# Exploring Cosmic Origins with CORE: The Instrument

## TL;DR

This paper presents the design of CORE, a space-based polarimeter for precise measurement of CMB polarization, optimized for budget constraints and capable of multi-band observations with high sensitivity.

## Contribution

It introduces a novel, no-moving-parts instrument with diffraction-limited detectors covering 60-600 GHz, suitable for medium-size space missions within ESA's Cosmic Vision.

## Key findings

- Projected survey sensitivity of 1.7 μK·arcmin after foreground removal
- Design flexibility for a downscoped version with 3.2 μK·arcmin sensitivity
- Use of Kinetic Inductance Detectors across 19 frequency bands

## Abstract

We describe a space-borne, multi-band, multi-beam polarimeter aiming at a precise and accurate measurement of the polarization of the Cosmic Microwave Background. The instrument is optimized to be compatible with the strict budget requirements of a medium-size space mission within the Cosmic Vision Programme of the European Space Agency. The instrument has no moving parts, and uses arrays of diffraction-limited Kinetic Inductance Detectors to cover the frequency range from 60 GHz to 600 GHz in 19 wide bands, in the focal plane of a 1.2 m aperture telescope cooled at 40 K, allowing for an accurate extraction of the CMB signal from polarized foreground emission. The projected CMB polarization survey sensitivity of this instrument, after foregrounds removal, is 1.7 {\mu}K$\cdot$arcmin. The design is robust enough to allow, if needed, a downscoped version of the instrument covering the 100 GHz to 600 GHz range with a 0.8 m aperture telescope cooled at 85 K, with a projected CMB polarization survey sensitivity of 3.2 {\mu}K$\cdot$arcmin.