A. E. Lange

Publications (228)359.03 Total impact

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  Available from: Graca Rocha

  Article: A Millimeter-wave Galactic Plane Survey with the BICEP Polarimeter

  E. M. Bierman, T. Matsumura, C. D. Dowell, B. G. Keating, P. Ade, D. Barkats, D. Barron, J. O. Battle, J. J. Bock, H. C. Chiang, [......], E. M. Leitch, P. V. Mason, N. J. Miller, H. T. Nguyen, C. Pryke, S. Richter, G. M. Rocha, C. Sheehy, Y. D. Takahashi, and K. W. Yoon
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  ABSTRACT: In order to study inflationary cosmology and the Milky Way Galaxy's composition and magnetic field structure, Stokes I, Q, and U maps of the Galactic plane covering the Galactic longitude range 260° < ℓ < 340° in three atmospheric transmission windows centered on 100, 150, and 220 GHz are presented. The maps sample an optical depth 1 AV 30, and are consistent with previous characterizations of the Galactic millimeter-wave frequency spectrum and the large-scale magnetic field structure permeating the interstellar medium. The polarization angles in all three bands are generally perpendicular to those measured by starlight polarimetry as expected and show changes in the structure of the Galactic magnetic field on the scale of 60°. The frequency spectrum of degree-scale Galactic emission is plotted between 23 and 220 GHz (including WMAP data) and is fit to a two-component (synchrotron and dust) model showing that the higher frequency BICEP data are necessary to tightly constrain the amplitude and spectral index of Galactic dust. Polarized emission is detected over the entire region within two degrees of the Galactic plane, indicating the large-scale magnetic field is oriented parallel to the plane of the Galaxy. A trend of decreasing polarization fraction with increasing total intensity is observed, ruling out the simplest model of a constant Galactic magnetic field orientation along the line of sight in the Galactic plane. A generally increasing trend of polarization fraction with electromagnetic frequency is found, varying from 0.5%-1.5% at frequencies below 50 GHz to 2.5%-3.5% above 90 GHz. The effort to extend the capabilities of BICEP by installing 220 GHz band hardware is described along with analysis of the new band.
  The Astrophysical Journal 10/2011; 741(2):81. · 6.02 Impact Factor
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  Available from: Angiola Orlando

  Article: The Keck Array: a pulse tube cooled CMB polarimeter

  C. D. Sheehy, P. A. R. Ade, R. W. Aikin, M. Amiri, S. Benton, C. Bischoff, J. J. Bock, J. A. Bonetti, J. A. Brevik, B. Burger, [......], M. C. Runyan, Z. Staniszewski, S. Stokes, R. Sudiwala, G. Teply, K. L. Thompson, J. E. Tolan, A. D. Turner, P Wilson, C. L. Wong
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  ABSTRACT: The Keck Array is a cosmic microwave background (CMB) polarimeter that will begin observing from the South Pole in late 2010. The initial deployment will consist of three telescopes similar to BICEP2 housed in ultra-compact, pulse tube cooled cryostats. Two more receivers will be added the following year. In these proceedings we report on the design and performance of the Keck cryostat. We also report some initial results on the performance of antenna-coupled TES detectors operating in the presence of a pulse tube. We find that the performance of the detectors is not seriously impacted by the replacement of BICEP2's liquid helium cryostat with a pulse tube cooled cryostat.
  04/2011;
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  Available from: Francesco Piacentini

  Article: Planck Early Results: The Planck mission

  Planck Collaboration, P. A. R. Ade, N. Aghanim, M. Arnaud, M. Ashdown, J. Aumont, C. Baccigalupi, M Baker, A. Balbi, A. J. Banday, [......], N. Vittorio, L. A. Wade, B. D. Wandelt, C Watson, S. D. M. White, M White, A Wilkinson, D. Yvon, A. Zacchei, A. Zonca
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  ABSTRACT: The European Space Agency's Planck satellite was launched on 14 May 2009, and has been surveying the sky stably and continuously since 13 August 2009. Its performance is well in line with expectations, and it will continue to gather scientific data until the end of its cryogenic lifetime. We give an overview of the history of Planck in its first year of operations, and describe some of the key performance aspects of the satellite. This paper is part of a package submitted in conjunction with Planck's Early Release Compact Source Catalogue, the first data product based on Planck to be released publicly. The package describes the scientific performance of the Planck payload, and presents results on a variety of astrophysical topics related to the sources included in the Catalogue, as well as selected topics on diffuse emission.
  01/2011;
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  Available from: François R. Bouchet

