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We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

ARM - Field Campaign - International Pyrgeometer Intercomparison  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Working Group hosted an International Pyrgeometer Intercomparison among Baseline Surface Radiation Network (BSRN) members September 20 - October 1, 1999. The comparison actually...

2

Uncertainty Estimates for SIRS, SKYRAD, & GNDRAD Data and Reprocessing the Pyrgeometer Data (Presentation)  

SciTech Connect (OSTI)

The National Renewable Energy Laboratory (NREL) and the Atmospheric Radiation Measurement (ARM) Climate Research Facility work together in providing data from strategically located in situ measurement observatories around the world. Both work together in improving and developing new technologies that assist in acquiring high quality radiometric data. In this presentation we summarize the uncertainty estimates of the ARM data collected at the ARM Solar Infrared Radiation Station (SIRS), Sky Radiometers on Stand for Downwelling Radiation (SKYRAD), and Ground Radiometers on Stand for Upwelling Radiation (GNDRAD), which ultimately improve the existing radiometric data. Three studies are also included to show the difference between calibrating pyrgeometers (e.g., Eppley PIR) using the manufacturer blackbody versus the interim World Infrared Standard Group (WISG), a pyrgeometer aging study, and the sampling rate effect of correcting historical data.

Reda, I.; Stoffel, T.; Habte, A.

2014-03-01T23:59:59.000Z

3

AMIE (ACRF MJO Investigation Experiment)  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

AMIE AMIE (ACRF MJO Investigation Experiment) Planning Meeting AMIE Science Steering Committee Chuck Long, Tony DelGenio, Bill Gustafson, Bob Houze, Mike Jensen, Steve Klein, Ruby Leung, Xaihong Liu, Ed Luke, Peter May, Sally McFarlane, Pat Minnis, Courtney Schumacher, Andy Vogelmann, Yi Wang, Xiaoqing Wu, Shaohong Xie Agenda * Proposal due May 1 !!!!!! * Primary purpose of this meeting is discussions and planning in support of

4

Microsoft PowerPoint - ARM_pyrgeometer.ppt  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

ARM-05-111 ARM-05-111 2 Outline * Why the need for longwave data restriction? - Important Considerations and the 12 Wm -2 longwave results problem * What ARM data are effected? - List of station-dates * Can the data be adjusted? - Using available 20-sec data samples * How is ARM addressing pyrgeometer calibration? - In search of a measurement reference * References * Acronyms * Appendix - Fundamentals of pyrgeometer operation and calibration 3 Why a Data Access Restriction? The ARM Program's data quality control measures discovered an unexpected shift in the time series of longwave irradiance data. This followed a change in pyrgeometer calibration procedures for field instruments deployed at all SIRS, SKYRAD, and GNDRAD installations beginning in August 2002 and completed in March 2004.

5

E-Print Network 3.0 - acrf instrumentation status Sample Search...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

that measure solar and terrestrial... in April 2002. 4. INSTRUMENT AND SITE MAINTENANCE ACRF field technicians, under the guidance of site opera... all ACRF sites; its...

6

Finite Cloud Effects at the ACRF TWP Site Patrick Taylor and...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Finite Cloud Effects at the ACRF TWP Site Patrick Taylor and Robert G. Ellingson Dept. of Meteorology, Florida State University, Tallahassee, FL 32306 Data: Observations are...

7

Atmospheric Radiation Measurement Climate Research Facility (ACRF) Annual Report 2007  

SciTech Connect (OSTI)

This annual report describes the purpose and structure of the program, and presents key accomplishments in 2007. Notable achievements include: • Successful review of the ACRF as a user facility by the DOE Biological and Environmental Research Advisory Committee. The subcommittee reinforced the importance of the scientific impacts of this facility, and its value for the international research community. • Leadership of the Cloud Land Surface Interaction Campaign. This multi-agency, interdisciplinary field campaign involved enhanced surface instrumentation at the ACRF Southern Great Plains site and, in concert with the Cumulus Humilis Aerosol Processing Study sponsored by the DOE Atmospheric Science Program, coordination of nine aircraft through the ARM Aerial Vehicles Program. • Successful deployment of the ARM Mobile Facility in Germany, including hosting nearly a dozen guest instruments and drawing almost 5000 visitors to the site. • Key advancements in the representation of radiative transfer in weather forecast models from the European Centre for Medium-Range Weather Forecasts. • Development of several new enhanced data sets, ranging from best estimate surface radiation measurements from multiple sensors at all ACRF sites to the extension of time-height cloud occurrence profiles to Niamey, Niger, Africa. • Publication of three research papers in a single issue (February 2007) of the Bulletin of the American Meteorological Society.

LR Roeder

2007-12-01T23:59:59.000Z

8

UPDATED AND IMPROVED ACRF GIS DATA AND MAPS A. Cialella and R. Wagener  

E-Print Network [OSTI]

UPDATED AND IMPROVED ACRF GIS DATA AND MAPS A. Cialella and R. Wagener For presentation at the ARM and improvements to the ACRF geographic information system (GIS) database will be presented, including land use, and hydrography. Ultimately the data will be used to create hyperlinked maps on the ARM Web page, with each

9

Atmospheric Radiation Measurement Climate Research Facility (ACRF) Annual Report 2008  

SciTech Connect (OSTI)

The Importance of Clouds and Radiation for Climate Change: The Earth’s surface temperature is determined by the balance between incoming solar radiation and thermal (or infrared) radiation emitted by the Earth back to space. Changes in atmospheric composition, including greenhouse gases, clouds, and aerosols, can alter this balance and produce significant climate change. Global climate models (GCMs) are the primary tool for quantifying future climate change; however, there remain significant uncertainties in the GCM treatment of clouds, aerosol, and their effects on the Earth’s energy balance. In 1989, the U.S. Department of Energy (DOE) Office of Science created the Atmospheric Radiation Measurement (ARM) Program to address scientific uncertainties related to global climate change, with a specific focus on the crucial role of clouds and their influence on the transfer of radiation in the atmosphere. To reduce these scientific uncertainties, the ARM Program uses a unique twopronged approach: • The ARM Climate Research Facility, a scientific user facility for obtaining long-term measurements of radiative fluxes, cloud and aerosol properties, and related atmospheric characteristics in diverse climate regimes; and • The ARM Science Program, focused on the analysis of ACRF and other data to address climate science issues associated with clouds, aerosols, and radiation, and to improve GCMs. This report provides an overview of each of these components and a sample of achievements for each in fiscal year (FY) 2008.

LR Roeder

2008-12-01T23:59:59.000Z

10

Results of First Outdoor Comparison Between Absolute Cavity Pyrgeometer (ACP) and Infrared Integrating Sphere (IRIS) Radiometer at PMOD (Presentation)  

SciTech Connect (OSTI)

The ACP and IRIS are developed to establish a world reference for calibrating pyrgeometers with traceability to SI units. The two radiometers are unwindowed with negligible spectral dependence, and traceable to SI units through the temperature scale (ITS-90). The first outdoor comparison between the two designs was held from January 28 to February 8, 2013 at the Physikalisch-Metorologisches Observatorium Davos (PMOD). The difference between the irradiance measured by ACP and that of IRIS was within 1 W/m2. A difference of 5 W/m2 was observed between the irradiance measured by ACP&IRIS and that of the interim World Infrared Standard Group (WISG).

Reda, I.; Grobner, J.; Wacker, S.; Stoffel, T.

2013-03-01T23:59:59.000Z

11

DOE/SC-ARM/P-07-002.3 ACRF Instrumentation Status: New, Current, and Future  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

3 3 ACRF Instrumentation Status: New, Current, and Future March 2007 James Liljegren ACRF Instrument Team Coordinator Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Summary The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Program Climate Research Facility instrumentation status. The report is divided into four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) Small Business Innovation Research instrument development. New information is highlighted in

12

Seasonal And Decadal Variation of the Mixed Layer Across the ACRF Using RWP Data  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Seasonal And Decadal Variation of the Mixed Layer Seasonal And Decadal Variation of the Mixed Layer Across the ACRF Using RWP Data Richard Coulter, Barry Lesht, and Brad Orr Argonne National Laboratory, Argonne, IL INTRODUCTION The radar wind profilers (RWPs) located at the ACRF Southern Great Plains site have been collecting data for more than a decade at the intermediate facilities (I1: Beaumont, KS; I2: Medicine Lodge, KS; I3 Meeker OK) and 15 years at the Central Facility. They provide a good picture of the temporal and spatial variation across the SGP site over this time period Here we elucidate the variation of the height of the mixed layer (z i ) and precipitation, two parameters that illustrate the potential richness of the wind profiler data beyond wind profiles. Daytime Mixed Layer An automated routine, operating

13

Use of Long Time-series ACRF Measurements to Improve Data Quality Analysis  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

2, 2008 2, 2008 Eighteenth ARM Science Team Meeting 1 Use of Long Time-Series ACRF Measurements to Improve Data Quality Analysis Sean Moore Mission Research and Technical Services Santa Barbara, CA ARM Data Quality Office University of Oklahoma Norman, OK March 12, 2008 Eighteenth ARM Science Team Meeting 2 ARM Data Quality Office Full Time Staff *Ken Kehoe *Randy Peppler *Karen Sonntag *Justin Monroe Student Analysts *Nathan Hiers (Sr) *Stephen Mullens (Sr) *Kimberly Rabon (Jr) *Lacey Evans (Jr) ARM Data Quality Office, National Weather Center The University of Oklahoma, Norman, OK Sean Moore Mission Research and Technical Services Santa Barbara, CA March 12, 2008 Eighteenth ARM Science Team Meeting 3 Daily Quality Checks * Automated software checks every measurement for outliers against some pre-defined limits.

14

Initial Evaluation of the Cumulus Potential Scheme at the ACRF SGP Site  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Meeting, Meeting, 12 March 2008 Initial Evaluation of the Cumulus Potential Scheme at the ACRF SGP Site Larry K. Berg, William I. Gustafson Jr., and Evgueni I. Kassianov Pacific Northwest National Laboratory ARM Science Team Meeting, 12 March 2008 Where are We Going? Development Simulation Evaluation Observations ARM Science Team Meeting, 12 March 2008 Development: Coupling Clouds to the Convective Boundary Layer * Shallow cumuli are turbulently coupled to the planetary boundary layer 4 3 2 1 0 Height (km) 6 5 4 3 2 1 0 Distance (km) Simulation courtesy of M. Ovtchinnikov ARM Science Team Meeting, 12 March 2008 Development: Coupling Clouds to the Convective Boundary Layer * Parameterization should represent this coupling * The Cumulus Potential (CuP) scheme is one way - Accounts for sub-grid

15

An electronic radiation of blackbody: Cosmic electron background  

E-Print Network [OSTI]

The Universe owns the electronic radiation of blackbody at temperature 2.725 K, which we call the cosmic electron background. We calculate its radiation spectrum. The energy distribution of number density of electrons in the cosmic electron background becomes zero as energy goes to both zero and infinity. It has one maximum peak near the energy level of 10**(-23) J.

Jian-Miin Liu

2008-02-23T23:59:59.000Z

16

A new compact fixed-point blackbody furnace  

SciTech Connect (OSTI)

More and more NMIs are realizing their primary scale themselves with fixed-point blackbodies as their reference standard. However, commercially available fixed-point blackbody furnaces of sufficient quality are not always easy to obtain. CHINO Corp. and NMIJ, AIST jointly developed a new compact fixed-point blackbody furnace. The new furnace has such features as 1) improved temperature uniformity when compared to previous products, enabling better plateau quality, 2) adoption of the hybrid fixed-point cell structure with internal insulation to improve robustness and thereby to extend lifetime, 3) easily ejectable and replaceable heater unit and fixed-point cell design, leading to reduced maintenance cost, 4) interchangeability among multiple fixed points from In to Cu points. The replaceable cell feature facilitates long term maintenance of the scale through management of a group of fixed-point cells of the same type. The compact furnace is easily transportable and therefore can also function as a traveling standard for disseminating the radiation temperature scale, and for maintaining the scale at the secondary level and industrial calibration laboratories. It is expected that the furnace will play a key role of the traveling standard in the anticipated APMP supplementary comparison of the radiation thermometry scale.

Hiraka, K.; Oikawa, H.; Shimizu, T.; Kadoya, S.; Kobayashi, T. [CHINO CORPORATION, Itabashi, Tokyo (Japan)] [CHINO CORPORATION, Itabashi, Tokyo (Japan); Yamada, Y.; Ishii, J. [National Metrology Institute of Japan, AIST, Tsukuba, Ibaraki (Japan)] [National Metrology Institute of Japan, AIST, Tsukuba, Ibaraki (Japan)

2013-09-11T23:59:59.000Z

17

Are GRB Blackbodies an Artifact of Spectral Evolution?  

E-Print Network [OSTI]

The analysis of gamma-ray burst (GRB) spectra with multi-component emission models has become an important part of the field. In particular, multi-component analysis where one component is a blackbody representing emission from a photosphere has enabled both a more detailed understanding of the energy content of the jet as well as the ability to examine the dynamic structure of the outflow. While the existence of a blackbody-like component has been shown to be significant and not a byproduct of background fluctuations, it is very possible that it can be an artifact of spectral evolution of a single component that is being poorly resolved in time. Herein, this possibility is tested by simulating a single component evolving in time and then folding the spectra through the $Fermi$ detector response to generate time-tagged event Gamma-ray Burst Monitor (GBM) data. We then fit both the time integrated and resolved generated spectral data with a multi-component model using standard tools. It is found that in {\\it t...

Burgess, J Michael

2014-01-01T23:59:59.000Z

18

Measurements of Martin-Puplett Interferometer Limitations using Blackbody Source  

SciTech Connect (OSTI)

Frequency domain measurements with Martin-Puplett interferometer is one of a few techniques capable of bunch length measurements at the level of ~ 100 fs. As the bunch length becomes shorter, it is important to know and be able to measure the limitations of the instrument in terms of shortest measurable bunch length. In this paper we describe an experiment using a blackbody source with the modified Martin-Puplett interferometer that is routine- ly used for bunch length measurements at the JLab FEL, as a way to estimate the shortest, measurable bunch length. The limitation comes from high frequency cut-off of the wire-grid polarizer currently used and is estimated to be 50 fs RMS. The measurements are made with the same Golay cell detector that is used for beam measure- ments. We demonstrate that, even though the blackbody source is many orders of magnitude less bright than the coherent transition or synchrotron radiation, it can be used for the measurements and gives a very good signal to noise ratio in combination with lock-in detection. We also compare the measurements made in air and in vacuum to characterize the very strong effect of the atmospheric absorption.

Evtushenko, Pavel E. [JLAB; Klopf, John M. [JLAB

2013-06-01T23:59:59.000Z

19

Tackling the blackbody shift in a strontium optical lattice clock  

E-Print Network [OSTI]

A major obstacle for optical clocks is the frequency shift due to black body radiation. We discuss how one can tackle this problem in an optical lattice clock; in our case 87-Sr: firstly, by a measurement of the dc Stark shift of the clock transition and, secondly, by interrogating the atoms in a cryogenic environment. Both approaches rely on transporting ultracold atoms over several cm within a probe cycle. We evaluate this approach of mechanically moving the optical lattice and conclude that it is feasible to transport the atoms over 50 mm within 300 ms. With this transport a dc Stark shift measurement will allow to reduce the contribution of the blackbody radiation to the fractional uncertainty below 2 Ã? 10^â??17 at room temperature by improving the shift coefficient known only from atomic structure calculations up to now. We propose a cryogenic environment at 77 K that will reduce this contribution to few parts in 10^â??18.

Middelmann, Thomas; Falke, Stephan; Winfred, Joseph S R Vellore; Riehle, Fritz; Sterr, Uwe

2010-01-01T23:59:59.000Z

20

Tackling the blackbody shift in a strontium optical lattice clock  

E-Print Network [OSTI]

A major obstacle for optical clocks is the frequency shift due to black body radiation. We discuss how one can tackle this problem in an optical lattice clock; in our case 87-Sr: firstly, by a measurement of the dc Stark shift of the clock transition and, secondly, by interrogating the atoms in a cryogenic environment. Both approaches rely on transporting ultracold atoms over several cm within a probe cycle. We evaluate this approach of mechanically moving the optical lattice and conclude that it is feasible to transport the atoms over 50 mm within 300 ms. With this transport a dc Stark shift measurement will allow to reduce the contribution of the blackbody radiation to the fractional uncertainty below 2 * 10^-17 at room temperature by improving the shift coefficient known only from atomic structure calculations up to now. We propose a cryogenic environment at 77 K that will reduce this contribution to few parts in 10^-18.

Thomas Middelmann; Christian Lisdat; Stephan Falke; Joseph S. R. Vellore Winfred; Fritz Riehle; Uwe Sterr

2010-09-10T23:59:59.000Z

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

The Status of the ACRF Millimeter Wave Cloud Radars (MMCRs), the Path Forward for Future MMCR Upgrades, the Concept of 3D Volume Imaging Radar and the UAV Radar  

SciTech Connect (OSTI)

The United States (U.S.) Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) operates millimeter wavelength cloud radars (MMCRs) in several climatological regimes. The MMCRs, are the primary observing tool for quantifying the properties of nearly all radiatively important clouds over the ACRF sites. The first MMCR was installed at the ACRF Southern Great Plains (SGP) site nine years ago and its original design can be traced to the early 90s. Since then, several MMCRs have been deployed at the ACRF sites, while no significant hardware upgrades have been performed. Recently, a two-stage upgrade (first C-40 Digital Signal Processors [DSP]-based, and later the PC-Integrated Radar AcQuisition System [PIRAQ-III] digital receiver) of the MMCR signal-processing units was completed. Our future MMCR related goals are: 1) to have a cloud radar system that continues to have high reliability and uptime and 2) to suggest potential improvements that will address increased sensitivity needs, superior sampling and low cost maintenance of the MMCRs. The Traveling Wave Tube (TWT) technology, the frequency (35-GHz), the radio frequency (RF) layout, antenna, the calibration and radar control procedure and the environmental enclosure of the MMCR remain assets for our ability to detect the profile of hydrometeors at all heights in the troposphere at the ACRF sites.

P Kollias; MA Miller; KB Widener; RT Marchand; TP Ackerman

2005-12-30T23:59:59.000Z

22

Aqueous blackbody calibration source for millimeter-wave/terahertz metrology  

SciTech Connect (OSTI)

This paper describes a calibrated broadband emitter for the millimeter-wave through terahertz frequency regime, called the aqueous blackbody calibration source. Due to its extremely high absorption, liquid water is chosen as the emitter on the basis of reciprocity. The water is constrained to a specific shape (an optical trap geometry) in an expanded polystyrene (EPS) container and maintained at a selected, uniform temperature. Uncertainty in the selected radiometric temperature due to the undesirable reflectance present at a water interface is minimized by the trap geometry, ensuring that radiation incident on the entrance aperture encounters a pair of s and a pair of p reflections at 45 deg. . For water reflectance Rw of 40% at 45 deg. in W-band, this implies a theoretical effective aperture emissivity of (1-R{sup 2}wsR{sup 2}wp)>98.8%. From W-band to 450 GHz, the maximum radiometric temperature uncertainty is {+-}0.40 K, independent of water temperature. Uncertainty from 450 GHz to 1 THz is increased due to EPS scattering and absorption, resulting in a maximum uncertainty of -3 K at 1 THz.

Dietlein, Charles; Popovic, Zoya; Grossman, Erich N

2008-10-20T23:59:59.000Z

23

Negative Ion Electron Photodetachment from a Near-Blackbody Photon Source  

Science Journals Connector (OSTI)

Negative Ion Electron Photodetachment from a Near-Blackbody Photon Source ... 12-15 For most negative ions, the ambient flux of photons from other sources, including the cell walls and the filament used in ion generation, is too small to be significant. ... When the filament voltage is pulsed negative, electrons from the heated filament are temporarily accelerated toward the adjacent trapping plate and into the cell, producing negative ions via dissociative attachment with neutral molecules. ...

Gordon A. Janaway; John I. Brauman

2000-01-21T23:59:59.000Z

24

An atomic clock with $1\\times 10^{-18}$ room-temperature blackbody Stark uncertainty  

E-Print Network [OSTI]

The Stark shift due to blackbody radiation (BBR) is the key factor limiting the performance of many atomic frequency standards, with the BBR environment inside the clock apparatus being difficult to characterize at a high level of precision. Here we demonstrate an in-vacuum radiation shield that furnishes a uniform, well-characterized BBR environment for the atoms in an ytterbium optical lattice clock. Operated at room temperature, this shield enables specification of the BBR environment to a corresponding fractional clock uncertainty contribution of $5.5 \\times 10^{-19}$. Combined with uncertainty in the atomic response, the total uncertainty of the BBR Stark shift is now $1\\times10^{-18}$. Further operation of the shield at elevated temperatures enables a direct measure of the BBR shift temperature dependence and demonstrates consistency between our evaluated BBR environment and the expected atomic response.

Beloy, K; Phillips, N B; Sherman, J A; Schioppo, M; Lehman, J; Feldman, A; Hanssen, L M; Oates, C W; Ludlow, A D

2014-01-01T23:59:59.000Z

25

Radiometric characterization of a high temperature blackbody in the visible and near infrared  

SciTech Connect (OSTI)

At the Physikalisch-Technische Bundesanstalt the radiance temperature in the range from 962 °C to 3000 °C is disseminated by applying a high temperature blackbody (HTBB) with a directly heated pyrolytic graphite cavity. The thermodynamic radiance temperature of the HTBB was measured in the temperature range from 1000 °C to 3000 °C by applying almost simultaneously absolutely calibrated silicon photodiode based filter radiometers with centre wavelengths at 476 nm, 676 nm, 800 nm, 900 nm and 1000 nm and InGaAs photodiode based filter radiometers with centre wavelengths at 1300 nm, 1550 nm and 1595 nm. The results demonstrate that, expressed in terms of irradiance, within an uncertainty of 0.1 % (k=1) in a broad wavelength range the thermodynamic radiance temperature of the HTBB is wavelength independent in the investigated temperature interval.

Taubert, R. D.; Hollandt, J. [Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, D-10587 Berlin (Germany)] [Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, D-10587 Berlin (Germany)

2013-09-11T23:59:59.000Z

26

ACRF Newsletter_May_FINAL  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Point Reyes is located at the edge of an abrupt and steep continental margin where cold ocean currents rise up from the ocean bottom. The ocean provides the moisture, and cold...

27

Analysis of residual spectra and the monopole spectrum for 3 K blackbody radiation by means of non-extensive thermostatistics  

E-Print Network [OSTI]

We analyze residual spectra of 3 K blackbody radiation (CMB) using non-extensive thermostatistics with a parameter q-1. The limits of |q-1|<1.2x10^{-5} and the temperature fluctuation |delta T|<(1.6-4.3)x10^{-5} are smaller than those by Tsallis et al. Moreover, analyzing the monopole spectrum by a formula including the chemical potential mu, we obtain the limits |q-1|<2.3x10^{-5} and |mu|<1.6x10^{-4}. |q-1| is comparable with the Sunyaev-Zeldovich effect y.

Minoru Biyajima; Takuya Mizoguchi

2012-10-22T23:59:59.000Z

28

Slide 1  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

in the in the Blackbody Calibration of Pyrgeometers By Ibrahim Reda, Julian Gröbner * , Tom Stoffel, Daryl Myers, and Bruce Forgan ** Eighteenth Atmospheric Radiation Measurement (ARM) Program Science Team Meeting *Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center (PMOD/WRC) ** Bureau of Meteorology, Australia Abstract Pyrgeometers are used to measure the atmospheric longwave irradiance through out the ARM program sites. Previous calibrations of pyrgeometers using ARM/Eppley/NREL blackbody were consistent, but introduced a difference in the historical clear sky measured irradiance. This difference was believed to be in the order of 12 W/m 2 . In this poster we show the improvements to the blackbody and calibration methodology by comparing our

29

PowerPoint Presentation  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

c Improvements in the Blackbody Calibration of Pyrgeometers Ibrahim Reda 1 Julian Gröbner 2 Tom Stoffel 1 Daryl Myers 1 Bruce Forgan 3 1. National Renewable Energy Laboratory (NREL) 2. Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center (PMOD/WRC) 3. Bureau of Meteorology, Australia Abstract Pyrgeometers are used to measure the atmospheric longwave irradiance through out the ARM program sites. Previous calibrations of pyrgeometers using ARM/Eppley/NREL blackbody were consistent, but introduced a difference in the historical clear sky measured irradiance. This difference was believed to be in the order of 12 W/m 2 . In this poster we show the improvements to the blackbody and calibration methodology by comparing our results to the

30

ACRF Data Collection and Processing Infrastructure  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

raw data stream and netCDF data stream will be similar, for obvious reasons. The ingest process is also responsible for correctly naming the raw file. This cannot be done earlier...

31

One-Loop Dominance in the Imaginary Part of the Polarizability: Application to Blackbody and Non-Contact van der Waals Friction  

E-Print Network [OSTI]

Phenomenologically important quantum dissipative processes include black-body friction (an atom absorbs counterpropagating blue-shifted photons and spontaneously emits them in all directions, losing kinetic energy) and non-contact van der Waals friction (in the vicinity of a dielectric surface, the mirror charges of the constituent particles inside the surface experience drag, slowing the atom). The theoretical predictions for these processes are modified upon a rigorous quantum electrodynamic (QED) treatment, which shows that the one-loop "correction" yields the dominant contribution to the off-resonant, gauge-invariant, imaginary part of the atom's polarizability at room temperature, for typical atom-surface interactions. The tree-level contribution to the polarizability dominates at high temperature.

U. D. Jentschura; G. Lach; M. De Kieviet; K. Pachucki

2014-11-11T23:59:59.000Z

32

reda(1)-99.PDF  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Pyrgeometer Calibrations for the ARM Program Pyrgeometer Calibrations for the ARM Program I. Reda, T. L. Stoffel, and J. A. Treadwell National Renewable Energy Laboratory Golden, Colorado J. Hickey The Eppley Laboratory, Inc. Newport, Rhode Island Introduction Pyrgeometers are used to measure the longwave radiation. Accurate measurements from these radiometers require regular calibration using temperature controlled blackbody radiators. The National Renewable Energy Laboratory (NREL) and The Eppley Laboratory, Inc. (EPLAB) are developing a new automated system for calibrating EPLAB Precision Infrared Radiometers (PIRs) for the Atmospheric Radiation Measurement (ARM) Program. Test results from the prototype system, now at NREL, will be used to develop a production version for deployment at the Southern Great Plains (SGP) Radiometer

33

ACRF Instrumentation Status: New, Current, and Future January 2007  

SciTech Connect (OSTI)

The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Program Climate Research Facility instrumentation status. The report is divided into four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) Small Business Innovation Research instrument development.

JC Liljegren

2007-01-01T23:59:59.000Z

34

Study of AC/RF properties of SRF ingot niobium  

SciTech Connect (OSTI)

In an attempt to correlate the performance of superconducting radiofrequency cavities made of niobium with the superconducting properties, we present the results of the magnetization and ac susceptibility of the niobium used in the superconducting radiofrequency cavity fabrication. The samples were subjected to buffer chemical polishing (BCP) surface and high temperature heat treatments, typically applied to the cavities fabrications. The analysis of the results show the different surface and bulk ac conductivity for the samples subjected to BCP and heat treatment. Furthermore, the RF surface impedance is measured on the sample using a TE011 microwave cavity for a comparison to the low frequency measurements.

Dhakal, Pashupati; Tsindlekht, Menachem I.; Genkin, Valery M.; Ciovati, Gianluigi; Myneni, Ganapati Rao

2013-09-01T23:59:59.000Z

35

Near-Blackbody Enclosed Particle Receiver  

Broader source: Energy.gov [DOE]

This presentation was delivered at the SunShot Concentrating Solar Power (CSP) Program Review 2013, held April 23–25, 2013 near Phoenix, Arizona.

36

Near-Blackbody Enclosed Particle Receiver  

Broader source: Energy.gov (indexed) [DOE]

Li, Austin Fleming, Charlie Folsom, Zhifen Wang (USU); Merrill Wilson (Ceramatec); Brain Koeppel (PNNL); Dana Goski, Matt Lambert (Allied Mineral). Project Objectives ...

37

Microsoft Word - ACRF4thQuarterFY09 draft_nb__sal.doc  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

6 6 Atmospheric Radiation Measurement Program Climate Research Facility Operations Quarterly Report July 1 - September 30, 2009 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research July 1 - September 30, 2009, DOE/SC-ARM/P-09-016 iii Contents 1. Data Availability ................................................................................................................................... 1 2. Scientific Users ..................................................................................................................................... 2 3. Safety .................................................................................................................................................... 4

38

Atmospheric Radiation Measurement Climate Research Facility (ACRF Instrumentation Status: New, Current, and Future)  

SciTech Connect (OSTI)

The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Climate Research Facility instrumentation status. The report is divided into the following four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) Small Business Innovation Research instrument development.

JW Voyles

2008-01-30T23:59:59.000Z

39

E-Print Network 3.0 - acrf millimeter wave Sample Search Results  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

millimeter-wave fre- quencies and above. Most parasitic elements can usually be ig- nored Source: Sarabandi, Kamal - Radiation Laboratory & Department of Electrical Engineering and...

40

EK101 Engineering Light Blackbody Radiation and Circuits  

E-Print Network [OSTI]

nm Space: 1.07e-3 m= 1.07 mm (microwave) 4. Make a night-light with your Arduino Kit: Read the Comments in Exercise 6 in the Vilros Ultimate Starter Kit. Download those Arduino Sketches

Bifano, Thomas

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Microsoft PowerPoint - ACposter_final2.ppt  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Markers appear only at appropriate resolutions SGP facility data ported from ACRF GIS SGP CF instrument data and high resolution aerial photograph ported from ACRF GIS...

42

Emission and absorption of photons and the black-body spectra in Lorentz-odd Electrodynamics  

E-Print Network [OSTI]

We study a number of issues related to the emission and absorption radiation by non-relativistic electrons within the framework of a Lorentz-breaking electrodynamics in (3+1) dimensions. Our main results concern how Planck-like spectrum law is sensitive to terms that violate Lorentz symmetry. We have realized that Planck law acquires extra terms proportional to the violating parameters: for the CPT-odd model, the leading extra terms appear to be linear or quadratic in these violating parameters according to the background vector is parallel or perpendicular to the photon wave-vector. In the CPT-even case a linear `correction' shows up. Among other possible ways to probe for these violations, by means of the present results, we may quote the direct observation of the extra contributions or an unbalancing in the mean occupation number of photon modes in a given thermal bath.

J. M. Fonseca; A. H. Gomes; W. A. Moura-Melo

2008-09-03T23:59:59.000Z

43

A Quantum Cascade Laser–Based Reflectometer for On-Orbit Blackbody Cavity Monitoring  

Science Journals Connector (OSTI)

Satellite measurements pinned to international standards are needed to monitor the earth’s climate, quantify human influence thereon, and test forecasts of future climate change. Credible observations require that measurement uncertainties be ...

P. Jonathan Gero; John A. Dykema; James G. Anderson

2009-08-01T23:59:59.000Z

44

Numerical models of blackbody-dominated gamma-ray bursts – II. Emission properties  

Science Journals Connector (OSTI)

......observations, we obtain rather flat light curves during the first 2-d...GRB-101225A, also known as the Christmas burst (CB; Thone et-al...thermal emission. The synthetic light curves (LCs) and spectra obtained...sh-109 c 2 (c being the speed of light in vacuum). This density corresponds......

C. Cuesta-Martínez; M. A. Aloy; P. Mimica; C. Thöne; A. de Ugarte Postigo

2015-01-01T23:59:59.000Z

45

Pressure-sensitive blackbody point radiation induced by infrared diode laser irradiation  

E-Print Network [OSTI]

Laboratory of Sono- and Photo-theranostic Technology, Harbin Institute of Technology, Harbin 150001, China 3

Cao, Wenwu

46

ACTIVITY SPECIFIC FIREARMS SAFETY PLAN FOR  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Atmospheric Radiation Measurement Climate Research Facility/ Atmospheric Radiation Measurement Climate Research Facility/ North Slope of Alaska/Adjacent Arctic Ocean (ACRF/NSA/AAO) Activity Specific Firearm Safety Plan for ACRF/North Slope of Alaska Sandia National Laboratories Department 6383, Energy, Climate & Atmospheric Management ACRF/NSA/AAO Revision 14 Activity Specific Firearm Safety Plan for June 2010 ACRF/North Slope of Alaska Signature Page This safety plan is approved by the undersigned and includes the firearm and ammunition storage practices described in this document. Mark D Ivey ACRF/NSA/AAO Site Manager _________________________________Date: ______ Mark D Ivey Department 06339 Manager _________________________________Date: _______ Michael L Heister SNL Safety Engineer _________________________________Date:________

47

Numerical models of blackbody-dominated gamma-ray bursts – I. Hydrodynamics and the origin of the thermal emission  

Science Journals Connector (OSTI)

......been performed and synthetic light curves are confronted with the...GRB 101225A (also called the Christmas burst, CB; T11) which, apart...ultraviolet-optical-infrared (UVOIR) light curve and SED also display a...there is a flattening of the light curve, suggestive of an associated......

C. Cuesta-Martínez; M. A. Aloy; P. Mimica

2015-01-01T23:59:59.000Z

48

ARM - Journal Articles 2008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

1 Journal Articles : 2008 Author Article Title Journal Research Highlight Funded By Berg Temporal variability of fair-weather cumulus statistics at the ACRF SGP site (Citation)...

49

Newsletter Southern Great Plains  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

as he joins the ACRF Operations Team (ARM photo). July 2005 3 Brad brings to ARM a broad background in remote sensing fieldwork, with extensive experience operating sophisticated...

50

Visiting Scientists and Researchers  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

this research will lead to improved representation of cloud and land surface feedbacks in climate models. This project will also enhance ACRF capabilities by expanding into...

51

1  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

maintained in an older version that was cumbersome and map production made difficult. Spatial data for the ARM Climate Research Facility (ACRF) sites have now been compiled in...

52

--No Title--  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Argonne Leadership Computing Facility (ALCF), Argonne Tandem Linear Accelerator System (ATLAS), ARM Climate Research Facility (ACRF), Center for Nanoscale Materials (CNM), and...

53

PowerPoint Presentation  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Facility (ACRF) Tropical Western Pacific sites. Model statistics are simulated using the Weather Research and Forecasting (WRF) Model. Simulations are compared to the observed...

54

Microsoft PowerPoint - Poster-PIRs to WISG 2007.ppt  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

ARM/NREL Pyrgeometer Calibration with Traceability to the ARM/NREL Pyrgeometer Calibration with Traceability to the World Infrared Standard Group (WISG) Ibrahim Reda 1 , Tom Stoffel 1 and Craig Webb 2 1 National Renewable Energy Laboratory, Golden, Colorado 2 AEROMET, Inc., Billings, Oklahoma Abstract For global acceptance, ARM broadband irradiance measurements must be made with radiometers calibrated to internationally recognized references. The World Meteorological Organization's Commission for Instruments and Methods of Observation (CIMO) established an interim pyrgeometer calibration standard in February 2006. The World Infrared Standard Group (WISG), comprised of four pyrgeometers, was developed by the Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center (PMOD/WRC). Working with PMOD/WRC, NREL has

55

 

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

1 1 Duplex Rules June 2010 Atmospheric Radiation Measurement Climate Research Facility/ North Slope of Alaska/Adjacent Arctic Ocean (ACRF/NSA/AAO) Duplex Rules Who can stay in the duplex? The rental for the duplex is paid out of the ACRF/NSA/AAO Site Manager's (SM's) Site Development and Operations budget at Sandia National Laboratories. ACRF personnel working directly on tasks for the ACRF/NSA/AAO Site will have priority in the use of the duplex. Other ACRF users will be accommodated on an as-available basis. A total of six bedrooms are now available in the duplex; 4 rooms have twin bunk beds, 1 room has 2 twin beds, and 1 room has a queen size bed. The duplex can accommodate 11 people with doubling up in the rooms that have bunk and twin beds. The Site Manager, Mark Ivey, will confirm extension of duplex

56

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

1 1 ACRF Ingest Software Status: New, Current, and Future February 2007 Annette Koontz, for ACRF Engineering Management Pacific Northwest National Laboratory PNNL Ingest Developers: Sutanay Choudhury Brian Ermold Krista Gaustad Annette Koontz Work supported by the U. S. Department of Energy, Office of Science, Office of Biological and Environmental Research February 2007, DOE/SC-ARM/P-07-004.1 Introduction The purpose of this report is to provide status of the ingest software used to process instrument data for the Atmospheric Radiation Measurement Program Climate Research Facility (ACRF). The report is divided into 4 sections: (1) for news about ingests currently under development, (2) for current production

57

ARM - Publications: Science Team Meeting Documents: Improved Method for  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Improved Method for Searching ACRF Data Quality and Problem Report Improved Method for Searching ACRF Data Quality and Problem Report Databases Doty, Kathy Brookhaven National Laboratory Wagener, Richard Brookhaven National Laboratory The implementation and use of a new ACRF Metadata Search Tool is presented. The tool has been developed to facilitate searching for ACRF metadata from a single, flexible and powerful user interface, rather than multiple interfaces as in the past. The metadata available for searching via the new tool includes Data Quality Reports (DQRs), Problem Identification Forms (PIFs), Attachments (additional information for PIFs), Data Quality Problem Reports (DQPRs), Corrective Action Reports (CARs), and some limited but useful search capabilities for Baseline Change Requests (BCRs) and Engineering Change Requests (ECRs). The system is built on common, proven

58

ARM - VAP Process - diffcor  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Productsdiffcor Productsdiffcor Documentation & Plots Technical Report Data Management Facility Plots (Quick Looks) ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send VAP : Correction of Diffuse Shortwave Measurements (DIFFCOR) Instrument Categories Derived Quantities and Models The DIFFCORR1DUTT VAP uses two techniques to correct shortwave (SW) data during daytime hours, using information from a collocated pyrgeometer. First, the detector-only correction technique uses data in the form of irradiance loss from the pyrgeometer detector. Second, the full-correction technique uses information from collocated pyrgeometer detector data, plus the difference between the case and dome temperatures. Both techniques

59

Microsoft PowerPoint - ARM_Stoffel.ppt  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

DOE/SC-ARM/P-05-011 DOE/SC-ARM/P-05-011 2 Outline * Why the need for longwave data restriction? - Important Considerations and the 12 Wm -2 longwave results problem * What ARM data are effected? - List of station-dates * Can the data be adjusted? - Using available 20-sec data samples * How is ARM addressing pyrgeometer calibration? - In Search of a Measurement Reference * References * Acronyms * Appendix - Fundamentals of pyrgeometer operation and calibration 3 Why a Data Access Restriction? The ARM Program's data quality control measures discovered an unexpected shift in the time series of longwave irradiance data following a change in pyrgeometer calibration procedures for field instruments deployed at all SIRS, SKYRAD, and GNDRAD installations beginning in August 2002 and completed in March 2004.

60

DRAFT Bear Safety Plan  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Bear Safety Plan June 2010 Bear Safety Plan June 2010 NSA_bsp_Rev9.doc 1 Atmospheric Radiation Measurement Climate Research Facility/ North Slope of Alaska/Adjacent Arctic Ocean (ACRF/NSA/AAO) Bear Safety Plan Background As a major part of DOE's participation in the US Global Change Research Program (USGCRP), the North Slope of Alaska (NSA) and Adjacent Arctic Ocean (AAO) Climate Research Facility (ACRF) exists on the North Slope of Alaska with its Central Facility near the town of Barrow. A secondary facility exists at Atqasuk, a town 100km inland from Barrow. Other instrumentation locations in more remote areas on the North Slope may be established in later stages of the project. Polar bears, and to a lesser extent, brown bears (barren ground grizzly) are significant hazards within the ACRF/NSA/AAO

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

U.S. Department of Energys Office of Science  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Office of Science Office of Science ARM Science Team Meeting Sheraton Waterside Hotel Norfolk, VA Rickey Petty March 13 th , 2008 Routine AVP Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) Office of Science U.S. Department of Energy Objectives Routine Flights sampling Low-altitude liquid-water clouds in the BL @ SGP Obtain representative statistics cloud microphysical properties. Validate retrieval algorithms Support process studies/model simulations of CLOWD-type clouds Office of Science U.S. Department of Energy ACRF Mission and Structure Management Structure Office of Science U.S. Department of Energy ACRF IOPR Process New Instruments: ARM IOPR system located at: http://www.arm.gov/acrf/fc.stm Field Campaign Guideline (PDF) Proposal Submission Form

62

ARM Orientation Workshop  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Obtaining Data from the Obtaining Data from the ACRF Archive Orientation for new Science Team Members One click to the ACRF Data Archive ACRF Data Archive - Newly Designed Home Page Emphasis on guiding users in their selection of data access tools Accessing ARM Data: Options Comparison of Browser/Interface Options Interface name Accessible data "Shopping" approach (armarchive@ornl.gov, 1-888-ARM-DATA) ARM Data Browser Routine ARM data "I know what I want. Do you have it?" Searching with predefined selection criteria. Catalog Interface Routine ARM data "I am not sure what I want. I need to see what you have available." Browsing a hierarchy of availability summaries. Thumbnail Browser Most routine ARM data "I will know what I want when I see it." Searching with a combination of predefined selection

63

Data Domain to Model Domain Conversion Package | Argonne National  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Data Domain to Model Domain Conversion Package Data Domain to Model Domain Conversion Package Data Domain to Model Domain Conversion Package The Data Domain to Model Domain Conversion Package project will develop methods and implement a novel approach for generating data ensembles by using the latest available statistical modeling tools and knowledge of relevant physical and chemical process to develop climatologically aware methods for processing ACRF and other spatially sparse data sets. Data collected at the Atmospheric Radiation Measurement Program Climate Research Facility (ACRF) sites are employed mainly in column radiation models, to validate the models and develop new parameterizations. Currently, no single methodology can be used with data collected at the spatial scale of the ACRF sites or from specific AmeriFlux locations, to

64

1  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Tools for Teaching Climate Change Studies Tools for Teaching Climate Change Studies A.M. Maestas and L.A. Jones Los Alamos National Laboratory Los Alamos, New Mexico Introduction The Atmospheric Radiation Measurement Climate Research Facility (ACRF) develops public outreach materials and educational resources for schools. Studies prove that science education in rural and indigenous communities improves when educators integrate regional knowledge of climate and environmental issues into school curriculum and public outreach materials. In order to promote understanding of ACRF climate change studies, ACRF Education and Outreach has developed interactive kiosks about climate change for host communities close to the research sites. A kiosk for the North Slope of Alaska (NSA) community was installed at the Iñupiat Heritage Center in 2003, and a

65

ARM/NSA Vehicle Use Policy  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Operating Procedures for Scaffold Use October 2007 Operating Procedures for Scaffold Use October 2007 Atmospheric Radiation Measurement Climate Research Facility/ North Slope of Alaska/Adjacent Arctic Ocean (ACRF/NSA/AAO) Operating Procedures for The Use of Scaffolds at ACRF/NSA/AAO Meteorological Towers Introduction: An aluminum scaffold structure is used at ARM Climate Research Facility/North Slope of Alaska/Adjacent Arctic Ocean (ACRF/NSA/AAO) Sites to access instruments mounted on the meteorological tower as shown in Figure 1 below. The scaffold is typically used for maintenance of instruments mounted on moveable booms or for maintenance of guest or temporary instruments. The scaffold is a commercially-available product that was purchased from Upright, Inc. and was fitted with aluminum grating platforms by Cubic Designs, Inc. of

66

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

4 4 ACRF Instrumentation Status: New, Current, and Future May 2007 James Liljegren ACRF Instrument Team Coordinator Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Summary The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Program Climate Research Facility instrumentation status. The report is divided into four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) Small Business Innovation Research instrument development. New information is highlighted in

67

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

3 3 ACRF Instrumentation Status: New, Current, and Future September 2006 James Liljegren ACRF Instrument Team Coordinator Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Summary The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Program Climate Research Facility instrumentation status. The report is divided into four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) Small Business Innovation Research instrument development. New information is highlighted in blue text.

68

Microsoft Word - Instrument Status - January 2007 formatted.doc  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

ACRF Instrumentation Status: New, Current, and Future January 2007 James Liljegren ACRF Instrument Team Coordinator Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Summary The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Program Climate Research Facility instrumentation status. The report is divided into four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) Small Business Innovation Research instrument development. New information is highlighted in

69

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

4 4 ACRF Instrumentation Status: New, Current, and Future October 2006 James Liljegren ACRF Instrument Team Coordinator Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Summary The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Program Climate Research Facility instrumentation status. The report is divided into four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) Small Business Innovation Research instrument development. New information is highlighted in blue text.

70

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

5 5 ACRF Instrumentation Status: New, Current, and Future May 2007 James Liljegren ACRF Instrument Team Coordinator Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Summary The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Program Climate Research Facility instrumentation status. The report is divided into four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) Small Business Innovation Research instrument development. New information is highlighted in

71

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

6 6 ACRF Instrumentation Status: New, Current, and Future June 2007 James Liljegren ACRF Instrument Team Coordinator Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Summary The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Program Climate Research Facility instrumentation status. The report is divided into four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) Small Business Innovation Research instrument development. New information is highlighted in

72

Microsoft Word - Instrument Status - February 2007 formatted_P-07-002.2.doc  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

2 2 ACRF Instrumentation Status: New, Current, and Future February 2007 James Liljegren ACRF Instrument Team Coordinator Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Summary The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Program Climate Research Facility instrumentation status. The report is divided into four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) Small Business Innovation Research instrument development. New information is highlighted in

73

Microsoft Word - Instrument Status - Nov-Dec 2006 formatted .doc  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

5 5 ACRF Instrumentation Status: New, Current, and Future November-December 2006 James Liljegren ACRF Instrument Team Coordinator Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Summary The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Program Climate Research Facility instrumentation status. The report is divided into four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) Small Business Innovation Research instrument development. New information is highlighted in

74

Nauru Island Effect Detection Data Set  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

During Nauru99 it was noted that the island was producing small clouds that advected over the ARM site. The Nauru Island Effect Study was run for 1.5 years and the methodology developed to detect the occurrence. Nauru ACRF downwelling SW, wind direction, and air temperature data are used, along with downwelling SW data from Licor radiometers located on the southern end of the island near the airport landing strip. A statistical analysis and comparison of data from the two locations is used to detect the likely occurrence of an island influence on the Nauru ACRF site data

Long, Chuck

75

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

1 1 ACRF Instrumentation Status: New, Current, and Future July 2006 James Liljegren ACRF Instrument Team Coordinator Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research Summary The purpose of this report is to provide a concise but comprehensive overview of Atmospheric Radiation Measurement Program Climate Research Facility instrumentation status. The report is divided into four sections: (1) new instrumentation in the process of being acquired and deployed, (2) existing instrumentation and progress on improvements or upgrades, (3) proposed future instrumentation, and (4) Small Business Innovation Research instrument development. New information is highlighted in blue text.

76

ARM Climate Research Facility Annual Report 2005  

SciTech Connect (OSTI)

Through the ARM Program, the DOE funded the development of several highly instrumented ground stations for studying cloud formation processes and their influence on radiative transfer, and for measuring other parameters that determine the radiative properties of the atmosphere. This scientific infrastructure, and resultant data archive, is a valuable national and international asset for advancing scientific knowledge of Earth systems. In fiscal year (FY) 2003, the DOE designated ARM sites as a national scientific user facility: the ARM Climate Research (ACRF). The ACRF has enormous potential to contribute to a wide range interdisciplinary science in areas such as meteorology, atmospheric aerosols, hydrology, biogeochemical cycling, and satellite validation, to name only a few.

