Design and tests of the hard X-ray polarimeter X-Calibur

TL;DR

X-Calibur is a newly designed hard X-ray polarimeter that combines a low-Z scatterer with CZT detectors to measure polarization in 10-80 keV X-rays, promising new insights into high-energy astrophysical phenomena.

Contribution

The paper presents the design, construction, and testing of X-Calibur, a novel polarimeter optimized for the 10-80 keV energy range, integrating a low-Z scatterer with CZT detectors.

Findings

High detection efficiency of approximately 100%.

Effective measurement of X-ray polarization in the 10-80 keV range.

Successful integration with the InFOCuS telescope.

Abstract

X-ray polarimetry promises to give qualitatively new information about high-energy astrophysical sources, such as binary black hole systems, micro-quasars, active galactic nuclei, and gamma-ray bursts. We designed, built and tested a hard X-ray polarimeter X-Calibur to be used in the focal plane of the InFOCuS grazing incidence hard X-ray telescope. X-Calibur combines a low-Z Compton scatterer with a CZT detector assembly to measure the polarization of 10-80 keV X-rays making use of the fact that polarized photons Compton scatter preferentially perpendicular to the electric field orientation. X-Calibur achieves a high detection efficiency of order unity.