We received the report of the Laser Advisory Panel. You may see the
report at Report_of_ATF_Laser_Panel
Due to a combination of reasons (PAC’99, the 4th Generation
Light Source Workshop at Argonne, ATF two week shutdown to install new
YAG Clean Room chiller and air conditioning modification) there will
be no reports for the next two weeks.
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|
Trajectory studies
(Reported by Vadim Sajaev) |
There was one run this week devoted to the trajectory study. A new
algorithm of orbit correction was tried. This method doesn’t use
the HeNe laser at all. We vary the main focusing in the Cornell wiggler
and measure the relative trajectory change. Analyzing these changes,
the focusing axis of the wiggler can be found in both planes. The result
of this test was satisfying (exciting!): trajectory in both planes was
corrected with accuracy of +-30 micons. It works better then the previous
method which relied on the HeNe laser, probably due to problem with
HeNe images in pop-in monitors. The images are still poor, even after
change of the mirrors.
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Optics
(reported by Adnan Doyuran) |
This week on Monday I checked the He-Ne positions on the wiggler pop-ins.
During the run we need to shift the beam with a thick glass, in the
x and y directions. In that case beam was clipping on the right side
of the mirrors at pop-ins 1, 3, and 4.. Monday and Wednesday Erik and
I spent some time to align the beam on the left central side of the
mirrors because we’ll be shifting the beam to the right.
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The Compton experiment ran two days, Tuesday and Friday. A search for
a signal is in progress.
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Technical staff tasks
(reported by Bill Cahill) |
1. Design periscope for new YAG oscillator.
2. Modify internal components for Compton Experiment.
3. Evaluate new gun cathode for possible trapped air chamber.
4. Terminated Heliax cable for joule meter readout.
5. Investigated phase jitter in linac rf system.
6. Researched and ordered components for linac water servo system.
7. Completed new phosphorus screen for LPOP1.
8. Completed assembly for HPOP1.5.
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Computer & Control
System (Reported by Bob Malone) |
Facility:
Orders have been placed for components needed to build a duplicate
frame grabber system and to improve the performance of the existing
one. The new frame grabber will be based on a 400 MHz Pentium II motherboard
with 128 MB memory. The present system will be upgraded from its 133
MHz processor/64 MB memory to match the new one. Both systems will
have the same operator interface and network control capabilities
and will be able to operate independently. Design changes for database
and network servers needed to support both machine are almost complete.
Expected arrival date for the new hardware is near the end of April
with deployment several weeks later.
YAG laser support:
A YAG laser camera scan was set up March 25 and allowed to run overnight.
Statistics from 18,100 video frames (4525 frames at 4 locations) were
captured and recorded. This information will provide a base line for
before/after comparisons once work on the YAG climate control has
been completed.
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YAG system (Reported
by Marcus Babzien) |
Over the previous weekend the YAG oscillator shut down on internal
interlock. The cause was eventually traced to a bad contact in the umbilical
between the controller and laser head. By the time this had been corrected
it was too late for any running on Monday, and a water leak had opened
up in the oscillator cooling loop. This was repaired Tuesday morning,
the system was realigned, and operated the rest of the day.
The new demo oscillator from Time Bandwidth Products was received on
Tuesday, and a quick check was performed to confirm no major damage
was suffered in shipping. Preparations were begun for testing the unit
after the HVAC shutdown next week.
Wednesday morning some time was made available from the HGHG run to
perform laser measurements in the gun hutch. Specifically, the gun entrance
window was visually inspected for fluorescence under illumination with
UV from the YAG system, and no emission was observed. Second, the back
reflections from the two surfaces of the window were found and the energy
in these reflections measured. Relative to the incident beam, approximately
3% reflects from each surface, which is close to the 4% expected. Together,
these measurements show no evidence of suspected damage to the entrance
window, and any double reflections in the forward direction should be
negligible. Other measurements with an improved dynamic range photodiode
showed that the pre-pulse arriving at the gun from the residual CO2
slicing pulse is down 3000 times relative to the main pulse. Post-pulses
where not observed above a noise level of 1% out to ~50 ns after the
main pulse.
Thursday the system was down for maintenance and preparation for the
upcoming shutdown and oscillator testing. Last night additional cameras
were installed to monitor oscillator pointing stability, and beam position
was measured overnight. Beam motion was observed directly out of the
oscillator, which was correlated with drifting temperature on the table,
and was the dominant component of downstream beam deviation into the
amplifiers.
Friday the laser was operated for the Compton experiment, and final
work plans for the shutdown were addressed.
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Schedule (reported
by Xijie Wang) |
Week of March 29, 1999
PAC 99, Monday through Friday
Mon-Friday
YAG room chiller installation, Babzien and Cahill.
Klystron insulation, Cahill.
Friday, April 2, 1999
ATF Clean up for PAC 99 tour: Cahill
Saturday, April 3, 1999.
12;00 PM - 3:00 PM, PAC 99 tour, Wang, Yakimenko, Pogorelsky, Kusche,
Malone,Yu
Week of April 5, 1999
Monday - Friday: ATF Chiller/HVAC work and Klystron insulation.
1. Remove wakefield experiment.
2. Reinstall Stella spectrometer.
3. Install new laser port window for the RF gun and new cathode (if
components are ready).
4. Test of new laser oscillator.
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