The future of X-ray polarimetry towards the 3-Dimensional photoelectron track reconstruction

Dawoon E. Kim; Alessandro Di Marco; Paolo Soffitta; Enrico Costa; Sergio Fabiani; Fabio Muleri; Ajay Ratheesh; Fabio La Monaca; John Rankin; Ettore Del Monte; Alda Rubini

arXiv · 2309.17206

The future of X-ray polarimetry towards the 3-Dimensional photoelectron track reconstruction

Dawoon E. Kim·Alessandro Di Marco·Paolo Soffitta·Enrico Costa·Sergio Fabiani·Fabio Muleri·Ajay Ratheesh·Fabio La Monaca·John Rankin·Ettore Del Monte·Alda Rubini

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Abstract

The development of the first X-ray polarimeter, based on the photoelectric effect 20 years ago and implemented thanks to advances in gas amplification structures and readout techniques, had a significant impact in opening a new window for X-ray polarimetry. This system measures the X-ray polarization by reconstructing the initial direction of the photoelectron, emitted by the interaction of an incident photon with an atomic electron, in a gas mixture from an ionization track collected on a two-dimensional plane. However, actual X-ray polarimeters, are still requiring relatively long exposure time and cannot coupled with high effective area mirrors or concentrators. In this context, the high yield polarimetry experiment in X-rays (Hype-X) project is currently underway, aiming to improve the sensitivity of the next generation X-ray polarimetry detectors taking advantage of the recent advancements in imaging techniques for high-resolution time projection chambers. In particular, we are evaluating the use of TIMEPIX3 to be applied for the read-out of a gas detector, which will allow us to obtain a three-dimensional image of the photoelectron track. To evaluate the improvement achievable by using a 3D track reconstruction, in this paper, we have reproduced a three-dimensional photoelectron track from a 'Geant4' Monte Carlo simulation and examined the sensitivity of X-ray polarimetry using a new three-dimensional track reconstruction algorithm. We report the improvement of the modulation factor with three-dimensional track reconstruction as $\sim5\%$ (relative) in the 2-8 keV range and $\sim17\%$ (relative) in the 2-4 keV range compared to the current two-dimensional polarimetry system. This is equivalent to add a further telescope to the three-telescope systems now employed in space on board the IXPE mission.

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Dawoon E. Kim, Alessandro Di Marco, Paolo Soffitta, Enrico Costa, Sergio Fabiani, Fabio Muleri, Ajay Ratheesh, Fabio La Monaca, John Rankin, Ettore Del Monte, Alda Rubini. 2023-09-29. The future of X-ray polarimetry towards the 3-Dimensional photoelectron track reconstruction. https://arxiv.org/abs/2309.17206

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