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Maffei, B.; Ade, Peter A. R.; Tucker, C.; Wakui, E.; Wylde, Richard; Murphy, John A.; Colgan, R.

doi:10.1023/a:1006784404316

Cited by 20 publications

(6 citation statements)

References 4 publications

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“…The length of the horns (if, for example, weight needs to be minimized) and the sidelobe levels can be reduced by adjusting the horn profile away from the standard conical shape (e.g. O'Sullivan et al, 2008, Maffei et al, 2000. Shaping can also be used to increase the aperture efficiency of a horn by moving the phase centre close to the aperture (as could a phase-flattening lens).…”

Section: Hornsmentioning

confidence: 99%

QUBIC: The QU bolometric interferometer for cosmology

Battistelli

Baù

Bennett

et al. 2011

Astroparticle Physics

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One of the major challenges of modern cosmology is the detection of B-mode polarization anisotropies in the Cosmic Microwave Background. These originate from tensor fluctuations of the metric produced during the inflationary phase. Their detection would therefore constitute a major step towards understanding the primordial Universe. The expected level of these anisotropies is however so small that it requires a new generation of instruments with high sensitivity and extremely good control of systematic effects. We propose the QUBIC instrument based on the novel concept of bolometric interferometry, bringing together the sensitivity advantages of bolometric detectors with the systematics effects advantages of interferometry. The instrument will directly observe the sky through an array of entry horns whose signals will be combined together using an optical combiner. The whole set-up is located inside a cryostat. Polarization modulation will be achieved using a rotating half-wave plate and the images of the interference fringes will be formed on two focal planes (separated by a polarizing grid) tiled with bolometers. We show that QUBIC can be considered as a synthetic imager, exactly similar to a usual imager but with a synthesized beam formed by the array of entry horns. Scanning the sky provides an additional modulation of the signal and improve the sky coverage shape. The usual techniques of map-making and power spectrum estimation can then be applied. We show that the sensitivity of such an instrument is comparable with that of an imager with the same number of horns. We anticipate a low level of beam-related systematics thanks to the fact that the synthesized beam is determined by the location of the primary horns. Other systematics should be under good control thanks to an autocalibration technique, specific to our concept, that will permit the accurate determination of most of the instrumental parameters that would otherwise lead to systematics. (C) 2011 Elsevier B.V. All rights reserved

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Section: Hornsmentioning

confidence: 99%

QUBIC: The QU bolometric interferometer for cosmology

Battistelli

Baù

Bennett

et al. 2011

Astroparticle Physics

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“…O'Sullivan et al, 2008, Maffei et al, 2000. Shaping can also be used to increase the aperture efficiency of a horn by moving the phase centre close to the aperture (as could a phase-flattening lens).…”

Section: Hornsmentioning

confidence: 99%

QUBIC: the Q&U Bolometric Interferometer for Cosmology

et al. 2012

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Context. One of the major challenges of modern cosmology is the detection of B-mode polarization anisotropies in the Cosmic Microwave Background. These originate from tensor fluctuations of the metric produced during the inflationary phase. Their detection would therefore constitute a major step towards understanding the primordial Universe. The expected level of these anisotropies is however so small that it requires a new generation of instruments with high sensitivity and extremely good control of systematic effects. Aims. We propose the QUBIC instrument based on the novel concept of bolometric interferometry, bringing together the sensitivity advantages of bolometric detectors with the systematics effects advantages of interferometry. Methods. The instrument will directly observe the sky through an array of entry horns whose signals will be combined together using an optical combiner. The whole set-up is located inside a cryostat. Polarization modulation will be achieved using a rotating half-wave plate and the images of the interference fringes will be formed on two focal planes (separated by a polarizing grid) tiled with bolometers. Results. We show that QUBIC can be considered as a synthetic imager, exactly similar to a usual imager but with a synthesized beam formed by the array of entry horns. Scanning the sky provides an additional modulation of the signal and improve the sky coverage shape. The usual techniques of map-making and power spectrum estimation can then be applied. We show that the sensitivity of such an instrument is comparable with that of an imager with the same number of horns. We anticipate a low level of beam-related systematics thanks to the fact that the synthesized beam is determined by the location of the primary horns. Other systematics should be under good control thanks to an autocalibration technique, specific to our concept, that will permit the accurate determination of most of the systematics parameters.

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“…Dual-profiled corrugated horns have been selected as the best design in terms of shape of the main lobe, very low level of cross polarization, level of sidelobes, control of the phase centre location, low weight and compactness (Clarricoats & Olver 1984;Olver & Xiang 1988;Villa et al 2002b;Maffei et al 2000;Murphy et al 2001). …”

Section: The Focal Plane Unit and The Feed Hornsmentioning

confidence: 99%

Trade-off between angular resolution and straylight contamination in the PLANCK Low Frequency Instrument

Sandri

Villa

Nesti³

et al. 2004

A&A

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Abstract. The study of cosmic microwave background (CMB) anisotropies represents one of the most powerful cosmological tools. After the great success of the two NASA satellite missions COBE and WMAP, P is the third generation of mmwave instruments designed for space observations of CMB anisotropies within the new Cosmic Vision 2020 ESA Science Programme. P will map the whole sky with unprecedented sensitivity, angular resolution and frequency coverage, using two instruments that share the focal region of a 1.5 m off-axis dual reflector telescope: the Low Frequency Instrument (LFI) and the High Frequency Instrument (HFI). In the optimisation of the optical interfaces of the LFI two concurrent demands have to be satisfied: the very good angular resolution (which affects the ability to reconstruct the angular power spectrum of the CMB anisotropies at high multipoles) and a very low level of straylight contamination (which may be one of the most serious sources of systematic effects). We present the results of the optical simulations aimed at establishing the trade-off between angular resolution and straylight rejection, carried out for the 100 GHz channel of the P LFI. Antenna patterns of different models of dual profiled corrugated conical feed horns have been simulated using advanced simulation techniques, considering the whole spacecraft geometry in order to obtain reliable sidelobe predictions. We show the optical computation accuracy necessary to provide strong straylight evaluation in reasonable computational time and demonstrate the inadequacy of a Gaussian feed model in realistic far beam predictions.

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Untitled

Cited by 20 publications

References 4 publications

QUBIC: The QU bolometric interferometer for cosmology

QUBIC: The QU bolometric interferometer for cosmology

QUBIC: the Q&U Bolometric Interferometer for Cosmology

Trade-off between angular resolution and straylight contamination in the PLANCK Low Frequency Instrument

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