Next week we welcome Shigeru Kashiwagi, a post-doc who is joining us
after finishing his Ph.D. in accelerator physics at KEK under well-known
Professor K. Oide. Shigeru will work on the Development of high-brightness
electron sources LDRD project and help on the Compton generation of
X-rays experiment.
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VISA
Experiment Progress (Reported by Aaron Tremaine) |
The leveling of the undulator support stands has been machined and
the redheads for the stands have been installed in the experimental
hall. VISA diagnostic designs are completed and the machining of the
jig (support) plates should be finished by next week. The following
week the pre-assembly of the system in building 726 will begin. Roger
and Ben are scheduled to come out then. As far as I know, Ruland, is
still planning on being here starting may 31 and staying 2 weeks to
set up the alignment system in the pre-staging area (726).
VISA Schedule (Pre-ATF assembly)
Possible tests on VISA experimental table in staging area before move
into
experimental hall
1. Install (at least one) pop-in/diagnostics
2. Steering magnets
3. Undulator/Alignment system
What still needs to be done to undulator support/table
- Submit to BNL shop (complete before pre-assembly)
1. Level support legs (submitted to shop on 5-5) [Done]
2. Bought jig plate (arrived at bnl on 5-6) [Done]
3. Drill holes in plate for optics set-up (design completed this
week)
This week FEL optics design completed (drill holes in plates)
Camera optics design
Pre-assembly of alignment system at SLAC completed (Ship to BNL)
May 24 Staging area assembly can begin. Area in building 726 must be
laser secured-in the works
Machining of supports/plates (completed)
Start re-assembling from the ground up including vacuum chamber
(R&B)
Pop-in diagnostics setup near completion (parts ordered)
May 10-21 NSLS shutdown (minimal tech support)
May 24 Start pre-assembly building 726
May 31-June 11 Set up alignment system and test in staging area-Build.
726 (Ruland)
June 14-? Continue with pre-assembly unpredictable time scale
Move to ATF Must be sure of system integrity. Late June is earliest
move
into ATF. Two week shutdown of ATF
I will get a more precise schedule on who is moving what and how
to
the ATF
Ruland/Roger’s scheduling for return
What additionally needs to be done to the ATF
(Safety Approval Forms, Plug door, shielding, coordinating with ATF
scheduling, ...etc.)
Controls/Data Acquisition (in the works)
We need to install controls for
1. magnet power supplies
2. actuators for diagnostics in undulator and final diagnostics (FEL/micro-bunching)
3. lens flippers (FEL diagnostics)
Data Acquisition (using a Power Mac G3) running
LabView 5.1
1. Can now read/save oscilloscope traces
2. Can now read/save/process video images
3. Need to be able to download through Ethernet ATF database
parameters Issues still needing to be addressed:
FEL light transport line from vault to FEL room
Diagnostics for FEL room
Joulemeter(s) and camera for FEL room
spectrometer/autocorrelator/frog
May 24-June13 Aaron gone
May 7-June 1 Alex gone
June 15 Pedro arrives
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Magnetic Measurements
(Reported by George Rakowsky) VISA: |
Studies of measurement errors in VISA fiducialization measurements
continued. Wear of gauge bar sockets and imperfect fit to tooling balls
was found to contribute up to 10 um to uncertainty. Data of repeat of
270 and 90 degree measurements is being evaluated.
The pulsed wire bench was disassembled and the granite table was returned
to RHIC on 5/14/99. We are reassembling the pulsed wire setup on our
12-ft granite table.
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STELLA
Experiment (Reported by Karl Kusche) |
1) ICA optical system restoration & realignment continues in
preparation for ICA recommissioning during the latter part of May.
2) Pump-down & leak-check of beamline #1 are complete, except
for the small section between the ICA gas cell and dipole (which is
currently under vacuum awaiting leak-check).
3) Cabling for the new GPOP4 camera was completed by Marc.
4) Drawings for the protection of GPOP1/2/3 were submitted to STI
for fabrication. Plans to modify the roof & replace the doors
(with curtains) of the ICA optical table to reduce dust and vibration
are being completed.
