What's all that x-ray detector stuff, anyhow?

Wednesday, November 14, 2012 - 3:00pm

Sven Herrmann, SLAC/PPA

X-ray detectors have enabled many scientific discoveries in a variety of fields such as astronomy, biology, material science, etc.

In this seminar an overview of the working principles and common variants of silicon-based x-ray detectors will be presented.

Pixel Array Detectors (PAD), now very popular, can be divided in two categories: photon counters and integrators.

Photon counter cameras can provide large dynamic range by detecting one photon at a time producing very good quality images but with a limitation on the maximum photon rate they can process. In addition due to their intrinsic working principle, i.e. based on a comparison of the signal with a threshold, signal charges split among pixels are difficult to detect. Therefore it will be more difficult to detect single photon signals with smaller pixel size.

Analog integrating detectors can cope with high instantaneous photon rates therefore they are the only choice when photons arrive all at once as for FEL experiments. Typically they have some limitations on the maximum dynamic range achievable in one single exposure but due to their analog nature they maintain the information even for signals below their intrinsic noise level.

The advent of x-ray FELs sources produced new challenges in the generation and collection of the signal charge and detector radiation hardness.

The talk will cover x-ray CCDs, hybrid pixel detectors and more exotic designs with emphasis on capability and limits of the available technology and a perspective on their applications at FELs.

What's all that x-ray detector stuff, anyhow?
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