Modelling TES non-linearity induced by a rotating HWP in a CMB polarimeter

Abstract

Most upcoming CMB experiments are planning to deploy between a few thousand and a few hundred thousand TES bolometers in order to drastically increase sensitivity and unveil the B-mode signal. Differential systematic effects and $1/f$ noise are two of the challenges that need to be overcome in order to achieve this result. In recent years, rotating Half-Wave Plates have become increasingly more popular as a solution to mitigate these effects, especially for those experiments that are targeting the largest angular scales. However, other effects may appear when a rotating HWP is being employed. In this paper we focus on HWP synchronous signals, which are due to intensity to polarization leakage induced by a rotating cryogenic multi-layer sapphire HWP employed as the first optical element of the telescope system. We use LiteBIRD LFT as a case study and we analyze the interaction between these spurious signals and TES bolometers, to determine whether this signal can contaminate the bolometer response. We present the results of simulations for a few different TES model assumptions and different spurious signal amplitudes. Modelling these effects is fundamental to find what leakage level can be tolerated and minimize non-linearity effects of the bolometer response.

arXiv comment7 pages, 4 figures, submitted to the Journal of Low Temperature Physics: LTD19 Special Edition

References in corpus (7)

• The Simons Observatory: Science goals and forecasts
• An All-Sky Analysis of Polarization in the Microwave Background
• A Probe of Primordial Gravity Waves and Vorticity
• The POLARBEAR-2 and the Simons Array Experiment
• LiteBIRD: JAXA's new strategic L-class mission for all-sky surveys of cosmic microwave background polarization
• Performance of a continuously rotating half-wave plate on the POLARBEAR telescope
• Intensity-Coupled-Polarization in Instruments with a Continuously Rotating Half-Wave Plate

Cited by in corpus (1)

• MNTES: Modeling Nonlinearity of TES detectors for Enhanced Cosmic Microwave Background measurements with LiteBIRD