SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS
A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 14 - JULY 18, 2006
89 ASTRONOMY
Includes observations of celestial bodies; astronomical instruments and techniques; radio, gamma-ray, x-ray, ultraviolet, and infrared astronomy; and astrometry.
20060019302 Lawrence Livermore National Lab., Livermore, CA USA
Current and Future Searches for Dark Matter
Bauer, D. A.; January 2006; 14 pp.; In English Report No.(s): DE2006-875540; FERMILAB-CONF-05-438-E; No Copyright; Avail.: National Technical Information Service (NTIS)
Recent experimental data confirms that approximately one quarter of the universe consists of cold dark matter. Particle theories provide natural candidates for this dark matter in the form of either Axions or Weakly Interacting Massive Particles (WIMPs). A growing body of experiments is aimed at direct or indirect detection of particle dark matter. I summarize the current status of these experiments and offer projections of their future sensitivity. NTIS
Dark Matter; Extraterrestrial Matter; Weakly Interacting Massive Particles; Bosons
20060019310 Ohio Univ., Athens, OH, USA
Few-nucleon Systems in the Laboratory, Supernovae, and the Cosmos. (Report for July 15, 2004-September 1, 2005)
Phillips, D.; Jan. 2006; 20 pp.; In English Report No.(s): DE2006-862400; No Copyright; Avail.: National Technical Information Service (NTIS)
This report describes progress made on research projects associated with my Department of Energy Outstanding Junior Investigator grant. NTIS
Nucleons; Supernovae
20060019385 New Mexico Univ., Albuquerque, NM USA
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A Compact Supermassive Binary Black Hole System
Rodriguez, C; Taylor, G B; Zavala, R T; Peck, A B; Pollack, L K; Romani, R W; Apr 3, 2006; 35 pp.; In English; Original contains color illustrations Report No.(s): AD-A446245; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA446245; Avail.: CASI: A03, Hardcopy
We report on the discovery of a supermassive binary black hole system in the radio galaxy 0402+379, with a projected separation between the two black holes of just 7.3 pc. This is the closest black hole pair yet found by more than two orders of magnitude. These results are based upon recent multi-frequency observations using the Very Long Baseline Array (VLBA) which reveal two compact, variable, flat-spectrum, active nuclei within the elliptical host galaxy of 0402+379. Multiepoch observations from the VLBA also provide constraints on the total mass and dynamics of the system. Low spectral resolution spectroscopy using the Hobby-Eberly Telescope indicates two velocity systems with a combined mass of the two black holes of 1.5 108 M . The two nuclei appear stationary while the jets emanating from the weaker of the two nuclei appear to move out and terminate in bright hot spots. The discovery of this system has implications for the number of close binary black holes that might be sources of gravitational radiation. Green Bank Telescope observations at 22 GHz to search for water masers in this interesting system are also presented. DTIC
Black Holes (Astronomy); Galaxies
20060020124 Fermi National Accelerator Lab., Batavia, IL, USA
Office Software Framework of the Pierre Auger Observatory
Argiro, S.; Barroso, S. L.; Dagoret-Campagne, S.; Gonzalez, J.; Nellen, L.; January 2005; 8 pp.; In English Report No.(s): DE2006-875555; FERMILAB-CONF-05-311-E-TD; No Copyright; Avail.: Department of Energy Information Bridge
The Pierre Auger Observatory is designed to unveil the nature and origin of the highest energy cosmic rays through the analysis of extensive air showers. The large and geographically dispersed collaboration of physicists and the wide-ranging collection of simulation and reconstruction tasks pose some special challenges for the offline analysis software. They have designed and implemented a general purpose framework which allows Auger collaborators to contribute algorithms and configuration instructions to build up the variety of applications they require. The framework includes machinery to manage these user codes, to organize the abundance of user-contributed configuration files, to facilitate multi-format file handling, and to provide access to event and time-dependent detector information residing in many data sources. A number of utilities are also provided, including a novel geometry package allowing manipulation of abstract geometrical objects independent of coordinate system choice. The framework is implemented in C++ and takes advantage of object oriented design and common open source tools, while keeping the user-side simple enough for C++ novices to learn in a reasonable time. The distribution system incorporates unit and acceptance testing in order to support rapid development of both the core framework and the contributed user codes. NTIS
Computer Programs; Observatories
20060020126 Fermi National Accelerator Lab., Batavia, IL, USA
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Timing Calibration and Synchronization of Surface and Fluorescence Detectors of the Pierre Auger Observatory
Allison, P.; Bellido, J.; Bertou, X.; Covault, C. E.; Fick, B. E.; January 2005; 8 pp.; In English Report No.(s): DE2006-875553; FERMILAB-CONF-05-309-E-TD; No Copyright; Avail.: Department of Energy Information Bridge
Reconstruction of cosmic ray arrival directions for Surface Detectors (SD) and Fluorescence Detectors (FD) of the Pierre Auger Observatory requires accurate timing (25 nanoseconds or better) between measurements at individual detectors and instrument triggers. Timing systems for both SD and FD are based on Motorola Oncore UT+ GPS receivers installed into custom-built time-tagging circuits that are calibrated in the laboratory to a statistical precision of better than 15 ns.We describe timing calibration and synchronization methods applied in the field for both the SD and the FD systems in four areas: (1) checks of timing offsets within the SD using co-located station pairs and timing residuals on reconstructed showers, (2) calibration within the FD using a custom-build LED calibration system, (3) calibration between SD and FD using laser signals fed simultaneously into an SD station and across the FD via the Central Laser Facility (CLF), and (4) studies of synchronization between FD and SD through the analysis of events detected by both systems, called hybrid events. These hybrid events allow for a much more accurate reconstruction of the shower and for relatively tight constraints on timing calibration offsets. We demonstrate that statistical and systematic timing uncertainties have no significant impact on the event reconstruction. NTIS