  Article: Planck early results. VI. The High Frequency Instrument data processing

  Planck HFI Core Team, P. A. R. Ade, N. Aghanim, R. Ansari, M. Arnaud, M. Ashdown, J. Aumont, A. J. Banday, M. Bartelmann, J. G. Bartlett, [......], F. Van Leeuwen, L. Vibert, D. Vibert, B. D. Wandelt, S. D. M. White, H. Wiesemeyer, A. Woodcraft, V. Yurchenko, D. Yvon, A. Zacchei
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  ABSTRACT: 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 857 GHz with an angular resolution ranging from 9.9 to 4.4^2. The white noise level is around 1.5 {\mu}K degree or less in the 3 main CMB channels (100--217GHz). 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.
  01/2011;
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  Available from: François R. Bouchet

  Article: Planck early results: first assessment of the High Frequency Instrument in-flight performance

  Planck HFI Core Team, P. A. R. Ade, N. Aghanim, R. Ansari, M. Arnaud, M. Ashdown, J. Aumont, A. J. Banday, M. Bartelmann, J. G. Bartlett, [......], L. Vibert, D. Vibert, L. A. Wade, B. D. Wandelt, S. D. M. White, H. Wiesemeyer, A. Woodcraft, V. Yurchenko, D. Yvon, A. Zacchei
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  ABSTRACT: The Planck High Frequency Instrument (HFI) is designed to measure the temperature and polarization anisotropies of the Cosmic Microwave Background and galactic foregrounds in six wide bands centered at 100, 143, 217, 353, 545 and 857 GHz at an angular resolution of 10' (100 GHz), 7' (143 GHz), and 5' (217 GHz and higher). HFI has been operating flawlessly since launch on 14 May 2009. The bolometers cooled to 100 mK as planned. The settings of the readout electronics, such as the bolometer bias current, that optimize HFI's noise performance on orbit are nearly the same as the ones chosen during ground testing. Observations of Mars, Jupiter, and Saturn verified both the optical system and the time response of the detection chains. The optical beams are close to predictions from physical optics modeling. The time response of the detection chains is close to pre-launch measurements. The detectors suffer from an unexpected high flux of cosmic rays related to low solar activity. Due to the redundancy of Planck's observations strategy, the removal of a few percent of data contaminated by glitches does not affect significantly the sensitivity. The cosmic rays heat up significantly the bolometer plate and the modulation on periods of days to months of the heat load creates a common drift of all bolometer signals which do not affect the scientific capabilities. Only the high energy cosmic rays showers induce inhomogeneous heating which is a probable source of low frequency noise.
  01/2011;
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  Available from: Angiola Orlando

