X-ray imaging polarimetry with a 2.5-$\mathrm{\mu}$m pixel CMOS sensor for visible light at room temperature

Kazunori Asakura; Kiyoshi Hayashida; Takashi Hanasaka; Tomoki Kawabata; Tomokage Yoneyama; Koki Okazaki; Shuntaro Ide; Hirofumi Noda; Hironori Matsumoto; Hiroshi Tsunemi; Hisamitsu Awaki; Hiroshi Nakajima

arXiv · 1906.00012

X-ray imaging polarimetry with a 2.5-$\mathrm{\mu}$m pixel CMOS sensor for visible light at room temperature

Kazunori Asakura·Kiyoshi Hayashida·Takashi Hanasaka·Tomoki Kawabata·Tomokage Yoneyama·Koki Okazaki·Shuntaro Ide·Hirofumi Noda·Hironori Matsumoto·Hiroshi Tsunemi·Hisamitsu Awaki·Hiroshi Nakajima

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Abstract

X-ray polarimetry in astronomy has not been exploited well, despite its importance. The recent innovation of instruments is changing this situation. We focus on a complementary MOS (CMOS) pixel detector with small pixel size and employ it as an x-ray photoelectron tracking polarimeter. The CMOS detector we employ is developed by GPixel Inc., and has a pixel size of 2.5 $\mathrm{\mu}$m $\times$ 2.5 $\mathrm{\mu}$m. Although it is designed for visible light, we succeed in detecting x-ray photons with an energy resolution of 176 eV (FWHM) at 5.9 keV at room temperature and the atmospheric condition. We measure the x-ray detection efficiency and polarimetry sensitivity by irradiating polarized monochromatic x-rays at BL20B2 in SPring-8, the synchrotron radiation facility in Japan. We obtain modulation factors of 7.63% $\pm$ 0.07% and 15.5% $\pm$ 0.4% at 12.4 keV and 24.8 keV, respectively. It demonstrates that this sensor can be used as an x-ray imaging spectrometer and polarimeter with the highest spatial resolution ever tested.

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Kazunori Asakura, Kiyoshi Hayashida, Takashi Hanasaka, Tomoki Kawabata, Tomokage Yoneyama, Koki Okazaki, Shuntaro Ide, Hirofumi Noda, Hironori Matsumoto, Hiroshi Tsunemi, Hisamitsu Awaki, Hiroshi Nakajima. 2019-05-31. X-ray imaging polarimetry with a 2.5-$\mathrm{\mu}$m pixel CMOS sensor for visible light at room temperature. https://arxiv.org/abs/1906.00012

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