[Ifeffit] current-amp recommendation
bravel at bnl.gov
Tue Nov 14 14:43:36 CST 2017
At NSLS-II, we use a solution developed here at BNL for quad BPMs and
other current-measurement operations. (I am using it for ion chambers
at my beam line.)
It is a box developed in the Instrumentation Division with a current
amplifier, an A2D converter, and a microprocessor all inside a box
that's about the size of a box of Pop Tarts. It has 4 SMA input
channels and a single gain for all four channels. SMA to BNC cables are
readily available from all the standard vendors. The output is an
ethernet cable. The microprocessor runs a small debian system and
starts an EPICS IOC and a DHCP client on boot. the 4 current get
exposed as 4 PVs and the IOC does a lot of useful statistics on the fly.
Seems to work pretty well.
You could contact Pete Siddons. (Search for Siddons at the BNL website.
When I tried it, the second hit was his staff page.)
On 11/14/2017 03:16 PM, Matthew Marcus wrote:
> 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.
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Bruce Ravel ------------------------------------ bravel at bnl.gov
National Institute of Standards and Technology
Synchrotron Science Group at NSLS-II
Building 743, Room 114
Upton NY, 11973
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