APS Top-Up Operational Notes

During the December 6 to 11 period, the APS ran in Top-Up mode.  Below are some notes on the performance of the beamline in Monochromatic mode during this Top-Up mode week.
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The image below shows a new screen which contains all the APS supplied
PV's for probing the injection process. The screens is available  on our main EPICS server.

A first test was made with the monochromator energy set to 10 keV, with a white beam slit open to 0.4mm by 0.4 mm, measuring the flux in ID-B at the end of the micromonochromator with an ion chamber, with a 0.1 s counting time. and a data acquisition rate of 10 Hz. Shown below is the ion chamber signal (blue, about 40000/0.1s) and the gate signal (brown, from 0-5)  The gate is either 0 or 1 and switches to zero during top up.   Clearly we lose the monochromatic flux during top up.   The time fluctuations of the monochromatic beam  are due to pressure fluctuations.

Below is another data set taken with 50 ms counting time on the scaler.  Four  injections have been overlapped to show a typical injection.  The monochromatic flux returns typically between 50 and 100 ms.  This is consistent with the fact that during the injection, the emmittance is blown up for I recall 60 ms until the orbit is restored.   One should be able
to gate their detectors to ignore these injections.

Eric Dufresne
MHATT-CAT
5/11/2007