Showing papers by "Joanne E. Hill published in 2018"
01 Feb 2018-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, a data processing algorithm for angular reconstruction and event selection applied to 2D photoelectron track images from X-ray polarimeters is presented, which reconstructs the initial emission angle of a photo-electron from the initial portion of the track, which is obtained by continuously cutting a track until the image moments or number of pixels fall below tunable thresholds.
Abstract: We present a data processing algorithm for angular reconstruction and event selection applied to 2-D photoelectron track images from X-ray polarimeters. The method reconstructs the initial emission angle of a photoelectron from the initial portion of the track, which is obtained by continuously cutting a track until the image moments or number of pixels fall below tunable thresholds. In addition, event selection which rejects round tracks quantified with eccentricity and circularity is performed so that polarimetry sensitivity considering a trade-off between the modulation factor and signal acceptance is maximized. The modulation factors with applying track selection are 26 . 6 ± 0 . 4 , 46 . 1 ± 0 . 4 , 62 . 3 ± 0 . 4 , and 61 . 8 ± 0 . 3 % at 2.7, 4.5, 6.4, and 8.0 keV, respectively, using the same data previously analyzed by Iwakiri et al. (2016), where the corresponding numbers are 26 . 9 ± 0 . 4 , 43 . 4 ± 0 . 4 , 54 . 4 ± 0 . 3 , and 59 . 1 ± 0 . 3 %. The method improves polarimeter sensitivity by 5%–10% at the high energy end of the band previously presented (Iwakiri et al. 2016).
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