Broad-Band Soft X-ray Polarimetry

TL;DR

This paper presents a novel broad-band soft X-ray polarimeter that measures linear polarization across 0.2 to 0.8 keV using multilayer optics and spectroscopic techniques, enabling detailed polarization studies of X-ray sources.

Contribution

The paper introduces a new instrument design for broad-band soft X-ray polarimetry utilizing multilayer-coated optics and spectroscopic dispersion, with potential applications in space missions.

Findings

Design achieves >50% modulation over 0.2-0.8 keV band.

Laboratory work on key components has begun.

Potential for deployment in small or large X-ray observatories.

Abstract

We developed an instrument design capable of measuring linear X-ray polarization over a broad-band using conventional spectroscopic optics. A set of multilayer-coated flats reflects the dispersed X-rays to the instrument detectors. The intensity variation with position angle is measured to determine three Stokes parameters: I, Q, and U -- all as a function of energy. By laterally grading the multilayer optics and matching the dispersion of the gratings, one may take advantage of high multilayer reflectivities and achieve modulation factors > 50% over the entire 0.2 to 0.8 keV band. This instrument could be used in a small orbiting mission or scaled up for the International X-ray Observatory. Laboratory work has begun that would demonstrate the capabilities of key components.