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 ∼10μm with a 4-μmϕ 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 σcloud=4.30±0.07μm. 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.
@article{arxiv.1905.13381,
title = {Measurement of Charge Cloud Size in X-ray SOI Pixel Sensors},
author = {Kouichi Hagino and Kenji Oono and Kousuke Negishi and Keigo Yarita and Takayoshi Kohmura and Takeshi G. Tsuru and Takaaki Tanaka and Hiroyuki Uchida and Sodai Harada and Tomoyuki Okuno and Kazuho Kayama and Yuki Amano and Hideaki Matsumura and Koji Mori and Ayaki Takeda and Yusuke Nishioka and Kohei Fukuda and Takahiro Hida and Masataka Yukumoto and Yasuo Arai and Ikuo Kurachi and Toshinobu Miyoshi and Shunji Kishimoto},
journal= {arXiv preprint arXiv:1905.13381},
year = {2019}
}
Comments
9 pages, 12 figures, accepted for publication in IEEE Transactions on Nuclear Science