are »glowing« exclusively for MPIA. With this new supercomputer, unprecedented processing power is available to MPIA researchers. With a total processing power of 1.1 teraflop, corresponding to 1 100 billion arithmetic operations per second, we just miss a place on the top 500 list of the worldwide fastest supercomputers. Hubert Klahr and Rachel Somerville, the leaders of the two theory groups at the MPIA, and Walter Rauh, head of computing at the MPIA, together devised the specifications for this computer and succeeded in getting it approved and largely financed by the computer advisory committee of the Max Planck Society (BAR). First scientific results obtained with this computer have already been published. The case history IV.12 Pia – A Mainframe Computer for the MPIA 107 Since the computing system Origin2000 was handed over to the Max Planck Computing Center in Garching, a 24-processor Beowulf cluster named Beehive with relatively slow Ethernet connections had been the most powerful computer available to theorists at the MPIA. In summer 2004, Stefan Hippler, together with Walter Rauh and Hubert Klahr, succeeded in procuring an upto-date 16-processor Opteron cluster with the help of the BAR. This mini-cluster comprises four modern Opteron quadboards with fast infiniband connections. However, soon these computing resources no longer sufficed, and MPIA researchers had to resort to external computing capacities. Above all, the simulation of turbulences in protoplanetary accretion disks is computationally very demanding. Here, the influence of turbulences on the formation of planets is investigated (cf. Chapter II.4: Planetesimal Formation by Gravitational Instability, p. 26 ff). However, the use of external computing resources always means narrow restrictions of computing time, a low priority compared to other users, and dependence on the goodwill of the operators of the computer facilities. In the spring of 2005, Rachel Somerville arrived at the MPIA to take over the theory group within the galaxy and cosmology department. Her simulations of galaxy evolution also depended on the use of mainframe computers. So the theory groups formed a strategic alliance, Fig. IV.12.1: The Pia cluster of the MPIA shortly after its commissioning at the computing center of the Max Planck Society in Garching. The middle rack contains in its lower part the 144port infiniband switch from Mellanox and in the upper part the two V40z access servers with the FC-Raid systems. The four other racks harbor 32 computer nodes (V20z) each.
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Max Planck Institute for Astronomy
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Contents Preface ..................
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6 I. General I.1 Scientific Goals U
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8 I. General massive protostars and
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10 I. General achieve higher angula
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12 I. General The institute is co-l
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14 I. General Point Source sensitiv
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16 I. General Edinburgh Groningen D
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18 II. Highlights II.1 Light Echoes
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20 II. Highlights 10 arcsec Fig. II
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22 II. Highlights AB Dor C AB Dor A
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24 II. Highlights II.3 The First He
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26 II. Highlights II.4 Planetesimal
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28 II. Highlights azimuthal directi
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30 II. Highlights ticles fall faste
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32 II. Highlights ANTU Seyfert 2 ga
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34 II. Highlights cretion disk, one
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36 II. Highlights 8.5 �m 2.3 ly 0
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38 II. Highlights II.6 Massive Star
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40 II. Highlights log M� /pc2 �
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42 II. Highlights II.7 Observations
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44 II. Highlights log IR luminosity
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46 II.8 Dynamics, Dust, and Young S
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48 II. Highlights and we see a temp
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50 III. Selected Research Areas III
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52 III. Scientific Work Fig. III.1.
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54 III. Scientific Work the Data Ar
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Page 112 and 113: 110 V. People and Events 1� 10�
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Page 152 and 153: 150 Conferences Conferences and Mee
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156 Publications Szalay, I. Szapudi
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158 Publications Hamilton, C. M., W
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160 Publications Brinkmann, D. G. Y
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162 Publications Zheng, X. Z., F. H
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164 Publications of the wheel mecha
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166 Publications ASP Conf. Ser. 331
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The Max Planck Society The Max Plan
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Max Planck Institute for Astronomy - Annual Report 2005

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