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STELLA Electron Beam Optics
(Reported by Ping He) |
We got some tracking results using MAD code. The results are shown
in the
figures below:
May_14_STELLA_skew_traj
The first (second) figure is horizontal (vertical) beam size. The two
horizontal lines, in both figures, mark the hard apertures of the gas
windows (at about +/- 10 cm from center) and laser mirrors (at about
+/- 5 cm from center).
The key of the various lines is as follows:
No Ksq: The original design which does not include the skew quadrupole
component of the wiggler.
Ksq, Normal T4: The original design, a skew quadrupole component in
the wiggler, Quadrupole Triplet 4 not rotated.
Ksq, skew T4 (two cases): With skew quadrupole component in wiggler
but Triplet 4 rotated 30 degrees and focus set at two points.
While it is clear that more optimization is necessary, it seems that
with the rotation of T4 (suggested by Vitaly Yakimenko) can lead to
a beam size that is as good as the original design without skew quadrupoles.
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Computer Control System
(Reported by Bob Malone) |
Cathode cleaning performed twice: May 8 and May 13. Laser energy fluctuations
noted as function of position on cathode. Code completed for new emittance
program. Testing in progress.
Design work underway for slow drift laser energy correction program.
Code work to begin next week.
New control system: correct optical fiber has arrived. Installation
to start next week.
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Technical Staff Tasks
(reported by Bill Cahill) |
Report not received in time.
YAG
System (Reported by Marcus Babzien) |
The measurements comparing the old YAG oscillator and the new Nd Ortovanadate
oscillator (in a temporary, unstable location) are presented in:
May_14_Laser_Osc._comp
Last weekend work continued on beam studies and cathode cleaning was
performed Friday. Sunday the laser was operated for pulse duration measurements.
Using the streak camera the green pulse was measured with different
configurations of streak camera settings. For all configurations the
range of measurements was 8-13 ps, but accounting for space charge and
saturation effects which cause broadening effects, the most likely number
is 10+-2 ps. The 8 ps number came from measurements at the highest sweep
speed of the camera, with which we have the least experience. Work continued
on adjusting the temperature of the amplifiers to match the oscillator
spectrum. The amplifier now operates near 15 degrees C, and the preamplifier
will be addressed next. This is not urgent for wavelength matching,
but has the additional benefit of lowering the heat load on the table.
Electronics on the table contributing heat are being removed as much
as possible, and this should be completed by the end of next week. An
overnight camera scan showed that there is still beam motion coming
from the new oscillator correlated to table temperature, and a thermal
isolation enclosure similar to the one used around the old oscillator
is now being designed.
Additional studies took place to understand the cause of energy modulation
observed when scanning the laser spot for cathode cleaning. The problem
is localized to the last three optics in the beam path before the gun,
and although initially the problem appeared to be caused by dirty optics,
more tests are needed to confirm this. However, cathode cleaning with
about 5% modulation was performed Thursday night.
HVAC work continued after the system failed to control humidity last
week. The temperature of the glycol coolant was reduced for greater
dehumidification. Also, work is underway to try to eliminate the need
for fans in the ceiling to provide airflow to the room. This should
reduce noise and vibration.
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Beam Studies (Reported
by Xijie wang) |
1. Cathode was cleaned last Friday (Malone, XJ). Before cathode cleaning,
laser energy variation with laser position on the cathode(10 to 15
%), it was eliminated after Marcus cleaned the lens and pick up optics.
It started to be visible (5%) at the last part of the cathode cleaning.
QE improved by about factor of two. Monday cathode cleaned again using
much higher laser energy than usual, Marcus could not complete eliminate
the laser energy variation (5-10 %), electron beam non-uniformity
observed.
2. Beam studies continued on Sunday (XJ, Marcus). Large laser energy
fluctuation (20 -30%) was observed. Open the laser enclosure and turn
on the fan, laser energy settle down (less than 15%) after couple
hours. Studies electron beam bunch length as function of the prism.
1.5 to 2.5 ps electron beam pulse length shortening observed without
prism. Laser energy fluctuation returned after couple hours.
3. Laser energy fluctuation and position variation prevented further
beam studies.
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ATF Schedule (Prepared
by Xijie Wang) |
This is a draft schedule, subject to change following adjustments to
the needs of experiments and developments in the hardware.