  Article: The QUaD Galactic Plane Survey II: A Compact Source Catalog

  T. Culverhouse, P. Ade, J. Bock, M. Bowden, M. L. Brown, G. Cahill, P. G. Castro, S. Church, R. Friedman, K. Ganga, [......], R. Schwarz, C. O'Sullivan, L. Piccirillo, N. Rajguru, B. Rusholme, A. N. Taylor, K. L. Thompson, A. H. Turner, E. Y. S. Wu, M. Zemcov
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  ABSTRACT: We present a catalog of compact sources derived from the QUaD Galactic Plane Survey. The survey covers ~800 square degrees of the inner galaxy (|b|<4 degrees) in Stokes I, Q and U parameters at 100 and 150 GHz, with angular resolution 5 and 3.5 arcminutes. 505 unique sources are identified in I, of which 239 are spatially matched between frequency bands, with 50 (216) detected at 100 (150) GHz alone; 182 sources are identified as ultracompact HII (UCHII) regions. Approximating the distribution of total intensity source fluxes as a power-law, we find a slope of $\gamma_{S,100}=-1.8\pm0.4$ at 100 GHz, and $\gamma_{S,150}=-2.2\pm0.4$ at 150 GHz. Similarly, the power-law index of the source two-point angular correlation function is $\gamma_{\theta,100}=-1.21\pm0.04$ and $\gamma_{\theta,150}=-1.25\pm0.04$. The total intensity spectral index distribution peaks at $\alpha_{I}\sim0.25$, indicating that dust emission is not the only source of radiation produced by these objects between 100 and 150 GHz; free-free radiation is likely significant in the 100 GHz band. Four sources are detected in polarized intensity P, of which three have matching counterparts in I. Three of the polarized sources lie close to the galactic center, Sagittarius A*, Sagittarius B2 and the Galactic Radio Arc, while the fourth is RCW 49, a bright HII region. An extended polarized source, undetected by the source extraction algorithm on account of its $\sim0.5^{\circ}$ size, is identified visually, and is an isolated example of large-scale polarized emission oriented distinctly from the bulk galactic dust polarization. Comment: 30 pages, 19 figures, two catalogs; submitted to ApJS; maps and catalogs downloadable from <http://find.spa.umn.edu/quad/quad_galactic>
  The Astrophysical Journal Supplement Series 01/2011; 195(1). · 13.46 Impact Factor
• Article: The QUaD Galactic Plane Survey. I. Maps and Analysis of Diffuse Emission

  T. Culverhouse, P. Ade, J. Bock, M. Bowden, M. L. Brown, G. Cahill, P. G. Castro, S. E. Church, R. Friedman, K. Ganga, [......], C. O' Sullivan, L. Piccirillo, C. Pryke, N. Rajguru, B. Rusholme, A. N. Taylor, K. L. Thompson, A. H. Turner, E. Y. S. Wu, and M. Zemcov
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  ABSTRACT: We present a survey of ~800 deg2 of the galactic plane observed with the QUaD telescope. The primary products of the survey are maps of Stokes I, Q, and U parameters at 100 and 150 GHz, with spatial resolution of 5' and 35, respectively. Two regions are covered, spanning approximately 245°-295° and 315°-5° in the galactic longitude l and –4° < b < +4° in the galactic latitude b. At 002 square pixel size, the median sensitivity is 74 and 107 kJy sr–1 at 100 GHz and 150 GHz respectively in I, and 98 and 120 kJy sr–1 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 the WMAP five-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 α s = –0.32 ± 0.03 and α d = 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 largely attributed 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 the WMAP W band, the latter giving 1.1% ± 0.4%.
  The Astrophysical Journal 09/2010; 722(2):1057. · 6.02 Impact Factor
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  Available from: Angiola Orlando

  Article: Antenna-coupled TES bolometer arrays for BICEP2/Keck and SPIDER.

  A Orlando, R W Aikin, M Amiri, J J Bock, J A Bonetti, J A Brevik, B Burger, G Chattopadthyay, P K Day, J P Filippini, [......], H T Nguyen, R W Ogburn, C D Reintsema, M C Runyan, Z Staniszewski, R Sudiwala, G Teply, A R Trangsrud, A D Turner, P Wilson
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  ABSTRACT: BICEP2/Keck and SPIDER are cosmic microwave background (CMB) polarimeters targeting the B-mode polar-ization induced by primordial gravitational waves from inflation. They will be using planar arrays of polarization sensitive antenna-coupled TES bolometers, operating at frequencies between 90 GHz and 220 GHz. At 150 GHz each array consists of 64 polarimeters and four of these arrays are assembled together to make a focal plane, for a total of 256 dual-polarization elements (512 TES sensors). The detector arrays are integrated with a time-domain SQUID multiplexer developed at NIST and read out using the multi-channel electronics (MCE) developed at the University of British Columbia. Following our progress in improving detector parameters uniformity across the arrays and fabrication yield, our main effort has focused on improving detector arrays optical and noise performances, in order to produce science grade focal planes achieving target sensitivities. We report on changes in detector design implemented to optimize such performances and following focal plane arrays characterization. BICEP2 has deployed a first 150 GHz science grade focal plane to the South Pole in December 2009.
  Proc SPIE 09/2010;
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  Available from: Krzysztof M. Gorski

