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Antiproton Source AperturesAntiproton Source Apertures
Steve WerkemaDOE Tevatron Operations Review
March 22, 2006
DOE Tevatron Operations Review – Steve Werkema 2
f OutlineOutline
1. Overview of Activities since March 2005a. AP2 lineb. Debuncherc. D-A lined. Accumulator
2. Work remaining for each of the above
3. Conclusions
Note that a Goal admittance of 35 mm-mrad means accepting a beam emittance of 330
mm-mrad
f
AP2 LineAP2 Line
Accomplishments and Work Remaining
DOE Tevatron Operations Review – Steve Werkema 4
f AP2 BeamlineAP2 Beamline
AP2 Accomplishments:
BPM DAQ Upgrade (completed in June 2005) Orbit control Lattice measurements Observation & correction of short and long term beam
motion trends
Four new dipole correctors have been installed Implemented automatic orbit correction during
stacking Much of the line has been steered to quad
centers Conducted an obstruction search with a
borescope No obstructions found
DOE Tevatron Operations Review – Steve Werkema 5
f AP2 BPM UpgradeAP2 BPM Upgrade BPM DAQ upgrade installation completed in June 2005 Debuncher injection kicker noise problem solved by
installing inline high pass filters and amplification of the signal at the source. These amplifiers are being replaced by low noise amplifiers
during the present shutdown BPM output is sent to the control system on every beam
pulse. The data is available as ACNET devices – allows easy readout by client software and other users.
AP2 BPM positions and intensities are routinely data logged. Software providing for the display, storage, and analysis of
AP2 BPM data has been written and is in operational use. RMS fluctuation in the readout of the AP2 BPMs varies from
100 μm to 500 μm (average is 200 μm). Good enough for orbit correction, but compromises lattice
measurements Should be improved with the installation of low noise pre-amps
DOE Tevatron Operations Review – Steve Werkema 6
f AP2 BPM UpgradeAP2 BPM Upgrade
AP2 BPM difference orbit during reverse proton studies
RMS is shown in green
We expect the installation of new low noise preamps will reduce the readout fluctuations to 100 – 200 μm.
5 mm
1 mm
DOE Tevatron Operations Review – Steve Werkema 7
f AP2 Beamline – Automatic steeringAP2 Beamline – Automatic steering
Data log display of four BPMs at the downstream end of the AP2 line from 10/1/05 to 1/16/06.
Introduction of automatic steering (a.k.a. Oscillation Overthruster) in the 120 GeV and AP2 lines significantly reduced variations in the AP2 beam trajectory.
10 mm
DOE Tevatron Operations Review – Steve Werkema 8
f AP2 BeamlineAP2 Beamline
Work Remaining:
Replace AP2 beam stop (i.e. eliminate 2 vacuum windows and 12 feet of spoiled vacuum) to becompleted this shutdown
Steer upstream end of the beamline (including Li Lens)
Match lattice to the Debuncher
f
DebuncherDebuncher
Accomplishments and Work Remaining
DOE Tevatron Operations Review – Steve Werkema 10
f DebuncherDebuncher
Debuncher Accomplishments: Completed installation and commissioning of all
moveable quad stands. We don’t plan to install any more!
Installed and commissioned a ramped Debuncher EXtraction (DEX) bump.
Lattice modified to decrease -functions at limiting apertures. Eliminates the need to widen the aperture of the band 4
stochastic cooling arrays Substantial beam study time to steer the closed orbit to
quad centers and work on the aperture Found and removed two aperture restrictions: horizontal
and vertical schottkys
Net Result: 25% increase in Deb Admittance in past year:
• Ax = 32.6 mm-mrad, Ay = 34.6 mm-mrad 32% increase in AP2 + Debuncher admittance:
• Ax = 33.3 mm-mrad, Ay = 31.2 mm-mrad
DOE Tevatron Operations Review – Steve Werkema 11
f Debuncher – Finding Limiting AperturesDebuncher – Finding Limiting Apertures
Debuncher “Running Wave” application:
A pair of trim dipoles are used to generate a closed orbit oscillation that is scanned in phase so that the maxima and minima move over the entire length of the Debuncher.
