Assembly and test of the gas pixel detector for X-ray polarimetry

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• 作者：H. Li^a ; ^b ; H. Feng^a ; ^b ; ^{hfeng@tsinghua.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; F. Muleri^c ; R. Bellazzini^d ; M. Minuti^d ; P. Soffitta^c ; A. Brez^d ; G. Spandre^d ; M. Pinchera^d ; C. Sgró ; ^d ; L. Baldini^d ; R. She^a ; ^b ; E. Costa^c
• 关键词：X-ray ; Polarimetry ; Gas ; Detector ; XIPE ; Astrophysics
• 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
• 出版年：2015
• 出版时间：21 December 2015
• 年：2015
• 卷：804
• 期：Complete
• 页码：155-162
• 全文大小：3221 K

文摘

The gas pixel detector (GPD) dedicated for photoelectric X-ray polarimetry is selected as the focal plane detector for the ESA medium-class mission concept X-ray Imaging and Polarimetry Explorer (XIPE). Here we show the design, assembly, and preliminary test results of a small GPD for the purpose of gas mixture optimization needed for the phase A study of XIPE. The detector is assembled in house at Tsinghua University following a design by the INFN-Pisa group. The improved detector design results in a good uniformity for the electric field. Filled with pure dimethyl ether (DME) at 0.8 atm, the measured energy resolution is 18% at 6 keV and inversely scales with the square root of the X-ray energy. The measured modulation factor is well consistent with that from simulation, up to ~0.6 above 6 keV. The residual modulation is found to be 0.30±0.15%$0.30\pm 0.15\%$ at 6 keV for the whole sensitive area, which can be translated into a systematic error of less than 1% for polarization measurement at a confidence level of 99%. The position resolution of the detector is about 80 μm in FWHM, consistent with previous studies and sufficient for XIPE requirements.