Antiproton Study Periods

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Antiproton Study PeriodsAntiproton Study Periods

Keith GollwitzerDOE Tevatron Operations Review

March 21, 2006

DOE Tevatron Operations Review – Gollwitzer 2

f Simplified Review of Operations/Studies ModeSimplified Review of Operations/Studies Mode

Stacking 120 GeV protons from MI

through P1-P2-AP1 Target producing secondaries Li Lens Negative 8.9 GeV/c secondaries

transported via AP2 beam line Debuncher Ring to compress

phase space (7x )2 & (50x ) in 2s

Transfer via D/A Accumulator stack pbars while

compressing phase space (5x )2 & build a core

Reverse Protons 8GeV protons from MI Transfer line is P1-P2-AP1-AP3 Circulate in Accumulator D/A transfer (really “A/D”) Circulate in (or partial turn

through) Debuncher Extract “up” AP2 towards

target station

AP2

Debuncher


f BackgroundBackground

We had reached the point where the instrumentation and orbit control made it possible to attempt: Determining the orbit offset with respect to the

center of the quadrupoles of the Debuncher ring and the AP2 beam line

Correct the orbit to minimize the orbit-quad center offsets

Set the AP2-Debuncher injection region

Proposed two week period of studies Studies two shifts a day Third shift stack to support a lower luminosity

collider program Set for early December


f Execution – Round 1Execution – Round 1

TeVatron breaks on Monday Nov 21 Scramble to find people for holiday weekend for start of

studies First finished preliminary studies to set procedures to be

used during studies period Institute third shift to investigate D/A beam line

15 days of reverse protons Debuncher: beam-quad center offsets, orbit correction and

centered devices about new orbit• D/A beam line done on owl shifts

AP2 & Debuncher Injection region: scanning and setting strengths of kicker and septum

AP2: beam-quad center offsets & orbit correction 4 days of stacking studies/start-up

Steer secondaries beam onto AP2 reverse proton BPM positions

Center Debuncher devices about beam General tune-up of kickers, RF, cooling systems, etc.


f Preliminary WorkPreliminary Work

Checkout of BPMs Preparation of timeline to

acquire beam without much interruption to ν program

Commissioning of TBT program for D/A into Debuncher for reverse protons

Procedures for extracting reverse protons from the Debuncher into the AP2 beam line

Attempt to minimize the effects of the Debuncher rotator cavities on the injected reverse protons


f Commissioned ItemsCommissioned Items

Debuncher Reverse Proton Turn-By-Turn system Debuncher Reverse Proton partial turn extraction up

AP2 Debuncher Component Centering application Debuncher Orbit-Quad offset procedure AP2 Orbit-Quad offset procedure AP2 Beam Line Correction for reverse protons One-Shot Timeline for establishing circulating

Debuncher beam Admittance measurements from data-logger “Deb Heat Rev p’s to AP2” sequencer aggregate Procedure for setting up the AP2-Debuncher Injection

region Procedure for D/A Beam Based Alignment Accumulator local vertical bump at injection


f Debuncher Work - 1Debuncher Work - 1

Determination of orbit-quad center offset Change quad excitation and look for orbit change 68 quads have shunts

• 10 quads have ability to control excitation alone• The rest are paired symmetrically about mid-point of straight

section Concern about excitation of two quads at one time and

determining offsets for each quad• Did quad excitation orbits for nominal orbits as well as for two

1-bumps per plane– Checked for consistency of change in offset determination

with the change of orbit due to the 1-bumps Vertical Orbit Correction

Attempted global fit to minimize orbit-quad center offsets• Re-checked orbit-quad center offsets: no improvement

– Use of motorized quad stands as correction devices Local orbit corrections to minimize orbit-quad center

offsets• Re-check while working around the ring: all <1mm offset


f Change in Debuncher Vertical OrbitChange in Debuncher Vertical Orbit

Several places the orbit changed by ~1cm Angle change at injection area All vertical trims and a majority of the

motorized quad stands were used to perform the correction


f Debuncher Work - 2Debuncher Work - 2

Horizontal Orbit Correction Injection Region was

only done Horizontal orbit-quad

center offsets determined

Centered motorized devices about orbit Total of 72 motors

Lattice measurements were performed


f Setting Injection RegionSetting Injection Region

Extracted beam up AP2 from Debuncher and determine orbit-quad center for the three down-stream most quads Determined horizontal closed orbit and AP2 orbit are

centered in quads.

