Q&U Bolometric Interferometer for Cosmology: Technical and Design Report

QUBIC COLABORATION (AUMONT, J. ET AL); GARCIA, B (COMO MIEMBRO DE QUBIC)

2016-04-01/2017-05-11

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iNTER Y mULTI DISCIPLINAR

Promocion general del conocimiento

QUBIC, now in its construction phase, is dedicated to the exploration of the inflation age of the Universe. By detectingand characterizing the Cosmic Microwave Background B-mode polarization, QUBIC will contribute to find the?smoking gun? of inflation and to discriminate among the numerous models consistent with current data. The primordialB-modes (as opposed to E-modes) is the unique direct observational signature of the inflationary phase thatis thought to have taken place in the early Universe, generating primeval perturbations, producing Standard Modelelementary particles and giving its generic features to our Universe (flatness, homogeneity. . . ).Recent results from the BICEP2 and the Planck collaborations have brought the importance of the quest for Bmodesto the attention of a wide audience well beyond the cosmology community. The original claim from BICEP2,contradicted by Planck later on has also shown how challenging the search for primordial B-mode polarization is,because of many difficulties: smallness of the expected signal, instrumental systematics that could possibly inducepolarization leakage from the large E signal into B, brighter than anticipated polarized foregrounds (dust) reducingto zero the initial hope of finding sky regions clean enough to have a direct primordial B-modes observation.QUBIC 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 systematicsallowed by the observation of interference fringe patterns, while operating at two frequencies to disentangle polarizedforegrounds from primordial B mode polarization.QUBIC is the only European ground based B-mode project with the scientific potential of discovering and measuringB-modes. It is the natural project for the European CMB community to continue at the edge-cutting level it hasreached with Planck.With the measurement of the Cosmic Microwave B-mode Polarization in two bands at 150 and 220 GHz, withtwo years of continuous observations from Alto Chorillos near San Antonio de los Cobres, Argentina, the first QUBICmodule would be able to constrain the ratio of the primordial tensor to scalar perturbations power spectra amplitudeswith a conservative projected uncertainty of (r) = 0:02, while having a good control of foregrounds contaminationthanks to its dual band nature.Depending on the scientific and technological results of the first module we could envidage to construct moreQUBIC modules operating at three frequencies (90, 150 and 220 GHz) that could feature design upgrades in orderto achieve a higher sensitivity, and could preferentially be deployed in Antartica to take benefit of its exquisiteatmospheric conditions. These could include different detectors (eg MKIDs), larger horn arrays or number of detectors,different optical combiner design, ... QUBIC is therefore a project dedicated to grow and could be a EuropenStage-IV CMB Polarization experiment.QUBIC has been and will be implemented through successive steps:1. R&D to design the instrument (now finalized)2. Validation of the detections chain (now finalized)3. Validation of the technological demonstrator (less detectors and horns than the final instrument, but in thenominal cryostat). This will occur in the course of 2017.4. Construction and operations of the of the first module which will happen in the second half of 2017.5. Optionaly, construction and operations of a number of additional modules to complete the QUBIC observatory.More details can be found on the QUBIC website : http://qubic.in2p3.fr/QUBIC/Home.html