Measurement of Charge Cloud Size in X-ray SOI Pixel Sensors

Kouichi Hagino; Kenji Oono; Kousuke Negishi; Keigo Yarita; Takayoshi Kohmura; Takeshi G. Tsuru; Takaaki Tanaka; Hiroyuki Uchida; Sodai Harada; Tomoyuki Okuno; Kazuho Kayama; Yuki Amano; Hideaki Matsumura; Koji Mori; Ayaki Takeda; Yusuke Nishioka; Kohei Fukuda; Takahiro Hida; Masataka Yukumoto; Yasuo Arai; Ikuo Kurachi; Toshinobu Miyoshi; Shunji Kishimoto

doi:10.1109/tns.2019.2920281

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arXiv · 1905.13381

Measurement of Charge Cloud Size in X-ray SOI Pixel Sensors

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Abstract

We report on a measurement of the size of charge clouds produced by X-ray photons in X-ray SOI (Silicon-On-Insulator) pixel sensor named XRPIX. We carry out a beam scanning experiment of XRPIX using a monochromatic X-ray beam at 5.0 keV collimated to $\sim 10$ $\mu$m with a 4-$\mu$m$\phi$ pinhole, and obtain the spatial distribution of single-pixel events at a sub-pixel scale. The standard deviation of charge clouds of 5.0 keV X-ray is estimated to be $\sigma_{\rm cloud} = 4.30 \pm 0.07$ $\mu$m. Compared to the detector response simulation, the estimated charge cloud size is well explained by a combination of photoelectron range, thermal diffusion, and Coulomb repulsion. Moreover, by analyzing the fraction of multi-pixel events in various energies, we find that the energy dependence of the charge cloud size is also consistent with the simulation.

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Kouichi Hagino, Kenji Oono, Kousuke Negishi, Keigo Yarita, Takayoshi Kohmura, Takeshi G. Tsuru, Takaaki Tanaka, Hiroyuki Uchida, Sodai Harada, Tomoyuki Okuno, Kazuho Kayama, Yuki Amano, Hideaki Matsumura, Koji Mori, Ayaki Takeda, Yusuke Nishioka, Kohei Fukuda, Takahiro Hida, Masataka Yukumoto, Yasuo Arai, Ikuo Kurachi, Toshinobu Miyoshi, Shunji Kishimoto. 2019-05-31. Measurement of Charge Cloud Size in X-ray SOI Pixel Sensors. https://doi.org/10.1109/tns.2019.2920281

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