A Polarization Modulator Unit for the Mid- and High-Frequency Telescopes of the LiteBIRD mission

TL;DR

This paper discusses the design and testing of a polarization modulator unit for the LiteBIRD mission's telescopes, crucial for detecting primordial gravitational waves by reducing noise and systematic errors.

Contribution

It introduces a novel polarization modulator unit based on a superconducting magnetic bearing for the LiteBIRD mission's telescopes.

Findings

Successful testing of PMU subsystems at room temperature

Design specifications meet mission requirements

Expected performance enhances CMB polarization measurements

Abstract

The LiteBIRD mission is a JAXA strategic L-class mission for all sky CMB surveys which will be launched in the 2020s. The main target of the mission is the detection of primordial gravitational waves with a sensitivity ofthe tensor-to-scalar ratio {\delta}r <0.001. The polarization modulator unit (PMU) represents a critical and powerful component to suppress 1/f noise contribution and mitigate systematic uncertainties induced by detector gain drift, both for the high-frequency telescope (HFT) and for the mid-frequency telescope (MFT). Each PMUs based on a continuously-rotating transmissive half-wave plate (HWP) held by a superconducting magnetic bearing in a 5K environment. In this proceeding we will present the design and expected performance of the LiteBIRD PMUs and testing performed on every PMU subsystem with a room-temperature rotating disk used as a stand-in for the cryogenic HWP rotor.