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MHATT-CAT Useful Operational Data for Run 3 of FY02


Eric Dufresne, Dohn Arms, Don Walko
MHATT-CAT
Started July 19, 2002
(www.mhatt.aps.anl.gov/Sectors/Sector7/Operations/FY02_run3/)



Table of Content:

Introduction.

The work shown below is an account of useful operational data taken during
run 3 of FY02 on 7ID. This page will contain useful stability information on the
7ID High Heat Load Monochromator and also on the various repairs and problems 
identified during the run.

Thursday, July 18, 2002. Time series with a 0.4 mm (H) by 0.4 mm (V)
white beam, with the mono at 10.0 keV.

The mono is stabilizing its second crystal temperature after the gap was opened
from around 11 mm to 21.768 mm around 16h12 on 7/18/02. The data was started
on 17h28 and lasts for more than 16 hours. Three figures are shown below.
Fig. 07-18.1 shows a time series of the intensity not
normalized to beam current decay. the data was taken every second. Matt DeCamp
tweaked the second crystal picomotor several time during the 8 hours. I am now
pretty convinced that the picomotor mechanical stage pth drifts after a tweak
I think in the future we should use the piezo electric transducer to tweak the
second crystal. It would make the second crystal more stable.

Fig. 07-18.2 shows a time serie of the 7ID-C Beam 
position. The vertical beam motion is very large during the first half of the 
time series (ignore large drops due to hutch access). Note also that no data is 
recorded when someone enters in 7ID-C.

Fig. 07-18.3 shows a time serie of the second crystal
temperature during the same time serie. The temperature takes about 4-5 hours 
to stabilize after opening the gap. I don't believe the data after 10 hours.
I suspect noise pick-up which I vaguely recall seems to be worse at night.
Intensity data started on 07/18/02.

Fig 07-18.1. Time series of the beam intensity in 7ID-C, starting at 17h28 on 07/18
and lasting 16 hours. The 7ID-C diode sum, the ring current, ion chamber in B and C are shown.

XBPM data started on 07/18/02.

Fig 07-18.2. The beam position, 49 m from the source, or 19 m from the High Heat Load mono
in 7ID-C during the same time series as Fig. 07-18.1. The time series is started on 07/18 at 17h28,
and lasts for 16 hours. The beam is not stable in the first half of the time series due to thermal drift
of the monochromator and possible mechanical drifts from the second crystal (pth).

Second crystal temperature on 07/18/02.

Fig 07-18.3. The second crystal temperature during the same time series as Fig. 07-18.1.
The time series is started on 07/18 at 17h28, and lasts for 16 hours.

Tuesday, August 14, 2002. Time series with a 0.5 mm (H) by 0.5 mm (V)
white beam, with the mono at 10.0 keV.

This time serie was started on 8/14 at 01h07 and lasts for 8.5 hours. The L5-20
opening was set to 0.5x0.5 mm shortly after the start of the time serie, within
the first three minutes. They were set at 0.3x0.3 mm before so the white beam 
area of the first crystal increased by (0.5/0.3)^2 ~ 2.8, a significant power
increase. 

Fig. 08-14.1 shows a time serie of the intensities
in 7ID-B, and C as well as the diode sum. The intensity drifts for several 
hours after the change of L5-20 opening. Fig. 08-14.2
shows a time serie of the beam position in the same time serie. The horizontal
position rapidly change by 20 um in about one hour, but the vertical position
drifts by more than 110 um over 5 hours, following the trends of Fig. 08-14.1.  
The second crystal pth was not tweaked, so no mechanical instabilities can
explain the vertical drift seen. The beam motion and loss of intensity is
likely due to the change in temperature of the second crystal.
Intensity data started on 08/14/02.

Fig 08-14.1. Time series of the beam intensity in 7ID-C, starting at 01h07 on 08/14
and lasting 8.5 hours. The 7ID-C diode sum, the ring current, ion chamber in B and C are shown.
Shortly after the start of the time series, the L5-20 slit opening was increased to
0.5x0.5 mm from 0.3x0.3mm.

XBPM data started on 08/14/02.

Fig 08-14.2. The beam position, 49 m from the source, or 19 m from the High Heat Load mono
in 7ID-C during the same time series as Fig. 08-14.1. The time series is started on 08/14 at 01h07,
and lasts for 8.5 hours. The beam drifts in the vertical direction because the second crystal
temperature is changing after opening the L5-20 opening. The second crystal picomotors
were not tweaked after the opening of the slits.


Last modified on 10/22/2002
by Eric Dufresne,
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