311 research outputs found
A Low Noise Thermometer Readout for Ruthenium Oxide Resistors
The thermometer and thermal control system, for the Absolute Radiometer for
Cosmology, Astrophysics, and Diffuse Emission (ARCADE) experiment, is
described, including the design, testing, and results from the first flight of
ARCADE. The noise is equivalent to about 1 Omega or 0.15 mK in a second for the
RuO_2 resistive thermometers at 2.7 K. The average power dissipation in each
thermometer is 1 nW. The control system can take full advantage of the
thermometers to maintain stable temperatures. Systematic effects are still
under investigation, but the measured precision and accuracy are sufficient to
allow measurement of the cosmic background spectrum.
Journal-ref: Review of Scientific Instruments Vol 73 #10 (Oct 2002)Comment: 5 pages text 7 figure
ARCADE 2 Measurement of the Extra-Galactic Sky Temperature at 3-90 GHz
The ARCADE 2 instrument has measured the absolute temperature of the sky at
frequencies 3, 8, 10, 30, and 90 GHz, using an open-aperture cryogenic
instrument observing at balloon altitudes with no emissive windows between the
beam-forming optics and the sky. An external blackbody calibrator provides an
{\it in situ} reference. Systematic errors were greatly reduced by using
differential radiometers and cooling all critical components to physical
temperatures approximating the CMB temperature. A linear model is used to
compare the output of each radiometer to a set of thermometers on the
instrument. Small corrections are made for the residual emission from the
flight train, balloon, atmosphere, and foreground Galactic emission. The ARCADE
2 data alone show an extragalactic rise of mK at 3.3 GHz in addition
to a CMB temperature of K. Combining the ARCADE 2 data with
data from the literature shows a background power law spectrum of [K] from 22 MHz to 10 GHz ( GHz)
in addition to a CMB temperature of K.Comment: 11 pages 5 figures Submitted to Ap
The Temperature of the CMB at 10 GHz
We report the results of an effort to measure the low frequency portion of
the spectrum of the Cosmic Microwave Background Radiation (CMB), using a
balloon-borne instrument called ARCADE (Absolute Radiometer for Cosmology,
Astrophysics, and Diffuse Emission). These measurements are to search for
deviations from a thermal spectrum that are expected to exist in the CMB due to
various processes in the early universe. The radiometric temperature was
measured at 10 and 30 GHz using a cryogenic open-aperture instrument with no
emissive windows. An external blackbody calibrator provides an in situ
reference. A linear model is used to compare the radiometer output to a set of
thermometers on the instrument. The unmodeled residuals are less than 50 mK
peak-to-peak with a weighted RMS of 6 mK. Small corrections are made for the
residual emission from the flight train, atmosphere, and foreground Galactic
emission. The measured radiometric temperature of the CMB is 2.721 +/- 0.010 K
at 10 GHz and 2.694 +/- 0.032 K at 30 GHz.Comment: 8 pages including 5 figures. Submitted to The Astrophysical Journa
ARCADE: Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission
The Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission
(ARCADE) is a balloon-borne instrument designed to measure the temperature of
the cosmic microwave background at centimeter wavelengths. ARCADE searches for
deviations from a blackbody spectrum resulting from energy releases in the
early universe. Long-wavelength distortions in the CMB spectrum are expected in
all viable cosmological models. Detecting these distortions or showing that
they do not exist is an important step for understanding the early universe. We
describe the ARCADE instrument design, current status, and future plans.Comment: 12 pages, 6 figures. Proceedings of the Fundamental Physics With CMB
workshop, UC Irvine, March 23-25, 2006, to be published in New Astronomy
Review
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Cancer Informatics for Cancer Centers (CI4CC): Building a Community Focused on Sharing Ideas and Best Practices to Improve Cancer Care and Patient Outcomes.
