QUBIC: the Q&U Bolometric Interferometer for Cosmology. A novel way to look at the polarized Cosmic Microwave Background.

In this paper we describe QUBIC, an experiment that takes up the challenge posed by the detection of primordial gravitational waves with a novel approach, that combines the sensitivity of state-of-the art bolometric detectors with the systematic effects control typical of interferometers. The so-called 'self-calibration' is a technique deeply rooted in the interferometric nature of the instrument and allows us to clean the measured data from instrumental effects. The first module of QUBIC is a dual band instrument (150 GHz and 220 GHz) that will be deployed in Argentina during Fall 2018

Thermal architecture for the QUBIC cryogenic receiver

International audienceQUBIC, the QU Bolometric Interferometer for Cosmology, is a novel forthcoming instrument to measure the B-mode polarization anisotropy of the Cosmic Microwave Background. The detection of the B-mode signal will be extremely challenging; QUBIC has been designed to address this with a novel approach, namely bolometric interferometry. The receiver cryostat is exceptionally large and cools complex optical and detector stages to 40 K, 4 K, 1 K and 350 mK using two pulse tube coolers, a novel 4He sorption cooler and a double-stage 3He/4He sorption cooler. We discuss the thermal and mechanical design of the cryostat, modelling and thermal analysis, and laboratory cryogenic testing

Detection chain and electronic readout of the QUBIC instrument

International audienceThe Q and U Bolometric Interferometer for Cosmology (QUBIC) Technical Demonstrator (TD) aiming to shows the feasibility of the combination of interferometry and bolometric detection. The electronic readout system is based on an array of 128 NbSi Transition Edge Sensors cooled at 350mK readout with 128 SQUIDs at 1K controlled and amplified by an Application Specific Integrated Circuit at 40K. This readout design allows a 128:1 Time Domain Multiplexing. We report the design and the performance of the detection chain in this paper. The technological demonstrator unwent a campaign of test in the lab. Evaluation of the QUBIC bolometers and readout electronics includes the measurement of I-V curves, time constant and the Noise Equivalent Power. Currently the mean Noise Equivalent Power is ~ 2 x 10-16W= p √H

QUBIC: the Q and U bolometric interferometer for cosmology

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Angular resolution at map level in the QUBIC instrument

Since its discovery in the 1960s, the cosmic microwave background (CMB) radiation has become a very important observational tool to understand the physics of the early universe. The parameter r, defined as the relative amplitude of tensor to scalar perturbations, is currently constrained to the range r < 0.056. QUBIC is a ground-based instrument designed to search for very weak B-mode signals in polarization anisotropies at intermediate angular scales (l 3c 30 12 200). To achieve this goal, QUBIC combines two widely used techniques in the CMB community: interferometry and bolometry. In this work, we compute the angular resolution for an end-to-end simulation using two independent methods: Fit and Sigma. We conclude that the reconstruction performed by the software is appropriate since the resolution measured with both calibrated methods coincides with the theoretical value of the expected resolution.Desde su descubrimiento en los a\u2dcnos 1960, el fondo c\ub4osmico de microondas (CMB, por sus siglas en ingl\ub4es) se ha convertido en una importante herramienta observacional para entender la f\ub4\u131sica del universo temprano. El par\ub4ametro r, definido como la amplitud de las perturbaciones tensoriales relativas a las escalares, est\ub4a acotado actualmente al rango r < 0.056. QUBIC es un instrumento terrestre dise\u2dcnado para buscar se\u2dcnales muy d\ub4ebiles de los modos B en las anisotrop\ub4\u131as de la polarizaci\ub4on a escalas angulares intermedias (l 3c 30 12 200). Para lograr este objetivo, QUBIC combina dos t\ub4ecnicas muy usadas en la comunidad CMB: interferometr\ub4\u131a y bolometr\ub4\u131a. En este trabajo calculamos la resoluci\ub4on angular de una simulaci\ub4on end-to-end con dos m\ub4etodos independientes: Fit y Sigma. Concluimos que la reconstrucci\ub4on que realiza el software es apropiada ya que la resoluci\ub4on medida con ambos m\ub4etodos calibrados coincide con los valores te\ub4oricos de la resoluci\ub4on esperada

Optical modelling and analysis of the Q and U bolometric interferometer for cosmology

International audienceRemnant radiation from the early universe, known as the Cosmic Microwave Background (CMB), has been redshifted and cooled, and today has a blackbody spectrum peaking at millimetre wavelengths. The QUBIC (Q&U Bolometric Interferometer for Cosmology) instrument is designed to map the very faint polaristion structure in the CMB. QUBIC is based on the novel concept of bolometric interferometry in conjunction with synthetic imaging. It will have a large array of input feedhorns, which creates a large number of interferometric baselines. The beam from each feedhorn is passed through an optical combiner, with an off-axis compensated Gregorian design, to allow the generation of the synthetic image. The optical-combiner will operate in two frequency bands (150 and 220 GHz with 25% and 18.2 % bandwidth respectively) while cryogenically cooled TES bolometers provide the sensitivity required at the image plane. The QUBIC Technical Demonstrator (TD), a proof of technology instrument that contains 64 input feed-horns, is currently being built and will be installed in the Alto Chorrillos region of Argentina. The plan is then for the full QUBIC instrument (400 feed-horns) to be deployed in Argentina and obtain cosmologically significant results. In this paper we will examine the output of the manufactered feed-horns in comparison to the nominal design. We will show the results of optical modelling that has been performed in anticipation of alignment and calibration of the TD in Paris, in particular testing the validity of real laboratory environments. We show the output of large calibrator sources (50 ° full width haf max Gaussian beams) and the importance of accurate mirror definitions when modelling large beams. Finally we describe the tolerance on errors of the position and orientation of mirrors in the optical combiner