J. Voyles

2005-12-31T23:59:59.000Z

77

Working Group Reports Calibration of Radiation Codes Used in Climate Models:  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Working Group Reports Calibration of Radiation Codes Used in Climate Models: Comparison of Clear-Sky Calculations with Observations from the Spectral Radiation Experiment and the Atmospheric Radiation Measurement Program R. G. Ellingson, S. Shen, and J. Warner University of Maryland College Park, Maryland Background The InterComparison of Radiation Codes in Climate Models (ICRCCM) showed large differences between model calculations of longwave fluxes and heating rates-even for clear-sky conditions (Luther et al. 1988). The discrepancies could not be resolved with either pyrgeometer measurements or line-by-line calculations because * Pyrgeometer errors are the magnitude of the discrepancies. * Uncertainties in the physics of line wings and in the proper treatment of the continuum make it impossible

78

ARM - Publications: Science Team Meeting Documents  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

International Pyrgeometer and Absolute Sky-scanning Radiometer Comparison International Pyrgeometer and Absolute Sky-scanning Radiometer Comparison at the NSA ARM site Barrow Stamnes, K. (a), Dutton, E.G. (b), Marty, Ch. (c), Michalsky, J.J. (d), Philipona, R. (e), Stoffel, T. (f), Storvold, R. (c), and Zak, B.D. (g), Stevens Institute of Technology, New Jersey (a), NOAA, Climate Monitoring and Diagnostics Laboratory (b), University of Alaska Fairbanks (c), State University of New York at Albany (d), World Radiation Center, Davos, Switzerland (e), National Renewable Energy Lab, Boulder (f), Sandia National Laboratories, Albuquerque (g) Eleventh Atmospheric Radiation Measurement (ARM) Science Team Meeting The first International Prgeometer and Absolute Sky-scanning Radiometer Comparison (IPASRC I), which was held in fall 1999 at the ARM SGP site in

79

ARM - Datastreams - rad  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Datastreamsrad Datastreamsrad Documentation Data Quality Plots ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Datastream : RAD Radiation measurements at AMF/Niamey, Niger/S1 Active Dates 2006.01.13 - 2008.12.13 Measurement Categories Radiometric Originating Instrument Radiation Measurements at AMF (RAD) Measurements Only measurements considered scientifically relevant are shown below by default. Show all measurements Measurement Units Variable Altitude above mean sea level m alt Base time in Epoch seconds since 1970-1-1 0:00:00 0:00 base_time Longwave broadband downwelling irradiance Downwelling Longwave Hemispheric Irradiance, Pyrgeometer W/m^2 down_long_hemisp ( time ) Downwelling Pyrgeometer Case Thermistor Resistance Kohms down_long_hemisp_case_resist ( time )

80

NREL Particle Receiver Will Enable High-Temperature CSP (Fact Sheet)  

SciTech Connect (OSTI)

Near-blackbody enclosed particle receiver can support high-temperature thermal energy storage and high-efficiency power cycles.

Not Available

2014-08-01T23:59:59.000Z

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

GOOGLE AND GIS INTEGRATED ON THE ARM WEBSITE: A WORK IN PROGRESS  

E-Print Network [OSTI]

GOOGLE AND GIS INTEGRATED ON THE ARM WEBSITE: A WORK IN PROGRESS A. Cialella and R. Wagener to zoom in at varying resolutions, with satellite images and/or street maps as backdrops. The ACRF GIS (ESRI ArcGIS) database was merged with Google to include markers for the SGP site facilities. A new SGP

82

U.S. Department of Energys Office of Science  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Energy's Energy's Office of Science University of Illinois Champaign, IL Rickey Petty October 14 th , 2008 ARM Aerial Vehicle Workshop Advances in Airborne Instrumentation Parameters Office of Science U.S. Department of Energy ARM Climate Research Facility (ACRF) - Mission  The U.S. Department of Energy's (DOE's) ARM Climate Research Facility (ACRF) has been designated a national user facility for the purpose of providing this unique asset for the study of global change to the broader national and international research community. Research at this facility will include the study of alterations in climate, land productivity, oceans or other water resources, atmospheric chemistry, and ecological systems that may alter the capacity of the Earth to sustain life. Global change research also includes the study,

83

Research Highlight  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

The Vertical Structure of Cloud Radiative Forcing at the ACRF SGP Revealed The Vertical Structure of Cloud Radiative Forcing at the ACRF SGP Revealed by 8 Years of Continuous Measurements Submitter: Mace, G., Utah State University Area of Research: Cloud Distributions/Characterizations Working Group(s): Cloud Modeling, Cloud Properties Journal Reference: Accepted to Journal of Climate, 2007. Figure 1. Cloud occurrence, coverage, radiative forcing, and radiation effects over a composite annual cycle that is derived by averaging all observations collected during a particular month for all years. a) cloud occurrence in 100 mb vertical bins, b) cloud coverage, c) infrared cloud radiative forcing in 100 mb vertical bins, d) solar cloud radiative forcing, e) net cloud radiative forcing, f,g,h) solar (dotted), IR (solid), and net (dashed) cloud radiative effect for TOA (f), atmosphere (g), and

84

ARM - Publications: Science Team Meeting Documents: Establishing Continuous  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Establishing Continuous Atmospheric Profiles at the North Slope of Alaska Establishing Continuous Atmospheric Profiles at the North Slope of Alaska ACRF Delamere, Jennifer Atmospheric and Environmental Research, Inc. Turner, David Pacific Northwest National Laboratory Mlawer, Eli Atmospheric & Environmental Research, Inc. Clough, Shepard Atmospheric and Environmental Research Miller, Mark Brookhaven National Laboratory Troyan, David Brookhaven National Laboratory Clothiaux, Eugene The Pennsylvania State University Accurate and continuous vertical profiles of the atmospheric state above the North Slope of Alaska ARM Climate Research Facility (NSA ACRF) are a necessity for both accurate forward radiative transfer calculations and cloud microphysical retrievals. In particular, such profiles are a critical component of two important initiatives at the NSA site, the Broadband

85

Remote/New sites: Many Field  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Remote/New sites: Many Field Remote/New sites: Many Field Campaigns require temporary installations on non-ACRF sites. This requires identification of landowners, negotiation of leases, and infrastructure logistics for electrical and internet connectivity. Argonne National Laboratory is managed by UChicago-Argonne LLC for the U.S. Department of Energy SGP Field Campaigns: The Other Side of Operations Brad W. Orr 1 Dan J. Rusk 2 John Schatz 2 Dan Nelson 2 David Breedlove 2 Douglas L. Sisterson 1 1 Argonne National Laboratory, Argonne, IL 2 ACRF/SGP, Cherokee Nation Distributors, Stilwell, OK Background Implementation All departments must work closely together to implement a campaign. In addition they must have the flexibility to adapt to new and unique instrument deployments. The

86

ARM - Publications: Science Team Meeting Documents: External Data Stream  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

External Data Stream Review External Data Stream Review Wagener, Richard Brookhaven National Laboratory Ma, Lynn DOE/Brookhaven National Laboratory Gregory, Laurie Brookhaven National Laboratory Tichler, Joyce DOE/Brookhaven National Laboratory Horwedel, Betsy Oak Ridge National Laboratory Cialella, Alice Brookhaven National Laboratory In terms of data volume, about half the data in the ACRF archive were generated outside of the ARM program and collected by the eXternal Data Center (XDC) from external sources, processed to standard formats, documented, and forwarded to the archive. This constitutes a unique resource drawing many users to the archive, however it involves a significant effort and we must assure that the effort is spent where it provides the most benefit to the ACRF science mission. Here, we present a

87

Research Highlight  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Five-Year Statistics of Shallow Clouds at the ACRF SGP Site Five-Year Statistics of Shallow Clouds at the ACRF SGP Site Download a printable PDF Submitter: Berg, L., Pacific Northwest National Laboratory Kassianov, E., Pacific Northwest National Laboratory Area of Research: Cloud Distributions/Characterizations Working Group(s): Cloud Modeling Journal Reference: Berg, LK, and EI Kassianov. 2008. "Temporal variability of fair-weather cumulus statistics at the ARM SGP site." Journal of Climate 21, 3344-3358. Figure 1. Five-year mean ARSCL VAP values of cloud fraction (black), cloud-base height (orange circles), cloud-top height (red), cloud thickness (blue), and cloud-chord length (green), and their average daily bias for each year (B) and low-altitude moisture (C). While fair-weather clouds (FWC) are small in size, they are ubiquitous,

88

ARM - Field Campaign - Routine AAF CLOWD Optical Radiative Observations  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

govCampaignsRoutine AAF CLOWD Optical Radiative Observations (RACORO) govCampaignsRoutine AAF CLOWD Optical Radiative Observations (RACORO) Campaign Links RACORO Website Related Campaigns Surface Radiation Comparison Transfer Measurements for RACORO 2009.01.20, Long, SGP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Routine AAF CLOWD Optical Radiative Observations (RACORO) 2009.01.22 - 2009.06.30 Website : http://acrf-campaign.arm.gov/racoro/ Lead Scientist : Andrew Vogelmann For data sets, see below. Description The ARM Aerial Facility (AAF) supported the Routine AAF Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign, led by principal investigator Andrew Vogelmann. During this long-term campaign, the AAF conducted routine flights at the ACRF Southern

89

1  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

and Improved Data Logging and Collection and Improved Data Logging and Collection System for Atmospheric Radiation Measurement Climate Research Facility, Tropical Western Pacific, and North Slope of Alaska Sky Radiation, Ground Radiation, and MET Systems M.T. Ritsche, D.J. Holdridge Environmental Research Division, Argonne National Laboratory Argonne, IL R. Pearson Australian Bureau of Meteorology Darwin, NT Australia Background Aging systems and technological advances mandated changes to the data collection systems at the Atmospheric Radiation Measurement (ARM) Program's Tropical Western Pacific (TWP) and North Slope of Alaska (NSA) ARM Climate Research Facility (ACRF) sites. Key reasons for the upgrade include the following: * Achieve consistency across all ACRF sites for easy data use and operational maintenance.

90

Sandia VG Template  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Company for the United States Company for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. * DOE/ARM = Dept of Energy/Atmospheric Radiation Measurement, DOE's principal climate research program; www.arm.gov DOE/ARM UAS Plans Through Sandia, DOE/ARM* is putting in place a UAS (Unmanned Aircraft Systems) hosting capability on the North Slope of Alaska ARM Climate Research Facilities (ACRF) already exist at Barrow and Atqasuk; DOE/ARM restricted airspace exists at Oliktok Point; only restricted airspace on the North Slope of Alaska Atqasuk ACRF UAS Basing Capability: Restricted Airspace R2204 along with Permit to Use the USAF Oliktok Point Radar Station Facilities under R2204 Oliktok Point USAF Long Range Radar Station

91

ARM - ARM Climate Research Facility Contributions to International Polar  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Research Support International Polar Year Begins at ACRF with 3-week Campaign in Barrow Aerosol Affects on Clouds To Be Studied Yearlong Study to Improve Polar Measurements of Radiative Energy Education Efforts Educational Kiosk CD Available at No Cost-Request Yours Today! POLAR-PALOOZA: Climate science goes on tour! Partnership Extends Support for National Science Teacher Conference Teacher's Domain Combines Culture and Climate Other Links ACRF IPY Home U.S. IPY Home ARM Climate Research Facility Contributions to International Polar Year (IPY) The Department of Energy's International Polar Year (IPY) contributions will be conducted at the Atmospheric Radiation Measurement Climate Research Facility (ARM) located in the North Slope of Alaska. This DOE user facility

92

Microsoft PowerPoint - Cimel_ARM_STM_2008_poster_final.ppt  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Cimel Sunphotometers Cimel Sunphotometers at ACRF Sites History and Current Status Laurie Gregory, Richard Wagener, and Lynn Ma Brookhaven National Laboratory, Upton, New York More Information Cimel (CSPHOT) Instrument Page: http://www.arm.gov/instruments/instrument.php?id=csphot Aeronet http://aeronet.gsfc.nasa.gov/ ARM eXternal Data Center (XDC): http://www.xdc.arm.gov/, xdc_oper@arm.gov. ARM Google: http://google.arm.gov/ search for "Cimel OR CSPHOT OR CSPOT" ARM Cimel Sunphotometers As of August 2007, the ARM External Data Center took on a limited form of mentorship for the Cimel Sunphotometers (CSPHOTs) to coordinate the National Aeronautics and Space Administration Aeronet's and ARM Climate Research Facility (ACRF) site operations' activities to ascertain proper functioning, calibration, and

93

ARM - Field Campaign - Boundary Layer CO2 Using CW Lidar  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

govCampaignsBoundary Layer CO2 Using CW Lidar govCampaignsBoundary Layer CO2 Using CW Lidar Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Boundary Layer CO2 Using CW Lidar 2005.05.21 - 2005.05.24 Lead Scientist : Michael Dobbs Description Overflights Underway at ACRF Southern Great Plains Site (M.Dobbs/J.Liljegren) Science collaborators at ITT Industries and the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) conducted flights over the Central Facility at ACRF's Southern Great Plains (SGP) site as part of the Climate Sources and Sink (CO2) Intensive Operational Period (IOP), using a CW lidar. The objective of the flights was to validate, by demonstration and comparison with SGP ground observations, the performance of the ITT system when used in conjunction with retrieval

94

 

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Issue: K Author: Mark D. Ivey Page 1 of 24 DR 6 / 30 / 2010 ES&H STANDARD OPERATING PROCEDURE (ES&H SOP) Title: ATMOSPHERIC RADIATION MEASUREMENT CLIMATE RESEARCH FACILITY/NORTH SLOPE OF ALASKA/ADJACENT ARCTIC OCEAN (ACRF/NSA/AAO) PROJECT OPERATING PLAN (U) Location: North Slope of Alaska and Adjacent Arctic Ocean Owners: Mark D Ivey, Department 6383, Manager Mark D Ivey, Department 6383, ACRF/NSA/AAO Site Project Manager and Site ES&H Coordinator Document Release or Change History: SP473406/Issue Release/Change No (Authorization No.) Date A DR E970005SA, Rev 0 07/14/97 B CN E970005SA, Rev 1 10/28/98 C CN E970005SA, Rev 2 03/15/00

95

Bench-Scale Cross Flow Filtration of  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

ARM-0707 ARM-0707 Report on the ARM Climate Research Facility EXPANSION WORKSHOP October 31 - November 1, 2007 Reston, Virginia Prepared for the U.S. Department of Energy under Contract DE AC05 76RL01830 Pacific Northwest National Laboratory Richland, Washington 99352 DOE/SC-ARM-0707 iii Executive Summary The U.S. Department of Energy (DOE) Office of Science created the Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) within the Office of Biological and Environmental Research (BER) to provide the infrastructure needed to address scientific uncertainties related to global climate change, with a specific focus on the crucial role of clouds and their influence on radiative feedback processes in the atmosphere. Designated as a national user facility the ACRF

96

Research Highlight  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Sub-Grid Scale Cloud Variability Affects Vertical Structure of Clouds and Sub-Grid Scale Cloud Variability Affects Vertical Structure of Clouds and Radiative Heating Submitter: McFarlane, S. A., U.S. Department of Energy Area of Research: General Circulation and Single Column Models/Parameterizations Working Group(s): Cloud Modeling Journal Reference: McFarlane, S. A., J. H. Mather, and T. P. Ackerman (2007), Analysis of tropical radiative heating profiles: A comparison of models and observations, J. Geophys. Res., 112, D14218, doi:10.1029/2006JD008290. Comparison of the distributions of cloud condensate for the ACRF TWP site at Manus using a) retrievals from the ACRF remote sensors, b) the CAM, c) all MMF columns, and d) MMF columns that do not contain precipitation. Note that the ARM observations do not include precipitation. Each panel consists

97

SGP Cloud and Land Surface Interaction Campaign (CLASIC): Measurement Platforms  

SciTech Connect (OSTI)

The Cloud and Land Surface Interaction Campaign (CLASIC) will be conducted from June 8 to June 30, 2007, at the U.S. Department of Energy’s Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site. Data will be collected using eight aircraft equipped with a variety of specialized sensors, four specially instrumented surface sites, and two prototype surface radar systems. The architecture of CLASIC includes a high-altitude surveillance aircraft and enhanced vertical thermodynamic and wind profile measurements that will characterize the synoptic scale structure of the clouds and the land surface within the ACRF SGP site. Mesoscale and microscale structures will be sampled with a variety of aircraft, surface, and radar observations. An overview of the measurement platforms that will be used during the CLASIC are described in this report. The coordination of measurements, especially as it relates to aircraft flight plans, will be discussed in the CLASIC Implementation Plan.

MA Miller; R Avissar; LK Berg; SA Edgerton; ML Fischer; TJ Jackson; B. Kustas; PJ Lamb; G McFarquhar; Q Min; B Schmid; MS Torn; DD Tuner

2007-06-01T23:59:59.000Z

98

ARM - Education Article  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

April 9, 2007 [Education] April 9, 2007 [Education] Barrow Teachers Learn About International Polar Year Bookmark and Share Two Barrow teachers, Gary Boen and Imelda Cabana, were sent to the NSTA conference in St. Louis. Science teachers in Barrow, Alaska, know that climate change is something their students can experience simply by stepping out into their own back yards. But that doesn't mean teachers don't need resources and materials to help them engage their students in climate studies. Last month, ACRF Education and Outreach sponsored two teachers from ACRF's host community of Barrow to attend the National Science Teachers Association (NSTA) 2007 National Conference in Saint Louis, Missouri. Imelda Cabana, from Eben Hopson Middle School, and Gary Boen, from Kiita Alternative School, were

99

Preliminary Analysis of ARM SGP Area Sky Cover and Downwelling SW Irradiance  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Clarifying and Implementing a Stricter DOD Definition Across Datastreams Clarifying and Implementing a Stricter DOD Definition Across Datastreams C. Sivaraman, B. Ermold, M. Macduff Pacific Northwest National Laboratory Definition of DOD: All dimension, attribute and variable types and names are considered part of a DOD. A change in any part of the DOD is considered a version change. Outcomes: ACRF enforces greater consistency in data Downstream users benefit (DQ, VAPs, scientists) Identify inconsistencies across datastreams Datastream development is more efficient BODS interface, updated libraries Improved data analysis tools for ACRF and ARM Visual Datastream history tool (below) Issues with current DOD history: The DOD History page: http://science.arm.gov/tool/dod/showdod.php * Tracks both content and structure. * Needs Custom Configuration

100

Research Highlight  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Using the ACRF Shortwave Spectrometer to Study the Transition Between Clear Using the ACRF Shortwave Spectrometer to Study the Transition Between Clear and Cloudy Regions Download a printable PDF Submitter: Marshak, A., NASA - Goddard Space Flight Center Chiu, J., University of Reading Knyazikhin, Y., Boston University Pilewskie, P., University of Colorado Wiscombe, W. J., Brookhaven National Laboratory Area of Research: Radiation Processes Working Group(s): Radiative Processes Journal Reference: Chiu C, A Marshak, Y Knyazikhin, P Pilewskie, and W Wiscombe. 2009. "Physical interpretation of the spectral radiative signature in the transition zone between cloud-free and cloudy regions." Atmospheric Chemistry and Physics, 9(4), 1419-1430. (a) Total sky images on 18 May 2007, and (b) plot of SWS normalized zenith radiances. In (b), arrows pointed at the time axis correspond to the times

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101

Bench-Scale Cross Flow Filtration of  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

2 2 ACRF Instrumentation Status: New, Current, and Future December 2008 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored b y the U.S. Government. Neither the United States nor any agency thereof, nor any of their em ployees, makes any warranty, express or i mplied, or assu mes

102

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

10 10 Atmospheric Radiation Measurement Program Climate Research Facility Operations Quarterly Report April 1 - June 30, 2006 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research April 1 - June 30, 2006, ARM 06-010 Contents 1 Data Availability....................................................................................................................... 1 2 Site Visit Requests, Archive Accounts, and Research Computer Accounts............................. 2 3 Safety ........................................................................................................................................ 3 Tables 1 Operational Statistics for the Fixed ACRF and AMF Sites for the Period April 1 -

103

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Atmospheric Radiation Measurement Program Climate Research Facility Operations Quarterly Report October 1 - December 31, 2006 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research October 1 - December 31, 2006, DOE/SC-ARM/P-07-001 Contents 1. Data Availability....................................................................................................................... 1 2. Site Visit Requests, Archive Accounts, and Research Computer Accounts............................. 2 3. Safety ........................................................................................................................................ 3 Tables Table 1. Operational Statistics for the Fixed ACRF and AMF Sites for the Period October 1 -

104

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

4 4 Atmospheric Radiation Measurement Program Climate Research Facility Operations Quarterly Report January 1 - March 31, 2005 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research January 1 - March 31, 2005, ARM-05-014 Contents 1 Data Availability....................................................................................................................... 1 2 Site Visit Requests, Archive Accounts, and Research Computer Accounts............................. 2 3 Safety ........................................................................................................................................ 3 Tables 1 Operational Statistics for the Fixed ACRF Sites for the Period January 1 -

105

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

5 5 Atmospheric Radiation Measurement Program Climate Research Facility Operations Quarterly Report April 1 - June 30, 2005 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research April 1 - June 30, 2005, ARM-05-015 Contents 1 Data Availability....................................................................................................................... 1 2 Site Visit Requests, Archive Accounts, and Research Computer Accounts............................. 2 3 Safety ........................................................................................................................................ 3 Tables 1 Operational Statistics for the Fixed ACRF Sites for the Period April 1 -

106

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

3 3 Atmospheric Radiation Measurement Program Climate Research Facility Operations Quarterly Report October 1 - December 31, 2004 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research October 1 - December 31, 2004, ARM-05-013 Contents 1 Data Availability....................................................................................................................... 1 2 Safety ........................................................................................................................................ 3 Tables 1 Operational Statistics for the ACRF Sites for the Period October 1, 2003- December 31, 2004 Site Visit Requests, Archive Accounts, and Research Computer

107

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

8 8 Atmospheric Radiation Measurement Program Climate Research Facility Operations Quarterly Report January 1 - March 31, 2006 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research January 1 - March 31, 2006, ARM 06-008 Contents 1 Data Availability....................................................................................................................... 1 2 Site Visit Requests, Archive Accounts, and Research Computer Accounts............................. 2 3 Safety ........................................................................................................................................ 3 Tables 1 Operational Statistics for the Fixed ACRF and AMF Sites for the Period January 1 -

108

Quality Assurance of ARM Program Climate Research Facility Data  

SciTech Connect (OSTI)

This report documents key aspects of the Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) data quality assurance program as it existed in 2008. The performance of ACRF instruments, sites, and data systems is measured in terms of the availability, usability, and accessibility of the data to a user. First, the data must be available to users; that is, the data must be collected by instrument systems, processed, and delivered to a central repository in a timely manner. Second, the data must be usable; that is, the data must be inspected and deemed of sufficient quality for scientific research purposes, and data users must be able to readily tell where there are known problems in the data. Finally, the data must be accessible; that is, data users must be able to easily find, obtain, and work with the data from the central repository. The processes described in this report include instrument deployment and calibration; instrument and facility maintenance; data collection and processing infrastructure; data stream inspection and assessment; the roles of value-added data processing and field campaigns in specifying data quality and haracterizing the basic measurement; data archival, display, and distribution; data stream reprocessing; and engineering and operations management processes and procedures. Future directions in ACRF data quality assurance also are presented.

RA Peppler; KE Kehoe; KL Sonntag; CP Bahrmann; SJ Richardson; SW Christensen; RA McCord; DJ Doty; R Wagener; RC Eagan; JC Lijegren; BW Orr; DL Sisterson; TD Halter; NN Keck; CN Long; MC Macduff; JH Mather; RC Perez; JW Voyles; MD Ivey; ST Moore; DL Nitschke; BD Perkins; DD Turner

2008-03-01T23:59:59.000Z

109

stoffel-98.pdf  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

5 5 Broadband and Spectral Irradiance Measurements at the Radiometer Calibration Facility During the 1997 Integrated Intensive Observation Period T. L. Stoffel National Renewable Energy Laboratory Golden, Colorado G. Hodges Cooperative Institute for Research in the Environmental Sciences Boulder, Colorado J. J. Michalsky State University of New York at Albany Albany, New York Summary A unique collection of broadband and spectral solar irradiance measurements was made at the Radiometer Calibration Facility (RCF) during the 1997 Integrated Intensive Observation Period (IOP). Absolute cavity radiometers, ultraviolet photometers, photosynthetically active radiation (PAR) photometers, pyranometers, pyrgeometers, and a scanning spectroradiometer were deployed at the Southern Great Plains (SGP) site to meet the

110

Concentrated Solar Thermoelectric Power  

Broader source: Energy.gov (indexed) [DOE]

SOLAR POWER PROGRAM REVIEW 2013 Receiver Cavity * Receiver cavity can reduce heat loss from black surface or selective surface 18 With blackbody absorber: With 20%...

111

An investigation of extratropical cyclogenesis in the Gulf of Mexico using geosynchronous satellite information  

E-Print Network [OSTI]

Severe Storms Forecast Center Numerical Weather Prediction PVA SFSS SMS TCT TIROS VISSR Positive Vorticity Advection Satellite Field Service Station Synchronous Meteorological Satellite Equivalent Blackbody Temperature Cloud Top Temperature... Severe Storms Forecast Center Numerical Weather Prediction PVA SFSS SMS TCT TIROS VISSR Positive Vorticity Advection Satellite Field Service Station Synchronous Meteorological Satellite Equivalent Blackbody Temperature Cloud Top Temperature...

Heckman, Brian Eugene

2012-06-07T23:59:59.000Z

112

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

10 10 Atmospheric Radiation Measurement Program Climate Research Facility Operations Quarterly Report April 1 - June 30, 2007 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research April 1 - June 30, 2007, DOE/SC-ARM/P-07-010 Contents 1. Data Availability....................................................................................................................... 1 2. Site Visit Requests, Archive Accounts, and Research Computer Accounts............................. 2 3. Safety ........................................................................................................................................ 4 Tables 1. Operational Statistics for the Fixed ACRF Sites for the Period April 1 - June 30, 2007.

113

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

9 9 Atmospheric Radiation Measurement Program Climate Research Facility Operations Quarterly Report January 1 - March 31, 2009 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research January 1 - March 31, 2008, DOE/SC-ARM/P-09-009 Contents 1. Data Availability....................................................................................................................... 1 2. Site Visit Requests, Archive Accounts, and Research Computer Accounts............................. 2 3. Safety ........................................................................................................................................ 4 Tables Table 1. Operational Statistics for the Fixed ACRF Sites for the Period January 1 - March 31,

114

ARM TR-008  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

1 1 Atmospheric Radiation Measurement Program Climate Research Facility Operations Quarterly Report October 1 - December 31, 2007 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research October 1 - December 31, 2007, DOE/SC-ARM/P-08-001 Contents 1. Data Availability....................................................................................................................... 1 2. Site Visit Requests, Archive Accounts, and Research Computer Accounts............................. 2 3. Safety ........................................................................................................................................ 4 Tables Table 1. Operational Statistics for the Fixed ACRF Sites for the Period October 1 - December

115

Raman Lidar (RL) Handbook  

SciTech Connect (OSTI)

The Raman lidar at the ARM Climate Research Facility (ACRF) Southern Great Plains (SGP) Central Facility (SGPRL) is an active, ground-based laser remote sensing instrument that measures height and time resolved profiles of water vapor mixing ratio and several cloud- and aerosol-related quantities. The system is a non-commercial custom-built instrument developed by Sandia National Laboratories specifically for the ARM Program. It is fully computer automated, and will run unattended for many days following a brief (~5-minute) startup period. The self-contained system (requiring only external electrical power) is housed in a climate-controlled 8’x8’x20’ standard shipping container.

Newsom, RK

2009-03-01T23:59:59.000Z

116

Charge  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

2 2 DOE Review of the Atmospheric Radiation Measurement (ARM) Climate Research Facility February 3-4, 2005 American Geophysical Union, Washington, D.C. June 2005 W.R. Ferrell Climate Change Research Division Pacific Northwest National Laboratory Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DOE/SC-ARM-0502 CONTENTS 1. INTRODUCTION .................................................................................................................. 1 2. SUMMARY OF ACRF INFRASTRUCTURE REVIEW PANEL COMMENTS................ 3 2.1 Management.................................................................................................................... 3 2.2 Research Support ............................................................................................................

117

Research Highlight  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Downward Longwave Irradiance Uncertainty Under Arctic Atmospheres: Downward Longwave Irradiance Uncertainty Under Arctic Atmospheres: Measurements and Modeling Submitter: Marty, C., Swiss Federal Institute of Snow and Avalanche Research Area of Research: Radiation Processes Working Group(s): Radiative Processes Journal Reference: Marty, C., R. Philipona, J. Delamere, E.G. Dutton, J. Michalsky, K. Stamnes, R. Storvold, T. Stoffel, S.A. Clough, and E.J. Mlawr, Downward longwave irradiance uncertainty under arctic atmospheres: Measurements and modeling, J. Geophys. Res., 108(D12), 4358, doi:10.1029/2002JD002937, 2003. IPASRC-II instruments deployed at ARM's Barrow Station. Members of 11 international institutions converged at the Atmospheric Radiation Measurement (ARM) Program's North Slope of Alaska (NSA) site in Barrow, Alaska, to conduct the Second International Pyrgeometer and

118

ARM - Publications: Science Team Meeting Documents  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Comparisons Between Measured and Modeled Longwave Irradiances During Arctic Comparisons Between Measured and Modeled Longwave Irradiances During Arctic Winter: Results from the Second International Pyrgeometer and Absolute Sky-Scanning Radiometer Comparison (IPARSC-II) Marty, Ch.(a), Storvold, R.(a), Philipona, R.(b), Delamere, J.(c), Dutton, E.(d), Michalsky, J.(e), Stamnes, K.(f), Eide, H.(f), and Stoffel, T.(g), Geophysical Institute, University of Alaska Fairbanks (a), World Radiation Center, Davos, Switzerland (b), Atmospheric and Environmental Research, Boston (c), Climate Monitoring and Diagnostics Laboratory NOAA, Boulder (d), State University of New York at Albany (e), Stevens Institute of Technology, Hoboken, New Jersey (f), National Renewable Energy Laboratory, Golden (g) Twelfth Atmospheric Radiation Measurement (ARM) Science Team Meeting

119

ARM - Publications: Science Team Meeting Documents: Determination of the  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Determination of the Arctic Indirect Aerosol Effect from AERI and Determination of the Arctic Indirect Aerosol Effect from AERI and Multispectral Radiometer Data Lubin, Dan University of California, San Diego Vogelmann, Andrew Brookhaven National Laboratory We have detected and quantified the aerosol indirect radiative effect in the longwave by identifying the spectral signatures of liquid water clouds having smaller droplet effective droplet radius using AERI. Statistically significant differences in the longwave emission spectra appear between low CN and high CN cases as measured in NOAA CMDL aerosol number concentration data at Barrow, Alaska. An independent verification of this indirect effect detection is provided by downwelling longwave flux measurements from the NSA pyrgeometers, which show consistently larger fluxes in the high CN

120

1  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Results from the Longwave Effective Cloud Fraction Results from the Longwave Effective Cloud Fraction in the Cloudiness Intercomparison E.E. Takara and R.G. Ellingson Department of Meteorology Florida State University Tallahassee, Florida Introduction While it may seem to be a simple quantity, cloud amount is somewhat elusive. Different types of instruments placed next to each other can give different cloud amounts because they use different parts of the spectrum, have different fields of view, sampling rates, etc. Another consideration is that cloud amount depends on the physical scale under consideration. The cloud amount appropriate for comparison to a single pyrgeometer is not likely to be useful for a grid square with 100-km sides. In terms of N e , the average longwave surface flux F, over an area that is compared to individual clouds,

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

splitt(2)-99.PDF  

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Improvement in the Assessment of SIRS Broadband Improvement in the Assessment of SIRS Broadband Longwave Radiation Data Quality M. E. Splitt University of Utah Salt Lake City, Utah C. P. Bahrmann Cooperative Institute for Meteorological Satellite Studies University of Oklahoma Norman, Oklahoma Introduction Validation of the performance of the Solar Infrared Station (SIRS) pyrgeometers is being conducted for the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP). Cloud and Radiation Testbed (CART) site extended facilities (EFs). Improvements to this effort include comparison of the downwelling longwave irradiance to estimates from several published algorithms based on surface meteorological conditions (including temperature, vapor pressure, and the clearness index). The algorithms provide estimates for clear skies, overcast skies, and all-sky conditions (during daylight

122

ARM - Publications: Science Team Meeting Documents  

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Cloud-Radiation-Aerosol Experiment (1996) at IAPh, Russia Cloud-Radiation-Aerosol Experiment (1996) at IAPh, Russia Golitsyn, G.S., Anikine, P.P., and Sviridenkov, M.A., Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences Eighth Atmospheric Radiation Measurement (ARM) Science Team Meeting In 1996, local measurements of the optical properties of the near-surface aerosol were carried out parallel with aureole measurements of the aerosol in the atmospheric column. The spectral radiation was measured by a complex of spectrometers. Global radiation was controlled by standard equipment (pyrheliometer, pyranometer, pyrgeometer). A microwave sounder was used to determine the liquid water path of clouds and water vapor content. Advanced Very High Resolution Radiometer (AVHRR) data from the National Oceanic and

123

Clough-SA  

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Longwave Broadband QME Based on ARM Longwave Broadband QME Based on ARM Pyrgeometer and AERI Measurements S. A. Clough, A. D. Brown, C. Andronache, and E. J. Mlawer Atmospheric and Environmental Research, Inc. Cambridge, Massachusetts T. R. Shippert and D. D. Turner Pacific Northwest National Laboratory Richland, Washington D. C. Tobin, H. E. Revercomb, and R. O. Knuteson University of Maryland College Park, Maryland Introduction Accurate modeling of the downwelling longwave flux at the surface is critical to our understanding of a number of important issues: the earth's energy balance; processes at the atmosphere's lower boundary including ice melt and ocean forcing; and evaluating our ability to model atmospheric fluxes for dynamical models including numerical weather prediction and climate models. Under the Atmospheric

124

ARM - Field Campaign - IPASRC II Campaign  

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govCampaignsIPASRC II Campaign govCampaignsIPASRC II Campaign Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : IPASRC II Campaign 2001.03.05 - 2001.03.16 Lead Scientist : Rune Storvold Data Availability All IPASRC II related data will be collected from the different principal investigators at the University of Alaska in Fairbanks, Geophysical Institute. For further information, contact Chris Marty, (907) 474-7360, or Rune Storvold, (907) 474-6639. For data sets, see below. Summary The second IPASRC II was successfully carried out at the NSA-CART site at Barrow from March 5 to March 15, 2001. During most of the time, great weather and clear skies provided measurements of longwave downward irradiances between 130 and 170 Wm-2 and air temperatures between -25 and -35 degrees Celsius. All pyrgeometers were

125

ARM - Publications: Science Team Meeting Documents  

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Atmospheric Longwave Irradiance Uncertainty Atmospheric Longwave Irradiance Uncertainty Philipona, R. (a), Dutton, E.G. (b), Wood, N. (b), Anderson, G. (b), Stoffel, T. (c), Reda, I. (c), Michalsky, J.J. (d), Wendling, P. (e), Stiffter, A. (e), Clough, S.A. (f), Mlawer, E.J. (f), Revercomb, H. (g), and Shippert, T. (h), World Radiation Center, Davos, Switzerland (a), NOAA, Climate Monitoring and Diagnosic Laboratory (b), National Renewable Energy Laboratory (c), State University of New York at Albany (d), DLR, Oberfaffenhofen, Germany (e), Atmospheric and Environmental Research Inc. (f), University of Wisconsin-Madison (g), Pacific Northwest National Laboratory (h) Eleventh Atmospheric Radiation Measurement (ARM) Science Team Meeting The first International Pyrgeometer and Absolute Sky-scanning Radiometer

126

The Derivation of a Model Solar Chromosphere from Radio Data  

Science Journals Connector (OSTI)

...equivalent black-body temperature of the sun's disk and the...separated and their distributions over the solar disk...chromosphere with electron temperature at that level. Optical...function of electron temperature and density so that...

1950-01-01T23:59:59.000Z

127

The Earth's heat balance and the greenhouse effect  

Science Journals Connector (OSTI)

This section was abstracted from Gerlich and Tscheuschner (2007). Radiation is the only means of heat transfer between bodies in the vacuum of space. The radiation emitted by a blackbody plane surface is a spe...

Donald Rapp

2014-01-01T23:59:59.000Z

128

Defects, thermal phenomena and design in photonic crystal systems  

E-Print Network [OSTI]

The physics of blackbodies has been an ongoing source of fascination and scientific research for over a hundred years. Kirchhoff's law states that emissivity and absorptivity are equal for an object in thermal equilibrium. ...

Chan, David Lik Chin

2006-01-01T23:59:59.000Z

129

Regge-calculus model for the Tolman universe  

Science Journals Connector (OSTI)

A model for the Tolman universe is constructed from 600 equilateral tetrahedrons, each containing blackbody radiation, and connected so as to form a closed space. The dynamics of this universe is studied using the techniques of Regge calculus.

P. A. Collins and Ruth M. Williams

1974-11-15T23:59:59.000Z

130

Quantum Solar Energy Conversion and Application to Organic Solar Cells  

Science Journals Connector (OSTI)

When studying the limits of solar energy conversion, either by thermal or quantum processes, the sun has traditionally been treated as a blackbody (thermal equilibrium) radiator with surface temperature 5 800 ...

Gottfried H. Bauer; Peter Würfel

2003-01-01T23:59:59.000Z

131

Advanced nanofabrication of thermal emission devices  

E-Print Network [OSTI]

Nanofabricated thermal emission devices can be used to modify and modulate blackbody thermal radiation. There are many areas in which altering thermal radiation is extremely useful, especially in static power conversion, ...

Hurley, Fergus (Fergus Gerard)

2008-01-01T23:59:59.000Z

132

Quantum-coupled single-electron thermal to electric conversion scheme  

E-Print Network [OSTI]

Thermal to electric energy conversion with thermophotovoltaics relies on radiation emitted by a hot body, which limits the power per unit area to that of a blackbody. Microgap thermophotovoltaics take advantage of evanescent ...

Wu, D. M.

133

Orr 2009 ARM STM poster2.ppt  

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Status: Design, testing and implementation has been begun at SGP Status: Design, testing and implementation has been begun at SGP A U.S. Department of Energy laboratory managed by UChicago-Argonne, LLC Accomplishments and Status of SGP During 2008 Brad W. Orr 1 Dan J. Rusk 2 John Schatz 2 David Breedlove 2 Richard Eagan 1 1 Argonne National Laboratory, Argonne, IL 2 ACRF/SGP, Cherokee Nation Distributors, Stilwell, OK INSTRUMENTS GENERAL STATISTICS * Instrument Availability - Averaged over 95% during 2008. * Electronic Repair Lab - $20,000 in savings * Calibrations - Over 140 instruments calibrated * Guest Instruments Supported - 40 * Site visitors - Over 100 visits by scientists and guests at the Central Facility. * Field Campaigns - 18 Campaigns supported last year. Acknowledgments We would like to thank the entire SGP staff for another year of excellence and for their continued support of all aspects of operations. This

134

PowerPoint Presentation  

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Spectral Shortwave Spectral Shortwave Quality Measurement Experiment (SW QME) at the Southern Great Plains ACRF J. Delamere, E. Mlawer (AER, Inc.) P. Kiedron (CIRES/U. Colorado) J. Michalsky (NOAA/ESRL/GMD) C. Long, C. Flynn, T. Shippert (PNNL) P. Pilewskie, P. McBride (LASP/U. Colorado) The Shortwave QME Paradigm Critical evaluation of all components of closure study in the shortwave..... * Radiometric measurement quality * Accuracy of calculation (LBLRTM/CHARTS) * Line parameters (HITRAN) * MT_CKD continuum model * Extraterrestrial spectrum * Model inputs * Radiosonde, MWRRET * Spectral Surface Albedo * Aerosol Properties (ABE) * Cloud Properties (Microbase) Spectral Surface Albedo Algorithm 1. Based on the 6 MFR channel albedos, every surface classified as either: * Snow * Brown Vegetation/Soil

135

Microsoft Word - 2009-07 Instrument Report_DOE-SC-ARM-P-09-004.7.doc  

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7 7 ACRF Instrumentation Status and Information JW Voyles July 2009 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

136

delamere_swqme_arm08_poster.ppt  

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Shortwave Spectral Radiative Closure Studies Shortwave Spectral Radiative Closure Studies at the ARM Southern Great Plains Climate Research Facility Step 2: Input these properties to the line-by-line radiative transfer model LBLRTM/CHARTS with the HITRAN 2004 line parameter database, including updates through 2007, and MT_CKD continuum model. Compute transmittance, radiance/irradiance. Step 3: Determine best estimate of radiative properties from available radiometric measurements. Step 5: Diagnose cause of measurement/model discrepancies. Improve Steps 1 through4. Step 1: Determine best estimate of atmospheric and surface properties at the SGP ACRF. To do this, use ARM's sophisticated aerosol and cloud remote sensing instrumentation, daily radiosonde launches, and surface microwave radiometers.

137

Communications: NREL PowerPoint Presentation Template with Light Background  

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AMF/GNDRAD Reconfiguration: AMF/GNDRAD Reconfiguration: Moving the White CoolCell ARM Radiative Processes Working Group Analyses by Mary Anderberg & Tom Stoffel March 10, 2008 ACRF Upwelling Irradiances Infrared UIR Shortwave US Pt Reyes, CA Banizoumbou Niger AMF Upwelling Irradiances Warren et al. visits FKB... BCR 01402: Move 7 m before on 10 m Tower AMF Upwelling Irradiances July 14, 2007 UIR US AMF Upwelling Irradiances July 15, 2007 UIR US AMF Upwelling Irradiances August 1, 2007 UIR US AMF Upwelling Irradiances August 5, 2007 UIR US Surface Albedo (AM) Surface Albedo (PM) Radiometer View Factors * * * 90% Irradiance Contribution Height (AGL) Effective Radius 3 m 9 m 10 m 29 m Radiometer Sensitivities Pyranometer +/- 10 Wm -2 vs 0.4% of 200 Wm-2 (0.8 Wm

138

ARM - 2006 Science Team Meeting Presentations  

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Presentations Presentations 2006 Meeting 2006 Meeting Home Proceedings Sorted by Author Proceedings Sorted by Title Pictures Posters Presentations Meeting Archives ARM Science Team Meeting Proceedings Past Science Team Meetings 2006 Science Team Meeting Presentations Monday, March 27, 2006 ARM Orientation for New and Current PIs: Overview and History Warren Wiscombe (PDF, 6 MB) ARM Orientation for New and Current PIs: Infrastructure Overview 2006 Jimmy Voyles (PDF, 4MB) ARM Orientation for New and Current PIs: An Incomplete Introduction to ACRF Instrumentation Jim Liljegren (PDF, 4MB) ARM Orientation for New and Current PIs: ARM Data Quality Office - Real-Time Assessment of ARM Data Randy Peppler (PDF, 12MB) ARM Orientation for New and Current PIs: Getting Data from the ARM Archive

139

Microsoft Word - 2009-04 Instrument Report_DOE-SC-ARM-P=09.004.4.doc  

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4 4 ACRF Instrumentation Status and Information JW Voyles April 2009 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

140

Research Highlight  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

A Proposed Measurement Standard for Diffuse Radiation Flux A Proposed Measurement Standard for Diffuse Radiation Flux Download a printable PDF Submitter: Michalsky, J. J., DOC/NOAA/OAR/ESRL Area of Research: Radiation Processes Working Group(s): Radiative Processes Journal Reference: Michalsky, J. J., C. Gueymard, P. Kiedron, L. J. B. McArthur, R. Philipona, and T. Stoffel, 2007: A proposed working standard for the measurement of diffuse horizontal shortwave irradiance, J. Geophys. Res., 112, D16112, doi:10.1029/2007JD008651. The three pyranometers proposed for the international standard for diffuse flux are shown here in action during the 2006 campaign at the ACRF SGP site. Of note are the shadows of the blocking balls on the domes of each pyranometer. The blocking balls are moved by a solar tracker to continuously shade the pyranometers.