The Week of May 17, 1999
Monday
9:00 AM - 6:00PM: YAG LASER Work: Heat source Removal (Mark), laser
beam transport studies 6:00 PM - 11:00 PM: Beam Studies( if cathode
cleaned and reasonable stable, bunch length studies as function of the
grating and spot size, emittance, bunch length measurement only if no
cathode cleaned ) (XJ, Yakimenko). Cathode cleaning if laser stable.
Tuesday:
9:00 AM - 6:00PM: YAG LASER Work: Heat source Removal (Mark), vibration
studies in the YAG room (Yakimenko, Marcus).
4:00 PM - 10 PM: Beam Studies (Testing RF stability when AC on)(Yakimenko).
Wednesday
9:00 AM - 6:00 PM: Finish up heat source removal (Mark), Testing the
phase jitter and energy fluctuation, and other stability of the laser
after heat source removal.
6:00 PM - 11:00 PM: Beam Studies
Thursday
9:00 AM - 8:00 PM Beam Studies using beam to test RF and laser stability
under normal operating time and condition: XJ, Yakimenko, Marcus
Friday
9:00 AM - 8:00 PM Beam Studies using beam to test RF and laser stability
under normal operating time and condition: XJ, Yakimenko, Marcus
Week of May 24, 1999
Marcus will take oscillator to Washington DC, no beam running. Following
projects will take advantage of the available time:
1. YAG room vibration (Plant Engineering, Cahill, Marcus).
2. YAG room humility improvement (Plant Engineering, Cahill, Marcus).
3. ATF Klystron noise problem.(Mark)
4. YAG laser water tank relocation.(Cahill)
5. Both Klystron and gun water system improvements.(Mark and Harrington)
6. CO2 work. (Igor)
7. Experimental hall work (John)
Week of June 1, 1999
Monday Holiday
Tuesday
9:00 AM - 3:00 PM: Oscillator Installation and testing (Marcus).
3:00 PM - 8:00 PM Beam Studies (Yakimenko, Malone).
Wednesday
9:00 AM - 5:00 PM: HGHG trajectory studies(YU)
Thursday
9:00 AM - 5:00 PM: Stella studies (Kusche)
June 7, 1999
Monday
9:00 AM - 4:00 PM YAG Laser studies (Marcus)
4:00 PM - 10:00 PM Beam Studies (XJ, Yakimenko)
Tuesday
9:00 AM - 5:00 PM: HGHG (YU).
Wednesday
9:00 AM - 5:00 PM: Stella studies (Kusche)
Thursday
9:00 AM - 5:00 PM: HGHG (YU).
Friday
9:00 AM - 5:00 PM: Stella studies (Kusche)
Week of June 14, 1999
1. Install oscillator in the final position with temperature stabilization.
2. Starting install VISA components.
3. Install normal incident optics if it is ready
Week of June 21
Monday:
Continue VISA work, and Test oscillator stability.
Tuesday:
9:00 - 5:00 PM
Visa installation
Beam studies in the tunnel.
Wednesday
9:00 AM - 4:00 PM: Beam Studies in the tunnel. VISA work in the experimental
hall.
4:00PM - 10:00 PM: Smith-Purcell Experiment (assume Smith-Purcell People
agree0
Thursday
9:00 AM - 4:00 PM: Beam Studies in the tunnel. VISA work in the experimental
hall.
4:00PM - 10:00 PM: Smith-Purcell Experiment (assume Smith-Purcell People
agree)
Friday
9:00 AM - 4:00 PM: Beam Studies in the tunnel. VISA work in the experimental
hall.
4:00PM - 10:00 PM: Stella
Week of June 28, 1999
Monday
9:00 AM - 4:00 PM: Beam Studies in the tunnel. VISA work in the experimental
hall.
4:00PM - 10:00 PM: HGHG experiment (Yu).
Tuesday
9:00 AM - 4:00 PM: Beam Studies in the tunnel. VISA work in the experimental
hall.
4:00PM - 10:00 PM: Stella experiment.
Wednesday
9:00 AM - 4:00 PM: Beam Studies in the tunnel. VISA work in the experimental
hall.
4:00PM - 10:00 PM: HGHG experiment. (Yu).
Thursday
9:00 AM - 4:00 PM: Beam Studies in the tunnel. VISA work in the experimental
hall.
4:00PM - 10:00 PM: Stella experiment.
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