I've gotten involved with a project in which stabilization of the position of a monochromatic, soft X-ray beam is needed. The offending frequencies seem to be vibration frequencies like 57 and 116Hz. We have in mind to use a thin Au film with a gap in the middle, measuring the drain current from the films, much as people normally use the jaws of slits. Now, I'd like to find a couple of current amplifiers which are small enough so that they can be connected with very short cables to the BNC connectors on the air-side of this detector, and which would have decent frequency response and low noise with inputs of the order of 0.1-1nA. Although this topic is outside the realm of XAFS analysis with IFEFFIT, I figure that people on this group might have some good experience. mam