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
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141

ARM - Field Campaign - Cloud LAnd Surface Interaction Campaign (CLASIC)  

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govCampaignsCloud LAnd Surface Interaction Campaign (CLASIC) govCampaignsCloud LAnd Surface Interaction Campaign (CLASIC) Campaign Links CLASIC Website Related Campaigns CLASIC - SAM Support 2007.06.09, DeVore, SGP CLASIC - 9.4 GHz Phase Array Radar 2007.06.08, Kollias, SGP CLASIC - Southern Great Plains Aerosol Evolution Study (SGPAES) 2007.06.08, Collins, SGP CLASIC - Land Surface 2007.06.01, Jackson, SGP CLASIC - Radiosonde Campaign 2007.06.01, Orr, SGP CLASIC - SGP Particle Phase Experiment 2007.06.01, Martin, SGP CLASIC - Land-Cloud Coupled Data Assimilation System 2007.06.01, Jackson, SGP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Cloud LAnd Surface Interaction Campaign (CLASIC) 2007.06.01 - 2007.06.30 Website : http://acrf-campaign.arm.gov/clasic/ Lead Scientist : Mark Miller

142

StormVEx_2009ARM_poster  

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StormVEx Question: StormVEx Question: Can these distinctions be made in orographic clouds with snow akes, water droplets, and active dynamics? Aerial view of SPL Summer/Fall at SPL Winter/Spring at SPL Science team at AMF2 location during Winter 2009 site visit SPL The core goal of ACRF is improving the representation of clouds in global models. The ability to convert the remote sensing measurements to cloud properties has been ham- pered by a critical shortage of correlative data for valida- tion and development of new algorithms. Such data sets are normally created by episodic and expensive aircraft measurements. StormVEx will create a correlative data set equivalent to ~200-300 aircraft flights in liquid and mixed phase clouds. This will be achieved by placing the AMF2 in

143

Bench-Scale Cross Flow Filtration of  

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8 8 ACRF Instrumentation Status: New, Current, and Future August 2008 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

144

Bench-Scale Cross Flow Filtration of  

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5 5 The Status of the ACRF Millimeter Wave Cloud Radars (MMCRs), the Path Forward for Future MMCR Upgrades, the Concept of 3D Volume Imaging Radar and the UAV Radar P. Kollias, M. Miller Brookhaven National Laboratory K. Widener, R. Marchand, T. Ackerman Pacific Northwest National Laboratory December 2005 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed,

145

Slide 1  

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Southern Great Plains Atmospheric Southern Great Plains Atmospheric Moisture Budget for CLASIC Peter J. Lamb 1,2 , Avraham Zangvil 3 , Diane H. Portis 1 1 1 Cooperative Institute for Mesoscale Meteorological Studies The University of Oklahoma 2 School of Meteorology, The University of Oklahoma 3 Meteorology Unit, Blaustein Institute for Desert Research, Ben Gurion University of the Negev, Israel ARM Science Team Meeting March 2009 CLASIC CLOUD AND LAND SURFACE INTERACTION CAMPAIGN Southern Great Plains Site ARM Climate Research Facility (ACRF) June 9-30 2007 CLASIC Science Questions (1) What are the roles of cumulus convection and spatial variations in land cover in depleting low-level water vapor as it is advected into the SGP region? (2) What are the relationships between cumulus clouds and the soil-plant-atmosphere

146

Research Highlight  

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Estimating Cloud and Rainfall Parameters in a Vertical Column Above the Estimating Cloud and Rainfall Parameters in a Vertical Column Above the ACRF SGP Site Download a printable PDF Submitter: Matrosov, S. Y., CIRES/NOAA/ESRL/University of Colorado Area of Research: Cloud Distributions/Characterizations Working Group(s): Cloud Properties Journal Reference: N/A An example of MMCR (a) and WACR (b) ARM radar measurements of a stratiform precipitating event and the corresponding estimates of mean rain rate (c) and cloud IWP and LWP (d). A comprehensive characterization of all hydrometeors in the vertical column is an important task, which is crucial for model parameterization and validation purposes. For many years, the remote sensing efforts within the Atmospheric Radiation Measurement (ARM) Program were focused primarily on either non-precipitating or only weakly-precipitating (e.g., drizzling)

147

Bench-Scale Cross Flow Filtration of  

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6 6 ACRF Instrumentation Status: New, Current, and Future June 2008 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

148

DOE/SC-ARM/P-07-004  

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3 3 ACRF Ingest Software Status: New, Current, and Future Revision 3 A.S. Koontz, S. Choudhury B.D. Ermold K.L. Gaustad November 2007 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor an agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service

149

DOE/SC-ARM/P-07-004  

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3 3 ACRF Ingest Software Status: New, Current, and Future Revision 6 A.S. Koontz, S. Choudhury B.D. Ermold N. N. Keck K.L. Gaustad R.C. Perez April 2008 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor an agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service

150

Bench-Scale Cross Flow Filtration of  

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1 1 ACRF Instrumentation Status: New, Current, and Future November 2008 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

151

Cold Weather Hazards  

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0 0 Cold Weather Hazards June 2010 NSA_cwh_Rev10.doc 1 Atmospheric Radiation Measurement Climate Research Facility/ North Slope of Alaska/Adjacent Arctic Ocean (ACRF/NSA/AAO) Cold Weather Hazards Winter Conditions at the North Slope of Alaska The North Slope of Alaska is north of the Arctic Circle at latitudes ranging from 69 to 72 degrees. Barrow, the largest town on the North Slope (pop. 4500), is the site of a National Weather Service Station, which has been active for several decades, so the climatology of the Alaska arctic coastal region as represented by Barrow is relatively well known. The North Slope is covered with ice and snow typically eight months of the year (October-May). During part of November, all of December, and most of January, the sun does not come above the horizon; this

152

do_over.sized.v2.pdf  

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author author Andy Vogelmann vogelmann@bnl.gov 631-474-4424 SUMMARY SUMMARY Preliminary tests provided of an artificial neural network, trained on C-Pol data, that uses infrared satellite data to determine precipitation regimes. * Encouraging results show skill in most classes, including the difficult stratiform-anvil discrimination. * Differences arise between comparable neural net trainings that will be the addressed in further research. TWP Cloud Behavior Analyses - Approaches for Model Validation with ACRF Observations Andrew M Vogelmann 1 , Ed Luke 1 , Courtney Schumacher 2 , Mike Jensen 1 , Erwin Boer 3 , Pavlos Kollias 4 , Minghua Zhang 5 1 Brookhaven National Laboratory, 2 Texas A&M University, 3 LUEBEC, 4 McGill University, 5 State University of New York at Stony Brook

153

Microsoft Word - 2009-06 Instrument Report_DOE_SC_ARM_P_09_004.6.doc  

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6 6 ACRF Instrumentation Status and Information JW Voyles June 2009 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

154

Bench-Scale Cross Flow Filtration of  

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0 0 ACRF Instrumentation Status: New, Current, and Future October 2008 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

155

3. New Cloud Climatology  

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New Cloud Climatology New Cloud Climatology Computed for the summers (May-Au- gust) 2000 through 2004 (Berg and Kassianov 2008). Uses ARSCL VAP, Total Sky Imager, and radar wind profiler. * * Initial Evaluation of the Cumulus Potential Scheme at the ACRF SGP Site Larry Berg, William Gustafson, and Evgueni Kassianov Pacific Northwest National Laboratory 1. Motivation Shallow clouds are poorly predicted by current global and regional scale models. A new parameterization has been devel- oped that links the boundary-layer turbu- lence and the shallow clouds. 2. The CuP Parameterization The Cumulus Potential (CuP) param- eterization uses Probability Density Functions (PDFs) of temperature and moisture to represent the subgrid scale

156

Microsoft Word - 2009-02 Instrument Report_DOE-SC-ARM-P-09.004.2.doc  

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2 2 ACRF Instrumentation Status: New, Current, and Future JW Voyles February 2009 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

157

Bench-Scale Cross Flow Filtration of  

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9 9 ACRF Instrumentation Status: New, Current, and Future September 2008 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

158

ARM - Facility News Article  

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New Data Stream Available from Millimeter Wave Cloud Radar New Data Stream Available from Millimeter Wave Cloud Radar Bookmark and Share Inside the instrument shelter, the MMCR data system collects radar spectral data and processes these into reflectivity, vertical velocities, and spectral width. Inside the instrument shelter, the MMCR data system collects radar spectral data and processes these into reflectivity, vertical velocities, and spectral width. As a result of upgrades to the Millimeter Wave Cloud Radar (MMCR) processors (see http://www.arm.gov/acrf/updates051504.stm#nsammcr) at the ARM Climate Research Facility Southern Great Plains (SGP) and North Slope of Alaska (NSA) locales, two MMCR data streams-mmcrcalC1.a1 (calibration data) and mmcrmomentsC1.a1 (spectral "moments" data)-have been combined

159

ARM - Publications: Science Team Meeting Documents: MICROBASE, A Continuous  

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MICROBASE, A Continuous Baseline Microphysical Retrieval: Status and Future MICROBASE, A Continuous Baseline Microphysical Retrieval: Status and Future Plans Miller, Mark Brookhaven National Laboratory Johnson, Karen Brookhaven National Laboratory Michael, Paul Brookhaven National Laboratory Mace, Gerald University of Utah The MICROBASE_PI and MICROBASE_PA value-added products (VAPs) are integral components of the Broadband Heating Rate Profile (BBHRP) project of the Atmospheric Radiation Measurement (ARM) Program. The goal of the BBHRP project is to determine atmospheric heating and cooling rate profiles in the column above the active sensors at each ARM Climate Research Facility (ACRF) sites and within a larger volume around each site, representative of a global climate model grid cell. To produce the heating rate profiles,

160

Research Highlight  

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"Roobik" Is Part of the Answer, Not a Puzzle "Roobik" Is Part of the Answer, Not a Puzzle Submitter: Turner, D. D., National Oceanic and Atmospheric Administration Area of Research: Radiation Processes Working Group(s): Radiative Processes Journal Reference: N/A Taking place during the arid Arctic winter, the RHUBC will obtain measurements in the far-infrared (15-40 microns), when the so-called "Arctic" infrared window between 16 and 40 microns is semi-transparent. Between February and March 2007 at the ACRF North Slope of Alaska site in Barrow, high-spectral-resolution observations will be collected by three state-of-the-art Fourier Transform Spectrometers sampling at different bands in the far-infrared. The Radiative Heating in Underexplored Bands Campaign, or RHUBC (pronounced "roobik"), will make detailed observations

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161

ARM XDC Datastreams  

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Diagnostic Analyses Diagnostic Analyses Documentation ECMWFDIAG Instrument External Datastream Descriptions ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send European Centre for Medium Range Weather Forecasts Diagnostic Analyses (ECMWFDIAG) Information updated on July 3, 2013, 6:19 pm GMT General Data Description Diagnostic Analyses data are derived from ECMWF model runs in simulated vertical profiles of diagnostic variables at specific locations or for area averages. The Physical Parametrization Group at ECMWF generates these data as a courtesy to ARM for all the ACRF sites including the changing location of the mobile facility. These data can only be distributed to ARM scientists. ARM scientists who obtain these data must agree to acknowledge use of the data in their

162

Research Highlight  

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The Evolution and Distribution of Water Vapor and Microphysical Properties The Evolution and Distribution of Water Vapor and Microphysical Properties in Cirrus Clouds Download a printable PDF Submitter: Comstock, J. M., Pacific Northwest National Laboratory Area of Research: Radiation Processes Working Group(s): Cloud Modeling, Cloud Properties Journal Reference: Comstock JM, R Lin, DO Starr, and P Yang. 2008. "Understanding ice supersaturation, particle growth, and number concentration in cirrus clouds." Journal of Geophysical Research - Atmospheres, 113, D23211, doi:10.1029/2008JD010332. Vertical velocity (Vm) derived from millimeter cloud radar (MMCR) Doppler velocity measurements in cirrus clouds observed over the ACRF SGP site. Cloud model simulations of cirrus clouds using large-scale forcing (left panel) and cloud-scale forcing (right panel).

163

1  

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Factors Controlling the Properties of Multi-Phase Factors Controlling the Properties of Multi-Phase Arctic Stratocumulus Clouds A. Fridlind and A. Ackerman National Aeronautics and Space Administration - Ames Research Center Moffett Field, California S. Menon and I. Sednev Lawrence Berkeley National Laboratory Berkeley, California Introduction The October 2004 Multi-Phase Arctic Cloud Experiment (M-PACE) Intensive Operational Period (IOP) at the Atmospheric Radiation Measurement (ARM) Climate Research Facility's (ACRF's) North Slope of Alaska (NSA) locale focused on measuring the properties of autumn transition-season arctic stratus and the environmental conditions controlling them, including concentrations of heterogeneous ice nuclei. Our work aims to use a large-eddy simulation (LES) code with embedded size-resolved cloud

164

Microsoft Word - 2009-03 Instrument Report_DOE-SC-ARM-P-09-004.3.doc  

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3 3 ACRF Instrumentation Status: New, Current, and Future JW Voyles March 2009 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

165

Bench-Scale Cross Flow Filtration of  

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0 0 ACRF Instrumentation Status: New, Current, and Future November - December 2007 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

166

ARM - Field Campaign - Indirect and Semi-Direct Aerosol Campaign (ISDAC)  

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govCampaignsIndirect and Semi-Direct Aerosol Campaign (ISDAC) govCampaignsIndirect and Semi-Direct Aerosol Campaign (ISDAC) Campaign Links ISDAC Website Related Campaigns Parameterization of Extinction Coefficient in Ice and Mixed-Phase Arctic Clouds During ISDAC 2010.10.01, Korolev, AAF ISDAC - Second Year Supplemental Surface Spectral Irradiance Measurements 2009.04.07, Lubin, NSA ISDAC - NASA ARCTAS Coordination with ARM 2008.04.01, Ferrare, NSA ISDAC / RISCAM - Humidified Tandem Differential Mobility Analyzer (HTDMA) 2008.04.01, Collins, NSA ISDAC - Hemispheric Flux Spectroradiometer 2008.03.31, Lubin, NSA Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Indirect and Semi-Direct Aerosol Campaign (ISDAC) 2008.04.01 - 2008.04.30 Website : http://acrf-campaign.arm.gov/isdac/

167

ARM - 2006 ARM Science Team Meeting  

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Meeting Meeting 2006 Meeting 2006 Meeting Home Proceedings Sorted by Author Proceedings Sorted by Title Pictures Posters Presentations Meeting Archives ARM Science Team Meeting Proceedings Past Science Team Meetings 2006 ARM Science Team Meeting March 27-18 | Albuquerque, New Mexico | Hyatt Regency Albuquerque The Hyatt Regency - Albequerque The Hyatt Regency - Albequerque Meeting Highlights Just over 300 ARM scientists and ACRF infrastructure staff took part in the 16th ARM Science Team meeting held in Albuquerque, New Mexico, on March 27-31, 2006. After an initial day of focused meetings among the ARM Working Groups, Dr. David Thomassen, Acting Associate Director of DOE's Office of Biological and Environmental Research (BER), opened the meeting's plenary session with remarks about the role of ARM within the DOE, and its

168

Research Highlight  

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Continuous Clear-Sky Longwave from Surface Measurements Continuous Clear-Sky Longwave from Surface Measurements Download a printable PDF Submitter: Long, C. N., Pacific Northwest National Laboratory Turner, D. D., National Oceanic and Atmospheric Administration Area of Research: Radiation Processes Working Group(s): Radiative Processes Journal Reference: Long, CN, and DD Turner. 2008. "A method for continuous estimation of clear-sky downwelling longwave radiative flux developed using ARM surface measurements." Journal of Geophysical Research 113, D18206, doi:10.1029/2008JD009936. Comparison of clear-sky RT model calculations (black) and our estimates (gray) with detected LW effective clear-sky measurements from the ACRF SGP site from 1 March through 31 May 2003, showing that our LW estimates do as well as detailed model calculations in comparison with actual LW

169

Bench-Scale Cross Flow Filtration of  

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2 2 ACRF Instrumentation Status: New, Current, and Future February 2008 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

170

1  

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Wave Cloud Radar Upgrades: Wave Cloud Radar Upgrades: Review, Status, and Plans K.B. Widener Pacific Northwest National Laboratory Richland, Washington K.P. Moran National Oceanic and Atmospheric Administration- Earth System Research Laboratory-Physical Sciences Division Boulder, Colorado Introduction The Atmospheric Radiation Measurement (ARM) Program currently operates five millimeter-wave cloud radars (MMCRs) at the ARM Climate Research Facility (ACRF) Southern Great Plains (SGP) site, North Slope of Alaska (NSA) locale's Barrow site, and Tropical Western Pacific (TWP) locale's Manus, Nauru, and Darwin sites. Currently, three different signal processors are deployed, and we are in process of upgrading the remaining two radars to provide higher reliability and efficiency along with

171

1  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Analyses from TWP-ICE Analyses from TWP-ICE C.N. Long and J.H. Mather Pacific Northwest National Laboratory Richland, Washington N. Tapper and J. Beringer Monash University Melbourne, Australia B. Atkinson Australian Bureau of Meteorology Darwin, Australia Introduction Surface data collected during Tropical Warm Pool-International Cloud Experiment (TWP-ICE) includes radiation and standard meteorological measurements at six remote sites, as well as those at the ARM Climate Research Facility (ACRF) Darwin site (Figure 1). Five of these remote sites include not only unshaded broadband hemispheric shortwave (SW) and longwave (LW) instruments, but also a multi- detector SW radiometer designed to simultaneously measure both the downwelling diffuse and total SW

172

ARM - Field Campaign - ASSIST: Atmospheric Sounder Spectrometer for  

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govCampaignsASSIST: Atmospheric Sounder Spectrometer for Infrared govCampaignsASSIST: Atmospheric Sounder Spectrometer for Infrared Spectral Technology Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : ASSIST: Atmospheric Sounder Spectrometer for Infrared Spectral Technology 2008.07.08 - 2008.07.18 Lead Scientist : Michael Howard For data sets, see below. Description Goals of assist were to intercompare radiance spectra and profile retrievals from a new AERI-like instrument, called "ASSIST" with the SGP site AERI(s) and calculations from Radiosondes measurements. * To bring the ASSIST instrument to the SGP ACRF and perform simultaneous measurements of the sky radiation with those from the AERI. * On relatively cloud-free days, release a special radiosonde at the

173

DOE/SC-ARM/P-07-004  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

2 2 ACRF Ingest Software Status: New, Current, and Future Revision 2 A.S. Koontz, S. Choudhury B.D. Ermold K.L. Gaustad September 2007 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor an agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service

174

DOE/SC-ARM/P-07-004  

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5 5 ACRF Ingest Software Status: New, Current, and Future A.S. Koontz, S. Choudhury B.D. Ermold N. N. Keck K.L. Gaustad R.C. Perez June 2008 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor an agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service

175

Bench-Scale Cross Flow Filtration of  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

8 8 ACRF Instrumentation Status: New, Current, and Future September - October 2007 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

176

Slide 1  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

deployment (fiber) deployment (fiber) 9.20-25.2006, 10.25.2006-1.15.2007 Communication: in the field similar to above: instrument to computer via optical fiber Original location: ~250m SE of Great White Sample data: A Total Precipitation Sensor at the Barrow ACRF Site ABSTRACT A Yankee Environmental TPS-3100 Total Precipitation Sensor was installed near the Barrow ARM Climate Research Facility (south of the NOAA facility and east of the Great White shelter) in September 2006. Data ingest software was completed by the end of 2006. Precipitation data from the TPS-3100 are being collected and archived at present. The sensor head of the TPS-3100, the "hotplate" sensor, consists of two heated plates about five inches in diameter. The plates are oriented parallel to the ground, one facing

177

1  

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Refurbishment and Upgrade of the Refurbishment and Upgrade of the Atmospheric Radiation Measurement Raman Lidar D.D. Turner Pacific Northwest National Laboratory Richland, Washington J.E.M. Goldsmith Sandia National Laboratories Livermore, California Introduction The Atmospheric Radiation Measurement Program (ARM) Climate Research Facility (ACRF) Raman lidar (CARL) is an autonomous, turn-key system that profiles water vapor, aerosols, and clouds throughout the diurnal cycle for days without attention (Goldsmith et al. 1998). CARL was first deployed to the Southern Great Plains CRF during the summer of 1996 and participated in the 1996 and 1997 water vapor intensive operational periods (IOPs). Since February 1998, the system has collected over 38,000 hrs of data (equivalent of almost 4.4 years), with an average monthly uptime of 62% during

178

Expansion of Facilities on the North Slope of Alaska in Time for the  

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Expansion of Facilities on the North Slope of Alaska in Time for the Expansion of Facilities on the North Slope of Alaska in Time for the International Polar Year Zak, Bernard Sandia National Laboratories Ivey, Mark Sandia National Laboratories Zirzow, Jeffrey Sandia National Laboratories Brower, Walter UIC Science Division ARM/NSA Ivanoff, James NSA Whiteman, Doug NSA/AAO Sassen, Kenneth University of Alaska Fairbanks Truffer-Moudra, Dana University of Alaska Fairbanks Category: Infrastructure & Outreach The International Polar Year (IPY; 2007-2008) will stimulate research in both polar regions, primarily focusing on the rapid climate-related changes occurring at high latitudes. In part in preparation for the IPY, facilities at the NSA ACRF are undergoing expansion. In addition, with funding through NOAA, Phase 1 of the planned $60M Barrow Global Climate Change Research

179

The ARM Atmospheric Emitted Radiance Interferometer (AERI): Status and  

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The ARM Atmospheric Emitted Radiance Interferometer (AERI): Status and The ARM Atmospheric Emitted Radiance Interferometer (AERI): Status and Preliminary Assessments of Instrument Deployments in 2006 Dedecker, Ralph University of Wisconsin Demirgian, Jack Argonne National Laboratory Knuteson, Robert University Of Wisconsin Revercomb, Henry University of Wisconsin-Madison Tobin, David University of Wisconsin-Madison Turner, David University of Wisconsin-Madison Category: Instruments One of the key operational instruments at the Atmospheric Radiation Measurement Climate Research Facility (ACRF) is the Atmospheric Emitted Radiance Interferometer (AERI). This instrument provides the ARM program with surface-based observations of infrared spectrally resolved radiance from a vertically directed cone with better than 1% accuracy. The data from

180

Research Highlight  

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Raman Lidar Observations of Aerosol Humidification Near Clouds Raman Lidar Observations of Aerosol Humidification Near Clouds Submitter: Ferrare, R. A., NASA - Langley Research Center Area of Research: Aerosol Properties Working Group(s): Aerosol Journal Reference: Ferrare, R., et al., Evaluation of Daytime Measurements of Aerosols and Water Vapor Made by an Operational Raman Lidar over the Southern Great Plains, J. Geophys. Res., 111, D05S08, doi:10.1029/2005JD005836, 2006. Relative humidity profiles derived from the Raman lidar during the ALIVE 2005 field experiment. Aerosol extinction profiles derived from the Raman lidar during the ALIVE 2005 field experiment. Aerosol humidification factor f(RH) from Raman lidar measured profiles of aerosol extinction and relative humidity. Upgrades to the Raman lidar at the ARM Climate Research Facility (ACRF)

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Microsoft Word - 2009-05 Instrument Report DOE-SC-ARM-P-09-004.5.doc  

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5 5 ACRF Instrumentation Status and Information JW Voyles May 2009 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

182

Sky Cover from MFRSR Observations  

SciTech Connect (OSTI)

The diffuse all-sky surface irradiances measured at two nearby wavelengths in the visible spectral range and their model clear-sky counterparts are two main components of a new method for estimating the fractional sky cover of different cloud types, including cumulus clouds. The performance of this method is illustrated using 1-min resolution data from ground-based Multi-Filter Rotating Shadowband Radiometer (MFRSR). The MFRSR data are collected at the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site during the summer of 2007 and represent 13 days with cumulus clouds. Good agreement is obtained between estimated values of the fractional sky cover and those provided by a well-established independent method based on broadband observations.

Kassianov, Evgueni I.; Barnard, James C.; Berg, Larry K.; Flynn, Connor J.; Long, Charles N.

2011-07-01T23:59:59.000Z

183

Cloud Occurrence Frequency at the Barrow, Alaska, ARM Climate Research Facility for 2008 Third Quarter 2009 ARM and Climate Change Prediction Program Metric Report  

SciTech Connect (OSTI)

Clouds represent a critical component of the Earth’s atmospheric energy balance as a result of their interactions with solar and terrestrial radiation and a redistribution of heat through convective processes and latent heating. Despite their importance, clouds and the processes that control their development, evolution and lifecycle remain poorly understood. Consequently, the simulation of clouds and their associated feedbacks is a primary source of inter-model differences in equilibrium climate sensitivity. An important step in improving the representation of cloud process simulations is an improved high-resolution observational data set of the cloud systems including their time evolution. The first order quantity needed to understand the important role of clouds is the height of cloud occurrence and how it changes as a function of time. To this end, the Atmospheric Radiation Measurement (ARM) Climate Research Facilities (ACRF) suite of instrumentation has been developed to make the observations required to improve the representation of cloud systems in atmospheric models.

M Jensen; K Johnson; JH Mather

2009-07-14T23:59:59.000Z

184

Narrow Field of View Zenith Radiometer (NFOV) Handbook  

SciTech Connect (OSTI)

The two-channel narrow field-of-view radiometer (NFOV2) is a ground-based radiometer that looks straight up and measures radiance directly above the instrument at wavelengths of 673 and 870 nm. The field-of-view of the instrument is 1.2 degrees, and the sampling time resolution is one second. Measurements of the NFOV2 have been used to retrieve optical properties for overhead clouds that range from patchy to overcast. With a one-second sampling rate of the NFOV2, faster than almost any other ARM Climate Research Facility (ACRF) instrument, we are able, for the first time, to capture changes in cloud optical properties at the natural time scale of cloud evolution.

Chiu, C; Marshak, A; Hodges, G; Barnard, JC; Schmelzer, J

2008-11-01T23:59:59.000Z

185

1  

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Cloud Properties Derived from Cloud Properties Derived from Dual-View Satellite Data over the Continental United States J. Kirk Ayers and R. Palikonda Analytical Services and Materials Inc. Hampton, Virginia P. Minnis National Aeronautics and Space Administration-Langley Research Center Hampton, Virginia P. Heck CIMSS/University of Wisconsin Madison, Wisconsin R. Arduini Science Applications International Corporation Hampton, Virginia Corresponding Author J. Kirk Ayer (j.k.ayers@larc.nasa.gov) Introduction Development of a consistent, accurate quantification of the cloud field over the Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains site (an area with extensive surface observations) is crucial to the development of improved parameterizations in models

186

ARM - Evaluation Product - SASHE Langley Regressions  

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ProductsSASHE Langley Regressions ProductsSASHE Langley Regressions Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Evaluation Product : SASHE Langley Regressions Site(s) PVC SGP General Description The Shortwave Array Spectroradiometer Hemispheric (SAS-He) is a ground-based instrument that measures both direct and diffuse shortwave irradiance. In this regard, the instrument is similar to the Multi-Filter Rotating Shadowband Radiometer (MFRSR) - an instrument that has been in the ACRF stable for more than 15 years. However, the two instruments differ significantly in wavelength resolution and range. In particular, the SAS-He provides hyperspectral measurements from about 350 nm to 1700 nm at a wavelength resolution from 1 to several nanometers, while the MFRSR only

187

Research Highlight  

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Spectral Invariant Behavior of Zenith Radiance Around Cloud Edges Observed Spectral Invariant Behavior of Zenith Radiance Around Cloud Edges Observed by ARM SWS Download a printable PDF Submitter: Marshak, A., NASA - Goddard Space Flight Center Knyazikhin, Y., Boston University Chiu, J., University of Reading Wiscombe, W. J., Brookhaven National Laboratory Area of Research: Radiation Processes Working Group(s): Radiative Processes Journal Reference: Marshak A, Y Knyazikhin, JC Chiu, and WJ Wiscombe. 2009. "Spectral invariant behavior of zenith radiance around cloud edges observed by ARM SWS." Geophysical Research Letters, 36, L16802, doi:10.1029/2009GL039366. (top) Time-wavelength color contour plot of ARM shortwave spectrometer (SWS) spectra measured from 21:35:24 to 21:40:24 UTC on 18 May 2007 at the ARM Climate Research Facility (ACRF) Southern Great Plains (SGP) site in

188

DOE/SC-ARM/P-07-004  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

1 1 ACRF Ingest Software Status: New, Current, and Future Revision 4 A.S. Koontz, S. Choudhury B.D. Ermold K.L. Gaustad January 2008 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor an agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service

189

Slide 1  

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Participation Participation in CINDY2011 (Cooperative Indian Ocean Experiment on Intraseasonal Variability in Year 2011) and Coordination between CINDY/DYNAMO and AMIE (ACRF MJO Investigation Experiment) Chidong Zhang RSMAS, University of Miami Chris Fairall, Richard Johnson, Mike McPhaden Background I: Importance of the MJO/TIV *Monsoons, ENSO, IODZM *Teleconnections, extratropical circulation/weather * Extreme events (midlat rainfall, tropical storm/cyclones) *Earth's rotation rate, length of the day *Atmospheric and oceanic chemistry and biosystem (ozone, CO 2 , aerosols, chlorophyll) *Prediction potential (> 20 days) Background II: Challenges presented by the MJO *A poster child of numerical model deficiency *inability to consistently/knowingly reproduce the MJO/TIV by global climate models

190

DOE/SC-ARM/P-07-004  

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2 2 ACRF Ingest Software Status: New, Current, and Future Revision 5 A.S. Koontz S. Choudhury B.D. Ermold N. N. Keck K.L. Gaustad R.C. Perez March 2008 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor an agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service

191

Barrow  

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5 5 Barrow & Atqasuk Visitor Guide June 2010 Atmospheric Radiation Measurement Climate Research Facility/ North Slope of Alaska/Adjacent Arctic Ocean (ACRF/NSA/AAO) Informal Introduction to Barrow and Atqasuk, Alaska Barrow * Introduction: The ARM Climate Research Facility/North Slope of Alaska/Adjacent Arctic Ocean Barrow Site is located a few miles to the east of Barrow, near the northern-most point of the United States. Barrow is typically accessible only by air or boat, although special "rollagon" trains have gone in and out of Barrow in past winters. The population of Barrow in the year 2000 was 4,500 residents. Since Barrow serves as the seat of the North Slope Borough government, it has many amenities that might not be expected in a town of its

192

Microsoft Word - 2009-09 Instrument Report_DOE-SC-ARM-P-09-004.9.doc  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

9 9 ACRF Instrumentation Status and Information JW Voyles September 2009 Work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research DISCLAIMER This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not

193

PowerPoint Presentation  

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CPWG Instruments Group CPWG Instruments Group Report Chuck Long With help from: Rich Coulter, Jim Mather, Kevin Widener, Eugene Clothiaux, Jimmy Voyles, Others... Moving forward * New 3-channel MWRs - Purchase of 2 this FY, soliciting bids - Tentative plans for 2/yr until one for each CF and spares are purchased. * Photo-acoustic aerosol absorption instrument in process * Upgrade for the BOM C-Pol radar has gone through On hold * SUNY Oxygen A-band instrument - de-scoped by the ACRF Review Board - Concerns over having 3 separate "development" instrument systems come in all in the same year MMCRs * Barrow antenna replaced in December * Measuring circular cross-pol until early Feb when problem found (thanks Jay and Hans!) * SGP antenna next for replacement * SGP to be upgraded to PIRAQ in next

194

ARM - Datastreams - aeriengineer  

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Datastreamsaeriengineer Datastreamsaeriengineer Documentation Data Quality Plots Citation DOI: 10.5439/1025145 [ What is this? ] Generate Citation ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Datastream : AERIENGINEER Atmospheric Emitted Radiance Interferometer (AERI): engineering data Active Dates 1997.10.21 - 2014.01.02 Measurement Categories Radiometric Originating Instrument Atmospheric Emitted Radiance Interferometer (AERI) Measurements Only measurements considered scientifically relevant are shown below by default. Show all measurements Measurement Units Variable Ambient blackbody temperature - apex K ABBapexTemp ( time ) Ambient Blackbody apex temperature weight /1 ABBapexTempWeight ( time ) Ambient blackbody temperature K ABBbottomTemp ( time )

195

ARM - Datastreams - aeri01summary  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

summary summary Documentation Data Quality Plots Citation DOI: 10.5439/1025141 [ What is this? ] Generate Citation ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Datastream : AERI01SUMMARY Atmospheric Emitted Radiance Interferometer (AERI) 01: summary data Active Dates 1995.07.22 - 2014.01.02 Measurement Categories Radiometric Originating Instrument Atmospheric Emitted Radiance Interferometer (AERI) Measurements Only measurements considered scientifically relevant are shown below by default. Show all measurements Measurement Units Variable Ambient blackbody temperature - apex K ABBapexTemp ( time ) Ambient blackbody temperature K ABBbottomTemp ( time ) Ambient blackbody temperature - rim top K ABBtopTemp ( time )

196

Steady-state nonequilibrium temperature gradients in hydrogen gas–metal systems: challenging the second law of thermodynamics  

Science Journals Connector (OSTI)

Differences in gas reaction rates between disparate surfaces have been proposed as a means to achieve steady-state pressure and temperature gradients within a single blackbody cavity, thereby challenging the second law of thermodynamics (Sheehan 1998 Phys. Rev. E 57 6660; Sheehan 2001 Phys. Lett. A 280 185; Capek and Sheehan 2005 Challenges to the Second Law of Thermodynamics (Theory and Experiment) (Fundamental Theories of Physics Series vol 146) (Dordrecht: Springer)). This paper reports on laboratory tests of this hypothesis; specifically, molecular hydrogen is found to dissociate preferentially on rhenium surfaces versus tungsten at identical elevated temperatures and reduced pressures (T ? 2100 K; ). Steady-state nonequilibrium H/H2 ratios over the surfaces suggest that temperature gradients could be maintained under blackbody cavity conditions. Preliminary results from bimetallic blackbody cavity experiments are discussed.

D P Sheehan; J T Garamella; D J Mallin; W F Sheehan

2012-01-01T23:59:59.000Z

197

Coupling between Solid 3He on Aerogel and Superfluid 3He in the Low Temperature Limit  

SciTech Connect (OSTI)

We have cooled liquid 3He contained in a 98% open aerogel sample surrounded by bulk superfluid 3He-B at zero pressure to below 120 {mu}K. The aerogel sample is placed in a quasiparticle blackbody radiator cooled by a Lancaster-style nuclear cooling stage to {approx}200 {mu}K. We monitor the temperature of the 3He inside the blackbody radiator using a vibrating wire resonator. We find that reducing the magnetic field on the aerogel sample causes substantial cooling of all the superfluid inside the blackbody radiator. We believe this is due to the demagnetization of the solid 3He layers on the aerogel strands. This system has potential for achieving extremely low temperatures in the confined fluid.

Bradley, D. I.; Fisher, S. N.; Guenault, A. M.; Haley, R. P.; Pickett, G. R.; Tsepelin, V.; Whitehead, R. C. V. [Department of Physics, Lancaster University, Lancaster, LA1 4YB (United Kingdom); Skyba, P. [Department of Physics, Lancaster University, Lancaster, LA1 4YB (United Kingdom); Institute of Experimental Physics, Watsonova 47, 04353 Kosice (Slovakia)

2006-09-07T23:59:59.000Z

198

Contributions of the Atmospheric Radiation Measurement (ARM) Program and the ARM Climate Research Facility to the U.S. Climate Change Science Program  

SciTech Connect (OSTI)

The Earth’s surface temperature is determined by the balance between incoming solar radiation and thermal (or infrared) radiation emitted by the Earth back to space. Changes in atmospheric composition, including greenhouse gases, clouds, and aerosols can alter this balance and produce significant climate change. Global climate models (GCMs) are the primary tool for quantifying future climate change; however, there remain significant uncertainties in the GCM treatment of clouds, aerosol, and their effects on the Earth’s energy balance. The 2007 assessment (AR4) by the Intergovernmental Panel on Climate Change (IPCC) reports a substantial range among GCMs in climate sensitivity to greenhouse gas emissions. The largest contributor to this range lies in how different models handle changes in the way clouds absorb or reflect radiative energy in a changing climate (Solomon et al. 2007). In 1989, the U.S. Department of Energy (DOE) Office of Science created the Atmospheric Radiation Measurement (ARM) Program within the Office of Biological and Environmental Research (BER) to address scientific uncertainties related to global climate change, with a specific focus on the crucial role of clouds and their influence on the transfer of radiation in the atmosphere. To address this problem, BER has adopted a unique two-pronged approach: * The ARM Climate Research Facility (ACRF), a scientific user facility for obtaining long-term measurements of radiative fluxes, cloud and aerosol properties, and related atmospheric characteristics in diverse climate regimes. * The ARM Science Program, focused on the analysis of ACRF data to address climate science issues associated with clouds, aerosols, and radiation, and to improve GCMs. This report describes accomplishments of the BER ARM Program toward addressing the primary uncertainties related to climate change prediction as identified by the IPCC.

SA Edgerton; LR Roeder

2008-09-30T23:59:59.000Z

199

RADIATIVE TRANSFER IN ULTRARELATIVISTIC OUTFLOWS  

SciTech Connect (OSTI)

Analytical and numerical solutions are obtained for the equation of radiative transfer in ultrarelativistic opaque jets. The solution describes the initial trapping of radiation, its adiabatic cooling, and the transition to transparency. Two opposite regimes are examined. (1) Matter-dominated outflow. Surprisingly, radiation develops enormous anisotropy in the fluid frame before decoupling from the fluid. The radiation is strongly polarized. (2) Radiation-dominated outflow. The transfer occurs as if radiation propagated in vacuum, preserving the angular distribution and the blackbody shape of the spectrum. The escaping radiation has a blackbody spectrum if (and only if) the outflow energy is dominated by radiation up to the photospheric radius.

Beloborodov, Andrei M., E-mail: amb@phys.columbia.edu [Physics Department and Columbia Astrophysics Laboratory, Columbia University, 538 West 120th Street New York, NY 10027 (United States)

2011-08-20T23:59:59.000Z

200

Relativistic Thermodynamics  

Science Journals Connector (OSTI)

It is shown that a generalized formulation of statistical mechanics provides a unified logical basis for the construction of a manifestly covariant theory of relativistic thermodynamics in contrast to heuristic approaches, such as the original theory by Planck and Einstein, and more recent ones by Ott and Møller. The generalized formalism is applied to discuss the relativistic thermodynamics of blackbody radiation, including such processes as the absorption and reflection of a light beam as well as the adiabatic cooling of cosmic blackbody radiation in Milne's model of the universe. The measurement of the temperature of a light beam is also discussed.

VICTOR H. HAMITY

1969-11-25T23:59:59.000Z

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Some remarks on black hole thermodynamics  

E-Print Network [OSTI]

Two thermodynamic "paradoxes" of black hole physics are re-examined. The first is that there is a thermal instability involving two coupled blackbody cavities containing two black holes, and second is that a classical black hole can swallow up entropy in the form of ambient blackbody photons without increasing its mass. The resolution of the second paradox by Bekenstein and by Hawking is re-visited. The link between Hawking radiation and Wigner's superluminal tunneling time is discussed using two equivalent Feynman diagrams, and Feynman's re-interpretation principle.

R. Y. Chiao

2010-12-27T23:59:59.000Z

202

JOURNAL DE PHYSIQUE CoZZoque C7, suppldment au n07, Tome 40, JuiZZet 1979, page C7-803 THE USEOF GAS DISCHARGESAS LLTRAVIOLETRADIOMETRIC STANDARDS  

E-Print Network [OSTI]

investigated: 1) a hydrogen wall-stabilized arc; 2) a blackbody- 1imi ted 1ine thermal arc plasma; 3) an argon "mini-arc"; 4) an argon "maxi-arc"; 5) a deuterium lamp; 6) a krypton dimer rf discharge lamp undertaken. The use of a hydrogen arc plasma as an absolute primary standard of uv spectral radiance has been

Paris-Sud XI, Université de

203

M. V. Casterline, C. Salvaggio, A. J. Garrett, J. W. Faulring, B. D. Bartlett, and P. S. Salvaggio, "Improved temperature retrieval methods for the validation of a hydrodynamic simulation of a partially frozen power plant  

E-Print Network [OSTI]

to extend the capabilities of the model to incorporate snow and ice as possible phenomena in the modeled surface temperatures and in-flight blackbody imagery to produce accurate temperature maps of the pond in interest. A sensitivity analysis was implemented within the data reduction technique to produce accurate

Salvaggio, Carl

204

RAPID DETAILED BALANCE CALCULATIONS FOR MULTIPLE ENERGY GAP SOLAR CELLS S. P. Bremner, M. Y. Levy, C. B. Honsberg  

E-Print Network [OSTI]

of a particular solar cell design providing a framework for assessing novel device designs [5,6] and a guide. This method uses Incomplete Riemann Zeta Integrals as a replacement for the Bose-Einstein integral when as blackbodies with the fluxes given by the so called Bose-Einstein integral. The calculation of these fluxes

Honsberg, Christiana

205

Radiometric Modeling of Cavernous Targets to Assist in the Determination of Absolute Temperature  

E-Print Network [OSTI]

Radiometric Modeling of Cavernous Targets to Assist in the Determination of Absolute Temperature108, Aiken, SC, USA ABSTRACT Determining the temperature of an internal surface within cavernous of these internal surfaces. The cavernous target has often been assumed to be a blackbody, but in field experiments

Salvaggio, Carl

206

Radiation thermometry standards at NMIJ from ?30 °C to 2800 °C  

SciTech Connect (OSTI)

NMIJ has established a national standard scale in radiation thermometry from ?30 °C to 2800 °C. At low temperatures from 160 °C down to ?30 °C large aperture fluid-bath blackbodies have been constructed for the calibration of thermal infrared thermometers. In the range from 160 °C to 420 °C, the standard scale has been realized on 1.6 ?m thermometers calibrated against In, Sn, and Zn blackbodies. A variable temperature blackbody using an air-bath furnace has recently been developed for direct comparison measurements of a 10 ?m thermometer with a 1.6 ?m thermometers up to 500 °C. In the higher range of the temperature scale, dissemination consists of three schemes: the range from 400 °C to 1100 °C by Zn, Al, Ag and Cu fixed-point blackbodies: above the Ag point by 0.9 ?m and 0.65 ?m thermometers: and above the Cu point by metal-carbon high-temperature fixed points.

Ishii, J.; Yamada, Y.; Sasajima, N.; Shimizu, Y. [National Metrology Institute of Japan, AIST, Tsukuba, Ibaraki, 305-8563 (Japan)] [National Metrology Institute of Japan, AIST, Tsukuba, Ibaraki, 305-8563 (Japan)

2013-09-11T23:59:59.000Z

207

PASJ: Publ. Astron. Soc. Japan 60, 191208, 2008 April 25 c 2008. Astronomical Society of Japan.  

E-Print Network [OSTI]

PASJ: Publ. Astron. Soc. Japan 60, 191�208, 2008 April 25 c 2008. Astronomical Society of Japan blackbody radiation with a stellar effective temperatures, T , of 30�60 kK and free�free radiation from-infrared spectra and the cm data by this clump-corrected free�free radiation with mass-loss rates similar to those

Okabe, Nobuhiro

208

PASJ: Publ. Astron. Soc. Japan 60, 191--208, 2008 April 25 # 2008. Astronomical Society of Japan.  

E-Print Network [OSTI]

PASJ: Publ. Astron. Soc. Japan 60, 191--208, 2008 April 25 c # 2008. Astronomical Society of Japan blackbody radiation with a stellar effective temperatures, T # , of 30--60 kK and free--free radiation from�infrared spectra and the cm data by this clump�corrected free--free radiation with mass�loss rates similar to those

Okabe, Nobuhiro

209

SPECTRAL SOLAR IRRADIANCE AND ITS ENTROPIC EFFECT ON EARTH'S CLIMATE  

E-Print Network [OSTI]

comparison with a conventional approach by using a blackbody Sun's brightness temperature exhibits Experiment (SORCE) satellite are used to examine the magnitude and spectral distribution of the Earth radiation received at the top of the atmosphere (TOA) is the same as that radiated at the Sun's surface

210

Astronomy 45 problem set 2 Spring 1997 Astronomy 45. Introduction to Astrophysics  

E-Print Network [OSTI]

can assume that the Sun is a blackbody of temperature T fi = 5700 K and radius 7 \\Theta 10 10 cm. 3 on the average, you actually get a value drawn from a statistical distribution with a mean of N and a standard g spacecraft is launched from Earth and is to be accelerated radially away from the Sun using

Press, William H.

211

Physically-based modeling, simulation and rendering of fire for computer animation  

Science Journals Connector (OSTI)

We give an up-to-date survey on techniques and methods for fire simulation in computer graphics. Physically-based method prevails over traditional non-physical methods for realistic visual effect. In this paper, we explore visual simulation of fire-related ... Keywords: Blackbody radiation, Chemical reaction, Fire, Navier---Stokes equations, Physically-based simulation, Visual adaption

Zhanpeng Huang, Guanghong Gong, Liang Han

2014-08-01T23:59:59.000Z

212

Infrared Thermometer (IRT) Handbook  

SciTech Connect (OSTI)

The Infrared Thermometer (IRT) is a ground-based radiation pyrometer that provides measurements of the equivalent blackbody brightness temperature of the scene in its field of view. The downwelling version has a narrow field of view for measuring sky temperature and for detecting clouds. The upwelling version has a wide field of view for measuring the narrowband radiating temperature of the ground surface.

VR Morris

2006-10-30T23:59:59.000Z

213

ENGO 431 AYMAN HABIB ENGO 431 Sample Questions: Chapters 1-4  

E-Print Network [OSTI]

is meant by a "Blackbody"? What are the factors that affect its conversion of absorbed heat into radiant examples of such systems used in remote sensing applications. What type of EM radiation each system (in your examples) uses? 25. What are the main uses of Radio waves in remote sensing? 26. What do

Habib, Ayman

214

This journal is c the Owner Societies 2011 Phys. Chem. Chem. Phys. Cite this: DOI: 10.1039/c1cp21204d  

E-Print Network [OSTI]

+ , D+ 2 , HT+ , etc.) are the simplest naturally occurring molecules. As such they are amenable to high to the blackbody radiation (BBR) electric field encountered in experimental high-resolution laser spectroscopy­Dicke spectroscopy of narrow vibrational optical lines (B10 Hz natural linewidth) in HD+ will become affected by BBR

215

In the Laboratory 1702 Journal of Chemical Education Vol. 76 No. 12 December 1999 JChemEd.chem.wisc.edu  

E-Print Network [OSTI]

's blackbody spectrum that are not already absorbed by naturally occurring gases such as CO2, H2O, and O3 (the on the strength with which a given species absorbs infrared radiation, the spectral location of its absorb- ing gases, and GHGs are qualita- tively identified according to whether they absorb radiation

Elrod, Matthew J.

216

Metallic photonic-band-gap filament architectures for optimized incandescent lighting Sajeev John and Rongzhou Wang  

E-Print Network [OSTI]

Metallic photonic-band-gap filament architectures for optimized incandescent lighting Sajeev John occur 3,4 . Tra- ditionally incandescent lighting filaments, despite being driven from equilibrium the blackbody spectrum. This suggests the pos- sibility of higher efficiency incandescent lighting, through

John, Sajeev

217

TURBULENT PRESSURE IN THE ENVELOPES OF YELLOW HYPERGIANTS AND LUMINOUS BLUE VARIABLES  

E-Print Network [OSTI]

turbulent pressure) affects the structure and stability of luminous post­red-supergiant stars is critically zone lies too deep below the surface to influence the formal dynamical stability or instability more than a huge bubble of blackbody radiation. Since radiation pressure tends to decrease stellar

218

Vol.4 No.9 September 2008 www.nature.com/naturephysics Things ain't what they used to be. No  

E-Print Network [OSTI]

, as it was called then, was created in 1925 from the merger of Western Electric Research Laboratories and part-over from a receiver system built at the lab for the Echo satellite5 . But their data were dogged was in fact the signal of the Big Bang, now dissipated after billions of years to a black-body temperature

Loss, Daniel

219

CHARACTERIZING THE STELLAR PHOTOSPHERES AND NEAR-INFRARED EXCESSES IN ACCRETING T TAURI SYSTEMS  

SciTech Connect (OSTI)

Using NASA Infrared Telescope Facility SpeX data from 0.8 to 4.5 {mu}m, we determine self-consistently the stellar properties and excess emission above the photosphere for a sample of classical T Tauri stars (CTTS) in the Taurus molecular cloud with varying degrees of accretion. This process uses a combination of techniques from the recent literature as well as observations of weak-line T Tauri stars to account for the differences in surface gravity and chromospheric activity between the T Tauri stars and dwarfs, which are typically used as photospheric templates for CTTS. Our improved veiling and extinction estimates for our targets allow us to extract flux-calibrated spectra of the excess in the near-infrared. We find that we are able to produce an acceptable parametric fit to the near-infrared excesses using a combination of up to three blackbodies. In half of our sample, two blackbodies at temperatures of 8000 K and 1600 K suffice. These temperatures and the corresponding solid angles are consistent with emission from the accretion shock on the stellar surface and the inner dust sublimation rim of the disk, respectively. In contrast, the other half requires three blackbodies at 8000, 1800, and 800 K, to describe the excess. We interpret the combined two cooler blackbodies as the dust sublimation wall with either a contribution from the disk surface beyond the wall or curvature of the wall itself, neither of which should have single-temperature blackbody emission. In these fits, we find no evidence of a contribution from optically thick gas inside the inner dust rim.