  Article: Measuring Planck beams with planets

  K. M. Huffenberger, B. P. Crill, A. E. Lange, K. M. Gorski, C. R. Lawrence
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  ABSTRACT: Accurate measurement of the cosmic microwave background (CMB) anisotropy requires precise knowledge of the instrument beam. We explore how well the Planck beams will be determined from observations of planets, developing techniques that are also appropriate for other experiments. We simulate planet observations with a Planck-like scanning strategy, telescope beams, noise, and detector properties. Then we employ both parametric and non-parametric techniques, reconstructing beams directly from the time-ordered data. With a faithful parameterization of the beam shape, we can constrain certain detector properties, such as the time constants of the detectors, to high precision. Alternatively, we decompose the beam using an orthogonal basis. For both techniques, we characterize the errors in the beam reconstruction with Monte Carlo realizations. For a simplified scanning strategy, we study the impact on estimation of the CMB power spectrum. Finally, we explore the consequences for measuring cosmological parameters, focusing on the spectral index of primordial scalar perturbations, n_s. The quality of the power spectrum measurement will be significantly influenced by the optical modeling of the telescope. In our most conservative case, using no information about the optics except the measurement of planets, we find that a single transit of Jupiter across the focal plane will measure the beam window functions to better than 0.3% for the channels at 100-217 GHz that are the most sensitive to the CMB. Constraining the beam with optical modeling can lead to much higher quality reconstruction. Depending on the optical modeling, the beam errors may be a significant contribution to the measurement systematics for n_s. Comment: Fixed typo in Eq. 9; otherwise unchanged. 13 pages, 11 figures. Dedicated to memory of AEL
  07/2010;
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  Available from: Angiola Orlando

  Article: Optical Performance of the BICEP2 Telescope at the South Pole

  Randol W. Aikin, J. J. Bock, J. A. Brevik, C. D. Dowell, J. P. Filippini, S. R. Golwala, V. V. Hristov, A. E. Lange, H T Nguyen, A. Orlando, S Richter, M. C. Runyan, G. P. Teply
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  ABSTRACT: Bicep2 deployed to the South Pole during the 2009-2010 austral summer, and is now mapping the polarization of the cosmic microwave background (CMB), searching for evidence of inflationary cosmology. Bicep2 belongs to a new class of telescopes including the Keck Array (ground-based) and Spider (balloon-borne) that follow on Bicep’s strategy of employing small, cold, on-axis refracting optics. This common design provides key advantages ideal for targeting the polarization signature from inflation, including: (i) A large field of view, allowing substantial light collecting power despite the small aperture, while still resolving the degree-scale polarization of the CMB; (ii) liquid helium-cooled optics and cold stop, allowing for low, stable instrument loading; (iii) the ability to rotate the entire telescope about the boresight; (iv) a baffled primary aperture, reducing sidelobe pickup; and (v) the ability to characterize the far field optical performance of the telescope using ground-based sources. We describe the last of these advantages in detail, including our efforts to measure the main beam shape, beam-match between orthogonally-polarized pairs, polarization efficiency and response angle, sidelobe pickup, and ghost imaging. We do so with ground-based polarized microwave sources mounted in the far field as well as with astronomical calibrators. Ultimately, Bicep2’s sensitivity to CMB polarization from inflation will rely on precise calibration of these beam features.
  Proc SPIE 07/2010; 7741:77410V.
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  Available from: Angiola Orlando

  Article: Initial performance of the BICEP2 antenna-coupled superconducting bolometers at the South Pole