Cancer Informatics for Cancer Centers (CI4CC) is a grassroots, nonprofit 501c3 organization intended to provide a focused national forum for engagement of senior cancer informatics leaders, primarily aimed at academic cancer centers anywhere in the world but with a special emphasis on the 70 National Cancer Institute-funded cancer centers. Although each of the participating cancer centers is structured differently, and leaders' titles vary, we know firsthand there are similarities in both the issues we face and the solutions we achieve. As a consortium, we have initiated a dedicated listserv, an open-initiatives program, and targeted biannual face-to-face meetings. These meetings are a place to review our priorities and initiatives, providing a forum for discussion of the strategic and pragmatic issues we, as informatics leaders, individually face at our respective institutions and cancer centers. Here we provide a brief history of the CI4CC organization and meeting highlights from the latest CI4CC meeting that took place in Napa, California from October 14-16, 2019. The focus of this meeting was "intersections between informatics, data science, and population science." We conclude with a discussion on "hot topics" on the horizon for cancer informatics
ARCADE 2 Observations of Galactic Radio Emission
We use absolutely calibrated data from the ARCADE 2 flight in July 2006 to
model Galactic emission at frequencies 3, 8, and 10 GHz. The spatial structure
in the data is consistent with a superposition of free-free and synchrotron
emission. Emission with spatial morphology traced by the Haslam 408 MHz survey
has spectral index beta_synch = -2.5 +/- 0.1, with free-free emission
contributing 0.10 +/- 0.01 of the total Galactic plane emission in the lowest
ARCADE 2 band at 3.15 GHz. We estimate the total Galactic emission toward the
polar caps using either a simple plane-parallel model with csc|b| dependence or
a model of high-latitude radio emission traced by the COBE/FIRAS map of CII
emission. Both methods are consistent with a single power-law over the
frequency range 22 MHz to 10 GHz, with total Galactic emission towards the
north polar cap T_Gal = 0.498 +/- 0.028 K and spectral index beta = -2.55 +/-
0.03 at reference frequency 1 GHz. The well calibrated ARCADE 2 maps provide a
new test for spinning dust emission, based on the integrated intensity of
emission from the Galactic plane instead of cross-correlations with the thermal
dust spatial morphology. The Galactic plane intensity measured by ARCADE 2 is
fainter than predicted by models without spinning dust, and is consistent with
spinning dust contributing 0.4 +/- 0.1 of the Galactic plane emission at 22
GHz.Comment: 10 poges, 9 figures. Submitted to The Astrophysical Journa
ARCADE 2 Observations of Galactic Radio Emission
We use absolutely calibrated data from the ARCADE 2 flight in 2006 July to model Galactic emission at frequencies 3, 8, and 10 GHz. The spatial structure in the data is consistent with a superposition of free–free and synchrotron emission. Emission with spatial morphology traced by the Haslam 408 MHz survey has spectral index βsynch = −2.5±0.1, with free–free emission contributing 0.10±0.01 of the total Galactic plane emission in the lowest ARCADE 2 band at 3.15 GHz. We estimate the total Galactic emission toward the polar caps using either a simple plane-parallel model with csc |b| dependence or a model of high-latitude radio emission traced by the COBE/FIRAS map of C ii emission. Both methods are consistent with a single power law over the frequency range 22 MHz to 10 GHz, with total Galactic emission toward the north polar cap TGal = 10.12 ± 0.90 K and spectral index β = −2.55 ± 0.03 at reference frequency 0.31 GHz. Emission associated with the plane-parallel structure accounts for only 30% of the observed high-latitude sky temperature, with the residual in either a Galactic halo or an isotropic extragalactic background. The well-calibrated ARCADE 2 maps provide a new test for spinning dust emission, based on the integrated intensity of emission from the Galactic plane instead of cross-correlations with the thermal dust spatial morphology. The Galactic plane intensity measured by ARCADE 2 is fainter than predicted by models without spinning dust and is consistent with spinning dust contributing 0.4 ± 0.1 of the Galactic plane emission at 23 GHz
Interpretation of the ARCADE 2 Absolute Sky Brightness Measurement
We use absolutely calibrated data between 3 and 90 GHz from the 2006 balloon flight of the ARCADE 2 instrument, along with previous measurements at other frequencies, to constrain models of extragalactic emission. Such emission is a combination of the cosmic microwave background (CMB) monopole, Galactic foreground emission, the integrated contribution of radio emission from external galaxies, any spectral distortions present in the CMB, and any other extragalactic source. After removal of estimates of foreground emission from our own Galaxy, and an estimated contribution of external galaxies, we present fits to a combination of the flat-spectrum CMB and potential spectral distortions in the CMB.We find 2σ upper limits to CMB spectral distortions ofμ \u3c 6×10−4 and |Yff| \u3c 1×10−4. We also find a significant detection of a residual signal beyond that, which can be explained by the CMB plus the integrated radio emission from galaxies estimated from existing surveys. This residual signal may be due to an underestimated galactic foreground contribution, an unaccounted for contribution of a background of radio sources, or some combination of both. The residual signal is consistent with emission in the form of a power law with amplitude 18.4 ± 2.1 K at 0.31 GHz and a spectral index of −2.57 ± 0.05
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