McClure, M. K.; Calvet, N.; Hartmann, L.; Ingleby, L. [Department of Astronomy, University of Michigan, 500 Church Street, 830 Dennison Building, Ann Arbor, MI 48109 (United States); Espaillat, C. [Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hernandez, J. [Centro de Investigaciones de Astronomia (CIDA), Merida 5101-A (Venezuela, Bolivarian Republic of); Luhman, K. L. [Department of Astronomy and Astrophysics and the Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, University Park, PA 16802 (United States); D'Alessio, P. [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, 58089 Morelia, Michoacan (Mexico); Sargent, B., E-mail: melisma@umich.edu, E-mail: ncalvet@umich.edu, E-mail: lhartm@umich.edu, E-mail: lingleby@umich.edu, E-mail: cespaillat@cfa.harvard.edu, E-mail: hernandj@cida.ve, E-mail: kluhman@astro.psu.edu, E-mail: p.dalessio@astrosmo.unam.mx, E-mail: baspci@rit.edu [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States)

2013-05-20T23:59:59.000Z

220

A Study to Investigate Cloud Feedback Processes and Evaluate GCM Cloud Variations Using Statistical Cloud Property Composites From ARM Data  

SciTech Connect (OSTI)

The representation of clouds in Global Climate Models (GCMs) remains a major source of uncertainty in climate change simulations. Cloud climatologies have been widely used to either evaluate climate model cloud fields or examine, in combination with other data sets, climate-scale relationships between cloud properties and dynamical or microphysical parameters. Major cloud climatologies have been based either on satellite observations of cloud properties or on surface observers views of cloud type and amount. Such data sets provide either the top-down view of column-integrated cloud properties (satellites) or the bottom-up view of the cloud field morphology (surface observers). Both satellite-based and surface cloud climatologies have been successfully used to examine cloud properties, to support process studies, and to evaluate climate and weather models. However, they also present certain limitations, since the satellite cloud types are defined using radiative cloud boundaries and surface observations are based on cloud boundaries visible to human observers. As a result, these data sets do not resolve the vertical distribution of cloud layers, an issue that is important in calculating both the radiative and the hydrologic effects of the cloud field. Ground-based cloud radar observations, on the other hand, resolve with good accuracy the vertical distribution of cloud layers and could be used to produce cloud type climatologies with vertical layering information. However, these observations provide point measurements only and it is not immediately clear to what extent they are representative of larger regimes. There are different methods that can be applied to minimize this problem and to produce cloud layering climatologies useful for both cloud process and model evaluation studies. If a radar system is run continuously over a number of years, it eventually samples a large number of dynamical and microphysical regimes. If additional data sets are used to put the cloud layering information into the context of large-scale dynamical regimes, such information can be used to study interactions among cloud vertical distributions and dynamical and microphysical processes and to evaluate the ability of models to simulate those interactions. The U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program has established several Climate Research Facilities (ACRF) that provide continuous, long-term observations of clouds and radiation. ARM, with its overall goal of improving the treatment of radiation and clouds in climate models has provided unique observing systems for accelerating progress on the representation of cloud processes. In this project, six and a half years (January 1998 to June 2004) of cloud observations collected at the Southern Great Plains (SGP) Oklahoma ACRF were used to produce a cloud-type climatology. The climatology provides cloud amounts for seven different cloud types as well as information on the detailed structure of multi-layer cloud occurrences. Furthermore, the European Centre for Medium-Range Weather Forecasts (ECMWF) model output was used to define the dynamic regimes present during the observations of the cloud conditions by the vertically pointing radars at the SGP ACRF. The cloud-type climatology and the ECMWF SGP data set were then analyzed to examine and map dynamical conditions that favor the creation of single-layer versus multi-layer cloud structures as well as dynamical conditions that favor the occurrence of drizzle in continental stratus clouds. In addition, output from the ECMWF weather model forecasts was analyzed with the objective to compare model and radar derived cloud type statistics, in order to identify the major model deficiencies in cloud vertical distribution and map their seasonal variations. The project included two primary goals. The first was to create a cloud type climatology over the Southern Great Planes site that will show how cloud vertical distribution varies with dynamic and thermodynamic regime and how these variations would affect cloud climate fe

George Tselioudis

2009-08-11T23:59:59.000Z

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

DOE Research and Development Accomplishments RSS Archive 2005-2006  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

5-2006 5-2006 2007 · 2008 · 2009 George Smoot Courtesy of Lawrence Berkeley National Laboratory "Blackbody Form" Research Yields 2006 Nobel Prize George Smoot made an announcement in 1992 that "essentially silenced all the scientific critics of the Big Bang theory." (See the October 3, 2006 edition of Today at Berkeley Lab.) For research leading up to that announcement, Smoot was awarded the Nobel Prize in Physics 2006. Smoot, an astrophysicist at Berkeley Lab since 1974 and a UC Berkeley physics professor since 1994, shared the award with John C. Mather of NASA Goddard Space Flight Center. Together they discovered the blackbody form and anisotropy of the cosmic microwave background radiation. Read more on this discovery at the DOE R&D Accomplishments Featured Scientists page.

222

CMB  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Hubble Diagram Hubble Diagram CMB BBN Cosmic Microwave Background One of the predictions that the Big Bang theory leads to, concerns some left over pieces that could tell us the temperature of the universe.. IF we believe that the Big Bang is how the universe began, then theorists predict that we should see a remnant microwave background. It is microwave because that is the area of the spectrum in which it is found. When we look out into space with our bare eyes, we see bright objects and a whole lot of "empty" space. However, if we examine the sky with a radio telescope, we see an almost perfect blackbody spectrum in the microwave spectrum. What is a blackbody and why is it radiating? How did we find the Cosmic Microwave Background? And can we fit a curve to the data taken for the Cosmic

223

Nobel Prize in Physics 2006  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation" their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation" John C. Mather Button 1/2 of prize Button USA Button born 1945 Button CA - NASA Godard Space Flight Center, Greenbelt, Maryland, USA Button AA - NASA Godard Space Flight Center, Greenbelt, Maryland, USA Button WA - NASA Godard Space Flight Center, Greenbelt, Maryland, USA Button Additional Information George F. Smoot Button 1/2 of prize Button USA Button born 1945 Button CA - University of California, Berkeley, Berkeley California, USA Button AA - Lawrence Berkeley Laboratory, University of California, Berkeley, California, USA Button WA - Lawrence Berkeley Laboratory, University of California, Berkeley, California, USA Button Additional Information *Explanation of CA, AA & WA*

224

A Critical Analysis of Universality and Kirchhoff's Law: A Return to Stewart's Law of Thermal Emission  

E-Print Network [OSTI]

It has been advanced, on experimental (P.-M. Robitaille, IEEE Trans. Plasma Sci. 2003, v. 31(6), 1263-1267) and theoretical (P.M. Robitaille, Progr. Phys. 2006, v.2, 22-23) grounds, that blackbody radiation is not universal and remains closely linked to the emission of graphite and soot. In order to strengthen such claims, a conceptual analysis of the proofs for universality is presented. This treatment reveals that Gustav Robert Kirchhoff has not properly considered the combined effects of absorption, reflection, and the directional nature of emission in real materials. In one instance, this leads to an unintended movement away from thermal equilibrium within cavities. Using equilibrium arguments, it is demonstrated that the radiation within perfectly reflecting or arbitrary cavities does not necessarily correspond to that emitted by a blackbody.

Pierre-Marie Robitaille

2008-05-12T23:59:59.000Z

225

EUVE Spectroscopy of Polars  

E-Print Network [OSTI]

An admittedly pedantic but hopefully useful and informative analysis is presented of the EUVE 70--180 Angstrom spectra of nine polars. These spectra are fit with three different models---a blackbody, a pure-H stellar atmosphere, and a solar abundance stellar atmosphere---to reveal the presence of spectral features such as absorption lines and edges, and to investigate the sensitivity of the derived (kT, N_H, solid angle) and inferred (fractional emitting area, bolometric luminosity) parameters to the model assumptions. Among the models tested, the blackbody model best describes the observed spectra, although the untested irradiated solar abundance stellar atmosphere model is likely a better overall description of the EUV/soft X-ray spectra of polars.

Christopher W. Mauche

1998-10-07T23:59:59.000Z

226

EUVE spectroscopy of polars  

SciTech Connect (OSTI)

An admittedly pedantic but hopefully useful and informative analysis is presented of the EUVE 70-180 Å spectra of nine polars. These spectra are fit with three different models - a blackbody, a pure-H stellar atmosphere, and a solar abundance stellar atmosphere|to reveal the presence of spectral features such as absorption lines and edges, and to investigate the sensitivity of the derived (kT, NH, solid angle) and inferred (fractional emitting area, bolometric luminosity) parameters to the model assumptions. Among the models tested, the blackbody model best describes the observed spectra, although the untested irradiated solar abundance stellar atmosphere model is likely a better overall description of the EUV/soft X-ray spectra

Mauche, C W

1998-10-13T23:59:59.000Z

227

Characterization of near-terahertz complementary metal-oxide semiconductor circuits using a Fourier-transform interferometer  

DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

Optical methods for measuring of the emission spectra of oscillator circuits operating in the 400–600 GHz range are described. The emitted power from patch antennas included in the circuits is measured by placing the circuit in the source chamber of a Fourier-transform interferometric spectrometer. The results show that this optical technique is useful for measuring circuits pushing the frontier in operating frequency. The technique also allows the characterization of the circuit by measuring the power radiated in the fundamental and in the harmonics. This capability is useful for oscillator architectures designed to cancel the fundamental and use higher harmonics. The radiated power was measured using two techniques: direct measurement of the power by placing the device in front of a bolometer of known responsivity, and by comparison to the estimated power from blackbody sources. The latter technique showed that these circuits have higher emission than blackbody sources at the operating frequencies, and, therefore, offer potential spectroscopy applications.

Arenas, D. J. [Univ. of North Florida, Jacksonville, FL (United States); Shim, Dongha [Univ. of Florida, Gainesville, FL (United States); Koukis, D. I. [Univ. of Florida, Gainesville, FL (United States); Seok, Eunyoung [Univ. of Florida, Gainesville, FL and Texas Instruments, Dallas, TX (United States); Tanner, D. B. [Univ. of Florida, Gainesville, FL (United States); O, Kenneth K. [Univ. of Texas, Dallas, TX (United States)

2011-10-24T23:59:59.000Z

228

High speed infrared radiation thermometer, system, and method  

DOE Patents [OSTI]

The high-speed radiation thermometer has an infrared measurement wavelength band that is matched to the infrared wavelength band of near-blackbody emittance of ceramic components and ceramic thermal barrier coatings used in turbine engines. It is comprised of a long wavelength infrared detector, a signal amplifier, an analog-to-digital converter, an optical system to collect radiation from the target, an optical filter, and an integral reference signal to maintain a calibrated response. A megahertz range electronic data acquisition system is connected to the radiation detector to operate on raw data obtained. Because the thermometer operates optimally at 8 to 12 .mu.m, where emittance is near-blackbody for ceramics, interferences to measurements performed in turbine engines are minimized. The method and apparatus are optimized to enable mapping of surface temperatures on fast moving ceramic elements, and the thermometer can provide microsecond response, with inherent self-diagnostic and calibration-correction features.

Markham, James R. (Middlefield, CT)

2002-01-01T23:59:59.000Z

229

microwaverpp.dvi  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

microwave microwave background 1 26. COSMIC MICROWAVE BACKGROUND Revised September 2013 by D. Scott (University of British Columbia) and G.F. Smoot (UCB/LBNL). 26.1. Introduction The energy content in radiation from beyond our Galaxy is dominated by the cosmic microwave background (CMB), discovered in 1965 [1]. The spectrum of the CMB is well described by a blackbody function with T = 2.7255 K, this spectral form being one of the main pillars of the hot Big Bang model for the early Universe. The lack of any observed deviations from a blackbody spectrum constrains physical processes over cosmic history at redshifts z ∼ < 10 7 (see earlier versions of this review). All viable cosmological models predict a very nearly Planckian spectrum inside the current observational limits (although that could change with more sensitive spectral experiments in the future [2]). Currently the key CMB observable

230

Informal Preliminary Report on Comparisons of Prototype SPN-1 Radiometer to PARSL Measurements  

SciTech Connect (OSTI)

The prototype SPN-1 has been taking measurements for several months collocated with our PNNL Atmospheric Remote Sensing Laboratory (PARSL) solar tracker mounted instruments at the Pacific Northwest National Laboratory (PNNL) located in Richland, Washington, USA. The PARSL radiometers used in the following comparisons consist of an Eppley Normal Incident Pyrheliometer (NIP) and a shaded Eppley model 8-48 “Black and White” pyrgeometer (B&W) to measure the direct and diffuse shortwave irradiance (SW), respectively. These instruments were calibrated in mid-September by comparison to an absolute cavity radiometer directly traceable to the world standard group in Davos, Switzerland. The NIP calibration was determined by direct comparison, while the B&W was calibrated using the shade/unshade technique. All PARSL data prior to mid-September have been reprocessed using the new calibration factors. The PARSL data are logged as 1-minute averages from 1-second samples. Data used in this report span the time period from June 22 through December 1, 2006. All data have been processed through the QCRad code (Long and Shi, 2006), which itself is a more elaborately developed methodology along the lines of that applied by the Baseline Surface Radiation Network (BSRN) Archive (Long and Dutton, 2004), for quality control. The SPN-1 data are the standard total and diffuse SW values obtained from the analog data port of the instrument. The comparisons use only times when both the PARSL and SPN-1 data passed all QC testing. The data were further processed and analyzed by application of the SW Flux Analysis methodology (Long and Ackerman, 2000; Long and Gaustad, 2004, Long et al., 2006) to detect periods of clear skies, calculate continuous estimates of clear-sky SW irradiance and the effect of clouds on the downwelling SW, and estimate fractional sky cover.

Long, Charles N.

2014-06-17T23:59:59.000Z

231

Q&A with Nobelist George Smoot - 2009 BCCP Cosmology Workshop  

SciTech Connect (OSTI)

July 2009: What happens when dark matter and anti-dark mattter collide? If you were in a gravity free environment, what would happen to time? At the annual Cosmology Workshop at Lawrence Berkeley Lab, Nobelist George Smoot answers these questions and more from high school students and teachers. Dr. Smoot was co-awarded the 2006 Nobel Prize in Physics for the discovery of the blackbody form and anisotropy of the cosmic microwave background radiation. http://bccp.lbl.gov/

Smoot, George

2010-01-01T23:59:59.000Z

232

Supplementary Material The Open Atmospheric Science Journal, 2008, Volume 2 i Supplementary Material  

E-Print Network [OSTI]

the sun, which is ~240 W/m2 . A blackbody temperature of ~255°K yields a heat flux of 240 W/m2 . Indeed in the calculated 3.5 W/m2 forcing due to surface changes (ice sheet area, vegetation distribution, shoreline with that approach is that, unlike long-lived GHGs, aerosols are distributed heterogeneously, so it is difficult

Royer, Dana

233

BROADBAND SPECTRAL INVESTIGATIONS OF SGR J1550-5418 BURSTS  

SciTech Connect (OSTI)

We present the results of our broadband spectral analysis of 42 SGR J1550-5418 bursts simultaneously detected with the Swift/X-ray Telescope (XRT) and the Fermi/Gamma-ray Burst Monitor (GBM), during the 2009 January active episode of the source. The unique spectral and temporal capabilities of the XRT windowed timing mode have allowed us to extend the GBM spectral coverage for these events down to the X-ray domain (0.5-10 keV). Our earlier analysis of the GBM data found that the SGR J1550-5418 burst spectra were described equally well with either a Comptonized model or with two blackbody functions; the two models were statistically indistinguishable. Our new broadband (0.5-200 keV) spectral fits show that, on average, the burst spectra are better described with two blackbody functions than with the Comptonized model. Thus, our joint XRT-GBM analysis clearly shows for the first time that the SGR J1550-5418 burst spectra might naturally be expected to exhibit a more truly thermalized character, such as a two-blackbody or even a multi-blackbody signal. Using the Swift and RXTE timing ephemeris for SGR J1550-5418 we construct the distribution of the XRT burst counts with spin phase and find that it is not correlated with the persistent X-ray emission pulse phase from SGR J1550-5418. These results indicate that the burst emitting sites on the neutron star need not to be co-located with hot spots emitting the bulk of the persistent X-ray emission. Finally, we show that there is a significant pulse phase dependence of the XRT burst counts, likely demonstrating that the surface magnetic field of SGR J1550-5418 is not uniform over the emission zones, since it is anticipated that regions with stronger surface magnetic field could trigger bursts more efficiently.

Lin Lin; Goegues, Ersin; Kaneko, Yuki [Faculty of Engineering and Natural Sciences, Sabanc Latin-Small-Letter-Dotless-I University, Orhanl Latin-Small-Letter-Dotless-I Tuzla, Istanbul 34956 (Turkey); Baring, Matthew G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Granot, Jonathan [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Kouveliotou, Chryssa [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Van der Horst, Alexander; Watts, Anna L. [Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Gruber, David; Von Kienlin, Andreas [Max-Planck-Institut fuer extraterrestrische Physik, Postfach 1312, D-85748 Garching bei Mnchen (Germany); Younes, George [USRA, National Space Science and Technology Center, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Gehrels, Neil, E-mail: linlin@sabanciuniv.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2012-09-01T23:59:59.000Z

234

A NEW METHOD OF PULSE-WISE SPECTRAL ANALYSIS OF GAMMA-RAY BURSTS  

SciTech Connect (OSTI)

Time-resolved spectral analysis, though a very promising method to understand the emission mechanism of gamma-ray bursts (GRBs), is difficult to implement in practice because of poor statistics. We present a new method for pulse-wise time-resolved spectral study of the individual pulses of GRBs, using the fact that many spectral parameters are either constants or smooth functions of time. We use this method for the two pulses of GRB 081221, the brightest GRB with separable pulses. We choose, from the literature, a set of possible models that includes the Band model, blackbody with a power law (BBPL), and a collection of blackbodies with a smoothly varying temperature profile, along with a power law (mBBPL), and two blackbodies with a power law (2BBPL). First, we perform a time-resolved study to confirm the spectral parameter variations, and then we construct the new model to perform a joint spectral fit. We find that any photospheric emission in terms of blackbodies is required mainly in the rising parts of the pulses and the falling part can be adequately explained in terms of the Band model, with the low-energy photon index within the regime of synchrotron model. Interestingly, we find that 2BBPL is comparable or sometimes even better, though marginally, than the Band model, in all episodes. Consistent results are also obtained for the brightest GRB of Fermi era-GRB 090618. We point out that the method is generic enough to test any spectral model with well-defined parameter variations.

Basak, Rupal; Rao, A. R., E-mail: rupalb@tifr.res.in, E-mail: arrao@tifr.res.in [Tata Institute of Fundamental Research, Mumbai-400005 (India)

2013-05-10T23:59:59.000Z

235

Q&A with Nobelist George Smoot - 2009 BCCP Cosmology Workshop  

ScienceCinema (OSTI)

July 2009: What happens when dark matter and anti-dark mattter collide? If you were in a gravity free environment, what would happen to time? At the annual Cosmology Workshop at Lawrence Berkeley Lab, Nobelist George Smoot answers these questions and more from high school students and teachers. Dr. Smoot was co-awarded the 2006 Nobel Prize in Physics for the discovery of the blackbody form and anisotropy of the cosmic microwave background radiation.

George Smoot

2010-09-01T23:59:59.000Z

236

Interaction of fermions with black holes  

SciTech Connect (OSTI)

Bekenstein and Meisels used statistical thermodynamic arguments to obtain the probability distribution of fermions emitted by a black hole when a fermion is incident. In contrast with Bekenstein and Meisels, we model the black hole as a perfect blackbody surrounded by a mirror. Our probability distribution for emitted fermions agrees with the probability distribution of Bekenstein and Meisels, but the interpretation of how fermions interact with the black hole is different from the interpreteation given by Bekenstein and Meisels.

Jones T.O. III

1986-04-15T23:59:59.000Z

237

On parton distributions in a photon gas  

E-Print Network [OSTI]

In some cases it may be useful to know parton distributions in a photon gas. This may be relevant, e.g., for the analysis of interactions of high energy cosmic ray particles with the cosmic microwave background radiation. The latter can be considered as a gas of photons with an almost perfect blackbody spectrum. An approach to finding such parton distributions is described. The survival probability of ultra-high energy neutrinos traveling through this radiation is calculated.

I. Alikhanov

2009-06-19T23:59:59.000Z

238

Electron Cyclotron Emission from the Princeton Large Tokamak  

Science Journals Connector (OSTI)

Experimental measurements of electron cyclotron emission from the Princeton Large Tokamak plasma reveal that blackbody emission occurs at the fundamental frequency. Such emission, not possible by direct thermal excitation of electromagnetic waves, is herein attributed to thermal excitation of electrostatic (Bernstein) waves which then mode convert into electromagnetic waves. The local feature of the electrostatic wave generation permits spatially and temporally resolved measurements of electron temperature as for the second-harmonic emission.

J. Hosea; V. Arunasalam; R. Cano

1977-08-15T23:59:59.000Z

239

Turbulent Temperature Fluctuations in the Princeton Large Tokamak Plasma  

Science Journals Connector (OSTI)

We present the first experimental evidence for the existence of turbulent temperature fluctuations in plasmas. These measurements were accomplished by a spectral analysis of blackbody electron cyclotron emission. The fractional fluctuation in the mean electron energy is up to 10% for typical Princeton Large Tokamak discharges. The spectrum of temperature turbulence extends well beyond the electron diamagnetic-drift frequency f* and shows no resemblance to the simultaneously existing turbulent density fluctuations.

V. Arunasalam; R. Cano; J. C. Hosea; E. Mazzucato

1977-10-03T23:59:59.000Z

240

Ordinary-Mode Fundamental Electron-Cyclotron Resonance Absorption and Emission in the Princeton Large Torus  

Science Journals Connector (OSTI)

Fundamental electron-cyclotron resonance damping for 4-mm waves with ordinary polarization as well as blackbody emission is measured along the midplane of the plasma in the Princeton Large Torus. Optical depths obtained from the data are in good agreement with those predicted by hot-plasma theory. The use of ordinary-mode fundamental electron-cyclotron resonance heating in existing and future toroidal devices is supported by these results.

P. C. Efthimion; V. Arunasalam; J. C. Hosea

1980-02-11T23:59:59.000Z

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
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241

Airborne Infrared Target Tracking with the Nintendo Wii Remote Sensor  

E-Print Network [OSTI]

to target. 3.2 Design Rather than design for a particular distance, the highest-output available infrared source was selected for the beacon: a 500 W quartz tungsten halogen incandescent lamp. Determining the radiant power in the detectable spectrum...://terpconnect.umd.edu/ toh/models/Blackbody.html. [17] Forsythe, W. and Worthing, A., \\The Properties of Tungsten and the Character- istics of Tungsten Lamps," Astrophysics Journal , Vol. 61, April 1925, pp. 146{ 185. 34 ...

Beckett, Andrew 1984-

2012-11-12T23:59:59.000Z

242

Retrieval of Intensive Aerosol Properties from MFRSR observations: Partly Cloudy Cases  

SciTech Connect (OSTI)

An approach for the obtaining column intensive aerosol properties, namely the single scattering albedo (SSA) and asymmetry parameter (ASP), from the Multi-Filter Rotating Shadowband Radiometer (MFRSR) spectral observations under partly cloudy conditions is described. The approach involves the MFRSR-based aerosol retrieval for clear-sky periods and an interpolation of the retrieved column aerosol properties for cloudy periods. The observed weak diurnal variability of SSA and ASP at the surface and the close association of the surface intensive aerosol properties with their column counterparts form the basis of such interpolation. The approach is evaluated by calculating the corresponding clear-sky total, direct and diffuse fluxes at five wavelengths (415, 500, 615, 673 and 870 nm) and compare them with the observed fluxes. The aerosol properties provided by this approach are applied for (i) an examination of the statistical relationship between spectral (visible spectral range) and broadband values of the total normalized cloud radiative forcing and (ii) an estimation of the fractional sky cover. Data collected during 13 days with single-layer cumulus clouds observed at U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site during summer 2007 are applied to illustrate the performance and application of this approach.

Kassianov, Evgueni I.; Barnard, James C.; Berg, Larry K.; Flynn, Connor J.; Long, Charles N.

2010-09-30T23:59:59.000Z

243

Surface summertime radiative forcing by shallow cumuli at the Atmospheric Radiation Measurement Southern Great Plains site  

SciTech Connect (OSTI)

Although shallow cumuli are common over large areas of the globe, their impact on the surface radiative forcing has not been carefully evaluated. This study addresses this shortcoming by analyzing data from days with shallow cumuli collected over eight summers (2000-2007) at the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility (collectively ACRF) Southern Great Plains site. During periods with clouds, the average shortwave and longwave radiative forcings are 45.5 W m-2 and +11.6 W m-2, respectively. The forcing has been defined so that a negative (positive) forcing indicates a surface cooling (warming). On average, the shortwave forcing is negative, however, instances with positive shortwave forcing are observed approximately 20% of the time. These positive values of shortwave forcing are associated with three-dimensional radiative effects of the clouds. The three-dimensional effects are shown to be largest for intermediate cloud amounts. The magnitude of the three-dimensional effects decreased with averaging time, but it is not negligibly small even for large averaging times as long as four hours.

Berg, Larry K.; Kassianov, Evgueni I.; Long, Charles N.; Mills Jr., David L.

2011-01-08T23:59:59.000Z

244

Ice Concentration Retrieval in Stratiform Mixed-phase Clouds Using Cloud Radar Reflectivity Measurements and 1D Ice Growth Model Simulations  

SciTech Connect (OSTI)

Measurement of ice number concentration in clouds is important but still challenging. Stratiform mixed-phase clouds (SMCs) provide a simple scenario for retrieving ice number concentration from remote sensing measurements. The simple ice generation and growth pattern in SMCs offers opportunities to use cloud radar reflectivity (Ze) measurements and other cloud properties to infer ice number concentration quantitatively. To understand the strong temperature dependency of ice habit and growth rate quantitatively, we develop a 1-D ice growth model to calculate the ice diffusional growth along its falling trajectory in SMCs. The radar reflectivity and fall velocity profiles of ice crystals calculated from the 1-D ice growth model are evaluated with the Atmospheric Radiation Measurements (ARM) Climate Research Facility (ACRF) ground-based high vertical resolution radar measurements. Combining Ze measurements and 1-D ice growth model simulations, we develop a method to retrieve the ice number concentrations in SMCs at given cloud top temperature (CTT) and liquid water path (LWP). The retrieved ice concentrations in SMCs are evaluated with in situ measurements and with a three-dimensional cloud-resolving model simulation with a bin microphysical scheme. These comparisons show that the retrieved ice number concentrations are within an uncertainty of a factor of 2, statistically.

Zhang, Damao; Wang, Zhien; Heymsfield, Andrew J.; Fan, Jiwen; Luo, Tao

2014-10-01T23:59:59.000Z

245

Long-term Statistics of Continental Cumuli: Does Aerosol Trigger Cumulus Variability?  

SciTech Connect (OSTI)

Atmospheric aerosols may control the formation, maintenance, and dissipation of cumuli by changing their microphysics. Recent observational and modeling results exist both in support and against strong potential impacts of aerosol [1-3]. Typically, the aerosol impact on water clouds has been investigated for regions with high aerosol loading and/or large atmospheric moisture [4]. Can we provide observational evidence of the aerosol-cloud relationship for a relatively dry continental region with low/moderate aerosol burden? To address this question, we revisit the aerosol-cloud relationship at the Atmospheric Radiation Measurement (ARM) Climate Research Facility (ACRF) Southern Great Plains (SGP) site. In comparison with highly polluted regions, the SGP site is characterized by relatively small-to-moderate aerosol loading. Also, moisture content is small-to-moderate (compared to marine and coastal regions) for the SGP site. Because cumulus clouds have important impacts on climate forcing estimations [5] and are susceptible to aerosol effects [6], we focus on fair-weather cumuli (FWC) and their association with aerosol concentration and other potentially important factors. This association is investigated using a new 8-year aerosol and cloud climatology (2000-2007) developed with collocated and coincident surface and satellite observations.

Kassianov, Evgueni I.; Berg, Larry K.; McFarlane, Sally A.; Flynn, Connor J.; Turner, David D.

2009-02-01T23:59:59.000Z

246

A better presentation of Planck’s radiation law  

Science Journals Connector (OSTI)

Introductory physics and astronomy courses commonly use Wien’s displacement law to explain the colors of blackbodies including the Sun and other stars in terms of their temperatures. We argue here that focusing on the peak of the blackbody spectrum is misleading for three reasons. First the Planck curve is too broad for an individual spectral color to stand out. Second the location of the peak of the Planck curve depends on the choice of the independent variable in the plot. And third Wien’s displacement law is seldom used in actual practice to find a temperature and direct fitting to the Planck function is preferable. We discuss these flaws and argue that at the introductory level presentation of blackbody radiation in terms of photon statistics would be more effective pedagogically. The average energy of the emitted photons would then be presented in place of Wien’s displacement law and discussion of the Stefan-Boltzmann law would include the total number of photons emitted per second. Finally we suggest that the Planck spectrum is most appropriately plotted as a “spectral energy density per fractional bandwidth distribution ” using a logarithmic scale for the wavelength or frequency.

Jonathan M. Marr; Francis P. Wilkin

2012-01-01T23:59:59.000Z

247

The spectral irradiance traceability chain at PTB  

SciTech Connect (OSTI)

Spectral irradiance is a fundamental radiometric unit. Its application to measurement results requires qualified traceability to basic units of the international system of units (Systeme international d'unites, SI). The Physikalisch-Technische Bundesanstalt (PTB) is amongst other national metrological institutes (NMIs) responsible for the realization, maintenance and dissemination of various radiometric and photometric units based on and traceable to national standards. The unit of spectral irradiance is realized and represented by a blackbody-radiator as the national primary standard of the PTB. Based on Planck's radiation law, the irradiance is calculated and realized for any wavelength taking into account the exact knowledge of the radiation temperature and the geometrical parameters. Using a double-monochromator-based spectroradiometer system, secondary standard lamps can be calibrated by direct comparison to the blackbody-radiator (substitution method). These secondary standard lamps are then used at the PTB to calibrate standard lamps of customers. The customers themselves use these so-called transfer standards to calibrate their working standard lamps. These working standards are then used to calibrate own spectroradiometers or sources. This rather complex calibration chain is a common procedural method that for the customers generally leads to satisfying measurement results on site. Nevertheless, the standard lamps in use have to fulfill highest requirements concerning stability and reproducibility. Only this allows achieving comparably low transfer measurement uncertainties, which occur at each calibration step. Thus, the PTB is constantly investigating the improvement and further development of transfer standards and measurement methods for various spectral regions. The realization and dissemination of the spectral irradiance using the blackbody-radiator at the PTB is accomplished with worldwide approved minimized measurement uncertainties confirmed by international intercomparisons among NMIs. Ultimately, the spectral irradiance can be realized with expanded measurement uncertainties of far less than 1 % over a wide spectral range. Thus, for customers with high demands on low measurement uncertainties, it is possible to calibrate their working standards directly against the blackbody-radiator, taking into account the higher necessary effort. In special cases it is possible to calibrate the customer's spectroradiometric facilities directly in front of the blackbody-radiator. In the context of the European Metrology Research Project Traceability for surface spectral solar ultraviolet radiation, the traceability chain will be improved and adapted.

Sperfeld, P.; Pape, S.; Nevas, S. [Physikalisch-Technische Bundesanstalt, Bundesallee 10, 381160 Braunschweig (Germany)

2013-05-10T23:59:59.000Z

248

Quantum fields with noncommutative target spaces  

Science Journals Connector (OSTI)

Quantum field theories (QFT’s) on noncommutative spacetimes are currently under intensive study. Usually such theories have world sheet noncommutativity. In the present work, instead, we study QFT’s with commutative world sheet and noncommutative target space. Such noncommutativity can be interpreted in terms of twisted statistics and is related to earlier work of Oeckl [R. Oeckl, Commun. Math. Phys. 217, 451 (2001).], and others [A.?P. Balachandran, G. Mangano, A. Pinzul, and S. Vaidya, Int. J. Mod. Phys. A 21, 3111 (2006); A.?P. Balachandran, A. Pinzul, and B.?A. Qureshi, Phys. Lett. B 634, 434 (2006); A.?P. Balachandran, A. Pinzul, B.?A. Qureshi, and S. Vaidya, arXiv:hep-th/0608138; A.?P. Balachandran, T.?R. Govindarajan, G. Mangano, A. Pinzul, B.?A. Qureshi, and S. Vaidya, Phys. Rev. D 75, 045009 (2007); A. Pinzul, Int. J. Mod. Phys. A 20, 6268 (2005); G. Fiore and J. Wess, Phys. Rev. D 75, 105022 (2007); Y. Sasai and N. Sasakura, Prog. Theor. Phys. 118, 785 (2007)]. The twisted spectra of their free Hamiltonians has been found earlier by Carmona et al. [J.?M. Carmona, J.?L. Cortes, J. Gamboa, and F. Mendez, Phys. Lett. B 565, 222 (2003); J.?M. Carmona, J.?L. Cortes, J. Gamboa, and F. Mendez, J. High Energy Phys. 03 (2003) 058]. We review their derivation and then compute the partition function of one such typical theory. It leads to a deformed blackbody spectrum, which is analyzed in detail. The difference between the usual and the deformed blackbody spectrum appears in the region of high frequencies. Therefore we expect that the deformed blackbody radiation may potentially be used to compute a Greisen-Zatsepin-Kuzmin cutoff which will depend on the noncommutative parameter ?.

A. P. Balachandran; A. R. Queiroz; A. M. Marques; P. Teotonio-Sobrinho

2008-05-30T23:59:59.000Z

249

The Universe Adventure - Site Map  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Index Pages Index Pages Help Teachers Credits Developers Feedback Links Glossary: A-E | F-J | K-O | P-T | U-Z Fundamentals of Cosmology Cosmology The Beginnings of Cosmology The Ancient Universe The Modern Universe -> Cosmic Conundrums: Cosmology Light The Electromagnetic Spectrum -> Movie: Travelling Photons -> Down the Rabbit Hole: At the Speed of Light -> Classroom Cosmology: The Speed of Light Apparent Magnitude -> Sidequest: Absolute and Apparent Magnitude -> Down the Rabbit Hole: Luminosity versus Observed Brightness -> Down the Rabbit Hole: Standard Candles -> Cosmic Conundrums: Light Matter Blackbody Radiation -> Movie: Temperature Matter and Atoms -> Down the Rabbit Hole: Electric Charge -> Down the Rabbit Hole: Quantum Mechanics -> Cosmic Conundrums: Matter

250

Vaporization of color-singlet pairs from a quark-gluon plasma  

Science Journals Connector (OSTI)

We consider the hadronization of a QCD plasma by diffusion of quark-antiquark pairs through the plasma's surface. We apply the principle of detailed balance to argue that the surface is readily penetrable by color-singlet pairs. The resulting blackbody surface brightness exceeds that of other hadronization mechanisms. We note that the volume increase, needed to accommodate the plasma's high entropy in the dilute hadronic phase, compensates most of the combinatoric and statistical factors needed to select such pairs from the plasma. We conclude that the rate of evaporation of preformed pairs is ample to maintain phase equilibrium with a freely expanding meson gas outside the plasma.

Axel P. Vischer; Jitendra C. Parikh; Philip J. Siemens

1991-01-01T23:59:59.000Z

251

Detailed balance limit of power conversion efficiency for organic photovoltaics  

SciTech Connect (OSTI)

A fundamental difference between inorganic photovoltaic (IPV) and organic photovoltaic (OPV) cells is that charges are generated at the interface in OPV cells, while free charges can be generated in the bulk in IPV cells. In OPV cells, charge generation involves intrinsic energy losses to dissociate excitons at the interface between the donor and acceptor. By taking into account the energy losses, we show the theoretical limits of the power conversion efficiency set by radiative recombination of the carriers on the basis of the detailed balance relation between radiation from the cell and black-body radiation.

Seki, Kazuhiko, E-mail: k-seki@aist.go.jp [NRI, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, Higashi 1-1-1, Tsukuba, Ibaraki 305-8565 (Japan)] [NRI, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, Higashi 1-1-1, Tsukuba, Ibaraki 305-8565 (Japan); Furube, Akihiro [RIIF, AIST Tsukuba Central 2, Umezono 1-1-1, Tsukuba, Ibaraki 305-8568 (Japan)] [RIIF, AIST Tsukuba Central 2, Umezono 1-1-1, Tsukuba, Ibaraki 305-8568 (Japan); Yoshida, Yuji [RCPVT, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, Higashi 1-1-1, Tsukuba, Ibaraki 305-8565 (Japan)] [RCPVT, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 5, Higashi 1-1-1, Tsukuba, Ibaraki 305-8565 (Japan)

2013-12-16T23:59:59.000Z

252

A 16-channel heterodyne electron cyclotron emission radiometer on J-TEXT  

SciTech Connect (OSTI)

To study equilibrium temporal dynamics and the mechanisms of magnetohydrodynamic instabilities, a 16-channel heterodyne electron cyclotron emission (ECE) radiometer has been developed to view the J-TEXT tokamak from the low field side. The ECE radiometer detects second-harmonic extraordinary mode in the frequency band of 94-125 GHz which corresponds to resonances from 1.8 T to 2.2 T. This ECE system consists of an ECE transmission line, a radio frequency unit, and two 8-channel intermediate frequency units. An in situ blackbody calibration source is applied for system calibration by comparison of hot and cold sources in order to provide an absolute temperature measurement.

Yang, Z. J.; Zhuang, G.; Xiao, J. S.; Wang, Z. J. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Key Laboratory of Fusion and Advanced Electromagnetic Technology Ministry of Education, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Phillips, P. E.; Huang, H.; Rowan, W. L. [Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States)

2012-10-15T23:59:59.000Z

253

Planck's Radiation Law in the Quantized Universe  

E-Print Network [OSTI]

Physical research looks for clues to quantum properties of the gravitational field. On the basis of the common Schr\\"odinger theory, a simple model of the quantization of a Friedmann universe comprising dust and radiation is investigated. With regard to energy quantization, the result suggests a universal limitation of the energy spacing between neighbouring quantum states by the Planck energy. Applied to black-body radiation, a modified Planck radiation law follows. If this could be verified in the laboratory, it would provide a direct hint at quantum properties of the space-time manifold.

Rainer Collier

2014-09-15T23:59:59.000Z

254

Radiation pressure of light in a refractive medium  

Science Journals Connector (OSTI)

The radiation pressure and energy density of light in a refractive medium is calculated in terms of the index of refraction of the medium. The factor equal to the cube of the index of refraction that occurs in the expressions for the energy density and pressure of light in a refractive medium is shown to arise from the basic thermodynamic nature of the photon system and from the volume dependence of the index of refraction. It is shown that a mechanical pressure exists in a refractive medium which is in equilibrium with the blackbody radiation of the vacuum.

Richard A. Weiss

1976-01-01T23:59:59.000Z

255

Photo- and Thermodesorption of Helium on Pt(111)  

Science Journals Connector (OSTI)

In a detailed study of thermal desorption of monolayers of both H4e and H3e adsorbed on Pt(111) (binding energy about 9 meV), we have observed photodesorption induced by the blackbody radiation from a room temperature environment. This process proceeds independently of the thermal desorption. Theoretical treatments of both thermal and photodesorption are given and agree very well with the data in all important aspects. We conclude that the photodesorption is due to direct coupling of photons to the adsorbate.

T. Niedermayer; H. Schlichting; D. Menzel; S. H. Payne; H. J. Kreuzer

2002-08-30T23:59:59.000Z

256

Coherence Properties and Photon Correlation  

Science Journals Connector (OSTI)

An intensity-correlation experiment is proposed to test the second-order coherence of laser light from a cw-operated laser based on the Glauber formalism. The calculation utilizes the known form of the density matrix for radiation from a randomly excited source such as a discharge tube which is equivalent to filtered black-body radiation, and represents the laser radiation field by a coherent state. The intensity correlation calculated exhibits the standard Hanbury Brown-Twiss term and an extra term due to intensity interference between the Fourier components of the thermal field and the laser mode.

Hans Morawitz

1965-08-16T23:59:59.000Z

257

High-Performance Nanostructured Coating  

Broader source: Energy.gov [DOE]

The High-Performance Nanostructured Coating fact sheet details a SunShot project led by a University of California, San Diego research team working to develop a new high-temperature spectrally selective coating for receiver surfaces. These receiver surfaces, used in concentrating solar power systems, rely on high-temperature SSCs to effectively absorb solar energy without emitting much blackbody radiation.The optical properties of the SSC directly determine the efficiency and maximum attainable temperature of solar receivers, which in turn influence the power-conversion efficiency and overall system cost.

258

Light with nonzero chemical potential  

Science Journals Connector (OSTI)

Thermodynamic states and processes involving light are discussed in which the chemical potential of light is nonzero. Light with nonzero chemical potential is produced in photochemical reactions for example in a light emitting diode. The chemical potential of black-body radiation becomes negative upon a Joule expansion. The isothermal diffusion of light which is a common phenomenon is driven by the gradient in the chemical potential. These and other examples support the idea that light can be interpreted as a gas of photons with properties similar to a material gas.

F. Herrmann; P. Würfel

2005-01-01T23:59:59.000Z

259

Fourier Transform Infrared Spectroscopy for Process Monitoring and Control  

E-Print Network [OSTI]

-IR multi-component gas approach offers many advantages compared to single gas analyzers. The relative advantages and disadvantages are compared in Table 2. Analysis or Gas Temoerature Emission (or radiance R(II)) from a hot gas is related to its... temperature and concentration. The expression for R(II) is (2) where Rt,(II,TJ = Planck function at the gas temperature T,. The Planck function describes the spectral power of a perfectly absorbing black-body as a function of temperature. The 1...

Solomon, P. R.; Carangelo, M. D.; Carangelo, R. M.

260

Phase Transition to an Opaque Plasma in a Sonoluminescing Bubble  

Science Journals Connector (OSTI)

Time-resolved spectrum measurements of a sonoluminescing Xe bubble reveal a transition from transparency to an opaque Planck blackbody. As the temperature is <10?000??K and the density is below liquid density, the photon scattering length is 10?000 times too large to explain its opacity. We resolve this issue with a model that reduces the ionization potential. According to this model, sonoluminescence originates in a new phase of matter with high ionization. Analysis of line emission from Xe* also yields evidence of phase segregation for this first-order transition inside a bubble.

Brian Kappus; Shahzad Khalid; Avik Chakravarty; Seth Putterman

2011-06-08T23:59:59.000Z

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Limits on iron-dominated fallback disk in SN 1987A  

E-Print Network [OSTI]

The non-detection of a point source in SN1987A imposes an upper limit for the optical luminosity of L=2L_sun. This limits the size of a possible fallback disk around the stellar remnant. Assuming a steady-state thin disk with blackbody emission requires a disk smaller than 100,000 km if the accretion rate is at 30% of the Eddington rate (Graves et al. 2005). We have performed detailed non-LTE radiation transfer calculations to model the disk spectrum more realistically. It turns out that the observational limit on the disk extension becomes even tighter, namely 70,000 km.

K. Werner; T. Nagel; T. Rauch

2007-03-20T23:59:59.000Z

262

On horizons and the cosmic landscape  

E-Print Network [OSTI]

Susskind claims in his recent book The Cosmic Landscape that evidence for the existence and nature of `pocket universes' in a multiverse would be available in the detailed nature of the Cosmic Blackbody Background Radiation that constantly bathes all parts of our observable universe. I point out that acceptance of the complex chain of argument involved does not imply possible experimental verification of multiverses at the present time. Rather this claim relates only to theoretically possible observations in the very far future of the universe.

George F R Ellis

2006-03-15T23:59:59.000Z

263

REVISITING PUTATIVE COOL ACCRETION DISKS IN ULTRALUMINOUS X-RAY SOURCES  

SciTech Connect (OSTI)

Soft, potentially thermal spectral components observed in some ultra-luminous X-ray sources (ULXs) can be fit with models for emission from cool, optically thick accretion disks. If that description is correct, the low temperatures that are observed imply accretion onto 'intermediate-mass' black holes. Subsequent work has found that these components may follow an inverse relationship between luminosity and temperature, implying a non-blackbody origin for this emission. We have re-analyzed numerous XMM-Newton spectra of extreme ULXs. Crucially, observations wherein the source fell on a chip gap were excluded owing to their uncertain flux calibration, and the neutral column density along the line of sight to a given source was jointly determined by multiple spectra. The luminosity of the soft component is found to be positively correlated with temperature, and to be broadly consistent with L?T {sup 4} in the measured band pass, as per blackbody emission from a standard thin disk. These results are nominally consistent with accretion onto black holes with masses above the range currently known in Galactic X-ray binaries, though there are important caveats. Emission from inhomogeneous or super-Eddington disks may also be consistent with the data.

Miller, J. M.; King, A. L.; Reynolds, M. T.; Reis, R. C. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States)] [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States); Walton, D. J. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)] [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Fabian, A. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 OHA (United Kingdom)] [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 OHA (United Kingdom); Miller, M. C., E-mail: jonmm@umich.edu [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)

2013-10-20T23:59:59.000Z

264

The X-ray Position and Optical Counterpart of the Accretion-Powered Millisecond Pulsar XTE J1814-338  

E-Print Network [OSTI]

We report the precise optical and X-ray localization of the 3.2 ms accretion-powered X-ray pulsar XTE J1814-338 with data from the Chandra X-Ray Observatory as well as optical observations conducted during the 2003 June discovery outburst. Optical imaging of the field during the outburst of this soft X-ray transient reveals an R = 18 star at the X-ray position. This star is absent (R > 20) from an archival 1989 image of the field and brightened during the 2003 outburst, and we therefore identify it as the optical counterpart of XTE J1814-338. The best source position derived from optical astrometry is R.A. = 18h13m39.s04, Dec.= -33d46m22.3s (J2000). The featureless X-ray spectrum of the pulsar in outburst is best fit by an absorbed power-law (with photon index = 1.41 +- 0.06) plus blackbody (with kT = 0.95 +- 0.13 keV) model, where the blackbody component contributes approximately 10% of the source flux. The optical broad-band spectrum shows evidence for an excess of infrared emission with respect to an X-ray...

Krauss, M I; Dullighan, A; Juett, A M; Kaplan, D L; Chakraborty, D; Van Kerkwijk, M H; Steeghs, D; Jonker, P G; Markwardt, C B; Krauss, Miriam I.; Wang, Zhongxiang; Dullighan, Allyn; Juett, Adrienne M.; Kaplan, David L.; Chakrabarty, Deepto; Kerkwijk, Marten H. van; Steeghs, Danny; Jonker, Peter G.; Markwardt, Craig B.

2005-01-01T23:59:59.000Z

265

Two separate spectral substates within Low-Hard States of NS-LMXBs  

E-Print Network [OSTI]

The whole BeppoSAX archive was screened for observations of Neutron Star (NS) Low-Mass X-ray Binaries, in order to characterise the X-ray properties of this class of sources when observed in a Low Hard State (LHS). A total of 12 sources in the sample exhibited LHS spectra; half of the objects showed a "canonical" LHS spectrum, in which two separate populations of soft blackbody-distributed photons emerge. One, or possibly both the populations, is Comptonized by a hot (kT_e > 20 keV) electron plasma cloud. For the remaining 6 sources just a single population is sufficient to account for both the directly observed blackbody and the Comptonized radiation. The luminosities of the NS with canonical two-population spectra are found to be systematically higher than the ones of the sources showing the atypical, single photon population spectra. This suggests the possibility of two separate subclasses of LHS spectra. The transition from a subclass to the other is likely related to the accretion rate, which drives the ...

Cocchi, M

2011-01-01T23:59:59.000Z

266

Eyesight and the solar Wien peak  

Science Journals Connector (OSTI)

It is sometimes said that humans see best at yellow–green wavelengths because they have evolved under a Sun whose blackbody spectrum has a Wien peak in the green part of the spectrum. However as a function of frequency the solar blackbody spectrum peaks in the infrared. Why did human vision not evolve toward a peak sensitivity in this range if the eye is an efficient quantum detector of photons? The puzzle is resolved if we assume that natural selection acted in such a way as to maximize the amount of energy that can be detected by the retina across a range of wavelengths (whose upper and lower limits are fixed by biological constraints). It is then found that our eyes are indeed perfectly adapted to life under a class G2 star. Extending this reasoning allows educated guesses to be made about the kind of eyesight that might have evolved in extrasolar planetary systems such as that of the red dwarf Gliese 876.

