Measurement of the Charge Cloud Shape Generated in the Fully Depleted Back-Illuminated Charge-Coupled Device

The mesh experiment enables us to specify the X-ray point of interaction with a subpixel resolution. Miyata et al. [Jpn. J. Appl. Phys. 41 (2002) 5827] measured the charge cloud shape produced in a back-illuminated (BI) charge-coupled device (CCD). They found that there are two components of the charge cloud shape: a narrow component and a broad component. The size of the narrow component is 2.8-5.7 mum in units of standard deviation and strongly depends on the attenuation length of incident X-rays in Si, suggesting that it originates in the depletion region. On the other hand, the size of the broad component is roughly constant at similar or equal to 13 mum and does not depend on X-ray energies, suggesting that it originates in the field-free region. We applied the mesh experiment with the fully depleted BI CCD and found that there is a single component of the charge cloud with a size similar to that of the narrow component in Miyata et al.'s. We thus confirmed that the narrow and broad components originate in the depletion region and the field-free region, respectively.