8 research outputs found
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&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
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
Performance of NbSi transition-edge sensors readout with a 128 MUX factor for the QUBIC experiment
QUBIC (the Q&U Bolometric Interferometer for Cosmology) is a ground-based experiment which seeks to improve the current constraints on the amplitude of primordial gravitational waves. It exploits the unique technique,
among Cosmic Microwave Background experiments, of bolometric interferometry, combining together the sensitivity of bolometric detectors with the control of systematic effects typical of interferometers. QUBIC will
perform sky observations in polarization, in two frequency bands centered at 150 and 220 GHz, with two kilopixel focal plane arrays of NbSi Transition-Edge Sensors (TES) cooled down to 350 mK. A subset of the QUBIC
instrument, the so called QUBIC Technological Demonstrator (TD), with a reduced number of detectors with
respect to the full instrument, will be deployed and commissioned before the end of 2018.
The voltage-biased TES are read out with Time Domain Multiplexing and an unprecedented multiplexing
(MUX) factor equal to 128. This MUX factor is reached with two-stage multiplexing: a traditional one exploiting Superconducting QUantum Interference Devices (SQUIDs) at 1 K and a novel SiGe Application-Specific
Integrated Circuit (ASIC) at 60 K. The former provides a MUX factor of 32, while the latter provides a further
4. Each TES array is composed of 256 detectors and read out with four modules of 32 SQUIDs and two ASICs.
A custom software synchronizes and manages the readout and detector operation, while the TES are sampled
at 780 Hz (100kHz/128 MUX rate).
In this work we present the experimental characterization of the QUBIC TES arrays and their multiplexing
readout chain, including time constant, critical temperature, and noise properties
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