James M. Overduin

2003-01-01T23:59:59.000Z

267

X-ray Dip Monitoring of XB 1916-053  

E-Print Network [OSTI]

We report on the long term monitoring of X-ray dips from the ultracompact low-mass X-ray binary (LMXB) XB 1916-053. Roughly one-month interval observations were carried out with the Rossi X-ray Timing Explorer (RXTE) during 1996, during which the source varied between dim, hard states and more luminous, soft states. The dip spectra and dip lightcurves were compared against both the broadband luminosity and the derived mass accretion rate Mdot. The dips spectra could be fitted by an absorbed blackbody plus cut-off power law non-dip spectral model, with additional absorption ranging from 0 to >100 x 10^22 cm^-2. The amount of additional blackbody absorption was found to vary with the source luminosity. Our results are consistent with an obscuration of the inner disk region by a partially ionized outer disk. The size of the corona, derived from the dip ingress times, was found to be ~10^9 cm. The corona size did not correlate with the coronal temperature, but seemed to increase when \\Mdot also increased. We discuss our findings in the context of an evaporated accretion disk corona model and an ADAF-type model.

T. Narita; J. E. Grindlay; P. F. Bloser; Y. Chou

2003-05-06T23:59:59.000Z

268

Anisotropic thermal emission from magnetized neutron stars  

E-Print Network [OSTI]

The thermal emission from isolated neutron stars is not well understood. The X-ray spectrum is very close to a blackbody but there is a systematic optical excess flux with respect to the extrapolation to low energy of the best blackbody fit. This fact, in combination with the observed pulsations in the X-ray flux, can be explained by anisotropies in the surface temperature distribution.We study the thermal emission from neutron stars with strong magnetic fields in order to explain the origin of the anisotropy. We find (numerically) stationary solutions in axial symmetry of the heat transportequations in the neutron star crust and the condensed envelope. The anisotropy in the conductivity tensor is included consistently. The presence of magnetic fields of the expected strength leads to anisotropy in the surface temperature. Models with toroidal components similar to or larger than the poloidal field reproduce qualitatively the observed spectral properties and variability of isolated neutron stars. Our models also predict spectral features at energies between 0.2 and 0.6 keV.

J. F. Perez-Azorin; J. A. Miralles; J. A. Pons

2005-10-24T23:59:59.000Z

269

TESTING ACCRETION DISK STRUCTURE WITH SUZAKU DATA OF LMC X-3  

SciTech Connect (OSTI)

The Suzaku observation of LMC X-3 gives the best data to date on the shape of the accretion disk spectrum. This is due to the combination of very low absorbing column density along this line of sight, which allows the shape of the disk emission to be constrained at low energies by the CCDs while the tail can be simultaneously determined up to 30 keV by the high-energy detectors. These data clearly demonstrate that the observed disk spectrum is broader than a simple 'sum of blackbodies', and relativistic smearing of the emission is strongly required. However, the intrinsic emission should be more complex than a (color-corrected) sum of blackbodies as it should also contain photoelectric absorption edges from the partially ionized disk photosphere. These are broadened by the relativistic smearing, but the models predict {approx}3%-5% deviations for 1/3-1 solar abundance around the edge energies, significantly stronger than observed. This indicates that the models need to include more physical processes such as self-irradiation, bound-bound (line) absorption, and/or emission from recombination continua and/or lines. Alternatively, if none of these match the data, it may instead require that the accretion disk density and/or emissivity profile with height is different to that assumed. Thus, these data demonstrate the feasibility of observational tests of our fundamental understanding of the vertical structure of accretion disks.

Kubota, Aya [Department of Electronic Information Systems, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama-shi, Saitama 337-8570 (Japan); Done, Chris [Department of Physics, University of Durham, South Road, Durham, DH1 3LE (United Kingdom); Davis, Shane W. [School of Natural Sciences, Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States); Dotani, Tadayasu [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Mizuno, Tsunefumi [Department of Physics, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Ueda, Yoshihiro, E-mail: aya@shibaura-it.ac.j [Department of Astronomy, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan)

2010-05-01T23:59:59.000Z

270

Spectral Formation in X-Ray Pulsars: Bulk Comptonization in the Accretion Shock  

Science Journals Connector (OSTI)

Accretion-powered X-ray pulsars are among the most luminous X-ray sources in the Galaxy. However, despite decades of theoretical and observational work since their discovery, no satisfactory model for the formation of the observed X-ray spectra has emerged. In particular, the previously available theories are unable to reproduce the power-law variation observed at high energies in many sources. In this paper we present the first self-consistent calculation of the spectrum emerging from a pulsar accretion column that includes an explicit treatment of the energization occurring in the shock. Using a rigorous eigenfunction expansion method based on the exact dynamical solution for the velocity profile in the column, we obtain a closed-form expression for the Green's function describing the upscattering of radiation injected into the column from a monochromatic source located at the top of the thermal mound, near the base of the flow. The Green's function is convolved with a Planck distribution to calculate the radiation spectrum resulting from the reprocessing of blackbody photons emitted by the thermal mound. We demonstrate that the energization of the photons in the shock naturally produces an X-ray spectrum with a power-law shape at high energies and a blackbody shape at low energies, in agreement with many observations of accreting X-ray pulsars.

Peter A. Becker; Michael T. Wolff

2005-01-01T23:59:59.000Z

271

The dusty nuclear torus in NGC4151: constraints from Gemini NIFS observations  

E-Print Network [OSTI]

We have used a near-infrared nuclear spectrum (covering the Z, J, H and K bands) of the nucleus of NGC 4151 obtained with the Gemini Near-infrared Integral Field Spectrograph (NIFS) and adaptive optics, to isolate and constrain the properties of a near-IR unresolved nuclear source whose spectral signature is clearly present in our data. The near-IR spectrum was combined with an optical spectrum obtained with the Space Telescope Imaging Spectrograph which was used to constrain the contribution of a power-law component. After subtraction of the power-law component, the near-IR continuum is well fitted by a blackbody function, with $T=1285\\pm50 $K, which dominates the nuclear spectrum -- within an aperture of radius 0$\\farcs$3 -- in the near-IR. We attribute the blackbody component to emission by a dusty structure, with hot dust mass $M_{\\rm HD}=(6.9\\pm 1.5) \\times10^{-4} {\\rm M_\\odot}$, not resolved by our observations, which provide only an upper limit for its distance from the nucleus of 4 pc. If the reddenin...

Riffel, Rogemar A; Mcgregor, Peter J

2009-01-01T23:59:59.000Z

272

Thermality of the Hawking flux  

E-Print Network [OSTI]

Is the Hawking flux "thermal"? Unfortunately, the answer to this seemingly innocent question depends on a number of often unstated, but quite crucial, technical assumptions built into modern (mis-)interpretations of the word "thermal". The original 1850's notions of thermality --- based on classical thermodynamic reasoning applied to idealized "black bodies" or "lamp black surfaces" --- when supplemented by specific basic quantum ideas from the early 1900's, immediately led to the notion of the black-body spectrum, (the Planck-shaped spectrum), but "without" any specific assumptions or conclusions regarding correlations between the quanta. Many (not all) modern authors (often implicitly and unintentionally) add an extra, and quite unnecessary, assumption that there are no correlations in the black-body radiation; but such usage is profoundly ahistorical and dangerously misleading. Specifically, the Hawking flux from an evaporating black hole, (just like the radiation flux from a leaky furnace or a burning lump of coal), is only "approximately" Planck-shaped over a bounded frequency range. Standard physics (phase space and adiabaticity effects) explicitly bound the frequency range over which the Hawking flux is "approximately" Planck-shaped from both above and below --- the Hawking flux is certainly not exactly Planckian, and there is no compelling physics reason to assume the Hawking photons are uncorrelated.

Matt Visser

2014-09-27T23:59:59.000Z

273

Accurate calculations of Sr properties for a high-accuracy optical clock  

E-Print Network [OSTI]

We have carried out calculations towards the goal of reducing the inaccuracy of the Sr optical atomic clock to 1$\\times10^{-17}$ and below. We calculated a.c. polarizabilities of the $5s^2 ^1S_0$ and $5s5p ^3P_0^o$ clock states that are important for reducing the uncertainty of blackbody radiation-induced frequency shifts for the $^1S_0 - ^3P_0^o$ clock transition. We determined four low-lying even-parity states whose total contribution to the static polarizability of the $^3P_0^o$ clock state is at the level of 90%. We show that if the contribution of these states is experimentally known with 0.1% accuracy, the same accuracy can be achieved for the total polarizability of the $^3P_0^o$ state. The corresponding uncertainty for the blackbody shift at a fixed room temperature will be below 1$\\times10^{-17}$. The calculations are confirmed by a number of experimental measurements on various Sr properties.

S. G. Porsev; Andrew D. Ludlow; Martin M. Boyd; Jun Ye

2008-07-09T23:59:59.000Z

274

Polarized Mid-Infrared Synchrotron Emission in the Core of Cygnus A  

E-Print Network [OSTI]

We present high-angular (~0.4") resolution mid-infrared (MIR) polarimetric observations in the 8.7 ${\\mu}$m and 11.6 ${\\mu}$m filters of Cygnus A using CanariCam on the 10.4-m Gran Telescopio CANARIAS. A highly polarized nucleus is observed with a degree of polarization of 11${\\pm}$3% and 12${\\pm}$3% and position angle of polarization of 27${\\pm}$8 degrees and 35${\\pm}$8 degrees in a 0.38" (~380 pc) aperture for each filter. The observed rising of the polarized flux density with increasing wavelength is consistent with synchrotron radiation from the pc-scale jet close to the core of Cygnus A. Based on our polarization model, the synchrotron emission from the pc-scale jet is estimated to be 14% and 17% of the total flux density in the 8.7 ${\\mu}$m and 11.6 ${\\mu}$m filters, respectively. A blackbody component with a characteristic temperature of 220 K accounts for >75% of the observed MIR total flux density. The blackbody emission arises from a combination of (1) dust emission in the torus; and (2) diffuse dus...

Lopez-Rodriguez, E; Tadhunter, C; Mason, R; Perlman, E; Alonso-Herrero, A; Almeida, C Ramos; Ichikawa, K; Levenson, N A; Rodr?guez-Espinosa, J M; Alvarez, C A; Ram?rez, E A; Telesco, C M

2014-01-01T23:59:59.000Z

275

Low-Mass X-Ray Binary MAXI J1421-613 Observed by MAXI GSC and Swift XRT  

E-Print Network [OSTI]

Monitor of All sky X-ray Image (MAXI) discovered a new outburst of an X-ray transient source named MAXI J1421-613. Because of the detection of three X-ray bursts from the source, it was identified as a neutron star low-mass X-ray binary. The results of data analyses of the MAXI GSC and the Swift XRT follow-up observations suggest that the spectral hardness remained unchanged during the first two weeks of the outburst. All the XRT spectra in the 0.5-10 keV band can be well explained by thermal Comptonization of multi-color disk blackbody emission. The photon index of the Comptonized component is $\\approx$ 2, which is typical of low-mass X-ray binaries in the low/hard state. Since X-ray bursts have a maximum peak luminosity, it is possible to estimate the (maximum) distance from its observed peak flux. The peak flux of the second X-ray burst, which was observed by the GSC, is about 5 photons cm$^{-2}$ s$^{-1}$. By assuming a blackbody spectrum of 2.5 keV, the maximum distance to the source is estimated as 7 kpc...

Serino, Motoko; Ueda, Yoshihiro; Matsuoka, Masaru; Negoro, Hitoshi; Yamaoka, Kazutaka; Kennea, Jamie A; Fukushima, Kosuke; Nagayama, Takahiro

2015-01-01T23:59:59.000Z

276

A NEUTRON STAR STIFF EQUATION OF STATE DERIVED FROM COOLING PHASES OF THE X-RAY BURSTER 4U 1724-307  

SciTech Connect (OSTI)

Thermal emission during X-ray bursts is a powerful tool for determining neutron star (NS) masses and radii if the Eddington flux and the apparent radius in the cooling tail can be measured accurately and distances to the sources are known. We propose here an improved method of determining the basic stellar parameters using the data from the cooling phase of photospheric radius expansion (PRE) bursts covering a large range of luminosities. Because at that phase the blackbody apparent radius depends only on the spectral hardening factor (color correction), we suggest fitting the theoretical dependences of the color correction versus flux in Eddington units to the observed variations of the inverse square root of the apparent blackbody radius with the flux. For that we use a large set of atmosphere models for burst luminosities varying by three orders of magnitude and for various chemical compositions and surface gravities. We show that spectral variations observed during a long PRE burst from 4U 1724-307 are entirely consistent with the theoretical expectations for the passively cooling NS atmospheres. Our method allows us to more reliably determine both the Eddington flux (which is found to be smaller than the touchdown flux by 15%) and the ratio of the stellar apparent radius to the distance. We then find a lower limit on the NS radius of 14 km for masses below 2.3 M{sub Sun }, independently of the chemical composition. These results suggest that the matter inside NSs is characterized by a stiff equation of state. We also find evidence in favor of hydrogen-rich accreting matter and obtain an upper limit to the distance of 7 kpc. We finally show that the apparent blackbody emitting area in the cooling tails of the short bursts from 4U 1724-307 is two times smaller than that for the long burst and their evolution does not follow the theory. This makes their usage for determining the NS parameters questionable and casts serious doubt on the results of previous works that used similar bursts from other sources for analysis.

Suleimanov, Valery; Werner, Klaus [Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics, Eberhard Karls University, Sand 1, 72076 Tuebingen (Germany); Poutanen, Juri [Astronomy Division, Department of Physics, P.O. Box 3000, FI-90014 University of Oulu (Finland); Revnivtsev, Mikhail, E-mail: suleimanov@astro.uni-tuebingen.de, E-mail: werner@astro.uni-tuebingen.de, E-mail: juri.poutanen@oulu.fi [Space Research Institute (IKI), Russian Academy of Sciences, Profsoyuznaya 84/32, Moscow 117997 (Russian Federation)

2011-12-01T23:59:59.000Z

277

takara-98.pdf  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

9 9 Broken Cloud Field Approximations in the Longwave E. E. Takara and R. G. Ellingson University of Maryland College Park, Maryland Abstract Because clouds play an important role in the earth's radiation energy budget, improving the cloud models in general circulation models (GCMs) is a necessary step for climate studies. In partially cloudy skies, the geometric and optical properties of individual cloud elements need to be considered. In general, GCMs ignore the geometry of ice clouds and water clouds. They also ignore the optical properties of water clouds, modeling them as blackbodies. In this work, the accuracy of cloud approximations will be examined in the 8-µm to 12-µm window region. Calculations for water clouds and ice clouds of two geometries in two different atmospheric conditions show

278

CX-009561: Categorical Exclusion Determination | Department of Energy  

Broader source: Energy.gov (indexed) [DOE]

61: Categorical Exclusion Determination 61: Categorical Exclusion Determination CX-009561: Categorical Exclusion Determination Using Solid Particles as Heat Transfer Fluid for Use in Concentrating Solar Power (CSP) Plants CX(s) Applied: A9 Date: 12/04/2012 Location(s): Colorado Offices(s): Golden Field Office The U.S. DOE is proposing to provide federal funding to the University of Colorado, in partnership with the National Renewable Energy Laboratory to conduct computer based modeling that advances concentrated solar power (CSP) thermal systems. DOE funding would be used for computer based modeling to develop, verify and validate a first-principle modeling tool for use in the optimization, scale-up, and design of a near-blackbody receiver. CX-009561.pdf More Documents & Publications CX-005581: Categorical Exclusion Determination

279

 

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Chasing Dark Matter Axions to the Quantum Limit Chasing Dark Matter Axions to the Quantum Limit Steve Asztalos LLNL ABSTRACT The Axion Dark Matter eXperiment (ADMX) at LLNL searches for dark-matter axions through their Primakoff conversion to microwave photons, resonantly enhanced in a high-Q cavity permeated by a strong magnetic field. ADMX remains the world's quietest spectral receiver in the GHz regime, capable of detecting a single RF photon per minute above cavity blackbody and amplifier noise. ADMX had previously covered a frequency range of 460 to 812 MHz (1.9 - 3.4 micro-eV); over that octave of mass range axions were excluded as the Milky Way halo dark matter for well-motivated models of the coupling of the axion to two photons. An upgrade of ADMX has since been completed, which replaced the previous HFET amplifiers with SQUID

280

Science Showcase: George F. Smoot and Roger D. Kornberg | OSTI, US Dept of  

Office of Scientific and Technical Information (OSTI)

Science Showcase: George F. Smoot and Roger D. Kornberg Science Showcase: George F. Smoot and Roger D. Kornberg Feature Archive George Smoot George F. Smoot won the 2006 Nobel Prize in Physics. George F. Smoot and Roger D. Kornberg have joined the growing list of Nobel Laureates associated with DOE. Smoot won the 2006 Nobel Prize in Physics for his work in blackbody and anisotropy of the cosmic microwave background radiation. Smoot is an astrophysicist at DOE's Lawrence Berkeley National Lab and a UC Berkeley physics professor. He shared the award with John C. Mather of NASA Goddard Space Flight Center. Roger D. Kornberg of Stanford University won the 2006 Nobel Prize in Chemistry for his studies of the molecular basis of eukaryotic transcription. A significant portion of Kornberg's research leading to this prize was performed at the Stanford Synchrotron Radiation Laboratory

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

ARM - Datastreams - aerich2  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Datastreamsaerich2 Datastreamsaerich2 Documentation Data Quality Plots Citation DOI: 10.5439/1025144 [ What is this? ] Generate Citation ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Datastream : AERICH2 Atmospheric Emitted Radiance Interferometer (AERI): channel 2 data Active Dates 1994.01.10 - 2014.01.02 Measurement Categories Radiometric Originating Instrument Atmospheric Emitted Radiance Interferometer (AERI) Measurements Only measurements considered scientifically relevant are shown below by default. Show all measurements Measurement Units Variable AERI instrument unit serial number unitless AERIunitNumber ( time ) Observation Altitude m Altitude ( time ) Temperature of the AERI blackbody support structure K BBsupportStructureTemp ( time )

282

Berkeley Lab Nobel Laureates  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

George F. Smoot III George F. Smoot III 2006 Nobel Prize for Physics • October 3, 2006 Press Conference (Video) • Bibliography of Dr. Smoot's Works • October 3, 2006 Press Conference (Video) The October 3, 2006 press conference at Berkeley Lab introducing its newest Nobel Prize winner, George Smoot, to a throng of visiting media is available for viewing online. George F. Smoot III, Nobel Prize recipient, 2006 • Bibliography of Dr. Smoot's Works LBL-6468: Detection of anisotropy in the cosmic blackbody radiation LBL-6493: Radiometer system to map the cosmic background radiation LBL-7553: Abundances and spectra for cosmic ray nuclei from Li to Fe for 2-GeV/n to 150-GeV/n LBL-8266: Search for linear polarization of the cosmic background radiation LBL-9282: Southern hemisphere measurements of the anisotropy in the cosmic

283

ARM - Publications: Science Team Meeting Documents  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Parameterizing the Radiative Properties of Midlatitude Clouds Parameterizing the Radiative Properties of Midlatitude Clouds Sassen, K. (a), Comstock, J.M. (b), and Wang, Z. (a), University of Utah (a), Pacific Northwest National Laboratory (b) Eleventh Atmospheric Radiation Measurement (ARM) Science Team Meeting A major goal of the ARM program is to obtain the requisite information needed to improve the treatment of the radiative effects of clouds in large-scale models that ultimately must be relied on to predict the impact of human-induced activities on global climate change. The clouds of the middle and upper troposphere are especially difficult to treat because of their variable optical properties, which range from optically thin in the visible, and graybody emitters in the infrared, to dense blackbody emitters. Approaches to obtain this information involve the development of

284

Beam-Gas  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Gas Gas and Thermal Photon Scattering in the NLC Main Linac as a Source of Beam Halo P. Tenenbaum LCC-Note-0051 12-JAN-2001 Abstract Scattering of primary beam electrons off of residual gas molecules or blackbody radiation photons in the NLC main linac has been identified as a potential source of beam haloes which must be collimated in the beam delivery system. We consider the contributions from four scat- tering mechanisms: inelastic thermal-photon scattering, elastic beam-gas (Coulomb) scattering inelastic beam-gas (Bremsstrahlung) scattering, and atomic-electron scattering. In each case we develop the formalism necessary to estimate the backgrounds generated in the main linac, and determine the expected number of off-energy or large-amplitude particles from each process, assuming a main linac injection energy of 8 GeV and extraction energy of 500 GeV. 1 Introduction The

285

ARM - Field Campaign - AERI-ER Intercomparison IOP  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

govCampaignsAERI-ER Intercomparison IOP govCampaignsAERI-ER Intercomparison IOP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : AERI-ER Intercomparison IOP 2004.01.12 - 2006.06.29 Lead Scientist : David Turner Data Availability Data were collected and submitted to the ARM Archive for IOPs. For data sets, see below. Summary There were three, potentially four, phases to this experiment. The length of time required for each phase was the time needed to ensure at least one severe clear period, which occur relatively frequently in January and February on the North Slope. The phases were: 1) Run the two systems side-by-side in their nominal modes to ensure that the calibration is reproducible. 2) Adjust the set-point of the hot blackbody on the second system from 60

286

Exergy of boson and fermion fluxes  

Science Journals Connector (OSTI)

Particles with zero and non-zero rest mass are considered in both the classical and ultra-relativistic limits. Relationships that may be used for both fermions and bosons are derived. The exergy flux of free particles involves an efficiency-like factor affecting the energy flux. This factor contains the ambient temperature and the effective particle flux temperature and it is generally different from both the usual Carnot factor and the Petela factor appearing in the exergy of blackbody radiation fluxes, respectively. Some particular cases considered here show that free Fermi particles carry less available work than Bose particles and that the classical approximation yields higher values of the efficiency-like factors than the ultra-relativistic assumption.

Viorel Badescu

2009-01-01T23:59:59.000Z

287

Infrared spectroscopy of cataclysmic variables - II. Intermediate polars  

E-Print Network [OSTI]

We present infrared (0.97-2.45 micron) spectra of the intermediate polars PQ Gem (RE0751+14), BG CMi and EX Hya. The spectra show strong Paschen, Brackett and HeI emission lines from the accretion disc/stream. The infrared continua of PQ Gem and BG CMi can be represented by blackbodies of temperatures 4500 K and 5100 K, respectively, or by power-laws of the form f_nu \\propto nu^(0.6,0.9), respectively, and show no evidence of secondary star features. The continuum of EX Hya is doiminated by water bands from the red-dwarf secondary star, which has a spectral type of ~M3. Despite showing circular polarization, PQ Gem and BG CMi show no evidence for cyclotron humps and hence we are unable to measure their magnetic field strengths; any cyclotron emission present must contribute less than ~3 per cent of the infrared continuum flux.

V. S. Dhillon; T. R. Marsh; S. R. Duck; S. R. Rosen

1996-09-06T23:59:59.000Z

288

Broad-band Spectral Properties of Accreting X-ray Binary Pulsars  

E-Print Network [OSTI]

Broad-band spectra of accreting X-ray binary pulsars can be fit by a phenomenological model composed by a power law with a high energy rollover above 10 keV, plus a blackbody component with a temperature of few hundred eV. While, at least qualitatively, the hard tail can be explained in terms of (inverse) Compton scattering, the origin of the soft component cannot find a unique explanation. Recently a qualitative picture able to explain the overall broad band-spectrum of luminous X-ray pulsars was carried out by taking into account the effect of bulk Comptonization in the accretion column. After a review on these recent theoretical developments, I will present a case study of how different modelization of the continuum affect broad features, in particular the cyclotron resonance features in Vela X-1.

Mauro Orlandini

2005-10-10T23:59:59.000Z

289

A Germanium Back Contact Type Thermophotovoltaic Cell  

SciTech Connect (OSTI)

A Ge back contact type photovoltaic cell has been proposed to reduce resistance loss for high current densities in thermophotovoltaic systems. The back contact structure requires less surface recombination velocities than conventional structures with front grid contacts. A SiO2/SiNx double anti-reflection coating including a high refractive index SiNx layer was studied. The SiNx layer has an enough passivation effect to obtain high efficiency. The quantum efficiency of the Ge cell was around 0.8 in the 800-1600 nm wavelength range. The conversion efficiency for infrared lights was estimated at 18% for a blackbody surface and 25% for a selective emitter by using the quantum efficiency and a simulation analysis.

Nagashima, Tomonori; Okumura, Kenichi [Future Project Div., Toyota Motor Corporation, 1200 Mishuku, Susono, Shizuoka 410-1193 (Japan); Yamaguchi, Masafumi [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan)

2007-02-22T23:59:59.000Z

290

LSST beam simulator  

Science Journals Connector (OSTI)

It is always important to test new imagers for a mosaic camera before device acceptance and constructing the mosaic. This is particularly true of the LSST CCDs due to the fast beam illumination: at long wavelengths there can be significant beam divergence (defocus) inside the silicon because of the long absorption length for photons near the band gap. Moreover, realistic sky scenes need to be projected onto the CCD focal plane Thus, we need to design and build an f/1.2 re-imaging system. The system must simulate the entire LSST1 operation, including a sky with galaxies and stars with approximately black-body spectra superimposed on a spatially diffuse night sky emission with its complex spectral features.

J A Tyson; J Sasian; C Claver; G Muller; K Gilmor; M Klint

2014-01-01T23:59:59.000Z

291

Cosmological and astrophysical constraints on superconducting cosmic strings  

SciTech Connect (OSTI)

We investigate the cosmological and astrophysical constraints on superconducting cosmic strings (SCSs). SCS loops emit strong bursts of electromagnetic waves, which might affect various cosmological and astrophysical observations. We take into account the effect on the CMB anisotropy, CMB blackbody spectrum, BBN, observational implications on radio wave burst and X-ray or ?-ray events, and stochastic gravitational wave background measured by pulsar timing experiments. We then derive constraints on the parameters of SCS from current observations and estimate prospects for detecting SCS signatures in on-going observations. As a result, we find that these constraints exclude broad parameter regions, and also that on-going radio wave observations can probe large parameter space.

Miyamoto, Koichi [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582 (Japan); Nakayama, Kazunori, E-mail: miyamone@icrr.u-tokyo.ac.jp, E-mail: kazunori@hep-th.phys.s.u-tokyo.ac.jp [Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2013-07-01T23:59:59.000Z

292

The Big Bang, COBE, and the Relic Radiation of Creation (LBNL Science at the Theater)  

ScienceCinema (OSTI)

Berkeley Lab's George Smoot won the 2006 Physics Nobel Prize, together with John Mather of NASA Goddard Space Flight Center, for "the discovery of the blackbody form and anisotropy of the cosmic microwave background radiation." The anisotropy showed as small variations in the map of the early universe. This research looks back into the infant universe and provides a better understanding of the origin of galaxies and stars. The cosmic background radiation is a tool to understand the structure and history of the universe and the structure of space-time. These observations have provided increased support for the big bang theory of the universe's origin. The Cosmic Background Explorer (COBE) NASA satellite, launched in 1989, carries instruments that measured various aspects of cosmic microwave background radiation, and produced the data for these compelling scientific results, which opened up a field that continues very actively today.

Smoot, George

2011-04-28T23:59:59.000Z

293

Improved Spatial Resolution for Reflection Mode Infrared Microscopy  

SciTech Connect (OSTI)

Standard commercial infrared microscopes operating in reflection mode use a mirror to direct the reflected light from the sample to the detector. This mirror blocks about half of the incident light, however, and thus degrades the spatial resolution by reducing the umerical aperture of the objective. Here, we replace the mirror with a 50% beamsplitter to allow full illumination of the objective and retain a way to direct the reflected light to the detector. The improved spatial resolution is demonstrated using two different microscopes apable of diffraction-limited resolution: the first microscope is coupled to a synchrotron source and utilizes a single point detector, whereas the second microscope has a standard blackbody source and uses a focal planetarray (FPA) detector.

Bechtel, Hans A.; Martin, Michael C.; May, T.E.; Lerch, Philippe

2009-10-09T23:59:59.000Z

294

High efficiency rare-earth emitter for thermophotovoltaic applications  

SciTech Connect (OSTI)

In this work, we propose a rare-earth-based ceramic thermal emitter design that can boost thermophotovoltaic (TPV) efficiencies significantly without cold-side filters at a temperature of 1573?K (1300?°C). The proposed emitter enhances a naturally occurring rare earth transition using quality-factor matching, with a quarter-wave stack as a highly reflective back mirror, while suppressing parasitic losses via exponential chirping of a multilayer reflector transmitting only at short wavelengths. This allows the emissivity to approach the blackbody limit for wavelengths overlapping with the absorption peak of the rare-earth material, while effectively reducing the losses associated with undesirable long-wavelength emission. We obtain TPV efficiencies of 34% using this layered design, which only requires modest index contrast, making it particularly amenable to fabrication via a wide variety of techniques, including sputtering, spin-coating, and plasma-enhanced chemical vapor deposition.

Sakr, E. S.; Zhou, Z.; Bermel, P., E-mail: pbermel@purdue.edu [Birck Nanotechnology Center, School of Electrical and Computer Engineering, Purdue University, 1205 W. State St., West Lafayette, Indiana 47907 (United States)

2014-09-15T23:59:59.000Z

295

Single-crystal sapphire tubes as economical probes for optical pyrometry in harsh environments  

SciTech Connect (OSTI)

One-end-sealed single-crystal sapphire tubes are presented as a simple, robust, and economical alternative for bulky lightpipe probes. Thermal radiation from a blackbody cavity created at the inner surface of the sealed end is gathered by a simple lens-based collecting system and transmitted via optical fiber to the remote detection unit. Simplicity and applicability of the concept are demonstrated by the combination of commercially available sapphire tubes with a common optical pyrometer. Radiation thermometers with sapphire tubes as invasive probes can be useful for applications requiring immunity to electromagnetic interference, resistance to harsh environments, simple replacement in the case of failure, and enhanced mechanical firmness, enabling wider range probe positioning inside the medium of interest.

Ruzicka, Jakub; Houzvicka, Jindrich; Bok, Jiri; Praus, Petr; Mojzes, Peter

2011-12-20T23:59:59.000Z

296

Sr lattice clock at 1x10^{-16} fractional uncertainty by remote optical evaluation with a Ca clock  

E-Print Network [OSTI]

Optical atomic clocks promise timekeeping at the highest precision and accuracy, owing to their high operating frequencies. Rigorous evaluations of these clocks require direct comparisons between them. We have realized a high-performance remote comparison of optical clocks over km-scale urban distances, a key step for development, dissemination, and application of these optical standards. Through this remote comparison and a proper design of lattice-confined neutral atoms for clock operation, we evaluate the uncertainty of a strontium (Sr) optical lattice clock at the 1x10-16 fractional level, surpassing the best current evaluations of cesium (Cs) primary standards. We also report on the observation of density-dependent effects in the spin-polarized fermionic sample and discuss the current limiting effect of blackbody radiation-induced frequency shifts.

A. D. Ludlow; T. Zelevinsky; G. K. Campbell; S. Blatt; M. M. Boyd; M. H. G. de Miranda; M. J. Martin; J. W. Thomsen; S. M. Foreman; Jun Ye; T. M. Fortier; J. E. Stalnaker; S. A. Diddams; Y. Le Coq; Z. W. Barber; N. Poli; N. D. Lemke; K. M. Beck; C. W. Oates

2008-01-28T23:59:59.000Z

297

Proposal for a second-generation, lattice matched, multiple junction Ga{sub 2}AsSb TPV converter  

SciTech Connect (OSTI)

First order device modeling is used to show that spontaneously ordered Ga{sub 2}AsSb may prove useful in the newly-active field of thermophotovoltaic power generation. Optimal band gaps for single-, double- and triple-junction III-V devices are presented for a range of blackbody emitter temperatures (1000--2000 K), and it is shown that monolithic, current-matched devices may be constructed that are lattice-matched throughout the stack to an underlying InP substrate. Device efficiency, short-circuit current, fill factor, and open-circuit voltage calculations are presented. The power generation capabilities are expected to be substantial due to the proximity of the devices to the thermal radiators. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Horner, G.S. [Keithley Instruments, Solon Ohio (United States); Coutts, T.J.; Wanlass, M.W. [National Renewable Energy Laboratory, Golden Colorado (United States)

1995-01-05T23:59:59.000Z

298

Thermophotovoltaics for Combined Heat and Power Using Low NOx Gas Fired Radiant Tube Burners  

Science Journals Connector (OSTI)

Three new developments have now occurred making economical TPV systems possible. The first development is the diffused junction GaSb cell that responds out to 1.8 microns producing over 1 W/cm2 electric given a blackbody IR emitter temperature of 1250 C. This high power density along with a simple diffused junction cell makes an array cost of $0.50 per Watt possible. The second development is new IR emitters and filters that put 75% of the radiant energy in the cell convertible band. The third development is a set of commercially available ceramic radiant tube burners that operate at up to 1250 C. Herein we present near term and longer term spectral control designs leading to a 1.5 kW TPV generator / furnace incorporating these new features. This TPV generator / furnace is designed to replace the residential furnace for combined heat and power for the home.

Lewis Fraas; James Avery; Enrico Malfa; Joachim G. Wuenning; Gary Kovacik; Chris Astle

2003-01-01T23:59:59.000Z

299

Constraining resonant photon-axion conversions in the early universe  

SciTech Connect (OSTI)

The presence of a primordial magnetic field would have induced resonant conversions between photons and axion-like particles (ALPs) during the thermal history of the Universe. These conversions would have distorted the blackbody spectrum of the cosmic microwave background (CMB). In this context, we derive bounds on the photon-ALP resonant conversions using the high precision CMB spectral data collected by the FIRAS instrument on board of the Cosmic Background Explorer. We obtain upper limits on the product of the photon-ALP coupling constant g times the magnetic field strength B down to gB ?< 10{sup ?13} GeV{sup ?1} nG for ALP masses below the eV scale.

Mirizzi, Alessandro [Max-Planck-Institut für Physik (Werner Heisenberg Institut), Föhringer Ring 6, 80805 München (Germany); Redondo, Javier [Deutsches Elektronen Synchrotron, Notkestraße 85, 22607 Hamburg (Germany); Sigl, Günter, E-mail: amirizzi@mppmu.mpg.de, E-mail: javier.redondo@desy.de, E-mail: sigl@iap.fr [II. Institut für theoretische Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

2009-08-01T23:59:59.000Z

300

Non-planckian equilibrium radiation of plasma-like media  

SciTech Connect (OSTI)

Consideration of equilibrium radiation of plasma-like media shows that the spectral distribution of such radiation differs from that of Planckian equilibrium radiation (blackbody radiation). The physical reason for this difference consists in the impossibility of propagation of photons with the dispersion law {omega} = ck in systems of charged particles. The thermodynamics of equilibrium electromagnetic radiation in plasma is also considered. It is shown that the difference of the thermodynamic properties of such radiation from those of Planckian radiation is characterized by the parameter a = h{Omega}{sub p}/T. This difference is especially pronounced in plasma media in which a {>=} 1. Applications of the results obtained to plasmas of metals (first of all, liquid metals in which charged particles have no distant order) and to the plasma model of the early Universe are discussed.

Triger, S. A.; Khomkin, A. L. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2010-12-15T23:59:59.000Z

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301

Thermodynamics and Hawking radiation of five-dimensional rotating charged Goedel black holes  

SciTech Connect (OSTI)

We study the thermodynamics of Goedel-type rotating charged black holes in five-dimensional minimal supergravity. These black holes exhibit some peculiar features such as the presence of closed timelike curves and the absence of a globally spatial-like Cauchy surface. We explicitly compute their energies, angular momenta, and electric charges that are consistent with the first law of thermodynamics. Besides, we extend the covariant anomaly cancellation method, as well as the approach of the effective action, to derive their Hawking fluxes. Both the methods of the anomaly cancellation and the effective action give the same Hawking fluxes as those from the Planck distribution for blackbody radiation in the background of the charged rotating Goedel black holes. Our results further support that Hawking radiation is a quantum phenomenon arising at the event horizon.

Wu Shuangqing [College of Physical Science and Technology, HuaZhong Normal University, Wuhan, Hubei 430079 (China); Peng Junjin [College of Physical Science and Technology, HuaZhong Normal University, Wuhan, Hubei 430079 (China); College of Science, Wuhan Textile University, Wuhan, Hubei 430074 (China)

2011-02-15T23:59:59.000Z

302

Third Law of Thermodynamics and Electromagnetic Zero-Point Radiation  

Science Journals Connector (OSTI)

It is pointed out that the third law of thermodynamics, which has been verified experimentally for systems with electromagnetic interactions, is not part of traditional classical theory, and indeed is violated by hypothetical systems, such as an ideal gas, which exhibit equipartition of energy. In the context of quantum theory, the law may be understood from the description of thermodynamic systems as quantum systems having discrete energy levels. Along the same lines as a recent derivation of the blackbody radiation spectrum from classical theory involving classical electromagnetic zero-point radiation, it is shown that the third law holds in classical theory for all thermodynamic systems which interact (no matter how weakly) with electromagnetic radiation.

Timothy H. Boyer

1970-03-15T23:59:59.000Z

303

Visualizing infrared phenomena with a webcam  

Science Journals Connector (OSTI)

The concept of light (electromagnetic radiation) outside of the visible spectrum is an abstract concept for students in an introductory science class. When students are presented with demonstrations or experiments meant to explore this portion of the spectrum the equipment involved often hides the phenomena. A simple modification to a standard inexpensive web camera (webcam) can take advantage of the sensitivity of the charged-coupled-device (CCD) to the infrared (IR) portion of the spectrum allowing students to visualize many IR phenomena. This note reports how such a modified webcam can be used in lecture demonstrations and laboratory activities to study infrared phenomena including an IR light emitting diode(LED) the IR component of different light sources IR spectroscopy and blackbody radiation. As a final example the modified camera can be employed to view the charcoal under-drawing of a “painting” created for this paper and used in our classroom demonstrations.

N. A. Gross; M. Hersek; A. Bansil

2005-01-01T23:59:59.000Z

304

A soft x-ray transmission grating imaging-spectrometer for the National Ignition Facility  

SciTech Connect (OSTI)

A soft x-ray transmission grating spectrometer has been designed for use on high energy-density physics experiments at the National Ignition Facility (NIF); coupled to one of the NIF gated x-ray detectors (GXD) it records sixteen time-gated spectra between 250 and 1000eV with 100ps temporal resolution. The trade-off between spectral and spatial resolution leads to an optimized design for measurement of emission around the peak of a 100-300eV blackbody spectrum. Performance qualification results from the NIF, the Trident Laser Facility and VUV beamline at the National Synchrotron Light Source (NSLS), evidence a <100{micro}m spatial resolution in combination with a source-size limited spectral resolution that is <10eV at photon energies of 300eV.

Moore, A S; Guymer, T M; Kline, J L; Morton, J; Taccetti, M; Lanier, N E; Bentley, C; Workman, J; Peterson, B; Mussack, K; Cowan, J; Prasad, R; Richardson, M; Burns, S; Kalantar, D H; Benedetti, L R; Bell, P; Bradley, D; Hsing, W; Stevenson, M

2012-05-01T23:59:59.000Z

305

A soft x-ray transmission grating imaging-spectrometer for the National Ignition Facility  

SciTech Connect (OSTI)

A soft x-ray transmission grating spectrometer has been designed for use on high energy-density physics experiments at the National Ignition Facility (NIF); coupled to one of the NIF gated x-ray detectors it records 16 time-gated spectra between 250 and 1000 eV with 100 ps temporal resolution. The trade-off between spectral and spatial resolution leads to an optimized design for measurement of emission around the peak of a 100-300 eV blackbody spectrum. Performance qualification results from the NIF, the Trident Laser Facility and vacuum ultraviolet beamline at the National Synchrotron Light Source, evidence a <100 {mu}m spatial resolution in combination with a source-size limited spectral resolution that is <10 eV at photon energies of 300 eV.

Moore, A. S.; Guymer, T. M.; Morton, J.; Bentley, C.; Stevenson, M. [Directorate Science and Technology, AWE Aldermaston, Reading, RG7 4PR (United Kingdom); Kline, J. L.; Taccetti, M.; Lanier, N. E.; Workman, J.; Peterson, B.; Mussack, K.; Cowan, J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Prasad, R.; Richardson, M.; Burns, S.; Kalantar, D. H.; Benedetti, L. R.; Bell, P.; Bradley, D.; Hsing, W. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States)

2012-10-15T23:59:59.000Z

306

Importance of Compton scattering to radiation spectra of isolated neutron stars  

E-Print Network [OSTI]

Model atmospheres of isolated neutron stars with low magnetic field are calculated with Compton scattering taking into account. Models with effective temperatures 1, 3 and 5 MK, with two values of surface gravity log(g)g = 13.9 and 14.3), and different chemical compositions are calculated. Radiation spectra computed with Compton scattering are softer than the computed with Thomson scattering at high energies (E > 5 keV) for hot (T_eff > 1 MK) atmospheres with hydrogen-helium composition. Compton scattering is more significant to hydrogen models with low surface gravity. The emergent spectra of the hottest (T_eff > 3 MK) model atmospheres can be described by diluted blackbody spectra with hardness factors ~ 1.6 - 1.9. Compton scattering is less important for models with solar abundance of heavy elements.

V. Suleimanov; K. Werner

2006-12-22T23:59:59.000Z

307

CONSTRAINTS ON THE MASS AND RADIUS OF THE NEUTRON STAR XTE J1807-294  

SciTech Connect (OSTI)

The accreting millisecond pulsar XTE J1807-294 is studied through a pulse-shape modeling analysis. The model includes blackbody and Comptonized emission from the one visible hot spot and makes use of the Oblate Schwarzschild approximation for ray-tracing. We include a scattered light contribution, which accounts for flux scattered off an equatorial accretion disk to the observer including time delays in the scattered light. We give limits to mass and radius for XTE J1807-294 and compare these to limits determined for SAX J1808-3658 and XTE J1814-334 previously determined using similar methods. The resulting allowed region for mass-radius curves is small but consistent with a mass-radius relation with nearly constant radius ({approx}12 km) for masses between 1 and 2.5 solar masses.

Leahy, Denis A. [Department of Physics and Astronomy, University of Calgary, Calgary AB, T2N 1N4 (Canada); Morsink, Sharon M. [Department of Physics, University of Alberta, Edmonton AB, T6G 2E1 (Canada); Yi Chou, E-mail: leahy@ucalgary.ca, E-mail: morsink@ualberta.ca, E-mail: yichou@astro.ncu.edu.tw [Graduate Institute of Astronomy, National Central University, Jhongli 32001, Taiwan (China)

2011-11-20T23:59:59.000Z

308

ARM - Field Campaign - IR Cloud Camera Feasibility Study  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

govCampaignsIR Cloud Camera Feasibility Study govCampaignsIR Cloud Camera Feasibility Study Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : IR Cloud Camera Feasibility Study 2010.12.06 - 2010.12.13 Lead Scientist : Kyle Leesman For data sets, see below. Description During December 2010, a prototype LWIR cloud camera system was deployed at the Southern Great Plains Guest Instrument Facility (SGP-GIF). The system consisted of a microbolometer camera (~7-15 ìm) to capture sky imagery, a blackbody calibration source, and a GPS receiver used to estimate atmospheric column water vapor and constrain atmospheric compensation. The camera system collected calibrated sky radiance images co-incident with the SGP Central Facility with the goal of quantitatively assessing its ability

309

Apparatus for accurately measuring high temperatures  

DOE Patents [OSTI]

The present invention is a thermometer used for measuring furnace temperaes in the range of about 1800.degree. to 2700.degree. C. The thermometer comprises a broadband multicolor thermal radiation sensor positioned to be in optical alignment with the end of a blackbody sight tube extending into the furnace. A valve-shutter arrangement is positioned between the radiation sensor and the sight tube and a chamber for containing a charge of high pressure gas is positioned between the valve-shutter arrangement and the radiation sensor. A momentary opening of the valve shutter arrangement allows a pulse of the high gas to purge the sight tube of air-borne thermal radiation contaminants which permits the radiation sensor to accurately measure the thermal radiation emanating from the end of the sight tube.

Smith, Douglas D. (Knoxville, TN)

1985-01-01T23:59:59.000Z

310

X-RAY OBSERVATIONS OF HIGH-B RADIO PULSARS  

SciTech Connect (OSTI)

The study of high-magnetic-field pulsars is important for examining the relationships between radio pulsars, magnetars, and X-ray-isolated neutron stars (XINSs). Here, we report on X-ray observations of three such high-magnetic-field radio pulsars. We first present the results of a deep XMM-Newton observation of PSR J1734-3333, taken to follow up on its initial detection in 2009. The pulsar's spectrum is well fit by a blackbody with a temperature of 300 {+-} 60 eV, with bolometric luminosity L{sub bb}=2.0{sub -0.7}{sup +2.2} Multiplication-Sign 10{sup 32} erg s{sup -1}{approx}0.0036 E-dot for a distance of 6.1 kpc. We detect no X-ray pulsations from the source, setting a 1{sigma} upper limit on the pulsed fraction of 60% in the 0.5-3 keV band. We compare PSR J1734-3333 to other rotation-powered pulsars of similar age and find that it is significantly hotter, supporting the hypothesis that the magnetic field affects the observed thermal properties of pulsars. We also report on XMM-Newton and Chandra observations of PSRs B1845-19 and J1001-5939. We do not detect either pulsar, setting 3{sigma} upper limits on their blackbody temperatures of 48 and 56 eV, respectively. Despite the similarities in rotational properties, these sources are significantly cooler than all but one of the XINSs, which we attribute to the two groups having been born with different magnetic fields and hence evolving differently.

Olausen, S. A.; Kaspi, V. M. [Department of Physics, Rutherford Physics Building, McGill University, 3600 University Street, Montreal, Quebec, H3A 2T8 (Canada)] [Department of Physics, Rutherford Physics Building, McGill University, 3600 University Street, Montreal, Quebec, H3A 2T8 (Canada); Zhu, W. W. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, V6T 1Z1 (Canada)] [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, V6T 1Z1 (Canada); Vogel, J. K. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States)] [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Lyne, A. G.; Espinoza, C. M.; Stappers, B. W. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)] [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Manchester, R. N. [Australia Telescope National Facility, CSIRO Astronomy and Space Science, Epping, NSW 1710 (Australia)] [Australia Telescope National Facility, CSIRO Astronomy and Space Science, Epping, NSW 1710 (Australia); McLaughlin, M. A. [Department of Physics, West Virginia University, White Hall, Morgantown, WV 26506 (United States)] [Department of Physics, West Virginia University, White Hall, Morgantown, WV 26506 (United States)

2013-02-10T23:59:59.000Z

311

The X-ray Position and Optical Counterpart of the Accretion-Powered Millisecond Pulsar XTE J1814-338  

E-Print Network [OSTI]

We report the precise optical and X-ray localization of the 3.2 ms accretion-powered X-ray pulsar XTE J1814-338 with data from the Chandra X-Ray Observatory as well as optical observations conducted during the 2003 June discovery outburst. Optical imaging of the field during the outburst of this soft X-ray transient reveals an R = 18 star at the X-ray position. This star is absent (R > 20) from an archival 1989 image of the field and brightened during the 2003 outburst, and we therefore identify it as the optical counterpart of XTE J1814-338. The best source position derived from optical astrometry is R.A. = 18h13m39.s04, Dec.= -33d46m22.3s (J2000). The featureless X-ray spectrum of the pulsar in outburst is best fit by an absorbed power-law (with photon index = 1.41 +- 0.06) plus blackbody (with kT = 0.95 +- 0.13 keV) model, where the blackbody component contributes approximately 10% of the source flux. The optical broad-band spectrum shows evidence for an excess of infrared emission with respect to an X-ray heated accretion disk model, suggesting a significant contribution from the secondary or from a synchrotron-emitting region. A follow-up observation performed when XTE J1814-338 was in quiescence reveals no counterpart to a limiting magnitude of R = 23.3. This suggests that the secondary is an M3 V or later-type star, and therefore very unlikely to be responsible for the soft excess, making synchroton emission a more reasonable candidate.