  J. A. Brevik, R. W. Aikin, J. J. Bock, C. D. Dowell, J. P. Filippini, S. R. Golwala, V. V. Hristov, A. E. Lange, H T Nguyen, A. Orlando, M. Runyan, Z. Staniszewski
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  ABSTRACT: We report on the preliminary detector performance of the Bicep2 mm-wave polarimeter, deployed in 2009 to the South Pole. Bicep2 is currently imaging the polarization of the cosmic microwave background at 150 GHz using an array of 512 antenna-coupled superconducting bolometers. The antennas, band-defining filters and transition edge sensor (TES) bolometers are photolithographically fabricated on 4 silicon tiles. Each tile consists of an 8×8 grid of ~7 mm spatial pixels, for a total of 256 detector pairs. A patial pixel contains 2 sets of orthogonal antenna slots summed in-phase, with each set coupled to a TES by a filtered microstrip. The detectors are read out using time-domain multiplexed SQUIDs. The detector pair of each spatial pixel is differenced to measure polarization. We report on the performance of the Bicep2 detectors in the field, including the focal plane yield, detector and multiplexer optimization, detector noise and stability, and a preliminary estimate of the improvement in mapping speed compared to Bicep1.
  Proc SPIE 07/2010; 7741:77411H.
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  Available from: Angiola Orlando

  Conference Proceeding: The BICEP2 CMB polarization experiment

  R W Ogburn Iv, P A R Ade, R W Aikin, S Benton, J J Bock, J A Bonetti, J A Brevik, B Burger, C D Dowell, L Duband, [......], J E Ruhl, C Sheehy, Z Staniszewski, S A Stokes, R Sudiwala, G W Teply, J E Tolan, A D Turner, P Wilson, C L Wong
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  ABSTRACT: The Bicep2 telescope is designed to measure the polarization of the cosmic microwave background on angular scales near one degree, with the goal of searching for the B-mode polarization induced by primordial gravitational waves from inflation. Bicep2 follows the success of Bicep, which has set the most sensitive current limits on B-modes on 2-4 degree scales. The experiment adopts a new detector design in which beam-defining slot antennas are coupled to TES detectors photolithographically patterned in the same silicon wafer, with multiplexing SQUID readout. Bicep2 takes advantage of this design's higher focal-plane packing density, ease of fabrication, and multiplexing readout to field more detectors than Bicep1, improving mapping speed by nearly a factor of 10. Bicep2 was deployed to the South Pole in November 2009 with 500 polarization-sensitive detectors at 150 GHz, and is funded for two seasons of observation. The first months' data demonstrate the performance of the Caltech/JPL antenna-coupled TES arrays, and two years of observation with Bicep2 will achieve unprecedented sensitivity to B-modes on degree angular scales.
  SPIE; 07/2010
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  Available from: Angiola Orlando

  Article: Parameter Estimation from Improved Measurements of the CMB from QUaD

  QUaD collaboration, S Gupta, P. Ade, J. Bock, M. Bowden, M. L. Brown, G. Cahill, P. G. Castro, S. Church, T. Culverhouse, [......], L. Piccirillo, C. Pryke, N. Rajguru, B. Rusholme, R. Schwarz, A. N. Taylor, K. L. Thompson, A. H. Turner, E. Y. S. Wu, M. Zemcov
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  ABSTRACT: We evaluate the contribution of cosmic microwave background (CMB) polarization spectra to cosmological parameter constraints. We produce cosmological parameters using high-quality CMB polarization data from the ground-based QUaD experiment and demonstrate for the majority of parameters that there is significant improvement on the constraints obtained from satellite CMB polarization data. We split a multi-experiment CMB dataset into temperature and polarization subsets and show that the best-fit confidence regions for the LCDM 6-parameter cosmological model are consistent with each other, and that polarization data reduces the confidence regions on all parameters. We provide the best limits on parameters from QUaD EE/BB polarization data and we find best-fit parameters from the multi-experiment CMB dataset using the optimal pivot scale of k_p=0.013 Mpc-1 to be {omch2, ombh2, H_0, A_s, n_s, tau}= {0.113, 0.0224, 70.6, 2.29 times 10^-9, 0.960, 0.086}. Comment: 7 pages, 5 figures, updated to reflect published version, minor changes to spelling and format
  The Astrophysical Journal 06/2010; 716(2):1040-1046. · 6.02 Impact Factor
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  Available from: N. Castro-Rodriguez

