Hard X / soft gamma ray polarimetry using a Laue lens

TL;DR

This paper explores the use of Laue lens technology for high-sensitivity, high-angular resolution polarimetric observations in the 100 keV to 600 keV range, leveraging recent advances in crystal diffraction.

Contribution

It proposes a novel telescope design using Laue lenses for efficient gamma-ray polarimetry, combining crystal diffraction with pixelated detectors for improved performance.

Findings

Potential for high-sensitivity polarization measurements

Effective focusing of soft gamma rays with Laue lenses

Compatibility with Compton tracking detectors

Abstract

Hard X / soft gamma-ray polarimetric analysis can be performed efficiently by the study of Compton scattering anisotropy in a detector composed of fine pixels. But in the energy range above 100 keV where sources flux are extremely weak and instrumental background very strong, such delicate measurement is actually very difficult to perform. Laue lens is an emerging technology based on diffraction in crystals allowing the concentration of soft gamma rays. This kind of optics can be applied to realize an efficient high-sensitivity and high-angular resolution telescope, at the cost of a field of view reduced to a few arcmin though. A 20 m focal length telescope concept focusing in the 100 keV - 600 keV energy range is taken as example here to show that recent progresses in the domain of high-reflectivity crystals can lead to very appealing performance. The Laue lens being fully transparent to polarization, this kind of telescope would be well suited to perform polarimetric studies since the ideal focal plan is a stack of finely pixelated planar detectors - in order to reconstruct the point spread function - which is also ideal to perform Compton tracking of events.