Miriam I. Krauss; Zhongxiang Wang; Allyn Dullighan; Adrienne M. Juett; David L. Kaplan; Deepto Chakrabarty; Marten H. van Kerkwijk; Danny Steeghs; Peter G. Jonker; Craig B. Markwardt

2005-03-30T23:59:59.000Z

312

CONSTRAINTS ON NEUTRON STAR MASS AND RADIUS IN GS 1826-24 FROM SUB-EDDINGTON X-RAY BURSTS  

SciTech Connect (OSTI)

We investigate the constraints on neutron star mass and radius in GS 1826-24 from models of light curves and spectral evolution of type I X-ray bursts. This source shows remarkable agreement with theoretical calculations of burst energies, recurrence times, and light curves. We first exploit this agreement to set the overall luminosity scale of the observed bursts. When combined with a measured blackbody normalization, this leads to a distance- and anisotropy-independent measurement of the ratio between the redshift 1 + z and color-correction factor f{sub c}. We find 1 + z = 1.19-1.28 for f{sub c} = 1.4-1.5. We then compare the evolution of the blackbody normalization with flux in the cooling tail of bursts with predictions from spectral models of Suleimanov et al. The observations are well described by the models at luminosities greater than about one-third of the peak luminosity, with deviations emerging at luminosities below that. We show that this comparison leads to distance-independent upper limits on R{sub {infinity}} and neutron star mass of R{sub {infinity}} {approx}< 9.0-13.2 km and M < 1.2-1.7 M{sub Sun }, respectively, for solar abundance of hydrogen at the photosphere and a range of metallicity and surface gravity. The radius limits are low in comparison to previous measurements. This may be indicative of a subsolar hydrogen fraction in the GS 1826-24 photosphere, or of larger color corrections than that predicted by spectral models. Our analysis also gives an upper limit on the distance to GS 1826-24 of d < 4.0-5.5 kpc {xi}{sup -1/2}{sub b}, where {xi}{sub b} is the degree of anisotropy of the burst emission.

Zamfir, Michael; Cumming, Andrew [Department of Physics, McGill University, 3600 rue University, Montreal, QC H3A 2T8 (Canada); Galloway, Duncan K., E-mail: mzamfir@physics.mcgill.ca, E-mail: cumming@physics.mcgill.ca, E-mail: Duncan.Galloway@monash.edu [Monash Centre for Astrophysics (MoCA), School of Physics, and School of Mathematical Sciences, Monash University, VIC 3800 (Australia)

2012-04-10T23:59:59.000Z

313

BER Science Network Requirements Workshop -- July 26-27,2007  

SciTech Connect (OSTI)

The Energy Sciences Network (ESnet) is the primary provider of network connectivity for the US Department of Energy Office of Science, the single largest supporter of basic research in the physical sciences in the United States of America. In support of the Office of Science programs, ESnet regularly updates and refreshes its understanding of the networking requirements of the instruments, facilities, scientists, and science programs that it serves. This focus has helped ESnet to be a highly successful enabler of scientific discovery for over 20 years. In July 2007, ESnet and the Biological and Environmental Research (BER) Program Office of the DOE Office of Science organized a workshop to characterize the networking requirements of the science programs funded by the BER Program Office. These included several large programs and facilities, including Atmospheric Radiation Measurement (ARM) Program and the ARM Climate Research Facility (ACRF), Bioinformatics and Life Sciences Programs, Climate Sciences Programs, the Environmental Molecular Sciences Laboratory at PNNL, the Joint Genome Institute (JGI). National Center for Atmospheric Research (NCAR) also participated in the workshop and contributed a section to this report due to the fact that a large distributed data repository for climate data will be established at NERSC, ORNL and NCAR, and this will have an effect on ESnet. Workshop participants were asked to codify their requirements in a 'case study' format, which summarizes the instruments and facilities necessary for the science and the process by which the science is done, with emphasis on the network services needed and the way in which the network is used. Participants were asked to consider three time scales in their case studies--the near term (immediately and up to 12 months in the future), the medium term (3-5 years in the future), and the long term (greater than 5 years in the future). In addition to achieving its goal of collecting and characterizing the network requirements of the science endeavors funded by the BER Program Office, the workshop emphasized some additional points. These included the need for a future ESnet presence in the Denver area, a desire for ESnet to continue support of collaboration services, and the need for ESnet to support dedicated bandwidth or 'virtual circuit' services. In addition, it is clear that the BER facilities are going to experience significant growth in data production over the next 5 years. The reasons for this vary (model resolution and supercomputer allocations for climate, detector upgrades for EMSL and ARM, sequencing hardware upgrades for JGI), but all indicators point to significant growth in data volumes over the near to medium term. This growth in data volume, combined with the ever-expanding scope of scientific collaboration, will continue to demand ever-increasing bandwidth, reliability and service richness from the networks that support DOE science.

Tierney, Brian L.; Dart, Eli

2008-02-01T23:59:59.000Z

314

Towards the development of high temperature comparison artifacts for radiation thermometry  

SciTech Connect (OSTI)

This paper describes the methodology and first results of the development of high temperature fixed point artifacts of unknown temperature suitable for scale comparison purposes. This study is being undertaken at the Thermal Metrology Division of Inmetro, Brazil, as part of PhD studies. In this initial phase of the study two identical cobalt carbon eutectic cells were constructed and one doped with a known amount of copper. This was an attempt to achieve a controlled change in the transition temperature of the alloy during melting. Copper was chosen due to the relatively simple phase diagram it forms with carbon and cobalt. The cobalt, in powder form, was supplied by Alfa Aesar at 99.998 % purity, and was mixed with carbon powder (1,9 % by weight) of 99.9999 % purity. Complete filling of the crucible took 6 steps and was performed in a vertical furnace with graphite heating elements, in an inert gas atmosphere. The temperature measurements were performed using a KE LP3 radiation thermometer, which was previously evaluated for spectral responsivity, linearity and size-of-source effect (SSE). During these measurements, the thermometer stability was periodically checked using a silver fixed point blackbody maintained in a three zone furnace. The main purpose of the first part of this study is to dope a series of Co-C blackbody with differing amounts of copper, in order to alter their temperatures whilst still retaining good melting plateau performance. The long-term stability of the adjusted transition temperatures will also be investigated. Other dopants will be studied as the research progresses, and thermo chemical modeling will be performed in an attempt to understand the change in temperature with dopant concentration and so help select suitable dopants in the future. The overall objective is to construct comparison artifacts that have good performance, in terms of plateau shape and long-term temperature stability, but with unknown temperatures. These can then be used as comparison artifacts with no participant, except the pilot, knowing the temperature a priori.

Teixeira, R. N. [Inmetro, Duque de Caxias, RJ (Brazil)] [Inmetro, Duque de Caxias, RJ (Brazil); Machin, G. [NPL, Teddington (United Kingdom)] [NPL, Teddington (United Kingdom); Orlando, A. [PUC-Rio, Rio de Janeiro, RJ (Brazil)] [PUC-Rio, Rio de Janeiro, RJ (Brazil)

2013-09-11T23:59:59.000Z

315

TIDAL DISRUPTION FLARES: THE ACCRETION DISK PHASE  

SciTech Connect (OSTI)

The evolution of an accretion disk, formed as a consequence of the disruption of a star by a black hole, is followed by solving numerically hydrodynamic equations. The present investigation aims to study the dependence of resulting light curves on dynamical and physical properties of such a transient disk during its existence. One of the main results derived from our simulations is that blackbody fits of X-ray data tend to overestimate the true mean disk temperature. In fact, the temperature derived from blackbody fits should be identified with the color X-ray temperature rather than the average value derived from the true temperature distribution along the disk. The time interval between the beginning of the circularization of the bound debris and the beginning of the accretion process by the black hole is determined by the viscous (or accretion) timescale, which also fixes the rising part of the resulting light curve. The luminosity peak coincides with the beginning of matter accretion by the black hole and the late evolution of the light curve depends on the evolution of the debris fallback rate. Peak bolometric luminosities are in the range 10{sup 45}-10{sup 46} erg s{sup -1}, whereas peak luminosities in soft X-rays (0.2-2.0 keV) are typically one order of magnitude lower. The typical timescale derived from our preferred models for the flare luminosity to decay by two orders of magnitude is about 3-4 yr. Predicted soft X-ray light curves reproduce quite well data on galaxies in which a variable X-ray emission possibly related to a tidal event was detected. In the cases of NGC 3599 and IC 3599, data are reproduced well by models defined by a black hole with mass {approx}10{sup 7} M{sub sun} and a disrupted star of about 1 solar mass. The X-ray variation observed in XMMSL1 is consistent with a model defined by a black hole with mass {approx}3 x 10{sup 6} M{sub sun} and a disrupted star of 1 solar mass, while that observed in the galaxy situated in the cluster A1689 is consistent with a model including a black hole of {approx}10{sup 7} M{sub sun} and a disrupted star of {approx}0.5 M{sub sun}.

Montesinos Armijo, Matias; De Freitas Pacheco, Jose A. [Observatoire de la Cote d'Azur, Laboratoire Cassiopee, Universite de Nice Sophia-Antipolis Bd de l'Observatoire, BP 4229, 06304 Nice Cedex 4 (France)

2011-08-01T23:59:59.000Z

316

NREL: Concentrating Solar Power Research Home Page  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

A collage of Concentrating Solar Power photographs. The first photo shows a dish-engine solar system. The second is of a SAIC Stirling dish collector. And the third photo shows a SkyTrough solar concentrator located on a mesa top. A collage of Concentrating Solar Power photographs. The first photo shows a dish-engine solar system. The second is of a SAIC Stirling dish collector. And the third photo shows a SkyTrough solar concentrator located on a mesa top. NREL collaborates with industry to further the research and development (R&D) of concentrating solar power (CSP) plant and solar thermal technologies. NREL's projects in concentrating solar power focus on components R&D and systems analysis related to power tower and parabolic trough technologies: Collectors Receivers Power block Thermal energy storage Analysis. In addition, NREL has received funding through the following competitively awarded projects: 10-megawatt supercritical carbon dioxide (s-CO2) turbine test Near-blackbody, enclosed-particle receiver integrated with a

317

Taking the Band Function Too Far: A Tale of Two $\\alpha$'s  

E-Print Network [OSTI]

The long standing problem of identifying the emission mechanism operating in gamma-ray bursts (GRBs) has produced a myriad of possible models that have the potential of explaining the observations. Generally, the empirical Band function is fit to the observed gamma-ray data and the fit parameters are used to infer which radiative mechanisms are at work in GRB outflows. In particular, the distribution of the Band function's low-energy power law index, $\\alpha$, has led to the so-called synchrotron "line-of-death" (LOD) which is a statement that the distribution cannot be explained by the simplest of synchrotron models alone. As an alternatively fitting model, a combination of a blackbody in addition to the Band function is used, which in many cases provide a better or equally good fit. It has been suggested that such fits would be able to alleviate the LOD problem for synchrotron emission in GRBs. However, these conclusions rely on the Band function's ability to fit a synchrotron spectrum within the observed e...

Burgess, J Michael; Yu, Hoi-Fung

2014-01-01T23:59:59.000Z

318

Doppler-free spectroscopy of the 1S0-3P0 optical clock transition in laser-cooled fermionic isotopes of neutral mercury  

E-Print Network [OSTI]

We have performed for the first time direct laser spectroscopy of the 1S0-3P0 optical clock transition at 265.6 nm in fermionic isotopes of neutral mercury laser-cooled in a magneto-optical trap. Spectroscopy is performed by measuring the depletion of the magneto-optical trap induced by the excitation of the long-lived 3P0 state by a probe at 265.6 nm. Measurements resolve the Doppler-free recoil doublet allowing for a determination of the transition frequency to an uncer- tainty well below the Doppler-broadened linewidth. We have performed absolute measurement of the frequency with respect to an ultra-stable reference monitored by LNE-SYRTE fountain pri- mary frequency standards using a femtosecond laser frequency comb. The measured frequency is 1128575290808 +/- 5.6 kHz in 199Hg and 1128569561140 +/- 5.3 kHz in 201Hg, more than 4 orders of magnitude better than previous indirect determinations. Owing to a low sensitivity to blackbody radiation, mercury is a promising candidate for reaching the ultimate performance of optical lattice clocks.

M. Petersen; R. Chicireanu; S. T. Dawkins; D. V. Magalhães; C. Mandache; Y. Lecoq; A. Clairon; S. Bize

2008-07-22T23:59:59.000Z

319

A double-frequency dwarf nova oscillation  

E-Print Network [OSTI]

We have detected coherent oscillations (``dwarf nova oscillations'') in Hubble Space Telescope spectra of the dwarf nova OY Car. The oscillations were seen towards the end of a superoutburst of OY Car. The oscillations are extraordinary compared to the many other examples in the literature for two reasons. First, their amplitude is large, with a peak-to-peak variation of 8 to 20% of the total flux over the range 1100 to 2500A. However, most remarkably we find that there are two components present simultaneously. Both have periods close to 18sec (equivalent to 4800 cycles/day) but they are separated by 57.7+/-0.5 cycles/day. The lower frequency component of the pair has a strong second harmonic while its companion, which has about twice its amplitude, does not. The oscillation spectra appear hotter than the mean spectrum and approximately follow the continuum distribution of a black-body with a temperature in the range 30,000 to 50,000K. We tentatively suggest that the weaker non-sinusoidal component could represent the rotation of the white dwarf, although we have been unable to recover any such signal in quiescent data.

T. R. Marsh; Keith Horne

1998-06-02T23:59:59.000Z

320

Multicolour observations of V404 Cyg with ULTRACAM  

E-Print Network [OSTI]

We present high time-resolution multicolour observations of the quiescent soft X-ray transient V404 Cyg obtained with ULTRACAM. Superimposed on the secondary star's ellipsoidal modulation are large flares on timescales of a few hours, as well as several distinct rapid flares on timescales of tens of mins. The rapid flares, most of which show further variability and unresolved peaks, cover shorter timescales than those reported in previous observations. The power density spectrum (PDS) of the 5 s time-resolution data shows a quasi-periodic oscillation (QPO) feature at 0.78 mHz (=21.5 min). Assuming this periodicity represents the Keplerian period at the transition between the thin and advective disc regions, we determine the transition radius. We discuss the possible origins for the QPO feature in the context of the advection-dominated accretion flow model. We determine the colour of the large flares and find that the i' band flux per unit frequency interval is larger than that in the g' band. The colour is consistent with optically thin gas with a temperature of ~8000 K arising from a region with an equivalent blackbody radius of at least 2 Ro, which covers 3 percent of the accretion disc's surface. Our timing and spectral analysis results support the idea that the rapid flares (i.e. the QPO feature) most likely arise from regions near the transition radius.

T. Shahbaz; V. S. Dhillon; T. R. Marsh; C. Zurita; C. A. Haswell; P. A. Charles; R. I. Hynes; J. Casares

2003-09-23T23:59:59.000Z

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321

The Complete Census of 70-um-Bright Debris Disks within the FEPS (Formation and Evolution of Planetary Systems) Spitzer Legacy Survey of Sun-like Stars  

E-Print Network [OSTI]

(abbreviated) We report detection with the Spitzer Space Telescope of cool dust surrounding solar type stars. The observations were performed as part of the Legacy Science Program, ``Formation and Evolution of Planetary Systems'' (FEPS). From the overall FEPS sample (Meyer et al. 2006) of 328 stars having ages ~0.003-3 Gyr we have selected sources with 70 um flux densities indicating excess in their spectral energy distributions above expected photospheric emission........ .....The rising spectral energy distributions towards - and perhaps beyond - 70 um imply dust temperatures T_dust temperature, location, fractional luminosity, and mass of the dust from fitted single temperature blackbody models. For >1/3 of the debris sources we find that multiple temperature components are suggested, implying a spatial distribution of dust extending over many tens of AU. Because the disks are dominated by collisional processes, the parent body (planetesimal) belts may be extended as well. Preliminary assessment of the statistics of cold debris around sun-like stars shows that ~10% of FEPS targets with masses between 0.6 and 1.8 Msun and ages between 30 Myr and 3 Gyr exhibit 70 um emission in excess of the expected photospheric flux density. We find that fractional excess amplitudes appear higher for younger stars and that there may be a trend in 70 um excess frequency with stellar mass.

Lynne A. Hillenbrand; John M. Carpenter; Jinyoung Serena Kim; Michael R. Meyer; Dana E. Backman; Amaya Moro-Martin; David J. Hollenbach; Dean C. Hines; Ilaria Pascucci; Jeroen Bouwman

2007-12-30T23:59:59.000Z

322

On the Robustness of Cool Disc Components in Bright ULXs  

E-Print Network [OSTI]

In this letter, we comment on the robustness of putative cool (kT ~ 0.2 keV) accretion disc components in the X-ray spectra of the most luminous (L ~ 10^40 erg/s) ultra-luminous X-ray sources (ULXs) in nearby normal galaxies. When compared to stellar-mass black holes, the low disc temperatures observed in some ULXs may imply intermediate-mass black hole primaries. Recent work has claimed that such soft excesses are unlikely to be actual disc components, based on the lack of variability in these components, and in the overall source flux. Other work has proposed that alternative phenomenological models, and complex Comptonisation models, rule-out cool disc components in ULX spectra. An inspection of the literature on Galactic stellar-mass black holes and black hole candidates demonstrates that the flux behaviours seen in specific ULXs are consistent with phenomena observed in well-known Galactic X-ray binaries. Applying Comptonisation models to simulated disc blackbody plus power-law spectra shows that at the sensitivity achieved in even the best ULX spectra, Comptonisation fits are highly model-dependent, and do not yield meaningful constraints on the accretion flow. In contrast, the need for a soft, thermal component does not appear to be model-dependent. As we have previously noted, soft thermal components in ULX spectra may not represent accretion discs, but present alternatives to this interpretation are not robust.

J. M. Miller; A. C. Fabian; M. C. Miller

2005-12-22T23:59:59.000Z

323

Apparatus and method for transient thermal infrared spectrometry of flowable enclosed materials  

DOE Patents [OSTI]

A method and apparatus for enabling analysis of a flowable material enclosed in a transport system having an infrared transparent wall portion. A temperature differential is transiently generated between a thin surface layer portion of the material and a lower or deeper portion of the material sufficient to alter the thermal infrared emission spectrum of the material from the black-body thermal infrared emission spectrum of the material, and the altered thermal infrared emission spectrum is detected through the infrared transparent portion of the transport system while the altered thermal infrared emission spectrum is sufficiently free of self-absorption by the material of emitted infrared radiation. The detection is effected prior to the temperature differential propagating into the lower or deeper portion of the material to an extent such that the altered thermal infrared emission spectrum is no longer sufficiently free of self-absorption by the material of emitted infrared radiation. By such detection, the detected altered thermal infrared emission spectrum is indicative of characteristics relating to molecular composition of the material.

McClelland, John F. (Ames, IA); Jones, Roger W. (Ames, IA)

1993-03-02T23:59:59.000Z

324

Gamma bursts from neutron stars and stellar flares  

Science Journals Connector (OSTI)

If gamma bursts are locally galactic then the implied fluxes from a localized region of a neutron star surface are closed to the blackbody limit even at the extreme temperatures (of the order of 109 degrees) inferred from gamma?burst spectra. One reasonable model is the accretion of an astroid or comet (Harwit and Salpeter 1973) onto a magnetized neutron star. What is frequently described as tidal disruption instead becomes gravitational compression. Matter landing on a neutron star releases a specific energy density of several times c2/10. This energy density is ample to give rise to the inferred temperatures of 108 to 109 degrees. However radiation stress greatly exceeds the gravitational stress even at the neutron star surface and a near instantaneous adiabatic expansion of the hot surface layers cools them and terminates the release of any high temperature radiation. The effective temperature of the radiation then becomes roughly the Eddington limit of 2×107 degrees. Only by the restraint of the free surface expansion by a strong magnetic field (several times 1012 gauss) can the high temperature emission take place. The radiation from such a constrained plasma is not yet understood. The cooling mechanism is analogous to the collapse phase of solar and stellar flares.

Stirling A. Colgate

1982-01-01T23:59:59.000Z

325

Hydrodynamic solutions for a sonoluminescing gas bubble  

Science Journals Connector (OSTI)

Analytic solutions for a sonoluminescing gas bubble have been obtained which provide density pressure and temperature distributions for the gas inside a bubble oscillating under the ultrasonic field. The solutions have revealed that sonoluminescence should occur just prior to the bubble collapse and its duration is less than 300 ps and that increase and subsequent decrease in the bubble wall acceleration induces the quenching of gas followed by the substantial temperature rise up to 100?000 K which can be regarded as a thermal spike. The gas temperature inside the bubble near collapse is determined primarily by the amount of radiation heat loss. Shock formation during the bubble collapse is questionable because gas density as well as pressure at the bubble center are much greater than those at the bubble wall during this stage. It also turns out that the number of electrons ionized the ion species and the kinetic energy of electrons affect the spectrum of light emission crucially. The spectralradiance calculated is in good agreement with the observed data qualitatively which suggests that the origin of sonoluminescences is bremsstrahlung rather than thermal blackbody radiation. [Work supported by Korea Science and Engineering Foundation.

Ho?Young Kwak; Jung?Hee Na

1996-01-01T23:59:59.000Z

326

SIMULTANEOUS X-RAY AND RADIO OBSERVATIONS OF ROTATING RADIO TRANSIENT J1819-1458  

SciTech Connect (OSTI)

We present the results of simultaneous radio and X-ray observations of PSR J1819–1458. Our 94 ks XMM-Newton observation of the high magnetic field (?5 × 10{sup 13} G) pulsar reveals a blackbody spectrum (kT ? 130 eV) with a broad absorption feature, possibly composed of two lines at ?1.0 and ?1.3 keV. We performed a correlation analysis of the X-ray photons with radio pulses detected in 16.2 hr of simultaneous observations at 1-2 GHz with the Green Bank, Effelsberg, and Parkes telescopes, respectively. Both the detected X-ray photons and radio pulses appear to be randomly distributed in time. We find tentative evidence for a correlation between the detected radio pulses and X-ray photons on timescales of less than 10 pulsar spin periods, with the probability of this occurring by chance being 0.46%. This suggests that the physical process producing the radio pulses may also heat the polar-cap.

Miller, J. J.; McLaughlin, M. A. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Rea, N. [Institut de Ciències de l'Espai (IEEC-CSIC) Campus UAB, Fac. de Ciències, Torre C5, parell, 2a planta, E-08193 Barcelona (Spain); Lazaridis, K.; Keane, E. F.; Kramer, M. [Max Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Lyne, A. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)

2013-10-20T23:59:59.000Z

327

ON THE X-RAY EMISSION MECHANISMS OF THE PERSISTENT SOURCE AND VERY LOW FLUENCE BURSTS OF SGR J0501+4516  

SciTech Connect (OSTI)

We present here a detailed spectral study of the X-ray emission of the persistent source and the low-fluence bursts of SGR J0501+4516 observed during a deep XMM-Newton observation near the peak of its 2008 outburst. For the persistent emission, we employ a physically motivated continuum emission model and spectroscopically determine important source properties such as the surface magnetic field strength and the magnetospheric scattering optical depth. We find that the magnetar surface temperature near the peak of its activity is 0.38 keV, corresponding to an emission area of 131 km{sup 2} at a distance of 2 kpc. The surface magnetic field strength determined spectroscopically, B = 2.2 Multiplication-Sign 10{sup 14} G, is consistent with the dipole field strength inferred from the source spin and spin-down rate. We fit the stacked spectra of 129 very faint bursts with a modified blackbody model and find a temperature of 1.16 keV, corresponding to an emission area of 93 km{sup 2}. We also find evidence for cooling during the burst decay phase.

Lin Lin; Goegues, Ersin; Guever, Tolga [Faculty of Engineering and Natural Sciences, Sabanc Latin-Small-Letter-Dotless-I University, Orhanl Latin-Small-Letter-Dotless-I -Tuzla, Istanbul 34956 (Turkey); Kouveliotou, Chryssa, E-mail: linlin@sabanciuniv.edu [Science and Technology Office, ZP12, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States)

2012-12-20T23:59:59.000Z

328

Long Term Spectral Evolution of Tidal Disruption Candidates Selected by Strong Coronal Lines  

E-Print Network [OSTI]

We present results of follow-up optical spectroscopic observations of seven rare, extreme coronal line emitting galaxies reported by Wang et al. (2012) with Multi-Mirror Telescope (MMT). Large variations in coronal lines are found in four objects, making them strong candidates of tidal disruption events (TDE). For the four TDE candidates, all the coronal lines with ionization status higher than [Fe VII] disappear within 5-9 years. The [Fe VII] faded by a factor of about five in one object (J0952+2143) within 4 years, whereas emerged in other two without them previously. A strong increment in the [O III] flux is observed, shifting the line ratios towards the loci of active galactic nucleus on the BPT diagrams. Surprisingly, we detect a non-canonical [O III]5007/[O III]4959 2 in two objects, indicating a large column density of O$^{2+}$ and thus probably optical thick gas. This also requires a very large ionization parameter and relatively soft ionizing spectral energy distribution (e.g. blackbody with $T < ...

Yang, Chenwei; Ferland, Gary; Yuan, Weimin; Zhou, Hongyan; Jiang, Peng

2013-01-01T23:59:59.000Z

329

V819 TAU: A RARE WEAK-LINED T TAURI STAR WITH A WEAK INFRARED EXCESS  

SciTech Connect (OSTI)

We use Spitzer data to infer that the small infrared excess of V819 Tau, a weak-lined T Tauri star in Taurus, is real and not attributable to a 'companion' 10'' to the south. We do not confirm the mid-infrared excess in HBC 427 and V410 X-ray 3, which are also non-accreting T Tauri stars in the same region; instead, for the former object, the excess arises from a red companion 9'' to the east. A single-temperature blackbody fit to the continuum excess of V819 Tau implies a dust temperature of 143 K; however, a better fit is achieved when the weak 10 and 20 mum silicate emission features are also included. We infer a disk of sub-mum silicate grains between about 1 AU and several 100 AU with a constant surface density distribution. The mid-infrared excess of V819 Tau can be successfully modeled with dust composed mostly of small amorphous olivine grains at a temperature of 85 K, and most of the excess emission is optically thin. The disk could still be primordial, but gas-poor and therefore short-lived, or already at the debris disk stage, which would make it one of the youngest debris disk systems known.

Furlan, E. [Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 264-767, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Forrest, W. J.; Manoj, P.; Kim, K. H.; Watson, Dan M. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); Sargent, B. A., E-mail: Elise.Furlan@jpl.nasa.go, E-mail: forrest@pas.rochester.ed, E-mail: manoj@pas.rochester.ed, E-mail: khkim@pas.rochester.ed, E-mail: dmw@pas.rochester.ed, E-mail: sargent@stsci.ed [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2009-12-01T23:59:59.000Z

330

XMM-Newton observes flaring in the polar UZ For during a low state  

E-Print Network [OSTI]

During an XMM-Newton observation, the eclipsing polar UZ For was found in a peculiar state with an extremely low X-ray luminosity and occasional X-ray and UV flaring. For most of the observation, UZ For was only barely detected in X-rays and about 800 times fainter than during a high state previously observed with ROSAT. A transient event, which lasted about 900 s, was detected simultaneously by the X-ray instruments and, in the UV, by the Optical Monitor. The transient was likely caused by the impact of 10^17-10^18 g of gas on the main accretion region of the white dwarf. The X-ray spectrum of the transient is consistent with 7 keV thermal bremsstrahlung from the shock-heated gas in the accretion column. A soft blackbody component due to reprocessing of X-rays in the white dwarf atmosphere is not seen. The likely origin of the UV emission during the transient is cyclotron radiation from the accretion column. We conclude from our analysis that the unusual flaring during the low state of UZ For was caused by intermittent increases of the mass transfer rate due to stellar activity on the secondary.

Dirk Pandel; France A. Cordova

2002-07-12T23:59:59.000Z

331

Is RX J185635-375 a Quark Star?  

E-Print Network [OSTI]

Deep Chandra LETG+HRC-S observations of the isolated neutron star candidate RX J1856.5-3754 have been analysed to search for metallic and resonance cyclotron spectral features and for pulsation behaviour. As found from earlier observations, the X-ray spectrum is well-represented by a ~ 60 eV (7e5 K) blackbody. No unequivocal evidence of spectral line or edge features has been found, arguing against metal-dominated models. The data contain no evidence for pulsation and we place a 99% confidence upper limit of 2.7% on the unaccelerated pulse fraction over a wide frequency range from 1e-4 to 100 Hz. We argue that the derived interstellar medium neutral hydrogen column density of 8e19 heated by accretion of interstellar matter would be expected is either entirely coincidental, or current theoretical arguments excluding this scenario for RX J1856.5-3754 are premature. Taken at face value, the combined observational evidence -- a lack of spectral and temporal features and an implied radius at infinity of 3.8-8.2 km that is too small for current neutron star models -- points to a more compact object, such as allowed for quark matter equations of state.

J. J. Drake; H. L. Marshall; S. Dreizler; P. E. Freeman; A. Fruscione; M. Juda; V. Kashyap; F. Nicastro; D. O. Pease; B. J. Wargelin; K. Werner

2002-04-09T23:59:59.000Z

332

Irradiated atmospheres of accreting magnetic white dwarfs with an application to the polar AM Herculis  

E-Print Network [OSTI]

We present a pilot study of atmospheres of accreting magnetic white dwarfs irradiated by intense fluxes at ultraviolet to infrared wavelengths. The model uses a standard LTE stellar atmosphere code which is expanded by introducing an angle-dependent external radiation source. The present results are obtained for an external source with the spectral shape of a 10000K blackbody and a freely adjustable spectral flux. The model provides an explanation for the observed largely filled-up Lyman lines in the prototype polar AM Herculis during its high states. It also confirms the hypotheses (i) that irradiation by cyclotron radiation and other radiation sources is the principle cause for the large heated polar caps surrounding the accretion spots on white dwarfs in polars and (ii) that much of the reprocessed light appears in the far ultraviolet and not in the soft X-ray regime as suggested in the original simple theories. We also briefly discuss the role played by hard X-rays in heating the polar cap.

M. Koenig; K. Beuermann; B. T. Gaensicke

2005-12-22T23:59:59.000Z

333

Revisit emission spectrum and entropy quantum of the Reissner-Nordström black hole  

E-Print Network [OSTI]

Banerjee and Majhi's recent work shows that black hole's emission spectrum could be fully reproduced in the tunneling picture, where, as an intriguing technique, the Kruskal extension was introduced to connect the left and right modes inside and outside the horizon. Some attempt, as an extension, was focused on producing the Hawking emission spectrum of the (charged) Reissner-Nordstr\\"{o}m black hole in the Banerjee-Majhi's treatment. Unfortunately, the Kruskal extension in their observation was so badly defined that the ingoing mode was classically forbidden traveling towards the center of black hole, but could quantum tunnel across the horizon with the probability $\\Gamma=e^{-\\pi \\omega_0/\\kappa_+}$. This tunneling picture is unphysical. With this point as a central motivation, in this paper we first introduce such a suitable Kruskal extension for the (charged) Reissner-Nordstr\\"{o}m black hole that a perfect tunneling picture can be provided during the charged particle's emission. Then, under the new Kruskal extension, we revisit the Hawking emission spectrum and entropy spectroscopy as tunneling from the charged black hole. The result shows that the tunneling method is so universally robust that the Hawking blackbody emission spectrum from a charged black hole can be well reproduced in the tunneling mechanism, and its induced entropy quantum is a much better approximation for the forthcoming quantum gravity theory.

Qing-Quan Jiang

2012-10-15T23:59:59.000Z

334

Quantum Optomechanical Heat Engine  

E-Print Network [OSTI]

We investigate theoretically a quantum optomechanical realization of a heat engine. In a generic optomechanical arrangement the optomechanical coupling between the cavity field and the oscillating end-mirror results in polariton normal mode excitations whose character depends on the pump detuning and the coupling strength. By varying that detuning it is possible to transform their character from phonon-like to photon-like, so that they are predominantly coupled to the thermal reservoir of phonons or photons, respectively. We exploit the fact that the effective temperatures of these two reservoirs are different to produce a Otto cycle along one of the polariton branches. We discuss the basic properties of the system in two different regimes: in the optical domain it is possible to extract work from the thermal energy of a mechanical resonator at finite temperature, while in the microwave range one can in principle exploit the cycle to extract work from the blackbody radiation background coupled to an ultra-cold atomic ensemble.

Keye Zhang; Francesco Bariani; Pierre Meystre

2014-04-17T23:59:59.000Z

335

Swift X-ray and ultraviolet observations of the shortest orbital period double-degenerate system RX J0806.3+1527 (HM Cnc)  

E-Print Network [OSTI]

RX J0806.3+1527 (HM Cnc) is a pulsating X-ray source with 100 per cent modulation on a period of 321.5 s (5.4 min). This period reflects the orbital motion of a close binary system consisting of two interacting white dwarfs. Here we present a series of simultaneous X-ray (0.2-10 keV) and near-ultraviolet (2600 angstrom and 1928 angstrom) observations carried out with the Swift satellite. In the near-ultraviolet the counterpart of RX J0806.3+1527 was detected at flux densities consistent with a blackbody with temperature 27E+3 K. We found that the emission at 2600 angstrom is modulated at the 321.5-s period, with the peak ahead of the X-ray one by 0.28 cycles and coincident, within 0.05 cycles, with the optical. This phase-shift measurement confirms that the X-ray hot spot (located on the primary white dwarf) is at about 80-100 degrees from the direction connecting the two white dwarfs. Albeit at lower significance, the 321.5-s signature is present also in the 1928-angstrom data; at this wavelength, however, t...

Esposito, P; Dall'Osso, S; Covino, S

2013-01-01T23:59:59.000Z

336

Extreme temperature robust optical sensor designs and fault-tolerant signal processing  

DOE Patents [OSTI]

Silicon Carbide (SiC) probe designs for extreme temperature and pressure sensing uses a single crystal SiC optical chip encased in a sintered SiC material probe. The SiC chip may be protected for high temperature only use or exposed for both temperature and pressure sensing. Hybrid signal processing techniques allow fault-tolerant extreme temperature sensing. Wavelength peak-to-peak (or null-to-null) collective spectrum spread measurement to detect wavelength peak/null shift measurement forms a coarse-fine temperature measurement using broadband spectrum monitoring. The SiC probe frontend acts as a stable emissivity Black-body radiator and monitoring the shift in radiation spectrum enables a pyrometer. This application combines all-SiC pyrometry with thick SiC etalon laser interferometry within a free-spectral range to form a coarse-fine temperature measurement sensor. RF notch filtering techniques improve the sensitivity of the temperature measurement where fine spectral shift or spectrum measurements are needed to deduce temperature.

Riza, Nabeel Agha (Oviedo, FL); Perez, Frank (Tujunga, CA)

2012-01-17T23:59:59.000Z

337

Decay of the Cosmic Vacuum Energy  

E-Print Network [OSTI]

Energy-momentum conservation suggests that a vacuum in thermal equilibrium with a bath of radiation during inflation should gradually diminish the vacuum energy. We find that coupling to a bath of black-body radiation at temperature $T=H/2 \\pi$ requires the Hubble rate, $H$, to evolve as in the "intermediate inflation" scenario, with $H \\propto t^{-1/3}$, rather than as a constant. Such behaviour does not conflict with observations when the vacuum energy is described by a slowly-rolling scalar field, but will change the asymptotic states of the universe. We find that this scenario introduces a curvature singularity at early times. The scale factor takes a finite non-zero value at this singularity, while the energy densities in radiation and the vacuum diverge to positive and negative infinity, respectively. This shows that inflation is possible even when the energy density of the vacuum is large and negative. Furthermore, the introduction of an additional non-interacting perfect fluid into the space-time reve...

Clifton, Timothy

2014-01-01T23:59:59.000Z

338

XMM-NEWTON FINDS THAT SAX J1750.8-2900 MAY HARBOR THE HOTTEST, MOST LUMINOUS KNOWN NEUTRON STAR  

SciTech Connect (OSTI)

We have performed the first sensitive X-ray observation of the low-mass X-ray binary (LMXB) SAX J1750.8-2900 in quiescence with XMM-Newton. The spectrum was fit to both a classical blackbody model, and a non-magnetized, pure hydrogen neutron star (NS) atmosphere model. A power-law component was added to these models, but we found that it was not required by the fits. The distance to SAX J1750.8-2900 is known to be D = 6.79 kpc from a previous analysis of photospheric radius expansion bursts. This distance implies a bolometric luminosity (as given by the NS atmosphere model) of (1.05 {+-} 0.12) Multiplication-Sign 10{sup 34} (D/6.79 kpc){sup 2} erg s{sup -1}, which is the highest known luminosity for a NS LMXB in quiescence. One simple explanation for this surprising result could be that the crust and core of the NS were not in thermal equilibrium during the observation. We argue that this was likely not the case, and that the core temperature of the NS in SAX J1750.8-2900 is unusually high.

Lowell, A. W.; Tomsick, J. A.; Bodaghee, A.; Boggs, S. E. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States); Heinke, C. O. [Department of Physics, University of Alberta, Room 238 CEB, Edmonton, AB T6G 2G7 (Canada); Kaaret, P. [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Chaty, S.; Rodriguez, J. [AIM-Astrophysique Instrumentation Modelisation (UMR 7158 CEA/CNRS/Universite Paris 7 Denis Diderot), CEA Saclay, DSM/IRFU/Service d'Astrophysique, Bat. 709, L'Orme des Merisiers, FR-91 191 Gif-sur-Yvette Cedex (France); Walter, R., E-mail: alowell@ssl.berkeley.edu [INTEGRAL Science Data Centre, Observatoire de Geneve, Universite de Geneve, Chemin d'Ecogia, 16, 1290 Versoix (Switzerland)

2012-04-20T23:59:59.000Z

339

Shock break-out: how a GRB revealed the beginnings of a supernova  

E-Print Network [OSTI]

In February 2006, Swift caught a GRB in the act of turning into a supernova, and made the first ever direct observations of the break-out and early expansion of a supernova shock wave. GRB 060218 began with an exceptionally long burst of non-thermal gamma-rays, lasting over 2000 s, as a jet erupted through the surface of the star. While this was in progress, an optically-thick thermal component from the shock wave of the supernova explosion grew to prominence, and we were able to track the mildly relativistic expansion of this shell as the blackbody peak moved from the X-rays into the UV and optical bands. The initial radius of the shock implied that it was a blue supergiant which had exploded, but the lack of Hydrogen emission lines in the supernova spectrum indicated a more compact star. The most likely scenario is that the shock ploughed into the massive stellar wind of a Wolf-Rayet progenitor, with the shock breaking out and becoming visible to us once it reached the radius where the wind became optically-thin. I present the Swift observations of this landmark event, and discuss the new questions and answers it leaves us with.

A. J. Blustin

2007-01-29T23:59:59.000Z

340

The width of gamma-ray burst spectra  

E-Print Network [OSTI]

The emission processes active in the highly relativistic jets of gamma-ray bursts (GRBs) remain unknown. In this paper we propose a new measure to describe spectra: the width of the $EF_E$ spectrum, a quantity dependent only on finding a good fit to the data. We apply this to the full sample of GRBs observed by Fermi/GBM and CGRO/BATSE. The results from the two instruments are fully consistent. We find that the median widths of spectra from long and short GRBs are significantly different (chance probability $<10^{-6}$). The width does not correlate with either duration or hardness, and this is thus a new, independent distinction between the two classes. Comparing the measured spectra with widths of spectra from fundamental emission processes -- synchrotron and blackbody radiation -- the results indicate that a large fraction of GRB spectra are too narrow to be explained by synchrotron radiation from a distribution of electron energies: for example, 78% of long GRBs and 85% of short GRBs are incompatible wi...

Axelsson, Magnus

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "acrf pyrgeometer blackbody" from the National Library of EnergyBeta (NLEBeta).
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341

A Hybrid Design of Project-X  

E-Print Network [OSTI]

Project-X is a leading candidate of the next major accelerator construction project at Fermilab. The mission need of Project-X is to establish an intensity frontier for particle physics research, or more precisely, to build a multi-MW proton source for neutrino and other particle studies. Coupled with an upgraded Main Injector (MI) and Recycler, an 8 GeV superconducting RF (SRF) H-minus linac meets this need [1]. However, a more cost effective approach would be a hybrid design, namely, a combination of a 2 GeV SRF linac and an 8 GeV rapid cycling synchrotron (RCS) in lieu of an 8 GeV SRF linac. This alternative design also meets the mission need but at a lower cost since a synchrotron is cheaper than a SRF linac. It retains the ability to use a 2 GeV SRF linac for ILC technology development. It reuses the existing Debuncher enclosure and Booster RF. The transport line of 2 GeV H-minus particles is shorter than the present 8 GeV design since stronger bending magnets can be used. The blackbody radiation strippi...

Chou, W

2009-01-01T23:59:59.000Z

342

High Resolution Spectroscopy of 4U 1728-34 from a Simultaneous Chandra-RXTE Observation  

E-Print Network [OSTI]

We report on a simultaneous Chandra and RossiXTE observation of the LMXB atoll bursting source 4U 1728-34 performed on 2002 March 3-5. We fitted the 1.2-35 keV continuum spectrum with a blackbody plus a Comptonized component. An overabundance of Si by a factor of ~2 with respect to Solar abundance is required for a satisfactory fit. Large residuals at 6-10 keV can be fitted by a broad (FWHM ~ 1.6 keV) Gaussian emission line, or, alternatively, by absorption edges associated with Fe I and Fe XXV at ~7.1 keV and ~9 keV, respectively. In this interpretation, we find no evidence of a broad, or narrow Fe Kalpha line, between 6 and 7 keV. We tested our alternative modeling of the iron Kalpha region by reanalyzing a previous BeppoSAX observation of 4U 1728-34, finding a general agreement with our new spectral model.

A. D'Ai'; T. Di Salvo; R. Iaria; G. Lavagetto; N. R. Robba; L. Burderi; M. Mendez; M. van der Klis

2004-11-10T23:59:59.000Z

343

Millihertz QPOs and broad iron line from LMC X-1  

E-Print Network [OSTI]

We study the temporal and energy spectral characteristics of the persistent black hole X-ray binary LMC X-1 using two XMM-Newton and a Suzaku observation. We report the discovery of low frequency (~ 26-29 mHz) quasi-periodic oscillations (QPOs). We also report the variablity of the broad iron K-alpha line studied earlier with Suzaku. The QPOs are found to be weak with fractional rms amplitude in the ~ 1-2 % range and quality factor Q~2-10 . They are accompanied by weak red noise or zero-centered Lorentzian components with rms variability at the ~ 1-3 % level. The energy spectra consists of three varying components - multicolour disk blackbody (kT_{in} ~ 0.7-0.9 keV), high energy power-law tail (Gamma ~ 2.4 - 3.3) and a broad iron line at 6.4-6.9 keV. The broad iron line, the QPO and the strong power-law component are not always present. The QPOs and the broad iron line appear to be clearly detected in the presence of a strong power-law component. The broad iron line is found to be weaker when the disk is like...

Alam, Md Shah; Belloni, T; Mukherjee, D; Jhingan, S

2014-01-01T23:59:59.000Z

344

Archeops: A CMB anisotropy balloon experiment measuring a broad range of angular scales  

E-Print Network [OSTI]

The Cosmic Microwave Background Radiation is the oldest photon radiation that can be observed, having been emitted when the Universe was about 300,000 year old. It is a blackbody at 2.73 K, and is almost perfectly isotropic, the anisotropies being about one part to 100,000. However, these anisotropies, detected by the COBE satellite in 1992, constrain the cosmological parameters such as the curvature of the Universe. Archeops is a balloon-borne experiment designed to map these anisotropies. The instrument is composed of a 1.5 m telescope and bolometers cooled at 85 mK to detect radiation between 150 and 550 GHz. To lower parasitic signals, the instrument is borne by a stratospheric balloon during the arctic night. This instrument is also a preparation for the Planck satellite mission, as its design is similar to HFI. We discuss here the results of the first scientific flight from Esrange (near Kiruna, Sweden) to Russia on January 29th 2001, which led to a 22 % (sub)millimetre sky coverage unprecedented at this resolution. Here, we put some emphasis on interstellar dust foreground emission observations.

F. -Xavier Desert; the Archeops Collaboration

2001-12-01T23:59:59.000Z

345

Archeops: A balloon experiment to measure CMB anisotropies with a broad range of angular sizes  

E-Print Network [OSTI]

The Cosmic Microwave Background Radiation is the oldest photon radiation that can be observed, having been emitted when the Universe was about 300,000 year old. It is a blackbody at 2.73 K, and is almost perfectly isotropic, the anisotropies being about one part to 100,000. However, these anisotropies, detected by the COBE satellite in 1992, constrain the cosmological parameters such as the curvature of the Universe. Archeops is a balloon-borne experiment designed to map these anisotropies. The instrument is composed of a 1.5 m telescope and bolometers cooled at 85 mK to detect radiation between 150 and 550 GHz. To lower atmosphere parasitic signal, the instrument is lifted at 32 km altitude with a stratospheric balloon during the arctic night. This instrument is also a preparation for the Planck satellite mission, as its design is similar. We discuss here the results of the first scientific flight from Esrange (near Kiruna, Sweden) to Russia on January 29th 2001, which led to a 22 % (sub)millimetre sky coverage unprecedented at this resolution.

A. Benoit; the Archeops Collaboration

2001-12-01T23:59:59.000Z

346

Thermal and Bulk Comptonization in Accretion-powered X-Ray Pulsars  

Science Journals Connector (OSTI)

We develop a new theoretical model for the spectral formation process in accretion-powered X-ray pulsars based on a detailed treatment of the bulk and thermal Comptonization occurring in the accreting, shocked gas. A rigorous eigenfunction expansion method is employed to obtain the analytical solution for the Green's function describing the scattering of radiation injected into the column from a monochromatic source located at an arbitrary height above the stellar surface. The emergent spectrum is calculated by convolving the Green's function with source terms corresponding to bremsstrahlung, cyclotron, and blackbody emission. The energization of the photons in the shock, combined with cyclotron absorption, naturally produces an X-ray spectrum with a relatively flat continuum shape and a high-energy quasi-exponential cutoff. We demonstrate that the new theory successfully reproduces the phase-averaged spectra of the bright pulsars Her X-1, LMC X-4, and Cen X-3. In these luminous sources, it is shown that the emergent spectra are dominated by Comptonized bremsstrahlung emission.

Peter A. Becker; Michael T. Wolff

2007-01-01T23:59:59.000Z

347

Stars and statistical physics: A teaching experience  

Science Journals Connector (OSTI)

The physics of stars their workings and their evolution is a goldmine of problems in statistical mechanics and thermodynamics. We discuss many examples that illustrate the possibility of deepening student’s knowledge of statistical mechanics by an introductory study of stars. The matter constituting the various stellar objects provides examples of equations of state for classical or quantal and relativistic or non-relativistic gases. Maximum entropy can be used to characterize thermodynamic and gravitational equilibrium which determines the structure of stars and predicts their instability above a certain mass. Contraction accompanying radiation induces either heating or cooling which explains the formation of stars above a minimum mass. The characteristics of the emitted light are understood from blackbody radiation and more precisely from the Boltzmann–Lorentz kinetic equation for photons. The luminosity is governed by the transport of heat by photons from the center to the surface. Heat production by thermonuclear fusion is determined by microscopic balance equations. The stability of the steady state of stars is controlled by the interplay of thermodynamics and gravitation.