Set vertical closed orbit to nestle under the septum

Determine kicker strength to center beam in septum

Determine septum strength to put beam in the center of the three AP2 quads


f AP2 WorkAP2 Work

Able to have reverse protons every 15 seconds Determine downstream AP2 orbit-quad center

offsets Not able to do upstream due to bussed quads and

few BPMs to make offset determination

Corrected orbit to minimize offset Summary of orbit changes for reverse protons

Several places big changes, largest 2cm Large vertical angle at the end of AP2

Lattice measurements Installed new lattice which believed to better

match Debuncher


f AP2 Orbit ChangeAP2 Orbit Change


f Limiting ApertureLimiting Aperture

Running wave pointed to Debuncher transverse Schottkys

Will be discussed more in next talk


f Stacking StudiesStacking Studies

Steered secondaries to the vertical BPM positions found during the reverse proton studies

Steered to horizontal downstream BPM positions Upstream, the momentum distribution affects the

horizontal position

Problems with AP2 orbit “wandering” Traced to 120GeV protons starting with Main Injector Associated with amount of time between cycles

• Consistent cycle time is best Developed auto orbit correction program

• Does 120GeV proton correction• Then does AP2 secondaries correction• Identified need for additional AP2 trims

Centered Debuncher pickups


f Orbit Wandering – Stabilizing OrbitOrbit Wandering – Stabilizing Orbit

H

H

V

V

5mm

10m

m

10m

m

Wandering

Stabilized

AP1 Horiz. AP2 Vert


f Early JanuaryEarly January

Wrote up results from the December studies period

Prepared to install new AP2 trims Prepared to remove Debuncher transverse

Schottkys Determined if had more Debuncher quad

shunt freedom, then be able to change lattice Increase Debuncher admittance Removes Vertical Band 4 Arrays as limiting aperture Control was split for 6 pairs of quads


f Middle of JanuaryMiddle of January

Second TeV failure allowed for more dedicated time Installed two of four AP2 trims Obstruction search of AP2 beam pipe Removed Debuncher transverse Schottkys

• Tune measurements, main function, replaced by stochastic cooling pickups

Reverse protons to correct horizontal Debuncher orbit to quad centers in straight sections

• Correction in arcs would lead to energy change that we were not prepared to do at the time

Installed new Debuncher Lattice• Small change to AP2 lattice for matching

Centered Debuncher Devices about reverse proton orbit


f More JanuaryMore January

TeV repair period allowed Running Wave identified the Extraction Kicker as the

limiting aperture in both planes.• Vertically bumped beam 2mm and essentially achieved

goal• Horizontally could bump beam 8mm and make

admittance larger; but bump in dispersion changes beam energy

– Await shutdown work to motorize the kicker stand Different horizontal orbit also affected Extraction

• Optimized Debuncher EXtraction bump for D/A transfers

– Ramp correctors near end of Debuncher stacking cycle so that cooled smaller beam is closer to septum when kicker fires

• Also tuned extraction kicker and septum strengths to steer beam in D/A beam line


f FebruaryFebruary

Intensity Studies Measurement of intensities through the stacking

cycle• Function of stack cycle time (see next talk)• Function of proton intensity on target (see next slide)

– Also monitored proton beam quality

Accumulator Cooling studies Stacktail and Core systems (future slide)

Accumulator Aperture Investigation for less than two days (next talk)


f Intensity study – 4s cycle periodIntensity study – 4s cycle period

Injected intensity into Accumulator

Intensity end of Debuncher cycle

Intensity at end of AP2

Stacking rate

Proton beam on target

Nor

mal

ized

to B

eam

on

Tar

get a

nd 6

Boo

ster

turn

sCooling was optimized after each change of proton intensity

Many other diagnostics and settings were recorded – Flux to Accumulator is fine – Look to Accumulator Cooling

Early F

ebruary


f Stacktail System and the Core 4-8 GHz SystemStacktail System and the Core 4-8 GHz System

Had been using 4-8 GHz system as a helper for the 2-4 GHz core system. Decided it was time to move to 4-8 GHz. Because the 4-8 GHz core system runs at twice the frequency,

the electrodes are ½ the size so the system has a factor of two smaller momentum reach.

Moving the core closer to Stacktail to accommodate the smaller reach resulted in system instabilities at moderate stacks.

• Several attempts were made and we learned from each

We now : Use the 2-4 GHz core momentum system to augment the hand-

off between the Stacktail and the 4-8 GHz core momentum system

Run the 4-8 GHz core momentum system at MUCH larger gain.• Plans to increase the gain of the system

Run the Stacktail during deposition debunching to pre-form the distribution to match the Stacktail profile

Result: 20.1 mA/hr

Early F

ebruary


f Stacking PerformanceStacking Performance


f Stacking PerformanceStacking Performance

Best stacking for 1 hour for each day

Average Stacking rate for a week


f SummarySummary

We were able to take advantage of the TeVatron failures Two long periods of studies

Due to instrumentation and orbit control upgrades of the past few years, significant progress was done on the Debuncher admittance and progress made on the AP2 orbit How much? Next talk

We understand how to keep the studies on track for the lengthy time period Three study chiefs met 2-3 times daily to access

progress and direction

See an almost 25% increase in stacking See an almost 25% increase in stacking rate.rate.

Documents

Antiproton Study Periods