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

TL;DR

QUBIC is a ground-based bolometric interferometer using NbSi TESs and advanced multiplexing to measure polarized CMB fluctuations, aiming for high sensitivity and systematic immunity.

Contribution

This paper introduces the use of NbSi TESs with a novel multiplexing system in the QUBIC experiment for improved CMB polarization measurements.

Findings

Successful characterization of NbSi TES detectors in the lab.

Implementation of a high multiplexing factor of 128 with ASIC readout.

Validation of the detector and readout system performance.

Abstract

QUBIC (Q \& U Bolometric Interferometer for Cosmology) is an international ground-based experiment dedicated in the measurement of the polarized fluctuations of the Cosmic Microwave Background (CMB). It is based on bolometric interferometry, an original detection technique which combine 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 350mK.The voltage-biased TESs are read out with Time Domain Multiplexing based on Superconducting QUantum Interference Devices (SQUIDs) at 1 K and a novel SiGe Application-Specific Integrated Circuit (ASIC) at 60 K allowing to reach an unprecedented multiplexing (MUX) factor equal to 128. The QUBIC experiment is currently being characterized in the lab 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.