Structured generalized sliced Wasserstein distance for keV X-ray polarization analysis with Gas Pixel Detector

Fuente: arXiv
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Auteurs principaux: Ai, Pengcheng, Qin, Hongtao, Sun, Xiangming, Wang, Dong, Feng, Huanbo, Liu, Hongbang
Format: Preprint
Publié: 2026
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author Ai, Pengcheng
Qin, Hongtao
Sun, Xiangming
Wang, Dong
Feng, Huanbo
Liu, Hongbang
author_facet Ai, Pengcheng
Qin, Hongtao
Sun, Xiangming
Wang, Dong
Feng, Huanbo
Liu, Hongbang
contents Because of the special angular distribution of excited electrons by the photoelectric effect, the Gas Pixel Detector (GPD) is effective in measuring keV X-ray polarization of astrophysical events (e.g. gamma-ray bursts), by capturing ionization tracks of excited electrons as polarized images. Traditionally, the emission angles of photoelectrons are extracted from polarized images first, and statistics are then performed on these angles to infer the polarization direction and intensity. However, observation with the wide field of view requires the incident angle of X-rays not directly attainable through the traditional analysis process. In this paper, we propose using the generalized sliced Wasserstein (GSW) distance, projected by neural networks with random weights, as a completely data-driven approach to analyze X-ray polarization based on two-dimensional polarized images. We find the structures of the randomized neural networks matter when focusing on different aspects of the polarized images, and take advantage of the discrimination abilities by different neural network structures. The proposed method, named the structured GSW distance, successfully distinguishes polarized images with different configurations of incident angles and polarization directions. Furthermore, we build a simplified statistical model based on the von Mises distribution and the circular Wasserstein distance and compare the model against the proposed method, showing their high consistency. The computational method reported in this paper may benefit GPD-based polarimetry in astroparticle experiments and also pattern analysis on raw data from pixel detectors.
format Preprint
id arxiv_https___arxiv_org_abs_2603_03384
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Structured generalized sliced Wasserstein distance for keV X-ray polarization analysis with Gas Pixel Detector
Ai, Pengcheng
Qin, Hongtao
Sun, Xiangming
Wang, Dong
Feng, Huanbo
Liu, Hongbang
Data Analysis, Statistics and Probability
Instrumentation and Methods for Astrophysics
Instrumentation and Detectors
Because of the special angular distribution of excited electrons by the photoelectric effect, the Gas Pixel Detector (GPD) is effective in measuring keV X-ray polarization of astrophysical events (e.g. gamma-ray bursts), by capturing ionization tracks of excited electrons as polarized images. Traditionally, the emission angles of photoelectrons are extracted from polarized images first, and statistics are then performed on these angles to infer the polarization direction and intensity. However, observation with the wide field of view requires the incident angle of X-rays not directly attainable through the traditional analysis process. In this paper, we propose using the generalized sliced Wasserstein (GSW) distance, projected by neural networks with random weights, as a completely data-driven approach to analyze X-ray polarization based on two-dimensional polarized images. We find the structures of the randomized neural networks matter when focusing on different aspects of the polarized images, and take advantage of the discrimination abilities by different neural network structures. The proposed method, named the structured GSW distance, successfully distinguishes polarized images with different configurations of incident angles and polarization directions. Furthermore, we build a simplified statistical model based on the von Mises distribution and the circular Wasserstein distance and compare the model against the proposed method, showing their high consistency. The computational method reported in this paper may benefit GPD-based polarimetry in astroparticle experiments and also pattern analysis on raw data from pixel detectors.
title Structured generalized sliced Wasserstein distance for keV X-ray polarization analysis with Gas Pixel Detector
topic Data Analysis, Statistics and Probability
Instrumentation and Methods for Astrophysics
Instrumentation and Detectors
url https://arxiv.org/abs/2603.03384