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Tevatron Operations

This review highlights the significant progress made in Tevatron operations post the 2006 shutdown. It covers record luminosity and proton deliveries, maintenance tasks, beam-beam separation improvements, proton efficiency enhancements, and more. The paper also discusses the impact of beam-beam effects on luminosity lifetime and the importance of proton and pbar emittance for proton lifetime. **

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Tevatron Operations

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  1. Tevatron Operations Ron Moore DOE Tevatron Operations Review March 27, 2007 SC-1 Breakout

  2. Since the 2006 shutdown ended… • 209 HEP stores(give/take a few…not counting ones lost before HEP) • Record delivered lumi / week 24.4 → 44.9 pb-1 • Record peak luminosity 180 → 292 1030 cm-2 s-1 • Record # pbars at start HEP ≈ 3072 109 • Delivered > 1 fb-1 to CDF and D0 • Run 2 total delivered now > 2.6 fb-1, recorded > 2.0 fb-1 2007 DOE Tevatron Operations Review – R. Moore

  3. Run II Peak Luminosity 2007 DOE Tevatron Operations Review – R. Moore

  4. 2006 Tevatron Shutdown Tasks • Fixed known cold leaks in E2, A3, B4; replace failed dipole in F4 • Replaced all ≈1200 LHe Kautzky valves • Cause of 2 magnet failures prior in Nov 06 and Feb 07 • Completed reshimming on remaining 228 dipoles • Needed 3 shutdowns to do! Cryostat sagging – causing coupling • Unrolled quads in A3 (~10 mrad); unroll ~60 magnets with small rolls • Installed 2 new separators (B48, A17), replace 3 separators (A49) • Repaired TEL-1 and installed TEL-2 • Pulled cables for new sextupole circuits (2nd order chromaticity correction) • Completed IPM detector installation • Completed ring-wide hydrostatic level sensor installation • Many smaller tasks, lots of maintenance… • Smooth start-up after such a long shutdown • Run II upgrades effectively complete 2007 DOE Tevatron Operations Review – R. Moore

  5. Highlights since 2006 Shutdown • More pbars to HEP • Thanks to Pbar Source and Recycler • More protons to HEP • Injecting more protons • Better lifetime @ 150 GeV from new helical orbit • Improved luminosity lifetime • Additional separators increase beam-beam separation • Commission TEL-2 • Spare abort gap cleaner & demonstration of beam-beam compensation • Smooth orbits to desired HEP position every store • Improvement on orbit stabilization • Faster halo removal – save few minutes • Get to HEP sooner • Online luminosity fits and model comparison • New tools based on SDA/SuperTable data 2007 DOE Tevatron Operations Review – R. Moore

  6. 2006 shutdown Injecting More Proton and Pbars 2007 DOE Tevatron Operations Review – R. Moore

  7. 2006 shutdown Improved Proton Efficiency @ 150 GeV 2007 DOE Tevatron Operations Review – R. Moore

  8. Improved Proton Efficiency vs Pbar Intensity • New injection helix increased separation between beams (Yu. Alexahin) 2007 DOE Tevatron Operations Review – R. Moore

  9. FY07 Integrated Luminosity A18 vacuum leak E39/43 vacuum failure D32-5 failure feeder 46B fault 2007 DOE Tevatron Operations Review – R. Moore

  10. 2006 shutdown Getting More Proton and Pbars to HEP 2007 DOE Tevatron Operations Review – R. Moore

  11. Luminosity Lifetimes • Long-range beam-beam effects degrade lumi lifetime + integral • Nearest parasitic crossings (≈59 m from IPs) especially bad • Additional separators installed to allow increased separation • More separation  reduced beam-beam effects • ~20% increase @ upstream IP • Not as much @ downstream IP • Luminosity lifetime improved ~20% compared to pre-shutdown • Increased integrated luminosity per store (for similar luminosities and store lengths) 2007 DOE Tevatron Operations Review – R. Moore

  12. Comparing HEP Stores to Model without Beam-Beam • After shutdown, luminosity evolution agrees better to model without beam-beam effects • Most pbars lost during HEP are burned in luminosity • That’s good! • Protons suffer more from beam-beam effects • Especially with smaller pbars V. Lebedev 2007 DOE Tevatron Operations Review – R. Moore

  13. Better Lifetime  More Delivered Luminosity Based on luminosity lifetime fits and adjusting to 24 hour store duration 2007 DOE Tevatron Operations Review – R. Moore

