MHATT-CAT 7ID BPM Data for April 1, 2002
April 7, 2002
MHATT-CAT results from the High current studies on 04/01/02.
The work shown below is an account of useful operational data taken on 7ID-C
during the high current (130 mA) study period starting at 08h00 on April 1,
2002, and lasting until 17h00. The data reported below is from the 7ID-C
X-ray BPM which allows us to investigate submicron motion of the APS beam, 49 m
from the source point. The design follows Alkire et al. in JSR (?) and is used
at SBC-CAT and at other CATs around the ring. The electronics used to amplify
the quadrant diode signals has a bandwidth of a few seconds. For the data
reported below, the monochromator was set to diffract 10.0 keV X-rays, the
undulator was set to 10.055 keV, and our L5-20 slits were opened to pass a
0.4 mm by 0.4 mm white beam incident on our monochromator. Thus a rather
small power load was on the monochromator (on order 16 W/100mA) and we didn't
expect any problems to be found at the high current tests. Our experimenters
in 7ID-D used the beam for an experiment, thus the data below was interrupted at
times by hutch access and beam dumps. The beam appeared to be usable.
Fig. 04-01.1 shows the time series of the X-ray BPM
average current from the sum of its four diode outputs (diode/1.1754). The ring
current is also shown (IRing/131.174) as well as the signal from an ion chamber
in 7ID-B placed 36 m from the source and collecting all the flux (IC B/359601).
All the flux data are following the ring current before t = 6.2 hours. After
this time, the BPM sum and ID-B ion chamber signals decay while the ring current
remains relatively constant. It is possible that some heating of our
monochromator caused this effect.
Fig. 04-01.2 shows the time series of the X-ray BPM
X and Y position during the same time series. Several hutch access by our
experimenters and beam dumps cause fast glitches downward which should be
ignored. The beam was stable to about 35 microns during the day and it is
possible that the data following the fill-on-fill at 130 mA started after
t=5.5 hours shows a larger drift than we typically see at 100 mA. Before
t=5.5 hours, the APS current was down for about one hour, thus it is possible
that large horizontal drift after 5.5 hours is caused by some heating of our
Fig 04-01.1 . Time series of the beam intensity in 7ID-C, starting at
08h04 on 04/01
and lasting 9 hours. The ion chamber signal in a N2 filled ion chamber in
shown as well as the 7ID-C diode sum of the 4 quadrants, and
the APS ring current.
The ion chamber signal in 7ID-C C was disabled, thus is constant on the plot.
Fig 04-01.2. The beam position, 49 m from the source, or 19 m from the
Load mono in 7ID-C during the same time series as
Fig. 04-01.1. The time series is
started on 04/01 at 08h04, and lasts
for 9 hours. The beam is stable to about 35
microns in both the vertical
and horizontal directions.
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