Beam loss monitors are used to resolve the 19-fold ambiguity in the location of the orbit extrema.
DOE Tevatron Operations Review – Steve Werkema 12
f DebuncherDebuncher
Work remaining:
Debuncher extraction kicker aperture upgrade Improves horizontal aperture for |p/p| > 0
Motorize Debuncher extraction kicker stand Motorized girder will be installed this shutdown
53 MHz upgrade to Debuncher BPMs Allows orbit monitoring and correction during
stacking
Possible further adjustments to the lattice Quad shunts are being configured for this during the
present shutdown
Correct horizontal orbit in the arcs We skipped this on the first pass because it will
change the energy
f
D-A LineD-A Line
DOE Tevatron Operations Review – Steve Werkema 14
f D-A LineD-A Line
Accomplishments: Aligned orbit to quad centers Implemented injection error correction for
proton injection into the Debuncher andp injection into the Accumulator
Investigated matching to the Accumulator D-A line appears to be matched to the Accumulator
DOE Tevatron Operations Review – Steve Werkema 15
f D-A LineD-A LineLimiting apertures are the Accumulator injection septa (~10 mm-mrad)Beam from Debuncher is cooled transversely to < 3 during each stacking cycle
Efficiency to Accumulator I njection Orbit
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 1 2 3 4 5 6
Debuncher Cooling Time (sec)
Effi
cie
ncy
(R
ela
tiv
e t
o >
4 s
ec
me
as.
)
1st Turn 05
Last Turn 05
1st Turn 04
Last Turn 04
Eff ective aperture ~ 2.5 mm mrad
Conclusions: 1. Maximum transfer efficiency achieved
with cycle times > 2.0 sec 2. Beam bigger than 2 – 3 π could be
scraping upon injection into the Accumulator
f
AccumulatorAccumulator
Accomplishments and Work Remaining
DOE Tevatron Operations Review – Steve Werkema 17
f AccumulatorAccumulator
Accomplishments:Spent 4½ shifts of beam study time to improve the Accumulator aperture. Identified an aperture
restriction – quadrupole pickup• Quad pickup has
been removed Scanned all moveable
devices
DOE Tevatron Operations Review – Steve Werkema 18
f Accumulator AdmittanceAccumulator Admittance
Date Injection Central Core
8/25/1999HV
8.3 9.6
10.0 9.4
8.2 7.7
2/15/2006Start of studies
HV
6.3 7.4
2/17/2006End of studies
HV
6.3 9.2
7.0 7.9
6.6 6.6
Improvement: Horizontal – 11%, Vertical – 7%
Apertures remain substantially smaller than they were in 1999.
DOE Tevatron Operations Review – Steve Werkema 19
f AccumulatorAccumulator
Coupling on extraction and central orbits
CoreInjection
Horizontal
Vertical
DOE Tevatron Operations Review – Steve Werkema 20
f AccumulatorAccumulator
Work remaining: Correct central orbit to quad centers and re-
center moveable devices Correct coupling on the injection orbit Look carefully at acceptance of Accumulator
injection channel
DOE Tevatron Operations Review – Steve Werkema 21
f ConclusionsConclusions The Perfect Storm The confluence of: major Tevatron disasters copious beam study time + the upgrades installed so far + new instrumentation = a significant (~30%) improvement in the AP2 and Debuncher acceptance. We are now within 10% of our Run II upgrades admittance goals.
Several important tasks remain, indicating a good likelihood of even further improvement: Lattice improvements in the AP2 line and Debuncher New AP2 beam stop Debuncher extraction kicker upgrade Debuncher BPM 53 MHz upgrade Accumulator orbit correction Completion of the Lithium Lens upgrade (summer ‘06)