X-ray polarimetry based on gas pixel detectors (GPDs) has reached a high level of maturity thanks to the Imaging X-ray Polarimeter Explorer (IXPE) providing the first-ever spatially resolved polarimetric measurements. However, as this a new technique, a few unexpected effects have emerged in the course of in-flight operations. In particular, it was almost immediately found that, the unpolarized calibration sources on-board were showing radially polarized halos. The origin of these features was recognized in a correlation between the error in reconstructing the absorption point of the X-ray photon and the direction of its electric field vector. Here, we present and discuss this effect in detail, showing that it is possible to provide a simple and robust mathematical formalism to handle it. We further show its role and relevance for the recent IXPE measures as well as for the use of GPD-based techniques in general. We also illustrate how to model it in the context of studying extended sources.

Polarisation leakage due to errors in track reconstruction in gas pixel detectors

Silvestri S.;Baldini L.;
2023-01-01

Abstract

X-ray polarimetry based on gas pixel detectors (GPDs) has reached a high level of maturity thanks to the Imaging X-ray Polarimeter Explorer (IXPE) providing the first-ever spatially resolved polarimetric measurements. However, as this a new technique, a few unexpected effects have emerged in the course of in-flight operations. In particular, it was almost immediately found that, the unpolarized calibration sources on-board were showing radially polarized halos. The origin of these features was recognized in a correlation between the error in reconstructing the absorption point of the X-ray photon and the direction of its electric field vector. Here, we present and discuss this effect in detail, showing that it is possible to provide a simple and robust mathematical formalism to handle it. We further show its role and relevance for the recent IXPE measures as well as for the use of GPD-based techniques in general. We also illustrate how to model it in the context of studying extended sources.
2023
Bucciantini, N.; Di Lalla, N.; Romani, R. W. R.; Silvestri, S.; Negro, M.; Baldini, L.; Tennant, A. F.; Manfreda, A.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/1209848
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