  Article: The Herschel-SPIRE instrument and its in-flight performance

  M. J. Griffin, A. Abergel, A. Abreu, P. A. R. Ade, P. André, J. L. Augueres, T. Babbedge, Y. Bae, T. Baillie, J.-P. Baluteau, [......], N. Whitehouse, C. D. Wilson, B. Winter, A. L. Woodcraft, G. S. Wright, C. K. Xu, A. Zavagno, M. Zemcov, L Zhang, E. Zonca
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  ABSTRACT: The Spectral and Photometric Imaging Receiver (SPIRE), is the Herschel Space Observatory`s submillimetre camera and spectrometer. It contains a three-band imaging photometer operating at 250, 350 and 500 microns, and an imaging Fourier Transform Spectrometer (FTS) which covers simultaneously its whole operating range of 194-671 microns (447-1550 GHz). The SPIRE detectors are arrays of feedhorn-coupled bolometers cooled to 0.3 K. The photometer has a field of view of 4' x 8', observed simultaneously in the three spectral bands. Its main operating mode is scan-mapping, whereby the field of view is scanned across the sky to achieve full spatial sampling and to cover large areas if desired. The spectrometer has an approximately circular field of view with a diameter of 2.6'. The spectral resolution can be adjusted between 1.2 and 25 GHz by changing the stroke length of the FTS scan mirror. Its main operating mode involves a fixed telescope pointing with multiple scans of the FTS mirror to acquire spectral data. For extended source measurements, multiple position offsets are implemented by means of an internal beam steering mirror to achieve the desired spatial sampling and by rastering of the telescope pointing to map areas larger than the field of view. The SPIRE instrument consists of a cold focal plane unit located inside the Herschel cryostat and warm electronics units, located on the spacecraft Service Module, for instrument control and data handling. Science data are transmitted to Earth with no on-board data compression, and processed by automatic pipelines to produce calibrated science products. The in-flight performance of the instrument matches or exceeds predictions based on pre-launch testing and modelling: the photometer sensitivity is comparable to or slightly better than estimated pre-launch, and the spectrometer sensitivity is also better by a factor of 1.5-2. Comment: Accepted for publication in Astronomy & Astrophyics (Herschel first results special issue)
  05/2010;
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  Available from: Julien Brossard

  Article: Multi-mode horn design and beam characteristics for the Planck satellite

  J A Murphy, T Peacocke, B Maffei, I McAuley, F Noviello, V Yurchenko, P A R Ade, G Savini, J-M Lamarre, J Brossard, R Colgan, E Gleeson, A E Lange, Y Longval, G Pisano, J-L Puget, I Ristorcelli, R Sudiwala, R J Wylde
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  ABSTRACT: The ESA Planck satellite has begun studying the anisotropies of the cosmic microwave background radiation over the whole sky with unprecedented sensitivity and high angular resolution. The High Frequency Instrument, HFI, on Planck is observing simultaneously in six bands in the range 100 GHz to 857 GHz. The inclusion of non-CMB bands allows for robust removal of foreground sources from the data. This paper is concerned with the design, modeling and predicted performances of the two highest frequency channels centered on 545 GHz and 857 GHz, which use specialized multi-mode feedhorns, and are dedicated to observing these foregrounds. Multi-mode systems have the advantage of increasing the throughput, and thus sensitivity, of the detection assembly when diffraction limited resolution is not required. The horns are configured in a back-to-back setup which transmits the signal through filters to a detector horn. The modeling of the broadband beam patterns on the sky is shown to require careful analysis. Simulations of the complex interactions of the horns is computationally challenging when the detector horn in the relay system is included. The paper describes the approach to modeling these high frequency channels and discusses how the optical requirements on the horn designs are met in terms of spillover, edge taper, illumination of the telescope aperture and beam patterns on the sky.
  Journal of Instrumentation 04/2010; 5(04):T04001. · 1.87 Impact Factor
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  Available from: Francesco Piacentini

