An algorithm to calibrate and correct the response to unpolarized radiation of the X-ray polarimeter on board IXPE

Abstract

The Gas Pixel Detector is an X-ray polarimeter to fly on-board IXPE and other missions. To correctly measure the source polarization, the response of IXPE's GPDs to unpolarized radiation has to be calibrated and corrected. In this paper we describe the way such response is measured with laboratory sources and the algorithm to apply such correction to the observations of celestial sources. The latter allows to correct the response to polarization of single photons, therefore allowing great flexibility in all the subsequent analysis. Our correction approach is tested against both monochromatic and non-monochromatic laboratory sources and with simulations, finding that it correctly retrieves the polarization up to the statistical limits of the planned IXPE observations.

Accepted for publication in The Astronomical Journal. 18 pages, 14 figures

References in corpus (7)

• Analyzing the Data from X-ray Polarimeters with Stokes Parameters
• Design, Construction, and Test of the Gas Pixel Detectors for the IXPE Mission
• A Sealed Gas Pixel Detector for X-ray Astronomy
• Direct reading of charge multipliers with a self-triggering CMOS analog chip with 105k pixels at 50 micron pitch
• Re-detection and a Possible Time Variation of Soft X-ray Polarisation from the Crab
• PolarLight: a CubeSat X-ray Polarimeter based on the Gas Pixel Detector
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