The QUBIC experiment

The Q & U Bolometric Interferometer for Cosmology (QUBIC) is a cosmology experiment which aims to measure the B-mode polarization of the Cosmic Microwave Background (CMB). Measurements of the primordial B-mode pattern of the CMB polarization is in fact among the most exciting goals in cosmology as it would allow testing the inflationary paradigm, an exponential expansion occurred during the first 10 1233 seconds of the Universe age. A large number of experiments are attempting to measure the B-modes, from the ground and from the stratosphere using classic imaging techniques. The QUBIC collaboration is developing an innovative concept to measure CMB polarization implementing bolometric interferometry which mixes the high sensitivity of bolometric detectors with an accurate systematics control due to the interferometric nature of the experiment. QUBIC is at an advanced state of tests on all sub-systems and we are planning to start with measurements by the end of 2018 from Alto Chorillo in Argentina

QUBIC: the Q and U bolometric interferometer for cosmology

International audienc

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

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