  Article: Properties of Galactic Cirrus Clouds Observed by BOOMERANG

  M. Veneziani, P. A. R. Ade, J. J. Bock, A. Boscaleri, B. P. Crill, P. de Bernardis, G. De Gasperis, A. de Oliveira-Costa, G. De Troia, G. Di Stefano, [......], T. E. Montroy, P. Natoli, C. B. Netterfield, E. Pascale, F. Piacentini, D. Pietrobon, G. Polenta, S. Ricciardi, G. Romeo, and J. E. Ruhl
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  ABSTRACT: The physical properties of galactic cirrus emission are not well characterized. BOOMERANG is a balloon-borne experiment designed to study the cosmic microwave background at high angular resolution in the millimeter range. The BOOMERANG 245 and 345 GHz channels are sensitive to interstellar signals, in a spectral range intermediate between FIR and microwave frequencies. We look for physical characteristics of cirrus structures in a region at high galactic latitudes (b ~ –40°) where BOOMERANG performed its deepest integration, combining the BOOMERANG data with other available data sets at different wavelengths. We have detected eight emission patches in the 345 GHz map, consistent with cirrus dust in the Infrared Astronomical Satellite maps. The analysis technique we have developed allows us to identify the location and the shape of cirrus clouds, and to extract the flux from observations with different instruments at different wavelengths and angular resolutions. We study the integrated flux emitted from these cirrus clouds using data from Infrared Astronomical Satellite (IRAS), DIRBE, BOOMERANG and Wilkinson Microwave Anisotropy Probe in the frequency range 23-3000 GHz (13 mm-100 μm wavelength). We fit the measured spectral energy distributions with a combination of a gray body and a power-law spectra considering two models for the thermal emission. The temperature of the thermal dust component varies in the 7-20 K range and its emissivity spectral index is in the 1-5 range. We identified a physical relation between temperature and spectral index as had been proposed in previous works. This technique can be proficiently used for the forthcoming Planck and Herschel missions data.
  The Astrophysical Journal 03/2010; 713(2):959. · 6.02 Impact Factor
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  Available from: Graca Rocha

  Article: Characterization of the BICEP Telescope for High-precision Cosmic Microwave Background Polarimetry

  Y. D. Takahashi, P. A. R. Ade, D. Barkats, J. O. Battle, E. M. Bierman, J. J. Bock, H. C. Chiang, C. D. Dowell, L. Duband, E. F. Hivon, [......], A. E. Lange, E. M. Leitch, P. V. Mason, T. Matsumura, H. T. Nguyen, N. Ponthieu, C. Pryke, S. Richter, G. Rocha, and K. W. Yoon
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  ABSTRACT: The Background Imaging of Cosmic Extragalactic Polarization (BICEP) experiment was designed specifically to search for the signature of inflationary gravitational waves in the polarization of the cosmic microwave background (CMB). Using a novel small-aperture refractor and 49 pairs of polarization-sensitive bolometers, BICEP has completed three years of successful observations at the South Pole beginning in 2006 February. To constrain the amplitude of the inflationary B-mode polarization, which is expected to be at least 7 orders of magnitude fainter than the 3 K CMB intensity, precise control of systematic effects is essential. This paper describes the characterization of potential systematic errors for the BICEP experiment, supplementing a companion paper on the initial cosmological results. Using the analysis pipelines for the experiment, we have simulated the impact of systematic errors on the B-mode polarization measurement. Guided by these simulations, we have established benchmarks for the characterization of critical instrumental properties including bolometer relative gains, beam mismatch, polarization orientation, telescope pointing, sidelobes, thermal stability, and timestream noise model. A comparison of the benchmarks with the measured values shows that we have characterized the instrument adequately to ensure that systematic errors do not limit BICEP's two-year results, and identifies which future refinements are likely necessary to probe inflationary B-mode polarization down to levels below a tensor-to-scalar ratio r = 0.1.
  The Astrophysical Journal 02/2010; 711(2):1141. · 6.02 Impact Factor
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  Available from: Graca Rocha

  Article: Measurement of Cosmic Microwave Background Polarization Power Spectra from Two Years of BICEP Data

