F Antiproton Source Apertures Steve Werkema DOE Tevatron Operations Review March 22, 2006.

f

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


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


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


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


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


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



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


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.


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


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


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



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


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.



Coupling on extraction and central orbits

CoreInjection

Horizontal

Vertical



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


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)

F Antiproton Source Apertures Steve Werkema DOE Tevatron Operations Review March 22, 2006.

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