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

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$\varphi$ 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 ${\sigma }_{\mathrm{cloud}}=4.30\pm 0.07$ $\mu$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.

arXiv comment9 pages, 12 figures, accepted for publication in IEEE Transactions on Nuclear Science

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• In-Orbit Performance of the Hard X-ray Detector on board Suzaku
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Cited by in corpus (2)

• Development of the detector simulation framework for the Wideband Hybrid X-ray Imager onboard FORCE
• A detailed study on spectroscopic performance of SOI pixel detector with a pinned depleted diode structure for X-ray astronomy