Roger Balian; Jean-Paul Blaizot

1999-01-01T23:59:59.000Z

348

Numerical models of black body dominated GRBs: II. Emission properties  

E-Print Network [OSTI]

We extend an existing theoretical model to explain the class of Black-Body Dominated (BBD) gamma-ray bursts (GRBs), long lasting events characterized by the presence of a significant thermal component trailing the GRB prompt emission, and also by an absence of a traditional afterglow. GRB 101225A, the Christmas Burst, is a prototype of such class. It has been suggested that BBD-GRBs could be observed after a merger in a binary system consisting of a neutron star and a Helium core of a main sequence star. Using detailed relativistic hydrodynamic numerical simulations we model the propagation of ultrarelativistic jets through the environments created by such mergers. In this paper we focus on explaining the emission properties of the jet evolution computing the whole radiative signature (both thermal and non-thermal) of the jet dynamical evolution. A comprehensive parameter study of the jet/environment interaction has been performed and synthetic spectra and light curves are compared with the observational data...

Cuesta-Martínez, Carlos F; Mimica, Petar; Thöne, Christina C; de Ugarte-Postigo, Antonio

2014-01-01T23:59:59.000Z

349

Measurements of Conversion Efficiency for a Flat Plate Thermophotovoltaic System Using a Photonic Cavity Test System  

SciTech Connect (OSTI)

The performance of a 1 cm{sup 2} thermophotovoltaic (TPV) module was recently measured in a photonic cavity test system. A conversion efficiency of 11.7% was measured at a radiator temperature of 1076 C and a module temperature of 29.9 C. This experiment achieved the highest direct measurement of efficiency for an integrated TPV system. Efficiency was calculated from the ratio of the peak (load matched) electrical power output and the heat absorption rate. Measurements of these two parameters were made simultaneously to assure the validity of the measured efficiency value. This test was conducted in a photonic cavity which mimicked a typical flat-plate TPV system. The radiator was a large, flat graphite surface. The module was affixed to the top of a copper pedestal for heat absorption measurements. The heat absorption rate was proportional to the axial temperature gradient in the pedestal under steady-state conditions. The test was run in a vacuum to eliminate conductive and convective heat transfer mechanisms. The photonic cavity provides the optimal test environment for TPV efficiency measurements because it incorporates all important physical phenomena found in an integrated TPV system: high radiator emissivity and blackbody spectral shape, photon recycling, Lambertian distribution of incident radiation and complex geometric effects. Furthermore, the large aspect ratio between radiating surface area and radiator/module spacing produces a view factor approaching unity with minimal photon leakage.

E.J. Brown; C.T. Ballinger; S.R. Burger; G.W. Charache; L.R. Danielson; D.M. DePoy; T.J. Donovan; M. LoCascio

2000-05-30T23:59:59.000Z

350

Radiation in molecular dynamic simulations  

SciTech Connect (OSTI)

Hot dense radiative (HDR) plasmas common to Inertial Confinement Fusion (ICF) and stellar interiors have high temperature (a few hundred eV to tens of keV), high density (tens to hundreds of g/cc) and high pressure (hundreds of Megabars to thousands of Gigabars). Typically, such plasmas undergo collisional, radiative, atomic and possibly thermonuclear processes. In order to describe HDR plasmas, computational physicists in ICF and astrophysics use atomic-scale microphysical models implemented in various simulation codes. Experimental validation of the models used to describe HDR plasmas are difficult to perform. Direct Numerical Simulation (DNS) of the many-body interactions of plasmas is a promising approach to model validation but, previous work either relies on the collisionless approximation or ignores radiation. We present a new numerical simulation technique to address a currently unsolved problem: the extension of molecular dynamics to collisional plasmas including emission and absorption of radiation. The new technique passes a key test: it relaxes to a blackbody spectrum for a plasma in local thermodynamic equilibrium. This new tool also provides a method for assessing the accuracy of energy and momentum exchange models in hot dense plasmas. As an example, we simulate the evolution of non-equilibrium electron, ion, and radiation temperatures for a hydrogen plasma using the new molecular dynamics simulation capability.

Glosli, J; Graziani, F; More, R; Murillo, M; Streitz, F; Surh, M

2008-10-13T23:59:59.000Z

351

RADIATIVE HEATING OF THE SOLAR CORONA  

SciTech Connect (OSTI)

We investigate the effect of solar visible and infrared radiation on electrons in the Sun's atmosphere using a Monte Carlo simulation of the wave-particle interaction and conclude that sunlight provides at least 40% and possibly all of the power required to heat the corona, with the exception of dense magnetic flux loops. The simulation uses a radiation waveform comprising 100 frequency components spanning the solar blackbody spectrum. Coronal electrons are heated in a stochastic manner by low coherence solar electromagnetic radiation. The wave 'coherence time' and 'coherence volume' for each component is determined from optical theory. The low coherence of solar radiation allows moving electrons to gain energy from the chaotic wave field which imparts multiple random velocity 'kicks' to these particles causing their velocity distribution to broaden or heat. Monte Carlo simulations of broadband solar radiative heating on ensembles of 1000 electrons show heating at per particle levels of 4.0 x 10{sup -21} to 4.0 x 10{sup -20} W, as compared with non-loop radiative loss rates of {approx}1 x 10{sup -20} W per electron. Since radiative losses comprise nearly all of the power losses in the corona, sunlight alone can explain the elevated temperatures in this region. The volume electron heating rate is proportional to density, and protons are assumed to be heated either by plasma waves or through collisions with electrons.

Moran, Thomas G., E-mail: moran@grace.nascom.nasa.gov [Physics Department, Catholic University of America, 200 Hannan Hall, Washington, DC 20064 (United States) and NASA/GSFC, Code 671, Greenbelt, MD 20771 (United States)

2011-10-20T23:59:59.000Z

352

A Fundamental, Relativistic and Irreversible Law of Motion: A Unification of Newton's Second Law of Motion and the Second Law of Thermodynamics  

E-Print Network [OSTI]

Temperature is an outsider in the laws of motion given by Newton and Einstein and this oversight is the source of the predictions of time-reversal-invariance made by these two great systems of motion. By taking into consideration Planck's law of blackbody radiation and the Doppler effect, in thinking about Maxwell's electromagnetic wave equation, I have shown that photons, in the environment through which any charged particle moves, act as a source of temperature-dependent friction on everything from elementary particles to galaxies. Because the optomechanical friction is universal and inevitable, no real systems are conservative, and temperature can no longer be an outsider in a fundamental and irreducible law of motion. I have defined the change of entropy (\\Delta S) in irreversible systems at constant temperature in terms of the optomechanical friction. The Second Law of Thermodynamics, which states that \\Delta S > 0 for spontaneous processes, is explained by electromagnetic interactions between charged particles and the Doppler-shifted photons through which they move as opposed to chance and statistics. \\Delta S, as defined here, is not subject to Poincar\\'e's recurrence theorem. Consequently, the Second Law of Thermodynamics is shown to be a fundamental law rather than a statistical law. This result, which supports the idea that every instant of time is unique, is consistent with intuition and the routine experience of botanists.

Randy Wayne

2012-05-22T23:59:59.000Z

353

X-Raying an Accretion Disk in Realtime: the Evolution of Ionized Reflection during a Superburst from 4U 1636-536  

E-Print Network [OSTI]

When a thermonuclear X-ray burst ignites on an accreting neutron star, the accretion disk undergoes sudden strong X-ray illumination, which can drive a range of processes in the disk. Observations of superbursts, with durations of several hours, provide the best opportunity to study these processes and to probe accretion physics. Using detailed models of ionized reflection, we perform time resolved spectroscopy of the superburst observed from 4U 1636-536 in 2001 with RXTE. The spectra are consistent with a blackbody reflecting off a photoionized accretion disk, with the ionization state dropping with time. The evolution of the reflection fraction indicates that the initial reflection occurs from a part of the disk at larger radius, subsequently transitioning to reflection from an inner region of the disk. Even though this superburst did not reach the Eddington limit, we find that a strong local absorber develops during the superburst. Including this event, only two superbursts have been observed by an instrum...

Keek, L; Kuulkers, E; Strohmayer, T E

2014-01-01T23:59:59.000Z

354

Soft x-ray images of the laser entrance hole of ignition hohlraums  

SciTech Connect (OSTI)

Hohlraums are employed at the national ignition facility to convert laser energy into a thermal x-radiation drive, which implodes a fusion capsule, thus compressing the fuel. The x-radiation drive is measured with a low spectral resolution, time-resolved x-ray spectrometer, which views the region around the hohlraum's laser entrance hole. This measurement has no spatial resolution. To convert this to the drive inside the hohlraum, the size of the hohlraum's opening ('clear aperture') and fraction of the measured x-radiation, which comes from this opening, must be known. The size of the clear aperture is measured with the time integrated static x-ray imager (SXI). A soft x-ray imaging channel has been added to the SXI to measure the fraction of x-radiation emitted from inside the clear aperture. A multilayer mirror plus filter selects an x-ray band centered at 870 eV, near the peak of the x-ray spectrum of a 300 eV blackbody. Results from this channel and corrections to the x-radiation drive are discussed.

Schneider, M. B.; Meezan, N. B.; Alvarez, S. S.; Alameda, J.; Baker, S.; Bell, P. M.; Bradley, D. K.; Callahan, D. A.; Celeste, J. R.; Dewald, E. L.; Dixit, S. N.; Doeppner, T.; Eder, D. C.; Edwards, M. J.; Fernandez-Perea, M.; Hau-Riege, S.; Hsing, W.; Izumi, N.; Jones, O. S.; Kalantar, D. H. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); and others

2012-10-15T23:59:59.000Z

355

On the temperature profile of radiatively efficient geometrically thin disks in black hole binaries with the ASCA GIS  

E-Print Network [OSTI]

X-ray spectra of black hole binaries(BHBs) in the high/soft state were studied comprehensively by using ASCA GIS data, and partially RXTE PCA data. A mathematical disk model was applied to several BHBs to see if the observed accretion disk temperature profile was consistent with that expected from the standard accretion disk model. This model is called p-free disk, and assumes that the spectrum is composed of multi-temperature blackbody emission of which the local temperature T(r) at radius r is given by T(r) ~ r^-p with p being a positive free parameter. The standard disk roughly requires p~3/4, while a small deviation is expected depending on the inner boundary conditions, general relativistic effects and disk vertical structures.Our sample objects included LMC X-1, LMC X-3, XTE J2012+381, and GRO J1655-40. During the ASCA observations, these BHBs showed characteristics of the standard high/soft state. Under the standard modeling of high-state black hole binaries, the sources show Tin=0.76-1.17keV, the disk...

Kubota, A; Makishima, K; Nakazawa, K; Kubota, Aya; Ebisawa, Ken; Makishima, Kazuo; Nakazawa, Kazuhiro

2005-01-01T23:59:59.000Z

356

Importance of Compton scattering for radiation spectra of isolated neutron stars with weak magnetic fields  

E-Print Network [OSTI]

Emergent model spectra of neutron star atmospheres are widely used to fit the observed soft X-ray spectra of different types of isolated neutron stars. We investigate the effect of Compton scattering on the emergent spectra of hot (T_eff > 10^6 K) isolated neutron stars with weak magnetic fields. In order to compute model atmospheres in hydrostatic and radiative equilibrium we solve the radiation transfer equation with the Kompaneets operator. We calculate a set of models with effective temperatures in the range 1 - 5 * 10^6 K, with two values of surface gravity (log g = 13.9 and 14.3) and different chemical compositions. Radiation spectra computed with Compton scattering are softer than those computed without Compton scattering at high energies (E > 5 keV) for light elements (H or He) model atmospheres. The Compton effect is more significant in H model atmospheres and models with low surface gravity. The emergent spectra of the hottest (T_eff > 3 * 10^6 K) model atmospheres can be described by diluted blackbody spectra with hardness factors ~ 1.6 - 1.9. Compton scattering is less important in models with solar abundance of heavy elements.

V. Suleimanov; K. Werner

2007-02-15T23:59:59.000Z

357

Resonant Cyclotron Scattering and Comptonization in Neutron Star Magnetospheres  

E-Print Network [OSTI]

Resonant cyclotron scattering of the surface radiation in the magnetospheres of neutron stars may considerably modify the emergent spectra and impede efforts to constraint neutron star properties. Resonant cyclotron scattering by a non-relativistic warm plasma in an inhomogeneous magnetic field has a number of unusual characteristics: (i) in the limit of high resonant optical depth, the cyclotron resonant layer is half opaque, in sharp contrast to the case of non-resonant scattering. (ii) The transmitted flux is on average Compton up-scattered by ~ $1+ 2 beta_T$, where $\\beta_T$ is the typical thermal velocity in units of the velocity of light; the reflected flux has on average the initial frequency. (iii) For both the transmitted and reflected fluxes the dispersion of intensity decreases with increasing optical depth. (iv) The emergent spectrum is appreciably non-Plankian while narrow spectral features produced at the surface may be erased. We derive semi-analytically modification of the surface Plankian emission due to multiple scattering between the resonant layers and apply the model to anomalous X-ray pulsar 1E 1048.1--5937. Our simple model fits just as well as the ``canonical'' magnetar spectra model of a blackbody plus power-law.

Maxim Lyutikov; Fotis P. Gavriil

2005-07-22T23:59:59.000Z

358

Statistical mechanics of Bose gas in Sierpinski carpets  

E-Print Network [OSTI]

We carry out a mathematically rigorous investigation into the equilibrium thermodynamics of massless and massive bosons confined in generalized Sierpinski carpets (GSCs), a class of infinitely ramified fractals having non-integer Hausdorff dimensions $d_h$. Due to the anomalous walk dimension $d_w>2$ associated with Brownian motion on GSCs, all extensive thermodynamic quantities are shown to scale with the spectral volume with dimension $d_s = 2(d_h/d_w)$ rather than the Hausdorff volume. We prove that for a low-temperature, high-density ideal massive Bose gas in an unbounded GSC, Bose-Einstein condensation occurs if and only if $d_s>2$, or equivalently, if the Brownian motion on the GSC is transient. We also derive explicit expressions for the energy of blackbody radiation in a GSC, as well as the Casimir pressure on the parallel plate of a fractal waveguide modelled after a GSC. Our proofs involve extensive use of the spectral zeta function, obtained via a sharp estimate of the heat kernel trace. We believe that our results can be verified through photonic and cold atomic experiments on fractal structures.

Joe P. Chen

2012-02-06T23:59:59.000Z

359

The influence of accretion geometry on the spectral evolution during thermonuclear (type-I) X-ray bursts  

E-Print Network [OSTI]

Neutron star (NS) masses and radii can be estimated from observations of photospheric radius-expansion X-ray bursts, provided the chemical composition of the photosphere, the spectral colour-correction factors in the observed luminosity range, and the emission area during the bursts are known. By analysing 246 X-ray bursts observed by the Rossi X-ray Timing Explorer from 11 low-mass X-ray binaries, we find a dependence between the persistent spectral properties and the time evolution of the black body normalisation during the bursts. All NS atmosphere models predict that the colour-correction factor decreases in the early cooling phase when the luminosity first drops below the limiting Eddington value, leading to a characteristic pattern of variability in the measured blackbody normalisation. However, the model predictions agree with the observations for most bursts occurring in hard, low-luminosity, 'island' spectral states, but rarely during soft, high-luminosity, 'banana' states. The observed behaviour may...

Kajava, Jari J E; Latvala, Outi-Marja; Pursiainen, Miika; Poutanen, Juri; Suleimanov, Valery F; Revnivtsev, Mikhail G; Kuulkers, Erik; Galloway, Duncan K

2014-01-01T23:59:59.000Z

360

A grid of synthetic ionizing spectra for very hot compact stars from NLTE model atmospheres  

E-Print Network [OSTI]

The precise analysis of properties of planetary nebulae is strongly dependent on good models for the stellar ionizing spectrum. Observations in the UV - X-ray wavelength range as well as NLTE model atmosphere calculations of spectra of their exciting stars have shown that neither blackbody fluxes nor "standard" NLTE atmosphere models which are composed out of hydrogen and helium only are good approximations. Strong differences between synthetic spectra from these compared to observed spectra at energies higher than 54 eV (He II ground state) can be ascribed to the neglect of metal-line blanketing. Realistic modeling of the emergent fluxes of hot stars in the UV - X-ray wavelength range requires metal-line blanketed NLTE model atmospheres which include all elements from hydrogen up to the iron-group. For this purpose, we present a grid (solar and halo abundance ratios) of metal-line blanketed NLTE model atmosphere fluxes which covers the parameter range of central stars of planetary nebulae.

Thomas Rauch

2003-03-20T23:59:59.000Z

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361

Non-LTE modeling of supernova-fallback disks  

E-Print Network [OSTI]

We present a first detailed spectrum synthesis calculation of a supernova-fallback disk composed of iron. We assume a geometrically thin disk with a radial structure described by the classical alpha-disk model. The disk is represented by concentric rings radiating as plane-parallel slabs. The vertical structure and emission spectrum of each ring is computed in a fully self-consistent manner by solving the structure equations simultaneously with the radiation transfer equations under non-LTE conditions. We describe the properties of a specific disk model and discuss various effects on the emergent UV/optical spectrum. We find that strong iron-line blanketing causes broad absorption features over the whole spectral range. Limb darkening changes the spectral distribution up to a factor of four depending on the inclination angle. Consequently, such differences also occur between a blackbody spectrum and our model. The overall spectral shape is independent of the exact chemical composition as long as iron is the dominant species. A pure iron composition cannot be distinguished from silicon-burning ash. Non-LTE effects are small and restricted to few spectral features.

K. Werner; T. Nagel; T. Rauch

2006-08-24T23:59:59.000Z

362

Extreme Environment Silicon Carbide Hybrid Temperature & Pressure Optical Sensors  

SciTech Connect (OSTI)

This final report contains the main results from a 3-year program to further investigate the merits of SiC-based hybrid sensor designs for extreme environment measurements in gas turbines. The study is divided in three parts. Part 1 studies the material properties of SiC such as temporal response, refractive index change with temperature, and material thermal response reversibility. Sensor data from a combustion rig-test using this SiC sensor technology is analyzed and a robust distributed sensor network design is proposed. Part 2 of the study focuses on introducing redundancy in the sensor signal processing to provide improved temperature measurement robustness. In this regard, two distinct measurement methods emerge. A first method uses laser wavelength sensitivity of the SiC refractive index behavior and a second method that engages the Black-Body (BB) radiation of the SiC package. Part 3 of the program investigates a new way to measure pressure via a distance measurement technique that applies to hot objects including corrosive fluids.

Nabeel Riza

2010-09-01T23:59:59.000Z

363

MULTIWAVELENGTH OBSERVATIONS OF A0620-00 IN QUIESCENCE  

SciTech Connect (OSTI)

We present contemporaneous X-ray, ultraviolet, optical, near-infrared, and radio observations of the black hole binary system, A0620-00, acquired in 2010 March. Using the Cosmic Origins Spectrograph on the Hubble Space Telescope, we have obtained the first FUV spectrum of A0620-00 as well as NUV observations with the Space Telescope Imaging Spectrograph. The observed spectrum is flat in the FUV and very faint (with continuum fluxes {approx_equal} 1e - 17 erg cm{sup -2} s{sup -1} A{sup -1}). The UV spectra also show strong, broad (FWHM {approx} 2000 km s{sup -1}) emission lines of Si IV, C IV, He II, Fe II, and Mg II. The C IV doublet is anomalously weak compared to the other lines, which is consistent with the low carbon abundance seen in NIR spectra of the source. Comparison of these observations with previous NUV spectra of A0620-00 shows that the UV flux has varied by factors of 2-8 over several years. We compiled the dereddened, broadband spectral energy distribution (SED) of A0620-00 and compared it to previous SEDs as well as theoretical models. The SEDs show that the source varies at all wavelengths for which we have multiple samples. Contrary to previous observations, the optical-UV spectrum does not continue to drop to shorter wavelengths, but instead shows a recovery and an increasingly blue spectrum in the FUV. We created an optical-UV spectrum of A0620-00 with the donor star contribution removed. The non-stellar spectrum peaks at {approx_equal}3000 A. The peak can be fit with a T = 10,000 K blackbody with a small emitting area, probably originating in the hot spot where the accretion stream impacts the outer disk. However, one or more components in addition to the blackbody are needed to fit the FUV upturn and the red optical fluxes in the optical-UV spectrum. By comparing the mass accretion rate determined from the hot spot luminosity to the mean accretion rate inferred from the outburst history, we find that the latter is an order of magnitude smaller than the former, indicating that {approx}90% of the accreted mass must be lost from the system if the predictions of the disk instability model and the estimated interoutburst interval are correct. The mass accretion rate at the hot spot is 10{sup 5} the accretion rate at the black hole inferred from the X-ray luminosity. To reconcile these requires that outflows carry away virtually all of the accreted mass, a very low rate of mass transfer from the outer cold disk into the inner hot region, and/or radiatively inefficient accretion. We compared our broadband SED to two models of A0620-00 in quiescence: the advection-dominated accretion flow model and the maximally jet-dominated model. The comparison suggests that strong outflows may be present in the system, indicated by the discrepancies in accretion rates and the FUV upturn in flux in the SED.

Froning, Cynthia S.; France, Kevin; Khargharia, Juthika [Center for Astrophysics and Space Astronomy, University of Colorado, 593 UCB, Boulder, CO 80309-0593 (United States); and others

2011-12-10T23:59:59.000Z

364

Thermal links for the implementation of an optical refrigerator  

SciTech Connect (OSTI)

Optical refrigeration has been demonstrated by several groups of researchers, but the cooling elements have not been thermally linked to realistic heat loads in ways that achieve the desired temperatures. The ideal thermal link will have minimal surface area, provide complete optical isolation for the load, and possess high thermal conductivity. We have designed thermal links that minimize the absorption of fluoresced photons by the heat load using multiple mirrors and geometric shapes including a hemisphere, a kinked waveguide, and a tapered waveguide. While total link performance is dependent on additional factors, we have observed net transmission of photons with the tapered link as low as 0.04%. Our optical tests have been performed with a surrogate source that operates at 625 nm and mimics the angular distribution of light emitted from the cooling element of the Los Alamos solid state optical refrigerator. We have confirmed the optical performance of our various link geometries with computer simulations using CODE V optical modeling software. In addition we have used the thermal modeling tool in COMSOL MULTIPHYSICS to investigate other heating factors that affect the thermal performance of the optical refrigerator. Assuming an ideal cooling element and a nonabsorptive dielectric trapping mirror, the three dominant heating factors are (1) absorption of fluoresced photons transmitted through the thermal link, (2) blackbody radiation from the surrounding environment, and (3) conductive heat transfer through mechanical supports. Modeling results show that a 1 cm{sup 3} load can be chilled to 107 K with a 100 W pump laser. We have used the simulated steady-state cooling temperatures of the heat load to compare link designs and system configurations.

Epsteiin, Richard I [Los Alamos National Laboratory; Greenfield, Scott R [Los Alamos National Laboratory; Parker, John [HARVEY MUDD COLLEGE; Mar, David [HARVEY MUDD GOLLEGE; Von Der Porten, Steven [HARVEY MUDD COLLEGE; Hankinson, John [HARVEY MUDD COLLEGE; Byram, Kevin [HARVEY MUDD COLLEGE; Lee, Chris [HARVEY MUDD COLLEGE; Mayeda, Kai [HARVEY MUDD COLLEGE; Haskell, Richard [HARVEY MUDD COLLEGE; Yang, Qimin [HARVEY MUDD COLLEGE

2008-01-01T23:59:59.000Z

365

A HERSCHEL AND APEX CENSUS OF THE REDDEST SOURCES IN ORION: SEARCHING FOR THE YOUNGEST PROTOSTARS  

SciTech Connect (OSTI)

We perform a census of the reddest, and potentially youngest, protostars in the Orion molecular clouds using data obtained with the PACS instrument on board the Herschel Space Observatory and the LABOCA and SABOCA instruments on APEX as part of the Herschel Orion Protostar Survey (HOPS). A total of 55 new protostar candidates are detected at 70 {mu}m and 160 {mu}m that are either too faint (m{sub 24} > 7 mag) to be reliably classified as protostars or undetected in the Spitzer/MIPS 24 {mu}m band. We find that the 11 reddest protostar candidates with log {lambda}F{sub {lambda}}70/{lambda}F{sub {lambda}}24 > 1.65 are free of contamination and can thus be reliably explained as protostars. The remaining 44 sources have less extreme 70/24 colors, fainter 70 {mu}m fluxes, and higher levels of contamination. Taking the previously known sample of Spitzer protostars and the new sample together, we find 18 sources that have log {lambda}F{sub {lambda}}70/{lambda}F{sub {lambda}}24 > 1.65; we name these sources 'PACS Bright Red sources', or PBRs. Our analysis reveals that the PBR sample is composed of Class 0 like sources characterized by very red spectral energy distributions (SEDs; T{sub bol} < 45 K) and large values of sub-millimeter fluxes (L{sub smm}/L{sub bol} > 0.6%). Modified blackbody fits to the SEDs provide lower limits to the envelope masses of 0.2-2 M{sub Sun} and luminosities of 0.7-10 L{sub Sun }. Based on these properties, and a comparison of the SEDs with radiative transfer models of protostars, we conclude that the PBRs are most likely extreme Class 0 objects distinguished by higher than typical envelope densities and hence, high mass infall rates.

Stutz, Amelia M.; Robitaille, Thomas; Henning, Thomas; Krause, Oliver [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany)] [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Tobin, John J. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)] [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Stanke, Thomas [ESO, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Muenchen (Germany)] [ESO, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Muenchen (Germany); Megeath, S. Thomas; Fischer, William J. [Department of Physics and Astronomy, University of Toledo, 2801 W. Bancroft Street, Toledo, OH 43606 (United States)] [Department of Physics and Astronomy, University of Toledo, 2801 W. Bancroft Street, Toledo, OH 43606 (United States); Ali, Babar; Furlan, Elise [NHSC/IPAC/Caltech, 770 S. Wilson Avenue, Pasadena, CA 91125 (United States)] [NHSC/IPAC/Caltech, 770 S. Wilson Avenue, Pasadena, CA 91125 (United States); Di Francesco, James [National Research Council of Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)] [National Research Council of Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Hartmann, Lee [Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States)] [Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); Osorio, Mayra [Instituto de Astrofisica de Andalucia, CSIC, Camino Bajo de Huetor 50, E-18008 Granada (Spain)] [Instituto de Astrofisica de Andalucia, CSIC, Camino Bajo de Huetor 50, E-18008 Granada (Spain); Wilson, Thomas L. [Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States)] [Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Allen, Lori [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)] [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Manoj, P., E-mail: stutz@mpia.de [Department of Physics and Astronomy, 500 Wilson Boulevard, University of Rochester, Rochester, NY 14627 (United States)

2013-04-10T23:59:59.000Z

366

A CENSUS OF AM CVn STARS: THREE NEW CANDIDATES AND ONE CONFIRMED 48.3-MINUTE BINARY  

SciTech Connect (OSTI)

We present three new candidate AM CVn binaries, and one confirmed new system, from a spectroscopic survey of color-selected objects from the Sloan Digital Sky Survey (SDSS). All four systems were found from their helium emission lines in low-resolution spectra taken on the Hale telescope at Palomar, the Nordic Optical Telescope, and the William Herschel Telescope on La Palma. The ultra-compact binary nature of SDSS J090221.35+381941.9 was confirmed using phase-resolved spectroscopy at the Keck-I telescope. From the characteristic radial velocity 'S-wave' observed in the helium emission lines, we measure an orbital period of 48.31 +- 0.08 minutes. The continuum emission can be described with a blackbody or a helium white dwarf atmosphere of T{sub eff} approx 15,000 K, in agreement with theoretical cooling models for relatively massive accretors and/or donors. The absence in the spectrum of broad helium absorption lines from the accreting white dwarf suggests that the accreting white dwarf cannot be much hotter than 15,000 K, or that an additional component such as the accretion disk contributes substantially to the optical flux. Two of the candidate systems, SDSS J152509.57+360054.5 and SDSS J172102.48+273301.2, do show helium absorption in the blue part of their spectra in addition to the characteristic helium emission lines. This in combination with the high effective temperatures of approx18,000 K and approx16,000 K suggests both to be at orbital periods below approx40 minutes. The third candidate, SDSS J164228.06+193410.0, exhibits remarkably strong helium emission on top of a relatively cool (T{sub eff} approx 12,000 K) continuum, indicating an orbital period above approx50 minutes.

Rau, A. [Max-Planck Institute for Extraterrestrial Physics, Giessenbachstr. 1, Garching 85748 (Germany); Roelofs, G. H. A.; Steeghs, D. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Groot, P. J.; Nelemans, G. [Department of Astrophysics, IMAPP, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen (Netherlands); Marsh, T. R. [Department of Physics, University of Warwick, Coventry CV4 7Al (United Kingdom); Salvato, M.; Kasliwal, M. M., E-mail: arau@mpe.mpg.d [Caltech Optical Observatories, MS 105-24, California Institute of Technology, Pasadena, CA 91125 (United States)

2010-01-01T23:59:59.000Z

367

G048.66-0.29: PHYSICAL STATE OF AN ISOLATED SITE OF MASSIVE STAR FORMATION  

SciTech Connect (OSTI)

We present continuum observations of the infrared dark cloud (IRDC) G48.66-0.22 (G48) obtained with Herschel, Spitzer, and APEX, in addition to several molecular line observations. The Herschel maps are used to derive temperature and column density maps of G48 using a model based on a modified blackbody. We find that G48 has a relatively simple structure and is relatively isolated; thus, this IRDC provides an excellent target to study the collapse and fragmentation of a filamentary structure in the absence of complicating factors such as strong external feedback. The derived temperature structure of G48 is clearly non-isothermal from cloud to core scale. The column density peaks are spatially coincident with the lowest temperatures ({approx}17.5 K) in G48. A total cloud mass of {approx}390 M{sub Sun} is derived from the column density maps. By comparing the luminosity-to-mass ratio of 13 point sources detected in the Herschel/PACS bands to evolutionary models, we find that two cores are likely to evolve into high-mass stars (M{sub *} {>=} 8 M{sub Sun }). The derived mean projected separation of point sources is smaller than in other IRDCs but in good agreement with theoretical predications for cylindrical collapse. We detect several molecular species such as CO, HCO{sup +}, HCN, HNC, and N{sub 2}H{sup +}. CO is depleted by a factor of {approx}3.5 compared to the expected interstellar abundance, from which we conclude that CO freezes out in the central region. Furthermore, the molecular clumps, associated with the submillimeter peaks in G48, appear to be gravitationally unbound or just pressure confined. The analysis of critical line masses in G48 shows that the entire filament is collapsing, overcoming any internal support.

Pitann, J.; Linz, H.; Ragan, S.; Stutz, A. M.; Beuther, H.; Henning, Th.; Krause, O.; Launhardt, R.; Tackenberg, J. [Max-Planck-Institut fuer Astronomie (MPIA), Koenigstuhl 17, D-69117 Heidelberg (Germany)] [Max-Planck-Institut fuer Astronomie (MPIA), Koenigstuhl 17, D-69117 Heidelberg (Germany); Schmiedeke, A. [Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany)] [Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); Schuller, F. [Max-Planck-Institut fuer Radioastronomie (MPIfR), Auf dem Huegel 69, D-53121 Bonn (Germany)] [Max-Planck-Institut fuer Radioastronomie (MPIfR), Auf dem Huegel 69, D-53121 Bonn (Germany); Vasyunina, T., E-mail: pitann@mpia.de [Department of Chemistry, University of Virginia, Charlottesville, VA 22904 (United States)

2013-04-01T23:59:59.000Z

368

Raman spectroscopic studies of chemical speciation in calcium chloride melts  

SciTech Connect (OSTI)

Raman spectroscopy was applied to CaCl2 melts at 900 degrees C under both non-electrolyzed and electrolyzed conditions. The later used titania cathodes supplied by TIMET, Inc. and graphite anodes. Use of pulse-gating to collect the Raman spectra successfully eliminated any interference from black-body radiation and other stray light. The spectrum of molten CaCl2 exhibited no distinct, resolvable bands that could be correlated with a calcium chloride complex similar to MgCl42- in MgCl2 melts. Rather, the low frequency region of the spectrum was dominated by a broad “tail” arising from collective oscillations of both charge and mass in the molten salt “network.” Additions of both CaO and Ca at concentrations of a percent or two resulted in no new features in the spectra. Addition of CO2, both chemically and via electrolysis at concentrations dictated by stability and solubility at 900 degrees C and 1 bar pressure, also produced no new bands that could be correlated with either dissolved CO2 or the carbonate ion. These results indicated that Raman spectroscopy, at least under the conditions evaluated in the research, was not well suited for following the reactions and coordination chemistry of calcium ions, nor species such as dissolved metallic Ca and CO2 that are suspected to impact current efficiency in titanium electrolysis cells using molten CaCl2. Raman spectra of TIMET titania electrodes were successfully obtained as a function of temperature up to 900 degrees C, both in air and in-situ in CaCl2 melts. However, spectra of these electrodes could only be obtained when the material was in the unreduced state. When reduced, either with hydrogen or within an electrolysis cell, the resulting electrodes exhibited no measurable Raman bands under the conditions used in this work.

Windisch, Charles F.; Lavender, Curt A.

2005-02-01T23:59:59.000Z

369

EXTENDED TAILS FROM SGR 1806-20 BURSTS  

SciTech Connect (OSTI)

In 2004, SGR 1806-20 underwent a period of intense and long-lasting burst activity that included the giant flare of 2004 December 27-the most intense extra-solar transient event ever detected at Earth. During this active episode, we routinely monitored the source with Rossi X-ray Timing Explorer and occasionally with Chandra. During the course of these observations, we identified two relatively bright bursts observed with Konus-Wind in hard X-rays that were followed by extended X-ray tails or afterglows lasting hundreds to thousands of seconds. Here, we present detailed spectral and temporal analysis of these events observed about 6 and 1.5 months prior to the 2004 December 27 giant flare. We find that both X-ray tails are consistent with a cooling blackbody of constant radius. These spectral results are qualitatively similar to those of the burst afterglows recorded from SGR 1900+14 and recently from SGR 1550-5418. However, the latter two sources exhibit significant increase in their pulsed X-ray intensity following the burst, while we did not detect any significant changes in the rms pulsed amplitude during the SGR 1806-20 events. Moreover, we find that the fraction of energy partitioned to the burst (prompt energy release) and the tail (afterglow) differs by an order of magnitude between SGR 1900+14 and SGR 1806-20. We suggest that such differences can be attributed to differences in the crustal heating mechanism of these neutron stars combined with the geometry of the emitting areas.

Goegues, Ersin; Kaneko, Yuki [Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli-Tuzla, Istanbul 34956 (Turkey); Woods, Peter M. [Corvid Technologies, 689 Discovery Drive, Huntsville, AL 35806 (United States); Kouveliotou, Chryssa [Space Science Office, VP-62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Finger, Mark H. [Universities Space Research Association, 6767 Old Madison Pike, Huntsville, AL 35805 (United States); Pal'shin, Valentin; Golenetskii, Sergey; Frederiks, Dmitry [Ioffe Physical-Technical Institute of the Russian Academy of Sciences, 26 Polytekhnicheskaya, St Petersburg 194021 (Russian Federation); Airhart, Carol, E-mail: ersing@sabanciuniv.edu [Dynetics Inc., 1000 Explorer Boulevard, Huntsville, AL 35806 (United States)

2011-10-20T23:59:59.000Z

370

Atmospheres and Spectra of Strongly Magnetized Neutron Stars II: Effect of Vacuum Polarization  

E-Print Network [OSTI]

We study the effect of vacuum polarization on the atmosphere structure and radiation spectra of neutron stars with surface magnetic fields B=10^14-10^15 G, as appropriate for magnetars. Vacuum polarization modifies the dielectric property of the medium and gives rise to a resonance feature in the opacity; this feature is narrow and occurs at a photon energy that depends on the plasma density. Vacuum polarization can also induce resonant conversion of photon modes via a mechanism analogous to the MSW mechanism for neutrino oscillation. We construct atmosphere models in radiative equilibrium with an effective temperature of a few \\times 10^6 K by solving the full radiative transfer equations for both polarization modes in a fully ionized hydrogen plasma. We discuss the subtleties in treating the vacuum polarization effects in the atmosphere models and present approximate solutions to the radiative transfer problem which bracket the true answer. We show from both analytic considerations and numerical calculations that vacuum polarization produces a broad depression in the X-ray flux at high energies (a few keV \\la E \\la a few tens of keV) as compared to models without vacuum polarization; this arises from the density dependence of the vacuum resonance feature and the large density gradient present in the atmosphere. Thus the vacuum polarization effect softens the high energy tail of the thermal spectrum, although the atmospheric emission is still harder than the blackbody spectrum because of the non-grey opacities. We also show that the depression of continuum flux strongly suppresses the equivalent width of the ion cyclotron line and therefore makes the line more difficult to observe.

Wynn C. G. Ho; Dong Lai

2002-01-22T23:59:59.000Z

371

On Synthesis of the Big Bang Model with Freundlich's Redshift and its Cosmological Consequences  

E-Print Network [OSTI]

We derive exact theoretical value of the constant cosmic background radiation (CBR) temperature $T_0$ using the interconnections between the Gamow, Alpher and Herman (GAH) hot Big Bang cosmology model of the expanding Universe and the modified Freundlich redshift. As a result of this confluence an astonishing relationship between $T_0$ and the four fundamental physical constants $c$,$\\hbar$,$k$,$G$ is found including also the Melvin's value of the Freundlich constant $A_s$.Then the resulting predicted the CBR temperature is $T_0=2.76626 K$. This prediction show excellent agreement with the data obtained from ground-based and balloon-borne observations and also with a mean of the perfect black-body spectrum CMB temperature $2.725 K$ measured COBE in 1992. Using a new cosmological model we determine the horizon scale, age and mass of the present observable Universe. The calculations based on discrete redshift equations for the electromagnetic, electroweak phases and Planck epoch of the Universe predicts a graviton and string masses, which are originated beyond on Planck time. The predicted graviton mass $m_Gr$ is about five orders of magnitude less than the present "the best possible upper bounds on the mass of the graviton", which may be "discovered" in the proposed LISA observations. We present quantitative new results for the different quantum-cosmological parameters. Finally, it is showed that the mystery largeness and smallness dimensionless combination of the Quantum Cosmological constant $\\Lambda_0$ and Planck length $l_Pl$ may be derived as their ratio from the Trans-Planck redshift relation. Thus is found the meaning a famous largeness cosmological number $c^3/\\hbarG\\Lambda_0=2.8*10^{125}$ that is inverse of $\\Lambda_0 l_Pl^2=3.6*10^{-126}$, and "which in 1930s was a regarded as a major problem by Eddington and Dirac".

Asger G. Gasanalizade

2010-09-24T23:59:59.000Z

372

TOWARD IDENTIFYING THE UNASSOCIATED GAMMA-RAY SOURCE 1FGL J1311.7-3429 WITH X-RAY AND OPTICAL OBSERVATIONS  

SciTech Connect (OSTI)

We present deep optical and X-ray follow-up observations of the bright unassociated Fermi-LAT gamma-ray source 1FGL J1311.7-3429. The source was already known as an unidentified EGRET source (3EG J1314-3431, EGR J1314-3417), hence its nature has remained uncertain for the past two decades. For the putative counterpart, we detected a quasi-sinusoidal optical modulation of {Delta}m {approx} 2 mag with a period of {approx_equal}1.5 hr in the Rc, r', and g' bands. Moreover, we found that the amplitude of the modulation and peak intensity changed by {approx}>1 mag and {approx}0.5 mag, respectively, over our total six nights of observations from 2012 March to May. Combined with Swift UVOT data, the optical-UV spectrum is consistent with a blackbody temperature, kT {approx_equal} 1 eV and the emission volume radius R{sub bb} {approx_equal} 1.5 Multiplication-Sign 10{sup 4} d{sub kpc} km (d{sub kpc} is the distance to the source in units of 1 kpc). In contrast, deep Suzaku observations conducted in 2009 and 2011 revealed strong X-ray flares with a light curve characterized with a power spectrum density of P(f) {proportional_to} f {sup -2.0{+-}0.4}, but the folded X-ray light curves suggest an orbital modulation also in X-rays. Together with the non-detection of a radio counterpart, and significant curved spectrum and non-detection of variability in gamma-rays, the source may be the second 'radio-quiet' gamma-ray emitting millisecond pulsar candidate after 1FGL J2339.7-0531, although the origin of flaring X-ray and optical variability remains an open question.

Kataoka, J.; Takahashi, Y.; Maeda, K. [Research Institute for Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555 (Japan); Yatsu, Y.; Kawai, N. [Tokyo Institute of Technology, 2-12-1, Ohokayama, Meguro, Tokyo 152-8551 (Japan); Urata, Y.; Tsai, A. [Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan (China); Cheung, C. C. [National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001 (United States); Totani, T.; Makiya, R. [Department of Astronomy, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto 606-8502 (Japan); Hanayama, H.; Miyaji, T., E-mail: kataoka.jun@waseda.jp [Ishigakijima Astronomical Observatory, National Astronomical Observatory of Japan, 1024-1 Arakawa, Ishigaki, Okinawa, 907-0024 (Japan)

2012-10-01T23:59:59.000Z

373

SGR J1550-5418 BURSTS DETECTED WITH THE FERMI GAMMA-RAY BURST MONITOR DURING ITS MOST PROLIFIC ACTIVITY  

SciTech Connect (OSTI)

We have performed detailed temporal and time-integrated spectral analysis of 286 bursts from SGR J1550-5418 detected with the Fermi Gamma-ray Burst Monitor (GBM) in 2009 January, resulting in the largest uniform sample of temporal and spectral properties of SGR J1550-5418 bursts. We have used the combination of broadband and high time-resolution data provided with GBM to perform statistical studies for the source properties. We determine the durations, emission times, duty cycles, and rise times for all bursts, and find that they are typical of SGR bursts. We explore various models in our spectral analysis, and conclude that the spectra of SGR J1550-5418 bursts in the 8-200 keV band are equally well described by optically thin thermal bremsstrahlung (OTTB), a power law (PL) with an exponential cutoff (Comptonized model), and two blackbody (BB) functions (BB+BB). In the spectral fits with the Comptonized model, we find a mean PL index of -0.92, close to the OTTB index of -1. We show that there is an anti-correlation between the Comptonized E{sub peak} and the burst fluence and average flux. For the BB+BB fits, we find that the fluences and emission areas of the two BB functions are correlated. The low-temperature BB has an emission area comparable to the neutron star surface area, independent of the temperature, while the high-temperature BB has a much smaller area and shows an anti-correlation between emission area and temperature. We compare the properties of these bursts with bursts observed from other SGR sources during extreme activations, and discuss the implications of our results in the context of magnetar burst models.

Van der Horst, A. J.; Finger, M. H. [Universities Space Research Association, NSSTC, Huntsville, AL 35805 (United States); Kouveliotou, C. [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Gorgone, N. M. [Connecticut College, New London, CT 06320 (United States); Kaneko, Y.; Goegues, E.; Lin, L. [Sabanc Latin-Small-Letter-Dotless-I University, Orhanl Latin-Small-Letter-Dotless-I -Tuzla, Istanbul 34956 (Turkey); Baring, M. G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Guiriec, S.; Bhat, P. N.; Chaplin, V. L.; Goldstein, A. [University of Alabama, Huntsville, CSPAR, Huntsville, AL 35805 (United States); Granot, J. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Watts, A. L. [Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Bissaldi, E.; Gruber, D. [Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, Postfach 1312, 85748 Garching (Germany); Gehrels, N.; Harding, A. K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Gibby, M. H.; Giles, M. M., E-mail: A.J.VanDerHorst@uva.nl [Jacobs Technology, Inc., Huntsville, AL (United States); and others

2012-04-20T23:59:59.000Z

374

A LINGERING NON-THERMAL COMPONENT IN THE GAMMA-RAY BURST PROMPT EMISSION: PREDICTING GeV EMISSION FROM THE MeV SPECTRUM  

SciTech Connect (OSTI)

The high-energy GeV emission of gamma-ray bursts (GRBs) detected by Fermi/LAT has a significantly different morphology compared to the lower energy MeV emission detected by Fermi/GBM. Though the late-time GeV emission is believed to be synchrotron radiation produced via an external shock, this emission as early as the prompt phase is puzzling. A meaningful connection between these two emissions can be drawn only by an accurate description of the prompt MeV spectrum. We perform a time-resolved spectroscopy of the Gamma-ray Burst Monitor (GBM) data of long GRBs with significant GeV emission, using a model consisting of two blackbodies and a power law. We examine in detail the evolution of the spectral components and find that GRBs with high GeV emission (GRB 090902B and GRB 090926A) have a delayed onset of the power-law component in the GBM spectrum, which lingers at the later part of the prompt emission. This behavior mimics the flux evolution in the Large Area Telescope (LAT). In contrast, bright GBM GRBs with an order of magnitude lower GeV emission (GRB 100724B and GRB 091003) show a coupled variability of the total and the power-law flux. Further, by analyzing the data for a set of 17 GRBs, we find a strong correlation between the power-law fluence in the MeV and the LAT fluence (Pearson correlation: r = 0.88 and Spearman correlation: ? = 0.81). We demonstrate that this correlation is not influenced by the correlation between the total and the power-law fluences at a confidence level of 2.3?. We speculate the possible radiation mechanisms responsible for the correlation.

Basak, Rupal; Rao, A. R., E-mail: rupalb@tifr.res.in, E-mail: arrao@tifr.res.in [Tata Institute of Fundamental Research, Mumbai 400005 (India)

2013-09-20T23:59:59.000Z

375

A COOL DUST FACTORY IN THE CRAB NEBULA: A HERSCHEL STUDY OF THE FILAMENTS  

SciTech Connect (OSTI)

Whether supernovae are major sources of dust in galaxies is a long-standing debate. We present infrared and submillimeter photometry and spectroscopy from the Herschel Space Observatory of the Crab Nebula between 51 and 670 {mu}m as part of the Mass Loss from Evolved StarS program. We compare the emission detected with Herschel with multiwavelength data including millimeter, radio, mid-infrared, and archive optical images. We carefully remove the synchrotron component using the Herschel and Planck fluxes measured in the same epoch. The contribution from line emission is removed using Herschel spectroscopy combined with Infrared Space Observatory archive data. Several forbidden lines of carbon, oxygen, and nitrogen are detected where multiple velocity components are resolved, deduced to be from the nitrogen-depleted, carbon-rich ejecta. No spectral lines are detected in the SPIRE wavebands; in the PACS bands, the line contribution is 5% and 10% at 70 and 100 {mu}m and negligible at 160 {mu}m. After subtracting the synchrotron and line emission, the remaining far-infrared continuum can be fit with two dust components. Assuming standard interstellar silicates, the mass of the cooler component is 0.24{sup +0.32} {sub -0.08} M {sub Sun} for T = 28.1{sup +5.5} {sub -3.2} K. Amorphous carbon grains require 0.11 {+-} 0.01 M {sub Sun} of dust with T = 33.8{sup +2.3} {sub -1.8} K. A single temperature modified blackbody with 0.14 M {sub Sun} and 0.08 M {sub Sun} for silicate and carbon dust, respectively, provides an adequate fit to the far-infrared region of the spectral energy distribution but is a poor fit at 24-500 {mu}m. The Crab Nebula has condensed most of the relevant refractory elements into dust, suggesting the formation of dust in core-collapse supernova ejecta is efficient.

