Diagnostics of the CCD using the mesh experiment

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Vol. 436; no. 1; pp. 32 - 39
• Main Authors: Tsunemi, H., Hiraga, J., Mori, K., Yoshita, K., Miyata, E.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 21.10.1999
• Subjects: Charge cloud shape; Charge-coupled device; Mesh experiment; Subpixel resolution; Charge-coupled device; 95.55.Aq; Subpixel resolution; Charge cloud shape; Mesh experiment; 06.90.+v; 07.85.m
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/S0168-9002(99)00596-3

We present here the results of a mesh experiment with which we can measure the shape of a charge cloud generated by the photoabsorption of X-rays inside a charge-coupled device (CCD). The mesh used is made of gold of 13-μm thickness, and has many holes of 1.4 μ m diameter spaced 48 μ m apart. The CCD used has 12 μ m square pixels. A new criterion with which we can determine the precise alignment in the experiment is introduced to eliminate uncertainties. We measured the charge cloud size at three X-ray energies: Al-K (1.5 keV), Mo-L (2.3 keV) and Ti-K (4.5 keV). The shapes can be well represented not by a point-symmetric Gaussian function, but by an axial symmetric Gaussian function with σ of 0.7– 1.5 μ m. The charge cloud size depends weakly on the mean absorption length in silicon. We find that the charge cloud size can be well explained by a simple model inside the CCD. We discuss that the knowledge of the charge cloud size will enable us to improve the position resolution of the CCD.