Calibrating; Fluorescence; Observatories; Synchronism; Time Measurement
20060020128 Fermi National Accelerator Lab., Batavia, IL, USA
Atmospheric Aerosol Monitoring at the Pierre Auger Observatory
Cester, R.; Chiosso, M.; Chirin, J.; Clay, R.; Dawson, B.; January 2005; 8 pp.; In English Report No.(s): DE2006-875560; FERMILAB-CONF-05-293-TD; No Copyright; Avail.: Department of Energy Information Bridge
For a ground based cosmic-ray observatory the atmosphere is an integral part of the detector. Air fluorescence detectors (FDs) are particularly sensitive to the presence of aerosols in the atmosphere. These aerosols, consisting mainly of clouds and dust, can strongly affect the propagation of fluorescence and Cherenkov light from cosmic-ray induced extensive air showers. The Pierre Auger Observatory has a comprehensive program to monitor the aerosols within the atmospheric volume of the detector. In this paper the aerosol parameters that affect FD reconstruction will be discussed. The aerosol monitoring systems that have been deployed at the Pierre Auger Observatory will be briefly described along with some measurements from these systems. NTIS
Aerosols; Environmental Monitoring; Observatories
20060020129 Fermi National Accelerator Lab., Batavia, IL, USA
Trigger System of the Pierre Auger Surface Detector: Operation, Efficiency and Stability
Allard, D.; Armengaud, E.; Allekotte, I.; Allison, P.; Aublin, J.; January 2005; 8 pp.; In English Report No.(s): DE2006-875552; FERMILAB-CONF-05-310-E-TD; No Copyright; Avail.: Department of Energy Information Bridge
The trigger system of the Surface Detector (SD) of the Pierre Auger Observatory is described, from the identification of candidate showers (E \g 1 EeV) at the level of a single station, among a huge background (mainly single muons), up to the selection of real events and the rejection of random coincidences at a higher central trigger level (including the reconstruction accuracy). Efficiency of a single station trigger is evaluated using real data, and the high performance of event selection hierarchy will be demonstrated. NTIS
Actuators; Observatories; Stability
20060020130 Fermi National Accelerator Lab., Batavia, IL, USA
Angular Resolution of the Pierre Auger Observatory
Bonifazi, C.; January 2005; 8 pp.; In English Report No.(s): DE2006-875550; FERMILAB-CONF-05-301-E-TD; No Copyright; Avail.: Department of Energy Information Bridge
We studied the angular resolution of the Pierre Auger Detector using data collected from January 2004 to May 2005. The detector consists of two independent components, the fluorescence detector and the surface detector. Hybrid events, observed simultaneously by both components, have smaller reconstruction uncertainties than the events observed with only one component. The hybrid resolution is extracted from artificial showers generated by laser shots, while the surface detector angular accuracy is then determined from the comparison of the hybrid geometrical fit with the one obtained from the surface detector alone. We used adjacent surface detector stations to cross check our methods. The angular reconstruction accuracy of the surface detector events is given as a function of station multiplicity. NTIS
Angular Resolution; Observatories
20060020131 Fermi National Accelerator Lab., Batavia, IL, USA, Chicago Univ., Chicago, IL USA
New Technique to Measure Cosmic Ray Energy and Composition Via (2+1)d Lateral Distribution Function Fits to Surface Detector Array Data
Chou, A. S.; Pernas, M. D.; Yamamoto, T.; January 2005; 8 pp.; In English Report No.(s): DE2006-875551; FERMILAB-CONF-05-295-E; No Copyright; Avail.: Department of Energy Information Bridge
The concept of a one-dimensional lateral distribution function is extended to a set of (2+1)d functions which describe the spatial and temporal distributions of the muonic and electromagnetic components of extended air showers. By design, these functions incorporate the curvature and time structure of the shower front as well as the asymmetries in particle density and in time structure expected in inclined showers. These observables are sensitive to the mass of the primary cosmic ray and to the details of the hadronic interactions inducing the air shower. The (2+1)d functions smoothly interpolate between the values of X(sub max) and muon flux predicted by various simulations performed with different assumptions of primary composition and interaction model. A maximum likelihood fit to surface detector array data can then give simultaneous event-by-event measurements of the shower energy, X(sub max), and the muon content, from which the primary composition may subsequently be inferred. The methods outlined are applicable to a large number of existing and future shower detector arrays covering a range of energies. NTIS
Cosmic Rays; Distribution Functions
20060020132 Fermi National Accelerator Lab., Batavia, IL, USA
Studies of Signal Waveforms From the Water-Cherenkov Detectors of the Pierre Auger Observatory
Allison, P. S.; Bui-Duc, H.; Chye, J.; Dagoret-Campagne, S.; Dorofeev, A.; January 2005; 8 pp.; In English Report No.(s): DE2006-875556; No Copyright; Avail.: National Technical Information Service (NTIS)
The ground array of the Pierre Auger Observatory will consist of 1600 water-Cherenkov detectors. Such detectors give signals which can help differentiate between muons and electrons in extensive air showers. The relative numbers of muons and electrons is sensitive to the type of primary particle which initiated the shower. Results are presented using methods which describe the muon content and related information, such as the time structure of the shower front. NTIS
Observatories; Water; Waveforms
20060020745 NASA Johnson Space Center, Houston, TX, USA
Ar-Ar Age of Shergottite Dhofar 378: Formation or Early Shock Event?
