Antiproton Study Periods

1. Antiproton Study Periods Keith Gollwitzer DOE Tevatron Operations Review March 21, 2006

2. Simplified 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 DOE Tevatron Operations Review – Gollwitzer

3. Background • 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 DOE Tevatron Operations Review – Gollwitzer

4. Execution – 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. DOE Tevatron Operations Review – Gollwitzer

5. Preliminary 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 DOE Tevatron Operations Review – Gollwitzer

6. Commissioned 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 DOE Tevatron Operations Review – Gollwitzer

7. Debuncher 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 DOE Tevatron Operations Review – Gollwitzer

8. Change 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 DOE Tevatron Operations Review – Gollwitzer

9. Debuncher 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 DOE Tevatron Operations Review – Gollwitzer

10. Setting 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 DOE Tevatron Operations Review – Gollwitzer

11. AP2 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 DOE Tevatron Operations Review – Gollwitzer

12. AP2 Orbit Change DOE Tevatron Operations Review – Gollwitzer

13. Limiting Aperture • Running wave pointed to Debuncher transverse Schottkys Will be discussed more in next talk DOE Tevatron Operations Review – Gollwitzer

14. Stacking 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 DOE Tevatron Operations Review – Gollwitzer

15. Orbit Wandering – Stabilizing Orbit V Wandering H AP1 Horiz. AP2 Vert 10mm 10mm V 5mm H Stabilized DOE Tevatron Operations Review – Gollwitzer

16. Early 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 DOE Tevatron Operations Review – Gollwitzer

17. Middle 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 DOE Tevatron Operations Review – Gollwitzer

18. More 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 DOE Tevatron Operations Review – Gollwitzer

19. February • 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) DOE Tevatron Operations Review – Gollwitzer

20. Intensity study – 4s cycle period Cooling was optimized after each change of proton intensity Injected intensity into Accumulator Intensity end of Debuncher cycle Normalized to Beam on Target and 6 Booster turns Early February Intensity at end of AP2 Stacking rate Many other diagnostics and settings were recorded – Flux to Accumulator is fine – Look to Accumulator Cooling Proton beam on target DOE Tevatron Operations Review – Gollwitzer

21. Stacktail 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 February DOE Tevatron Operations Review – Gollwitzer

22. Stacking Performance DOE Tevatron Operations Review – Gollwitzer

23. Stacking Performance Best stacking for 1 hour for each day Average Stacking rate for a week DOE Tevatron Operations Review – Gollwitzer

24. Summary • 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 rate. DOE Tevatron Operations Review – Gollwitzer