100 research outputs found
Experimental study of coherent synchrotron radiation in the emittance exchange line at the A0-photoinjector
Next generation accelerators will require a high current, low emittance beam
with a low energy spread. Such accelerators will employ advanced beam
conditioning systems such as emittance exchangers to manipulate high brightness
beams. One of the goals of the Fermilab A0 photoinjector is to investigate the
transverse to longitudinal emittance exchange principle. Coherent synchrotron
radiation could limit high current operation of the emittance exchanger. In
this paper, we report on the preliminary experimental and simulation study of
the coherent synchroton radiation (CSR) in the emittance exchange line at the
A0 photoinjector.Comment: 4 pp. 14th Advanced Accelerator Concepts Workshop, 13-19 Jun 2010:
Annapolis, Marylan
Video-based Simulations: Considerations for Teaching Students with Developmental Disabilities
The use of video-based multimedia simulations for teaching functional skills to persons with developmental disabilities remains an unexplored application of technology for this group. This article examines the historical literature in this area, and discusses future considerations, design issues, and implications of using multimedia simulations. Implementation issues are presented, and suggestions regarding design, development, and application of multimedia simulations are offered. Considerations address the importance of appropriate role modeling and the combination of video-based simulation and in vivo training to foster generalization and maintenance in the context of transition to the real world.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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Parity Violation Constraints Using Cosmic Microwave Background Polarization Spectra from 2006 and 2007 Observations by the QUaD Polarimeter
We constrain parity-violating interactions to the surface of last scattering using spectra from the QUaD experiment’s second and third seasons of observations by searching for a possible systematic rotation of the polarization directions of cosmic microwave background photons. We measure the rotation angle due to such a possible ‘‘cosmological birefringence’’ to be (random) (systematic) using QUaD’s 100 and 150 GHz temperature-curl and gradient-curl spectra over the spectra over the multipole range 200 << 2000, consistent with null, and constrain Lorentz-violating interactions to <2 10 GeV (68% confidence limit). This is the best constraint to date on electrodynamic parity violation on cosmological scales.Astronom
Second and Third Season QUaD Cosmic Microwave Background Temperature and Polarization Power Spectra
We report results from the second and third seasons of observation with the QUaD experiment. Angular
power spectra of the cosmic microwave background are derived for both temperature and polarization at
both 100 GHz and 150 GHz, and as cross-frequency spectra. All spectra are subjected to an extensive
set of jackknife tests to probe for possible systematic contamination. For the implemented data cuts and
processing technique such contamination is undetectable. We analyze the difference map formed between the
100 and 150 GHz bands and find no evidence of foreground contamination in polarization. The spectra are
then combined to form a single set of results which are shown to be consistent with the prevailing LCDM
model. The sensitivity of the polarization results is considerably better than that of any previous experiment—
for the first time multiple acoustic peaks are detected in the E-mode power spectrum at high significance
The QUAD Galactic Plane Survey 1: Maps and Analysis of Diffuse Emission
We present a survey of ~ 800 square degrees of the galactic plane observed with the QUaD telescope. The
primary product of the survey are maps of Stokes I, Q and U parameters at 100 and 150 GHz, with spatial
resolution 5 and 3.5 arcminutes respectively. Two regions are covered, spanning approximately 245 - 295°
and 315 - 5° in galactic longitude l, and -4 < b < +4° in galactic latitude b. At 0:02° square pixel size, the
median sensitivity is 74 and 107 kJy/sr at 100 GHz and 150 GHz respectively in I, and 98 and 120 kJy/sr for
Q and U. In total intensity, we find an average spectral index of α = 2:35+-0:01(stat)+-0:02(sys) for |b| ≤1°,
indicative of emission components other than thermal dust. A comparison to published dust, synchrotron
and free-free models implies an excess of emission in the 100 GHz QUaD band, while better agreement is
found at 150 GHz. A smaller excess is observed when comparing QUaD 100 GHz data to WMAP 5-year
W band; in this case the excess is likely due to the wider bandwidth of QUaD. Combining the QUaD and
WMAP data, a two-component spectral fit to the inner galactic plane (|b| ≤1°) yields mean spectral indices
of αs = -0:32+-0:03 and αd = 2:84+-0:03; the former is interpreted as a combination of the spectral indices
of synchrotron, free-free and dust, while the second is attributed largely to the thermal dust continuum. In
the same galactic latitude range, the polarization data show a high degree of alignment perpendicular to the
expected galactic magnetic field direction, and exhibit mean polarization fraction 1:38+-0:08(stat)+-0:1(sys)%
at 100 GHz and 1:70+-0:06(stat)+-0:1(sys)% at 150 GHz. We find agreement in polarization fraction between
QUaD 100 GHz and WMAP W band, the latter giving 1:1+-0:4%
Polarization Calibration of the QUaD Experiment
We describe the polarization calibration of the QUaD experiment, including determination of the polarization efficiency of the detectors and their orientation angles. QUaD is a millimeter-wavelength polarimeter that observed the Cosmic Microwave Background (CMB) from a site at the South Pole. The experiment comprises a 2.64 m Cassegrain telescope equipped with a cryogenically cooled receiver containing an array of 62 polarization-sensitive bolometers. The focal plane contains pixels at two different frequency bands, 100 GHz and 150 GHz, with angular resolutions of 5prime and 3farcm5, respectively. The high angular resolution allows observation of CMB temperature and polarization anisotropies over a wide range of scales. The instrument commenced operation in early 2005 and collected science data during three successive Austral winter seasons of observation
Planck early results. VI. The High Frequency Instrument data processing
We describe the processing of the 336 billion raw data samples from the High Frequency Instrument (HFI) which we performed to produce six
temperature maps from the first 295 days of Planck-HFI survey data. These maps provide an accurate rendition of the sky emission at 100, 143,
217, 353, 545 and 857GHz with an angular resolution ranging from 9.9 to 4.4 . The white noise level is around 1.5 μK degree or less in the 3 main
CMB channels (100–217 GHz). The photometric accuracy is better than 2% at frequencies between 100 and 353 GHz and around 7% at the two
highest frequencies. The maps created by the HFI Data Processing Centre reach our goals in terms of sensitivity, resolution, and photometric
accuracy. They are already sufficiently accurate and well-characterised to allow scientific analyses which are presented in an accompanying series
of early papers. At this stage, HFI data appears to be of high quality and we expect that with further refinements of the data processing we should
be able to achieve, or exceed, the science goals of the Planck project
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