Park, J.; Bogard, Don D.; [2006]; 2 pp.; In English; 69th Meeting of the Meteoritical Society, 6-11 Aug. 2006, Zurich, Switzerland; No Copyright; Avail.: CASI: A01, Hardcopy
The Ar-39-Ar40 data for 16 stepwise temperature extractions of mixed mesostasis plus plagioclase show the following major characteristics. Changes in the K/Ca ratio and in the differential rate of Ar-39 release with extraction temperature suggest three distinct, but overlapping Ar diffusion domains: \h13%, 13-45%, and \g45% cumulative Ar-39 release:. The youngest Ar-Ar age, approx.162-165 Myr is observed at approx.28-40% Ar-39 release, which we attribute primarily to the mesostasis. Extractions releasing \g45% Ar-39, probably from plagioclase, suggest older Ar-Ar ages and indicate release of trapped martian Ar-40. An isochron plot for 8 extractions, releasing 3-45% of the Ar-39 and corrected for 36Arcos using directly measured 36Arcos, gives an Ar-Ar age of 143+/-4 Myr (where the +/- ignores the uncertainty in applying a correction for Ar-36cos). Applying a correction assuming only one-half of the measured Ar-36cos gives an age of 159+/-2 Myr. Correcting for cos-Ar-36 using the minimum measured Ar-36/Ar-37 ratio gives a minimum possible age of 138+/-5 Myr. All of these ages are within combined uncertainties of the Sm-Nd age of 157+/-24 Myr [4]. The trapped Ar-40/Ar-36 ratio obtained from the isochron is largely defined by the highest [K] data. Author
Argon Isotopes; Diffusion; Mars (Planet); Shergottites; Plagioclase
20060021473 NASA Ames Research Center, Moffett Field, CA, USA
Formation of the giant planets
Lissauer, Jack J.; [2006]; 1 pp.; In English; Planetary Science: Challenghes and Discoveries, 28 May - 2 Jun. 2006, lois, France; No Copyright; Avail.: Other Sources; Abstract Only
The observed properties of giant planets, models of their evolution and observations of protoplanetary disks provide constraints on the formation of gas giant planets. The four largest planets in our Solar System contain considerable quantities of hydrogen and helium, which could not have condensed into solid planetesimals within the protoplanetary disk. All three (transiting) extrasolar giant planets with well determined masses and radii also must contain substantial amounts of these light gases. Jupiter and Saturn are mostly hydrogen and helium, but have larger abundances of heavier elements than does the Sun. Neptune and Uranus are primarily composed of heavier elements. HD 149026 b, which is slightly more massive than is Saturn, appears to have comparable quantities of light gases and heavy elements. HD 209458 b and TrES-1 are primarily hydrogen and helium, but may contain supersolar abundances of heavy elements. Spacecraft flybys and observations of satellite orbits provide estimates of the gravitational moments of the giant planets in our Solar System, which in turn provide information on the internal distribution of matter within Jupiter, Saturn, Uranus and Neptune. Atmospheric thermal structure and heat flow measurements constrain the interior temperatures of planets. Internal processes may cause giant planets to become morecompositionally differentiated or alternatively more homogeneous; high-pressure laboratory .experiments provide data useful for modeling these processes. The preponderance of evidence supports the core nucleated gas accretion model. According to this model, giant planets begin their growth by the accumulation of small solid bodies, as do terrestrial planets. However, unlike terrestrial planets, the growing giant planet cores become massive enough that they are able to accumulate substantial amounts of gas before the protoplanetary disk dissipates. The primary questions regarding the core nucleated growth model is under what conditions planets with small cores/total heavy element abundances can accrete gaseous envelopes within the lifetimes of gaseous protoplanetary disks. Author
Gas Giant Planets; Protoplanetary Disks; Planetary Evolution; Helium; Hydrogen; Extrasolar Planets
Source: NASA
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