Simulations and performance of the QUBIC optical beam combiner

QUBIC, the Q & U Bolometric Interferometer for Cosmology, is a novel ground-based instrument that aims to measure the extremely faint B-mode polarisation anisotropy of the cosmic microwave background at intermediate angular scales (multipoles o

QUBIC: the Q and U bolometric interferometer for cosmology

International audienc

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

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

QUBIC: The Q and U bolometric interferometer for cosmology

The Q & U Bolometric Interferometer for Cosmology, QUBIC, is an innovative experiment designed to measure the polarization of the Cosmic Microwave Background and in particular the signature left therein by the inflationary expansion of the Universe. The expected signal is extremely faint, thus extreme sensitivity and systematic control are necessary in order to attempt this measurement. QUBIC addresses these requirements using an innovative approach combining the sensitivity of Transition Edge Sensor cryogenic bolometers, with the deep control of systematics characteristic of interferometers. This makes QUBIC unique with respect to others classical imagers experiments devoted to the CMB polarization. In this contribution we report a description of the QUBIC instrument including recent achievements and the demonstration of the bolometric interferometry performed in lab. QUBIC will be deployed at the observation site in Alto Chorrillos, in Argentina at the end of 2019

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

QUBIC: using NbSi TESs with a bolometric interferometer to characterize the polarisation of the CMB

Q & U Bolometric Interferometer for Cosmology (QUBIC) is an international ground-based experiment dedicated in the measurement of the polarized fluctuations of the Cosmic Microwave Background. It is based on bolometric interferometry, an original detection technique which combines the immunity to systematic effects of an interferometer with the sensitivity of low-temperature incoherent detectors. QUBIC will be deployed in Argentina, at the Alto Chorrillos mountain site near San Antonio de los Cobres, in the Salta Province. The QUBIC detection chain consists in 2048 NbSi transition edge sensors (TESs) cooled to 350 mK.The voltage-biased TESs are read out with time domain multiplexing based on Superconducting QUantum Interference Devices at 1 K and a novel SiGe application-specific integrated circuit at 60 K allowing to reach an unprecedented multiplexing factor equal to 128. The QUBIC experiment is currently being characterized in the laboratory with a reduced number of detectors before upgrading to the full instrument. I will present the last results of this characterization phase with a focus on the detectors and readout system