Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userQUBIC III: Laboratory Characterization
72
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
A prototype version of the Q & U Bolometric Interferometer for Cosmology (QUBIC) underwent a campaign of testing in the laboratory at Astroparticle Physics and Cosmology in Paris. We report the results of this Technological Demonstrator which successfully shows the feasibility of the principle of Bolometric Interferometry. Characterization of QUBIC includes the measurement of the synthesized beam, the measurement of interference fringes, and the measurement of polarization performance. A modulated and frequency tunable millimetre-wave source in the telescope far-field is used to simulate a point source. The QUBIC pointing is scanned across the point source to produce beam maps. Polarization modulation is measured using a rotating Half Wave Plate. The measured beam matches well to the theoretical simulations and gives QUBIC the ability to do spectro imaging. The polarization performance is excellent with less than 0.5% cross-polarization rejection. QUBIC is ready for deployment on the high altitude site at Alto Chorillo, Argentina to begin scientific operations.
rate research
Read More
QUBIC is an instrument aiming at measuring the B mode polarisation anisotropies at medium scales angular scales (30-200 multipoles). The search for the primordial CMB B-mode polarization signal is challenging, because of many difficulties: smallness of the expected signal, instrumental systematics that could possibly induce polarization leakage from the large E signal into B, brighter than anticipated polarized foregrounds (dust) reducing to zero the initial hope of finding sky regions clean enough to have a direct primordial B-modes observation. The QUBIC instrument is designed to address all aspects of this challenge with a novel kind of instrument, a Bolometric Interferometer, combining the background-limited sensitivity of Transition-Edge-Sensors and the control of systematics allowed by the observation of interference fringe patterns, while operating at two frequencies to disentangle polarized foregrounds from primordial B mode polarization. Its characteristics are described in details in this Technological Design Report.
The Q $&$ U Bolometric Interferometer for Cosmology (QUBIC) is a novel kind of polarimeter optimized for the measurement of the B-mode polarization of the Cosmic Microwave Background (CMB), which is one of the major challenges of observational cosmology. The signal is expected to be of the order of a few tens of nK, prone to instrumental systematic effects and polluted by various astrophysical foregrounds which can only be controlled through multichroic observations. QUBIC is designed to address these observational issues with a novel approach that combines the advantages of interferometry in terms of control of instrumental systematic effects with those of bolometric detectors in terms of wide-band, background-limited sensitivity. The QUBIC synthesized beam has a frequency-dependent shape that results in the ability to produce maps of the CMB polarization in multiple sub-bands within the two physical bands of the instrument (150 and 220 GHz). These features make QUBIC complementary to other instruments and makes it particularly well suited to characterize and remove Galactic foreground contamination. In this article, first of a series of eight, we give an overview of the QUBIC instrument design, the main results of the calibration campaign, and present the scientific program of QUBIC including not only the measurement of primordial B-modes, but also the measurement of Galactic foregrounds. We give forecasts for typical observations and measurements: with three years of integration on the sky and assuming perfect foreground removal as well as stable atmospheric conditions from our site in Argentina, our simulations show that we can achieve a statistical sensitivity to the effective tensor-to-scalar ratio (including primordial and foreground B-modes) $sigma(r)=0.015$.
QUBIC is a unique instrument that crosses the barriers between classical imaging architectures and interferometry taking advantage from both for high sensitivity and systematics mitigation. The scientific target is the detection of the primordial gravitational waves imprint on the Cosmic Microwave Background which are the proof of inflation, holy grail of modern cosmology. In this paper, we show the latest advances in the development of the architecture and the sub-systems of the first module of this instrument to be deployed in Dome Charlie Concordia base - Antarctica in 2015.
The Q and U Bolometric Interferometer for Cosmology (QUBIC) is a ground-based experiment that aims to detect B-mode polarisation anisotropies in the CMB at angular scales around the l=100 recombination peak. Systematic errors make ground-based observations of B modes at millimetre wavelengths very challenging and QUBIC mitigates these problems in a somewhat complementary way to other existing or planned experiments using the novel technique of bolometric interferometry. This technique takes advantage of the sensitivity of an imager and the systematic error control of an interferometer. A cold reflective optical combiner superimposes there-emitted beams from 400 aperture feedhorns on two focal planes. A shielding system composedof a fixed groundshield, and a forebaffle that moves with the instrument, limits the impact of local contaminants. The modelling, design, manufacturing and preliminary measurements of the optical components are described in this paper.
FIRST (Fibered Imager foR a Single Telescope instrument) is a post-AO instrument that enables high contrast imaging and spectroscopy at spatial scales below the diffraction limit. FIRST achieves sensitivity and accuracy by a unique combination of sparse aperture masking, spatial filtering by single-mode fibers and cross-dispersion in the visible. The telescope pupil is divided into sub-pupils by an array of microlenses, coupling the light into single-mode fibers. The output of the fibers are rearranged in a non redundant configuration, allowing the measurement of the complex visibility for every baseline over the 600-900 nm spectral range. A first version of this instrument is currently integrated to the Subaru Extreme AO bench (SCExAO). This paper focuses on the on-going instrument upgrades and testings, which aim at increasing the instruments stability and sensitivity, thus improving the dynamic range. FIRSTv2s interferometric scheme is based on a photonic chip beam combiner. We report on the laboratory characterization of two different types of 5-input beam combiner with enhanced throughput. The interferometric recombination of each pair of sub-pupils is encoded on a single output. Thus, to sample the fringes we implemented a temporal phase modulation by pistoning the segmented mirrors of a Micro-ElectroMechanical System (MEMS). By coupling high angular resolution and spectral resolution in the visible, FIRST offers unique capabilities in the context of the detection and spectral characterization of close companions, especially on 30m-class telescopes.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