Gomez, H. L.; Clark, C. J. R.; Gomez, E. L.; Gear, W. K. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA (United Kingdom); Krause, O.; Besel, M.-A.; Bouwman, J.; Henning, Th. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Barlow, M. J.; Swinyard, B. M.; Owen, P. J.; Matsuura, M. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Rho, J. [SOFIA Science Center, Universities Space Research Association, NASA Ames Research Center, MS 232, Moffett Field, CA 94035 (United States); Ivison, R. J.; Sibthorpe, B. [UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Polehampton, E. T. [Space Science and Technology Department, Rutherford Appleton Laboratory, Oxfordshire, OX11 0QX (United Kingdom)

2012-11-20T23:59:59.000Z

376

EFFECT OF A HIGH OPACITY ON THE LIGHT CURVES OF RADIOACTIVELY POWERED TRANSIENTS FROM COMPACT OBJECT MERGERS  

SciTech Connect (OSTI)

The coalescence of compact objects is a promising astrophysical source of detectable gravitational wave signals. The ejection of r-process material from such mergers may lead to a radioactively powered electromagnetic counterpart signal which, if discovered, would enhance the science returns. As very little is known about the optical properties of heavy r-process elements, previous light-curve models have adopted opacities similar to those of iron group elements. Here we consider the effect of heavier elements, particularly the lanthanides, which increase the ejecta opacity by several orders of magnitude. We include these higher opacities in time-dependent, multi-wavelength radiative transport calculations to predict the broadband light curves of one-dimensional models over a range of parameters (ejecta masses {approx}10{sup -3}-10{sup -1} M{sub Sun} and velocities {approx}0.1-0.3 c). We find that the higher opacities lead to much longer duration light curves which can last a week or more. The emission is shifted toward the infrared bands due to strong optical line blanketing, and the colors at later times are representative of a blackbody near the recombination temperature of the lanthanides (T {approx} 2500 K). We further consider the case in which a second mass outflow, composed of {sup 56}Ni, is ejected from a disk wind, and show that the net result is a distinctive two component spectral energy distribution, with a bright optical peak due to {sup 56}Ni and an infrared peak due to r-process ejecta. We briefly consider the prospects for detection and identification of these transients.

Barnes, Jennifer; Kasen, Daniel [Departments of Physics and Astronomy, 366 LeConte Hall, University of California, Berkeley, CA 94720 (United States)

2013-09-20T23:59:59.000Z

377

Models for X-Ray Emission from Isolated Pulsars  

E-Print Network [OSTI]

A model is proposed for the observed combination of power-law and thermal emission of keV X-rays from rotationally powered pulsars. For gamma-ray pulsars with accelerators very many stellar radii above the neutron star surface, 100 MeV curvature gamma-rays from $e^{-}$ or $e^{+}$ flowing starward out of such accelerators are converted to electron-positron pairs on closed field lines all around the star. These pairs strongly affect X-ray emission from near the star in two ways. (1) The pairs are a source of synchrotron emission immediately following their creation in regions where $B \\sim 10^{10}$ G. This emission, in the photon energy range 0.1 keV $\\lesssim E_{X} \\lesssim$ 5 MeV, has a power-law spectrum with energy index 0.5 and X-ray luminosity that depends on the backflow current, and is typically $\\sim 10^{33}$ \\lum. (2) The pairs ultimately form a cyclotron resonance ``blanket'' surrounding the star except for two holes along the open field line bundles which pass through it. In such a blanket the gravitational pull on electron-positron pairs toward the star is balanced by the hugely amplified push of outflowing surface emitted X-rays wherever cyclotron resonance occurs. Because of it the neutron star is surrounded by a leaky ``hohlraum'' of hot blackbody radiation with two small holes, which prevents direct X-ray observation of a heated polar cap of a gamma-ray pulsar. Weakly spin-modulated radiation from the blanket together with more strongly spin-modulated radiation from the holes through it would then dominate observed low energy (0.1--10 keV) emission. For non-gamma-ray pulsars, in which no such accelerators with their accompanying extreme relativistic backflow toward the star are ...

F. Y. -H. Wang; M. Ruderman; J. P. Halpern; T. Zhu

1997-11-24T23:59:59.000Z

378

Draft report on melt point as a function of composition for urania-based systems  

SciTech Connect (OSTI)

This report documents the testing of a urania (UO{sub 2.00}) sample as a baseline and the attempt to determine the melt point associated with 4 compositions of urania-ceria and urania-neodymia pseudo binaries provided by ORNL, with compositions of 95/5, and 80/20 and of (U/Ce)O{sub 2.00} and (U/Nd)O{sub 2.00} in the newly developed ceramic melt point determination system. A redesign of the system using parts fabricated from tungsten was undertaken in order to help prevent contamination and tungsten carbide formation in the crucibles. The previously developed system employed mostly graphite parts that were shown to react with the sample containment black-body crucible leading to unstable temperature readings and crucible failure, thus the redesign. Measured melt point values of UO{sub 2.00} and U{sub 0.95}Ce{sub 0.05}O{sub 2.00}, U{sub 0.80}Ce{sub 0.20}O{sub 2.00}, U{sub 0.95}Nd{sub 0.05}O{sub 2.00} and U{sub 0.80}Nd{sub 0.20}O{sub 2.00} were measured using a 2-color pyrometer. The value measured for UO{sub 2.00} was consistent with the published accepted value 2845 C {+-} 25 C, although a wide range of values has been published by researchers and will be discussed later in the text. For comparison, values obtained from a published binary phase diagram of UO{sub 2}-Nd{sub 2}O{sub 3} were used for comparison with our measure values. No literature melt point values for comparison with the measurements performed in this study were found for (U/Ce)O{sub 2.00} in our stoichiometry range.

Valdez, James A [Los Alamos National Laboratory; Byler, Darrin D [Los Alamos National Laboratory

2012-06-08T23:59:59.000Z

379

High efficiency radioisotope thermophotovoltaic prototype generator  

SciTech Connect (OSTI)

A radioisotope thermophotovoltaic generator space power system (RTPV) is lightweight, low-cost alternative to the present radioisotope thermoelectric generator system (RTG). The fabrication of such an RTPV generator has recently become feasible as the result of the invention of the GaSb infrared sensitive photovoltaic cell. Herein, the authors present the results of a parametric study of emitters and optical filters in conjuction with existing data on gallium antimonide cells. They compare a polished tungsten emitter with an Erbia selective emitter for use in combination with a simple dielectric filter and a gallium antimonide cell array. They find that the polished tungsten emitter is by itself a very selective emitter with low emissivity beyond 4 microns. Given a gallium antimonide cell and a tungsten emitter, a simple dielectric filter can be designed to transmit radiant energy below 1.7 microns and to reflect radiant energy between 1.7 and 4 microns back to the emitter. Because of the low long wavelength emissivity associated with the polished tungsten emitter, this simple dielectric filter then yields very respectable system performance. Also as a result of the longer wavelength fall-off in the tungsten emissivity curve, the radiation energy peak for a polished tungsten emitter operating at 1300 K shifts to shorter wavelengths relative to the blackbody spectrum so that the radiated energy peak falls right at the gallium antimonide cell bandedge. The result is that the response of the gallium antimonide cell is well matched to a polished tungsten emitter. The authors propose, therefore, to fabricate an operating prototype of a near term radioisotope thermophotovoltaic generator design consisting of a polished tungsten emitter, standard gallium antimonide cells, and a near-term dielectric filter.

Avery, J.E.; Samaras, J.E.; Fraas, L.M.; Ewell, R. [JX Crystals, Inc., Issaquah, WA (United States)

1995-10-01T23:59:59.000Z

380

EFFECTS OF LOCAL DISSIPATION PROFILES ON MAGNETIZED ACCRETION DISK SPECTRA  

SciTech Connect (OSTI)

We present spectral calculations of non-LTE accretion disk models appropriate for high-luminosity stellar mass black hole X-ray binary systems. We first use a dissipation profile based on scaling the results of shearing box simulations of Hirose et al. to a range of annuli parameters. We simultaneously scale the effective temperature, orbital frequency, and surface density with luminosity and radius according to the standard {alpha}-model. This naturally brings increased dissipation to the disk surface layers (around the photospheres) at small radii and high luminosities. We find that the local spectrum transitions directly from a modified blackbody to a saturated Compton scattering spectrum as we increase the effective temperature and orbital frequency while decreasing midplane surface density. Next, we construct annuli models based on the parameters of a L/L{sub Edd} = 0.8 disk orbiting a 6.62 solar mass black hole using two modified dissipation profiles that explicitly put more dissipation per unit mass near the disk surface. The new dissipation profiles are qualitatively similar to the one found by Hirose et al., but produce strong near power-law spectral tails. Our models also include physically motivated magnetic acceleration support based once again on scaling the Hirose et al. results. We present three full-disk spectra, each based on one of the dissipation prescriptions. Our most aggressive dissipation profile results in a disk spectrum that is in approximate quantitative agreement with certain observations of the steep power-law spectral states from some black hole X-ray binaries.

Tao, Ted [Department of Physics, St. Mary's College of Maryland, St. Mary's City, MD 20686 (United States); Blaes, Omer [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

2013-06-10T23:59:59.000Z

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381

Fluorescent microthermographic imaging  

SciTech Connect (OSTI)

In the early days of microelectronics, design rules and feature sizes were large enough that sub-micron spatial resolution was not needed. Infrared or IR thermal techniques were available that calculated the object`s temperature from infrared emission. There is a fundamental spatial resolution limitation dependent on the wavelengths of light being used in the image formation process. As the integrated circuit feature sizes began to shrink toward the one micron level, the limitations imposed on IR thermal systems became more pronounced. Something else was needed to overcome this limitation. Liquid crystals have been used with great success, but they lack the temperature measurement capabilities of other techniques. The fluorescent microthermographic imaging technique (FMI) was developed to meet this need. This technique offers better than 0.01{degrees}C temperature resolution and is diffraction limited to 0.3 {mu}m spatial resolution. While the temperature resolution is comparable to that available on IR systems, the spatial resolution is much better. The FMI technique provides better spatial resolution by using a temperature dependent fluorescent film that emits light at 612 nm instead of the 1.5 {mu}m to 12 {mu}m range used by IR techniques. This tutorial starts with a review of blackbody radiation physics, the process by which all heated objects emit radiation to their surroundings, in order to understand the sources of information that are available to characterize an object`s surface temperature. The processes used in infrared thermal imaging are then detailed to point out the limitations of the technique but also to contrast it with the FMI process. The FMI technique is then described in detail, starting with the fluorescent film physics and ending with a series of examples of past applications of FMI.

Barton, D.L.

1993-09-01T23:59:59.000Z

382

The Spitzer Infrared Spectrograph Debris Disk Catalog. I. Continuum Analysis of Unresolved Targets  

Science Journals Connector (OSTI)

During the Spitzer Space Telescope cryogenic mission, Guaranteed Time Observers, Legacy Teams, and General Observers obtained Infrared Spectrograph (IRS) observations of hundreds of debris disk candidates. We calibrated the spectra of 571 candidates, including 64 new IRAS and Multiband Imaging Photometer for Spitzer (MIPS) debris disks candidates, modeled their stellar photospheres, and produced a catalog of excess spectra for unresolved debris disks. For 499 targets with IRS excess but without strong spectral features (and a subset of 420 targets with additional MIPS 70 ?m observations), we modeled the IRS (and MIPS data) assuming that the dust thermal emission was well-described using either a one- or two-temperature blackbody model. We calculated the probability for each model and computed the average probability to select among models. We found that the spectral energy distributions for the majority of objects (~66%) were better described using a two-temperature model with warm (T gr ~ 100-500 K) and cold (T gr ~ 50-150 K) dust populations analogous to zodiacal and Kuiper Belt dust, suggesting that planetary systems are common in debris disks and zodiacal dust is common around host stars with ages up to ~1 Gyr. We found that younger stars generally have disks with larger fractional infrared luminosities and higher grain temperatures and that higher-mass stars have disks with higher grain temperatures. We show that the increasing distance of dust around debris disks is inconsistent with self-stirred disk models, expected if these systems possess planets at 30-150 AU. Finally, we illustrate how observations of debris disks may be used to constrain the radial dependence of material in the minimum mass solar nebula.

Christine H. Chen; Tushar Mittal; Marc Kuchner; William J. Forrest; Carey M. Lisse; P. Manoj; Benjamin A. Sargent; Dan M. Watson

2014-01-01T23:59:59.000Z

383

Causal Set Phenomenology  

E-Print Network [OSTI]

Central to the development of any new theory is the investigation of the observable consequences of the theory. In the search for quantum gravity, research in phenomenology has been dominated by models violating Lorentz invariance (LI) -- despite there being, at present, no evidence that LI is violated. Causal set theory is a LI candidate theory of QG that seeks not to quantise gravity as such, but rather to develop a new understanding of the universe from which both GR and QM could arise separately. The key hypothesis is that spacetime is a discrete partial order: a set of events where the partial ordering is the physical causal ordering between the events. This thesis investigates Lorentz invariant QG phenomenology motivated by the causal set approach. Massive particles propagating in a discrete spacetime will experience diffusion in both position and momentum in proper time. This thesis considers this idea in more depth, providing a rigorous derivation of the diffusion equation in terms of observable cosmic time. The diffusion behaviour does not depend on any particular underlying particle model. Simulations of three different models are conducted, revealing behaviour that matches the diffusion equation despite limitations on the size of causal set simulated. The effect of spacetime discreteness on the behaviour of massless particles is also investigated. Diffusion equations in both affine time and cosmic time are derived, and it is found that massless particles undergo diffusion and drift in energy. Constraints are placed on the magnitudes of the drift and diffusion parameters by considering the blackbody nature of the CMB. Spacetime discreteness also has a potentially observable effect on photon polarisation. For linearly polarised photons, underlying discreteness is found to cause a rotation in polarisation angle and a suppression in overall polarisation.

Lydia Philpott

2010-09-08T23:59:59.000Z

384

Coherence Properties of Optical Fields  

Science Journals Connector (OSTI)

This article presents a review of coherence properties of electromagnetic fields and their measurements, with special emphasis on the optical region of the spectrum. Analyses based on both the classical and quantum theories are described. After a brief historical introduction, the elementary concepts which are frequently employed in the discussion of interference phenomena are summarized. The measure of second-order coherence is then introduced in connection with the analysis of a simple interference experiment and some of the more important second-order coherence effects are studied. Their uses in stellar interferometry and interference spectroscopy are described. Analysis of partial polarization from the standpoint of correlation theory is also outlined. The general statistical description of the field is discussed in some detail. The recently discovered universal "diagonal" representation of the density operator for free fields is also considered and it is shown how, with the help of the associated generalized phase-space distribution function, the quantum-mechanical correlation functions may be expressed in the same form as the classical ones. The sections which follow deal with the statistical properties of thermal and nonthermal light, and with the temporal and spatial coherence of blackbody radiation. Later sections, dealing with fourth- and higher-order coherence effects include a discussion of the photoelectric detection process. Among the fourth-order effects described in detail are bunching phenomena, the Hanbury Brown-Twiss effect and its application to astronomy. The article concludes with a discussion of various transient superposition effects, such as light beats and interference fringes produced by independent light beams.

L. MANDEL and E. WOLF

1965-04-01T23:59:59.000Z

385

On the temperature profile of radiatively efficient geometrically thin disks in black hole binaries with the ASCA GIS  

E-Print Network [OSTI]

X-ray spectra of black hole binaries(BHBs) in the high/soft state were studied comprehensively by using ASCA GIS data, and partially RXTE PCA data. A mathematical disk model was applied to several BHBs to see if the observed accretion disk temperature profile was consistent with that expected from the standard accretion disk model. This model is called p-free disk, and assumes that the spectrum is composed of multi-temperature blackbody emission of which the local temperature T(r) at radius r is given by T(r) ~ r^-p with p being a positive free parameter. The standard disk roughly requires p~3/4, while a small deviation is expected depending on the inner boundary conditions, general relativistic effects and disk vertical structures.Our sample objects included LMC X-1, LMC X-3, XTE J2012+381, and GRO J1655-40. During the ASCA observations, these BHBs showed characteristics of the standard high/soft state. Under the standard modeling of high-state black hole binaries, the sources show Tin=0.76-1.17keV, the disk fraction to the total 0.7-10keV flux of 54-98%, and Nh=(0.7--12)E21/cm^2. The best-fit p-values were found in 0.6-0.8, and the standard value of p=3/4 was accepted for all the sources.The obtained p-values are also compared with those expected for the standard accretion disk in the Schwarzschild metric, and they were consistent with those expected from the standard accretion disk.

Aya Kubota; Ken Ebisawa; Kazuo Makishima; Kazuhiro Nakazawa

2005-05-17T23:59:59.000Z

386

LONG-TERM SPECTRAL EVOLUTION OF TIDAL DISRUPTION CANDIDATES SELECTED BY STRONG CORONAL LINES  

SciTech Connect (OSTI)

We present results of follow-up optical spectroscopic Multi-Mirror Telescope (MMT) observations of seven rare, extreme coronal line-emitting galaxies reported by Wang et al. Large variations in coronal lines are found in four objects, making them strong candidates for tidal disruption events (TDEs). For the four TDE candidates, all the coronal lines with ionization states higher than [Fe VII] disappear within 5-9 yr. The [Fe VII] line faded by a factor of about five in one object (J0952+2143) within 4 yr, whereas the line emerged in another two objects that previously did not show the line. A strong increment in the [O III] flux is observed, shifting the line ratios toward the loci of active galactic nuclei on the BPT diagram. Surprisingly, we detect a non-canonical [O III] {lambda}5007/[O III] {lambda}4959 ratio of {approx_equal} 2 in two objects, indicating a large column density of O{sup 2+} and thus probably optically thick gas. This result also requires a very large ionization parameter and a relatively soft ionizing spectral energy distribution (e.g., a blackbody with T < 5 Multiplication-Sign 10{sup 4} K). Our observations can be explained as the echoing of a strong ultraviolet to soft X-ray flare caused by TDEs on molecular clouds in the inner parsecs of the galactic nuclei. Reanalyzing the Sloan Digital Sky Survey spectra reveals double-peaked or strongly blue-shouldered broad lines in three of the objects, which disappeared in the MMT spectra of two objects and faded by a factor of 10 in 8 yr in the remaining object with a decrease in both the line width and centroid offset. We interpret these broad lines as arising from decelerating biconical outflows. Our results demonstrate that the signatures of echoing can persist for as long as 10 yr and can be used to probe the gas environment in quiescent galactic nuclei.

Yang Chenwei; Wang Tinggui; Zhou Hongyan; Jiang Peng [Key Laboratory for Research in Galaxies and Cosmology, University of Sciences and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Ferland, Gary [Department of Physics, University of Kentucky, Lexington, KY 40506 (United States); Yuan Weimin, E-mail: twang@ustc.edu.cn [National Astronomical Observatory, Chinese Academy of Sciences, 20A Datun Road, Beijing (China)

2013-09-01T23:59:59.000Z

387

SUPERNOVA RESONANCE-SCATTERING LINE PROFILES IN THE ABSENCE OF A PHOTOSPHERE  

SciTech Connect (OSTI)

In supernova (SN) spectroscopy relatively little attention has been given to the properties of optically thick spectral lines in epochs following the photosphere's recession. Most treatments and analyses of post-photospheric optical spectra of SNe assume that forbidden-line emission comprises most if not all spectral features. However, evidence exists that suggests that some spectra exhibit line profiles formed via optically thick resonance-scattering even months or years after the SN explosion. To explore this possibility, we present a geometrical approach to SN spectrum formation based on the 'Elementary Supernova' model, wherein we investigate the characteristics of resonance-scattering in optically thick lines while replacing the photosphere with a transparent central core emitting non-blackbody continuum radiation, akin to the optical continuum provided by decaying {sup 56}Co formed during the explosion. We develop the mathematical framework necessary for solving the radiative transfer equation under these conditions and calculate spectra for both isolated and blended lines. Our comparisons with analogous results from the Elementary Supernova code SYNOW reveal several marked differences in line formation. Most notably, resonance lines in these conditions form P Cygni-like profiles, but the emission peaks and absorption troughs shift redward and blueward, respectively, from the line's rest wavelength by a significant amount, despite the spherically symmetric distribution of the line optical depth in the ejecta. These properties and others that we find in this work could lead to misidentification of lines or misattribution of properties of line-forming material at post-photospheric times in SN optical spectra.

Friesen, Brian; Baron, E.; Branch, David; Chen Bin [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Rm. 100, Norman, OK 73019 (United States); Parrent, Jerod T. [6127 Wilder Lab, Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States); Thomas, R. C. [Computational Cosmology Center, Computational Research Division, Lawrence Berkeley National Laboratory, MS 50B-4206, 1 Cyclotron Road, CA 94720 (United States)

2012-11-15T23:59:59.000Z

388

13th TOPICAL CONFERENCE ON HIGH TEMPERATURE PLASMA DIAGNOSTICS SCIENTIFIC PROGRAM  

SciTech Connect (OSTI)

Electron cyclotron emission (ECE) has been employed as a standard electron temperature profile diagnostic on many tokamaks and stellarators, but most magnetically confined plasma devices cannot take advantage of standard ECE diagnostics to measure temperature. They are either overdense, operating at high density relative to the magnetic field (e.g. {omega}{sub pe} >> {Omega}{sub ce} in a spherical torus) or they have insufficient density and temperature to reach the blackbody condition ({tau} > 2). Electron Bernstein waves (EBWs) are electrostatic waves which can propagate in overdense plasmas and have a high optical thickness at the electron cyclotron resonance layers, as a result of their large K{sub i}. This talk reports on measurements of EBW emission on the CDX-U spherical torus, where B{sub 0} {approx} 2 kG, {approx} 10{sup 13} cm{sup -3} and T{sub e} {approx} 10 - 200 eV. Results will be presented for both direct detection of EBWs and for mode-converted EBW emission. The EBW emission was absolutely calibrated and compared to the electron temperature profile measured by a multi-point Thomson scattering diagnostic. Depending on the plasma conditions, the mode-converted EBW radiation temperature was found to be {le} T{sub e} and the emission source was determined to be radially localized at the electron cyclotron resonance layer. A Langmuir triple probe was employed to measure changes in edge density profile in the vicinity of the upper hybrid resonance where the mode conversion of the EBWs is expected to occur. Changes in the mode conversion efficiency may explain the observation of mode-converted EBW radiation temperatures below T{sub e}. Initial results suggest EBW emission and EBW heating are viable concepts for plasmas where {omega}{sub pe} >> {Omega}{sub ce}.

C. BARNES

2000-07-01T23:59:59.000Z

389

THE COMPTON-THICK SEYFERT 2 NUCLEUS OF NGC 3281: TORUS CONSTRAINTS FROM THE 9.7 {mu}m SILICATE ABSORPTION  

SciTech Connect (OSTI)

We present mid-infrared (mid-IR) spectra of the Compton-thick Seyfert 2 galaxy NGC 3281, obtained with the Thermal-Region Camera Spectrograph at the Gemini-South telescope. The spectra present a very deep silicate absorption at 9.7 {mu}m, and [S IV] 10.5 {mu}m and [Ne II] 12.7 {mu}m ionic lines, but no evidence of polycyclic aromatic hydrocarbon emission. We find that the nuclear optical extinction is in the range 24 mag {<=} A{sub V} {<=} 83 mag. A temperature T = 300 K was found for the blackbody dust continuum component of the unresolved 65 pc nucleus and the region at 130 pc SE, while the region at 130 pc NW reveals a colder temperature (200 K). We describe the nuclear spectrum of NGC 3281 using a clumpy torus model that suggests that the nucleus of this galaxy hosts a dusty toroidal structure. According to this model, the ratio between the inner and outer radius of the torus in NGC 3281 is R{sub 0}/R{sub d} = 20, with 14 clouds in the equatorial radius with optical depth of {tau}{sub V} = 40 mag. We would be looking in the direction of the torus equatorial radius (i = 60{sup 0}), which has outer radius of R{sub 0} {approx} 11 pc. The column density is N{sub H} {approx} 1.2 x 10{sup 24} cm{sup -2} and the iron K{alpha} equivalent width ({approx}0.5-1.2 keV) is used to check the torus geometry. Our findings indicate that the X-ray absorbing column density, which classifies NGC 3281 as a Compton-thick source, may also be responsible for the absorption at 9.7 {mu}m providing strong evidence that the silicate dust responsible for this absorption can be located in the active galactic nucleus torus.

Sales, Dinalva A.; Pastoriza, M. G.; Riffel, R. [Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, Porto Alegre, RS (Brazil); Winge, C. [Gemini Observatory, c/o Aura, Inc., Casilla 603, La Serena (Chile); RodrIguez-Ardila, A. [Laboratorio Nacional de Astrofisica/MCT, Rua dos Estados Unidos 154, Itajuba, MG (Brazil); Carciofi, A. C., E-mail: dinalva.aires@ufrgs.br [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, Sao Paulo, SP (Brazil)

2011-09-01T23:59:59.000Z

390

Photometric calibrations for 21st century science  

SciTech Connect (OSTI)

The answers to fundamental science questions in astrophysics, ranging from the history of the expansion of the universe to the sizes of nearby stars, hinge on our ability to make precise measurements of diverse astronomical objects. As our knowledge of the underlying physics of objects improves along with advances in detectors and instrumentation, the limits on our capability to extract science from measurements is set, not by our lack of understanding of the nature of these objects, but rather by the most mundane of all issues: the precision with which we can calibrate observations in physical units. In principle, photometric calibration is a solved problem - laboratory reference standards such as blackbody furnaces achieve precisions well in excess of those needed for astrophysics. In practice, however, transferring the calibration from these laboratory standards to astronomical objects of interest is far from trivial - the transfer must reach outside the atmosphere, extend over 4{pi} steradians of sky, cover a wide range of wavelengths, and span an enormous dynamic range in intensity. Virtually all spectrophotometric observations today are calibrated against one or more stellar reference sources, such as Vega, which are themselves tied back to laboratory standards in a variety of ways. This system's accuracy is not uniform. Selected regions of the electromagnetic spectrum are calibrated extremely well, but discontinuities of a few percent still exist, e.g., between the optical and infrared. Independently, model stellar atmospheres are used to calibrate the spectra of selected white dwarf stars, e.g. the HST system, but the ultimate accuracy of this system should be verified against laboratory sources. Our traditional standard star systems, while sufficient until now, need to be improved and extended in order to serve future astrophysics experiments. This white paper calls for a program to improve upon and expand the current networks of spectrophotometrically calibrated stars to provide precise calibration with an accuracy of equal to and better than 1% in the ultraviolet, visible and near-infrared portions of the spectrum, with excellent sky coverage and large dynamic range.

Kent, Stephen; /Fermilab; Kaiser, Mary Elizabeth; /Johns Hopkins U.; Deustua, Susana E.; /Baltimore, Space Telescope Sci.; Smith, J.Allyn; /Austin Peay State U.; Adelman, Saul; /Citadel Military Coll.; Allam, Sahar S.; /Fermilab; Baptista, Brian; /Indiana U.; Bohlin, Ralph C.; /Baltimore, Space Telescope Sci.; Clem, James L.; /Louisiana State U.; Conley, Alex; /Colorado U.; Edelstein, Jerry; /UC, Berkeley, Space Sci. Dept. /NOAO, Tucson

2009-02-01T23:59:59.000Z

391

UNVEILING THE STRUCTURE OF PRE-TRANSITIONAL DISKS  

SciTech Connect (OSTI)

In the past few years, several disks with inner holes that are relatively empty of small dust grains have been detected and are known as transitional disks. Recently, Spitzer has identified a new class of 'pre-transitional disks' with gaps based on near-infrared photometry and mid-infrared spectra; these objects have an optically thick inner disk separated from an optically thick outer disk by an optically thin disk gap. A near-infrared spectrum provided the first confirmation of a gap in the pre-transitional disk of LkCa 15 by verifying that the near-infrared excess emission in this object was due to an optically thick inner disk. Here, we investigate the difference between the nature of the inner regions of transitional and pre-transitional disks using the same veiling-based technique to extract the near-infrared excess emission above the stellar photosphere. However, in this work we use detailed disk models to fit the excess continua as opposed to the simple blackbody fits previously used. We show that the near-infrared excess emission of the previously identified pre-transitional disks of LkCa 15 and UX Tau A in the Taurus cloud as well as the newly identified pre-transitional disk of ROX 44 in Ophiuchus can be fit with an inner disk wall located at the dust destruction radius. We also present detailed modeling of the broadband spectral energy distributions of these objects, taking into account the effect of shadowing by the inner disk on the outer disk, but considering the finite size of the star, unlike other recent treatments. The near-infrared excess continua of these three pre-transitional disks, which can be explained by optically thick inner disks, are significantly different from that of the transitional disks of GM Aur, whose near-infrared excess continuum can be reproduced by emission from sub-micron-sized optically thin dust, and DM Tau, whose near-infrared spectrum is consistent with a disk hole that is relatively free of small dust. The structure of pre-transitional disks may be a sign of young planets forming in these disks and future studies of pre-transitional disks will provide constraints to aid in theoretical modeling of planet formation.

Espaillat, C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138 (United States); D'Alessio, P. [Centro de Radioastronomia y Astrofisica, Universidad Nacional Autonoma de Mexico, Morelia, Michoacan, Mexico 58089 (Mexico); Hernandez, J. [Centro de Investigaciones de Astronomia (CIDA), Merida, 5101-A (Venezuela, Bolivarian Republic of); Nagel, E. [Departamento de Astronomia, Universidad de Guanajuato, Guanajuato, Gto, Mexico 36240 (Mexico); Luhman, K. L. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Watson, D. M. [Department of Physics and Astronomy, University of Rochester, NY 14627-0171 (United States); Calvet, N.; McClure, M. [Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); Muzerolle, J., E-mail: cespaillat@cfa.harvard.ed, E-mail: p.dalessio@crya.unam.m, E-mail: jesush@cida.v, E-mail: erick@astro.ugto.m, E-mail: kluhman@astro.psu.ed, E-mail: dmw@pas.rochester.ed, E-mail: ncalvet@umich.ed, E-mail: melisma@umich.ed, E-mail: muzerol@stsci.ed [Space Telescope Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2010-07-01T23:59:59.000Z

392

Management of unconverted light for the National Ignition Facility target chamber  

SciTech Connect (OSTI)

The NIF target chamber beam dumps must survive high x-ray, laser, ion, and shrapnel exposures without excessive generation of vapors or particulate that will contaminate the final optics debris shields, thereby making the debris shields susceptible to subsequent laser damage. The beam dumps also must be compatible with attaining and maintaining the required target chamber vacuum and must not activate significantly under high neutron fluxes. Finally, they must be developed, fabricated, and maintained for a reasonable cost. The primary challenge for the beam dump is to survive up to 20 J/cm{sup 2} of lpm light and 1 - 2 J/cm{sup 2} of nominally 200 - 350 eV blackbody temperature x rays. Additional threats include target shrapnel, and other contamination issues. Designs which have been evaluated include louvered hot-pressed boron carbide (B{sub 4}C) or stainless steel (SS) panels, in some cases covered with transparent Teflon film, and various combinations of inexpensive low thermal expansion glasses backed by inexpensive absorbing glass. Louvered designs can recondense a significant amount of ablated material that would otherwise escape into the target chamber. Transparent Teflon was evaluated as an alternative way to capture ablated material. The thin Teflon sheet would need to be replaced after each shot since it exhibits both laser damage and considerable x- ray ablation with each shot. Uncontaminated B{sub 4}C, SS, and low thermal expansion glasses have reasonably small x-ray and laser ablation rates, although the glasses begin to fail catastrophically after 100 high fluence shots. Commercially available absorbing glasses require a pre-shield of either Teflon or low thermal expansion glass to prevent serious degradation by the x-ray fluence. Advantages of the hot-pressed B{sub 4}C and SS over glass are their performance against microshrapnel, their relative indifference to contamination, and their ability to be refurbished by aggressive cleaning using CO{sub 2} pellets, glass beads, high pressure water or ultrasonic tanks. In addition the expected replacement rate to avoid catastrophic failure makes the glass option more costly. SS is less expensive, more easily formed into a louver design with high capture efficiency, and otherwise equivalent to B{sub 4}C. Hence, it would be preferred as long as debris shield damage is not substantially greater for SS as compared to damage from an equivalent mass of contamination of B{sub 4}C. If debris shield damage is problematic, the escape of SS could be mitigated by use of a transparent Teflon film. The Teflon film would require increased target chamber pumping and cleaning capability to accommodate the x-ray decomposition products.

Anderson, A. T.; Bletzer, K.; Burnham, A. K.; Dixit, S; Genin, F. Y.; Hibbard, W.; Norton, J.; Scott, J. M.; Whitman, P. K.

1998-07-08T23:59:59.000Z

393

On the efficacy of imploding plasma liners for magnetized fusion target compression  

SciTech Connect (OSTI)

A new theoretical model is formulated to study the idea of merging a spherical array of converging plasma jets to form a 'plasma liner' that further converges to compress a magnetized plasma target to fusion conditions [Y. C. F. Thio et al., 'Magnetized target fusion in a spheroidal geometry with standoff drivers', Current Trends in International Fusion Research II, edited by E. Panarella (National Research Council Canada, Ottawa, Canada, 1999)]. For a spherically imploding plasma liner shell with high initial Mach number (M=liner speed/sound speed) the rise in liner density with decreasing radius r goes as {rho}{approx}1/r{sup 2}, for any constant adiabatic index {gamma}=d ln p/d ln {rho}. Accordingly, spherical convergence amplifies the ram pressure of the liner on target by the factor A{approx}C{sup 2}, indicating strong coupling to its radial convergence C=r{sub m}/R, where r{sub m}(R)=jet merging radius (compressed target radius), and A=compressed target pressure/initial liner ram pressure. Deuterium-tritium (DT) plasma liners with initial velocity {approx}100 km/s and {gamma}=5/3, need to be hypersonic M{approx}60 and thus cold in order to realize values of A{approx}10{sup 4} necessary for target ignition. For optically thick DT liners, T<2 eV, n>10{sup 19}-10{sup 20} cm{sup -3}, blackbody radiative cooling is appreciable and may counteract compressional heating during the later stages of the implosion. The fluid then behaves as if the adiabatic index were depressed below 5/3, which in turn means that the same amplification A=1.6x10{sup 4} can be accomplished with a reduced initial Mach number M{approx_equal}12.7({gamma}-0.3){sup 4.86}, valid in the range (10

Parks, P. B. [General Atomics, P.O. Box 85608, San Diego, California 92186-5688 (United States)

2008-06-15T23:59:59.000Z

394

THE CHANDRA X-RAY SURVEY OF PLANETARY NEBULAE (CHANPLANS): PROBING BINARITY, MAGNETIC FIELDS, AND WIND COLLISIONS  

SciTech Connect (OSTI)

We present an overview of the initial results from the Chandra Planetary Nebula Survey (CHANPLANS), the first systematic (volume-limited) Chandra X-Ray Observatory survey of planetary nebulae (PNe) in the solar neighborhood. The first phase of CHANPLANS targeted 21 mostly high-excitation PNe within {approx}1.5 kpc of Earth, yielding four detections of diffuse X-ray emission and nine detections of X-ray-luminous point sources at the central stars (CSPNe) of these objects. Combining these results with those obtained from Chandra archival data for all (14) other PNe within {approx}1.5 kpc that have been observed to date, we find an overall X-ray detection rate of {approx}70% for the 35 sample objects. Roughly 50% of the PNe observed by Chandra harbor X-ray-luminous CSPNe, while soft, diffuse X-ray emission tracing shocks-in most cases, 'hot bubbles'-formed by energetic wind collisions is detected in {approx}30%; five objects display both diffuse and point-like emission components. The presence (or absence) of X-ray sources appears correlated with PN density structure, in that molecule-poor, elliptical nebulae are more likely to display X-ray emission (either point-like or diffuse) than molecule-rich, bipolar, or Ring-like nebulae. All but one of the point-like CSPNe X-ray sources display X-ray spectra that are harder than expected from hot ({approx}100 kK) central stars emitting as simple blackbodies; the lone apparent exception is the central star of the Dumbbell nebula, NGC 6853. These hard X-ray excesses may suggest a high frequency of binary companions to CSPNe. Other potential explanations include self-shocking winds or PN mass fallback. Most PNe detected as diffuse X-ray sources are elliptical nebulae that display a nested shell/halo structure and bright ansae; the diffuse X-ray emission regions are confined within inner, sharp-rimmed shells. All sample PNe that display diffuse X-ray emission have inner shell dynamical ages {approx}< 5 Multiplication-Sign 10{sup 3} yr, placing firm constraints on the timescale for strong shocks due to wind interactions in PNe. The high-energy emission arising in such wind shocks may contribute to the high excitation states of certain archetypical 'hot bubble' nebulae (e.g., NGC 2392, 3242, 6826, and 7009).

Kastner, J. H.; Montez, R. Jr.; Rapson, V. [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Balick, B. [Department of Astronomy, University of Washington, Seattle, WA (United States); Frew, D. J.; De Marco, O.; Parker, Q. A. [Department of Physics and Astronomy and Macquarie Research Centre for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Sydney, NSW 2109 (Australia); Miszalski, B. [South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 (South Africa); Sahai, R. [Jet Propulsion Laboratory, California Institute of Technology, MS 183-900, Pasadena, CA 91109 (United States); Blackman, E.; Frank, A. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Chu, Y.-H. [Department of Astronomy, University of Illinois, Champagne-Urbana, IL (United States); Guerrero, M. A. [Instituto de Astrofisica de Astronomia, Glorieta de la Astronomia s/n, Granada 18008 (Spain); Lopez, J. A. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Campus Ensenada, Apdo. Postal 22860, Ensenada, B. C. (Mexico); Zijlstra, A. [School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Behar, E. [Department of Physics, Technion (Israel); Bujarrabal, V. [Observatorio Astronomico Nacional, Apartado 112, E-28803, Alcala de Henares (Spain); Corradi, R. L. M. [Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain); Nordhaus, J. [Center for Computational Relativity and Gravitation, Rochester Institute of Technology, Rochester, NY 14623 (United States); Sandin, C., E-mail: jhk@cis.rit.edu, E-mail: soker@physics.technion.ac.il, E-mail: eva.villaver@uam.es [Leibniz Institute for Astrophysics Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); and others

2012-08-15T23:59:59.000Z

395

SEARCH F O R LINEAR POLARIZATION O F THE COSMIC BACKGROUND RADIATION  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

SEARCH F SEARCH F O R LINEAR POLARIZATION O F THE COSMIC BACKGROUND RADIATION P h i l M. Lubin and George F. Smoot Space Sciences L a b o r a t o r y and Lawrence Berkeley L a b o r a t o r y U n i v e r s i t y of C a l i f o r n i a Berkeley, C a l i f o r n i a 94720 Received ABSTRACT W e p r e s e n t p r e l i m i n a r y measurements of t h e l i n e a r p o l a r i z a t i o n of t h e cosmic microwave background ( 3 ° K blackbody) r a d i a t i o n . These ground-based measurements a r e made a t 9 mm wavelength. W e f i n d no e v i d e n c e f o r l i n e a r p o l a r i z a t i o n , and s e t a n upper l i m i t f o r a p o l a r i z e d component of 0.8 m°K with a 95% confidence l e v e l . T h i s i m p l i e s t h a t t h e p r e s e n t rate of e x p a n s i o n of t h e Universe i s i s o t r o p i c t o one p a r t i n 1 0 , assuming no r e - i o n i z a t i o n of t h e p r i m o r d i a l plasma a f t e r recombination. 6 The observed cosmic microwave background r

396

High Efficiency, Illumination Quality OLEDs for Lighting  

SciTech Connect (OSTI)

The goal of the program was to demonstrate a 45 lumen per watt white light device based upon the use of multiple emission colors through the use of solution processing. This performance level is a dramatic extension of the team's previous 15 LPW large area illumination device. The fundamental material system was based upon commercial polymer materials. The team was largely able to achieve these goals, and was able to deliver to DOE a 90 lumen illumination source that had an average performance of 34 LPW a 1000 cd/m{sup 2} with peak performances near 40LPW. The average color temperature is 3200K and the calculated CRI 85. The device operated at a brightness of approximately 1000cd/m{sup 2}. The use of multiple emission colors particularly red and blue, provided additional degrees of design flexibility in achieving white light, but also required the use of a multilayered structure to separate the different recombination zones and prevent interconversion of blue emission to red emission. The use of commercial materials had the advantage that improvements by the chemical manufacturers in charge transport efficiency, operating life and material purity could be rapidly incorporated without the expenditure of additional effort. The program was designed to take maximum advantage of the known characteristics of these material and proceeded in seven steps. (1) Identify the most promising materials, (2) assemble them into multi-layer structures to control excitation and transport within the OLED, (3) identify materials development needs that would optimize performance within multilayer structures, (4) build a prototype that demonstrates the potential entitlement of the novel multilayer OLED architecture (5) integrate all of the developments to find the single best materials set to implement the novel multilayer architecture, (6) further optimize the best materials set, (7) make a large area high illumination quality white OLED. A photo of the final deliverable is shown. In 2003, a large area, OLED based illumination source was demonstrated that could provide light with a quality, quantity, and efficiency on par with what can be achieved with traditional light sources. The demonstration source was made by tiling together 16 separate 6-inch x 6-inch blue-emitting OLEDs. The efficiency, total lumen output, and lifetime of the OLED based illumination source were the same as what would be achieved with an 80 watt incandescent bulb. The devices had an average efficacy of 15 LPW and used solution-processed OLEDs. The individual 6-inch x 6-inch devices incorporated three technology strategies developed specifically for OLED lighting -- downconversion for white light generation, scattering for outcoupling efficiency enhancement, and a scalable monolithic series architecture to enable large area devices. The downconversion approach consists of optically coupling a blue-emitting OLED to a set of luminescent layers. The layers are chosen to absorb the blue OLED emission and then luminescence with high efficiency at longer wavelengths. The composition and number of layers are chosen so that the unabsorbed blue emission and the longer wavelength re-emission combine to make white light. A downconversion approach has the advantage of allowing a wide variety of colors to be made from a limited set of blue emitters. In addition, one does not have to carefully tune the emission wavelength of the individual electro-luminescent species within the OLED device in order to achieve white light. The downconversion architecture used to develop the 15LPW large area light source consisted of a polymer-based blue-emitting OLED and three downconversion layers. Two of the layers utilized perylene based dyes from BASF AG of Germany with high quantum efficiency (>98%) and one of the layers consisted of inorganic phosphor particles (Y(Gd)AG:Ce) with a quantum efficiency of {approx}85%. By independently varying the optical density of the downconversion layers, the overall emission spectrum could be adjusted to maximize performance for lighting (e.g. blackbody temp

Joseph Shiang; James Cella; Kelly Chichak; Anil Duggal; Kevin Janora; Chris Heller; Gautam Parthasarathy; Jeffery Youmans; Joseph Shiang

2008-03-31T23:59:59.000Z

397

Polycrystalline?thin?film thermophotovoltaic cells  

Science Journals Connector (OSTI)

Thermophotovoltaic (TPV) cells convert thermal energy to electricity. Modularity portability silent operation absence of moving parts reduced air pollution rapid start?up high power densities potentially high conversion efficiencies choice of a wide range of heat sources employing fossil fuels biomass and even solar radiation are key advantages of TPV cells in comparison with fuel cells thermionic and thermoelectric convertors and heat engines. The potential applications of TPV systems include: remote electricity supplies transportation co?generation electric?grid independent appliances and space aerospace and military power applications. The range of bandgaps for achieving high conversion efficiencies using low temperature (1000–2000 K) black?body or selective radiators is in the 0.5–0.75 eV range. Present high efficiency convertors are based on single crystalline materials such as In1?x Ga x As GaSb and Ga1?x In x Sb. Several polycrystalline thin films such as Hg1?x Cd x Te Sn1?x Cd2x Te2 and Pb1?x Cd x Te etc. have great potential for economic large?scale applications. A small fraction of the high concentration of charge carriers generated at high fluences effectively saturates the large density of defects in polycrystalline thin films. Photovoltaic conversion efficiencies of polycrystalline thin films and PV solar cells are comparable to single crystalline Si solar cells e.g. 17.1% for CuIn1?x Ga x Se2 and 15.8% for CdTe. The best recombination?state density N t is in the range of 10?15–10?16 cm?3 acceptable for TPV applications. Higher efficiencies may be achieved because of the higher fluences possibility of bandgap tailoring and use of selective emitters such as rare earth oxides (erbia holmia yttria) and rare earth?yttrium aluminium garnets. As compared to higher bandgap semiconductors such as CdTe it is easier to dope the lower bandgap semiconductors. TPV cell development can benefit from the more mature PV solar cell and opto?electronic (infrared detectors lasers and optical communications) technologies. Low bandgaps and larger fluences employed in TPV cells result in very high current densities which make it difficult to collect the current effectively. Techniques for laser and mechanical scribing integral interconnection and multi?junction tandem structures which have been fairly well developed for thin?film PV solar cells could be further refined for enhancing the voltages from TPV modules. Thin?film TPV cells may be deposited on metals or back?surface reflectors. Spectral control elements such as indium?tin oxide or tin oxide may be deposited directly on the TPV convertor. It would be possible to reduce the cost of TPV technologies based on single?crystal materials being developed at present to the range of US$ 2–5 per watt so as to be competitive in small to medium size commercial applications. However a further cost reduction to the range of US ¢ 35–$ 1 per watt to reach the more competitive large?scale residential consumer and hybrid?electric car markets would be possible only with the polycrystalline?thin film TPV cells.

Neelkanth G. Dhere

1996-01-01T23:59:59.000Z

398

Visible Spectrum Incandescent Selective Emitter  

SciTech Connect (OSTI)

The purpose of the work performed was to demonstrate the feasibility of a novel bi-layer selective emitter. Selective emitters are incandescent radiant bodies with emissivities that are substantially larger in a selected part of the radiation spectrum, thereby significantly shifting their radiated spectral distribution from that of a blackbody radiating at the same temperature. The major research objectives involved answering the following questions: (1) What maximum VIS/NIR radiant power and emissivity ratios can be attained at 2650 K? (2) What is the observed emitter body life and how does its performance vary with time? (3) What are the design tradeoffs for a dual heating approach in which both an internally mounted heating coil and electrical resistance self-heating are used? (4) What are the quantitative improvements to be had from utilizing a bi-layer emitter body with a low emissivity inner layer and a partially transmissive outer layer? Two approaches to obtaining selective emissivity were investigated. The first was to utilize large optical scattering within an emitter material with a spectral optical absorption that is much greater within the visible spectrum than that within the NIR. With this approach, an optically thick emitter can radiate almost as if optically thin because essentially, scattering limits the distance below the surface from which significant amounts of internally generated radiation can emerge. The performance of thin emitters was also investigated (for optically thin emitters, spectral emissivity is proportional to spectral absorptivity). These emitters were fabricated from thin mono-layer emitter rods as well as from bi-layer rods with a thin emitter layer mounted on a substrate core. With an initially estimated energy efficiency of almost three times that of standard incandescent bulbs, a number of energy, economic and environmental benefits such as less energy use and cost, reduced CO{sub 2} emissions, and no mercury contamination was initially projected. The work performed provided answers to a number of important questions. The first is that, with the investigated approaches, the maximum sustained emitter efficiencies are about 1.5 times that of a standard incandescent bulb. This was seen to be the case for both thick and thin emitters, and for both mono-layer and bi-layer designs. While observed VIS/NIR ratios represent improvements over standard incandescent bulbs, it does not appear sufficient to overcome higher cost (i.e. up to five times that of the standard bulb) and ensure commercial success. Another result is that high temperatures (i.e. 2650 K) are routinely attainable without platinum electrodes. This is significant for reducing material costs. A novel dual heating arrangement and insulated electrodes were used to attain these temperatures. Another observed characteristic of the emitter was significant grain growth soon after attaining operating temperatures. This is an undesirable characteristic that results in substantially less optical scattering and spectral selectivity, and which significantly limits emitter efficiencies to the values reported. Further work is required to address this problem.

Sonsight Inc.

2004-04-30T23:59:59.000Z