  H. C. Chiang, P. A. R. Ade, D. Barkats, J. O. Battle, E. M. Bierman, J. J. Bock, C. D. Dowell, L. Duband, E. F. Hivon, W. L. Holzapfel, [......], T. Matsumura, H. T. Nguyen, N. Ponthieu, C. Pryke, S. Richter, G. Rocha, C. Sheehy, Y. D. Takahashi, J. E. Tolan, and K. W. Yoon
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  ABSTRACT: Background Imaging of Cosmic Extragalactic Polarization (BICEP) is a bolometric polarimeter designed to measure the inflationary B-mode polarization of the cosmic microwave background (CMB) at degree angular scales. During three seasons of observing at the South Pole (2006 through 2008), BICEP mapped ~2% of the sky chosen to be uniquely clean of polarized foreground emission. Here, we present initial results derived from a subset of the data acquired during the first two years. We present maps of temperature, Stokes Q and U, E and B modes, and associated angular power spectra. We demonstrate that the polarization data are self-consistent by performing a series of jackknife tests. We study potential systematic errors in detail and show that they are sub-dominant to the statistical errors. We measure the E-mode angular power spectrum with high precision at 21 ≤ ℓ ≤ 335, detecting for the first time the peak expected at ℓ ~ 140. The measured E-mode spectrum is consistent with expectations from a ΛCDM model, and the B-mode spectrum is consistent with zero. The tensor-to-scalar ratio derived from the B-mode spectrum is r = 0.02+0.31 –0.26, or r < 0.72 at 95% confidence, the first meaningful constraint on the inflationary gravitational wave background to come directly from CMB B-mode polarization.
  The Astrophysical Journal 02/2010; 711(2):1123. · 6.02 Impact Factor
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  Available from: Angiola Orlando

  Article: Characterization of the Millimeter-Wave Polarization of Centaurus A with QUaD

  M. Zemcov, P. Ade, J. Bock, M. Bowden, M. L. Brown, G. Cahill, P. G. Castro, S. Church, T. Culverhouse, R. B. Friedman, [......], C. O'Sullivan, L. Piccirillo, C. Pryke, N. Rajguru, B. Rusholme, R. Schwarz, A. N. Taylor, K. L. Thompson, A. H. Turner, E. Y. S. Wu
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  ABSTRACT: Centaurus (Cen) A represents one of the best candidates for an isolated, compact, highly polarized source that is bright at typical cosmic microwave background (CMB) experiment frequencies. We present measurements of the 4 degree by 2 degree region centered on Cen A with QUaD, a CMB polarimeter whose absolute polarization angle is known to 0.5 degrees. Simulations are performed to assess the effect of misestimation of the instrumental parameters on the final measurement and systematic errors due to the field's background structure and temporal variability from Cen A's nuclear region are determined. The total (Q, U) of the inner lobe region is (1.00 +/- 0.07 (stat.) +/- 0.04 (sys.), -1.72 +/- 0.06 +/- 0.05) Jy at 100 GHz and (0.80 +/- 0.06 +/- 0.06, -1.40 +/- 0.07 +/- 0.08) Jy at 150 GHz, leading to polarization angles and total errors of -30.0 +/- 1.1 degrees and -29.1 +/- 1.7 degrees. These measurements will allow the use of Cen A as a polarized calibration source for future millimeter experiments. Comment: 9 pages, 8 figures, v2 matches version published in ApJ
  The Astrophysical Journal 02/2010; 710(2):1541. · 6.02 Impact Factor
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  Available from: Angiola Orlando

  Article: The QUaD Galactic Plane Survey 1: Maps And Analysis of Diffuse Emission

  T. Culverhouse, P. Ade, J. Bock, M. Bowden, M. L. Brown, G. Cahill, P. G. Castro, S. Church, R. Friedman, K. Ganga, [......], C. O' Sullivan, L. Piccirillo, C. Pryke, N. Rajguru, B. Rusholme, A. N. Taylor, K. L. Thompson, A. H. Turner, E. Y. S. Wu, M. Zemcov
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  ABSTRACT: 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 degrees in galactic longitude l, and -4<b<+4 degrees in galactic latitude b. At 0.02 degree 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 2.35+/-0.01 (stat) +/- 0.02 (sys) for |b|<1 degree, 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 degree) yields mean spectral indices of -0.32 +/- 0.03 and 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 150GHz. We find agreement in polarization fraction between QUaD 100 GHz and WMAP W band, the latter giving 1.1 +/- 0.4 %. Comment: 19 pages, 20 figures
  01/2010;