  14. Bunch-by-Bunch Tune Shifts: Store 5245 • Higher pbar intensities  proton/pbar head-on tune shifts ≈ equal! • Proton / pbar intensity ≈ 3, but proton/pbar emittance ≈ 3, too! • Consistent beam intensities store-to-store is helpful operationally • Otherwise, tune changes needed in advance to prevent lifetime problems • Pbar intensities vary more - lost stores, problems in upstream machines, etc. • Bunch leveling in Recycler also helpful for Tevatron and experiments • More uniform bunch dynamics, more uniform bunch-by-bunch luminosity 2007 DOE Tevatron Operations Review – R. Moore

  15. Tune Footprint Currently operate between 7/12 and 3/5 for collisions Considering moving near ½ integer 2007 DOE Tevatron Operations Review – R. Moore

  16. Beam Lifetimes • Pbar lifetime dominated by luminosity – good • Most protons lost in non-luminous processes – not so good Store 5245 Luminosity [μb-1/s] Proton Lifetime / ExpectedLifetime from Luminosity Pbar Lifetime / ExpectedLifetime from Luminosity 2007 DOE Tevatron Operations Review – R. Moore

  17. Smaller Pbar Emittance  Worse Proton Lifetime 2007 DOE Tevatron Operations Review – R. Moore

  18. Schematic of Beam-Beam Force on Proton Bunch 2007 DOE Tevatron Operations Review – R. Moore

  19. Example of Tight Tune Space for Protons Store 5008 L = 207 Longitudinal shaving Operator error – tune pushed too high 2007 DOE Tevatron Operations Review – R. Moore

  20. Store 5245 – Comparison to Model w/o Beam-Beam Initial Lumi = 286 μb-1/s ~10% loss from beam-beam 2007 DOE Tevatron Operations Review – R. Moore

  21. Reliability • Replaced all He Kautzky valve poppets in 2006 shutdown • Successfully tested higher bandwidth quench protection electronics (VFCs) • Implemented in 3 houses, gradually propagate to whole ring • Helps detect quench and pull abort in ≈350 μs (< 20 turns) • Migrated control applications from VMS to Linux • A BIG job requiring careful testing and implementation in operational environment • 2 Tevatron failure-driven shutdowns since June 2006 • Mouse-induced feeder glitch resulted in D3 dipole failure (Oct) • Failed O-ring caused loss of E3 cryo insulating vacuum (Nov) • New pbar cogging for ramp since early Jan 2007 • Pbars were in the abort gap previously – quench if abort up ramp • Now clear abort gap should prevent needless quenches (OK in only “trial” so far) • Implement new BLM electronics to allow aborts on high beam losses • Current system too inflexible – BLM aborts masked out during HEP 2007 DOE Tevatron Operations Review – R. Moore

  22. Tevatron Reliability 2007 DOE Tevatron Operations Review – R. Moore

  23. Integrated Lumi and Store Hours per Week 5 store running average scaled to 1 week 2007 DOE Tevatron Operations Review – R. Moore

  24. Looking Ahead • Implement 2nd order chromaticity correct @ low β • Correct second-order chromaticity @ low β better lifetime • Also required for possible new working point (near ½ integer) • Work with experiments in optimizing integrated vs peak luminosity • Multiple interactions cause difficulties for trigger and tracking • When is peak too high? Do we need higher intensities afforded by new working point? • Other minor improvements – they all add up! • Scrape (higher intensity) protons @ 150 GeV • Remove beam that would be lost anyway on ramp and squeeze • Get “brighter” protons to HEP • Investigating new cogging between pbar injections • Reduce beam-beam effects by changing locations of long-range crossings • Improve proton lifetime @ 150 GeV (bunch-dependent) • More reliable tune measurements • New 1.7 GHz Schottky electronics designed by FNAL (LARP) for LHC (better dynamic range) • New digital tune monitor to measure individual bunches (with tickling) • Better helices, improved transfer line matching, faster shot-setups, etc. 2007 DOE Tevatron Operations Review – R. Moore

  25. New Sextupole Circuits • Move 22 elements from existing SF&SD circuits to 12 new circuits • Correct 2nd order chromaticity in low-β lattice • Should reduce non-luminous proton losses • Operational with new power supplies since early February • Cables pulled during 2006 shutdown • Still configured as “normal” chromaticity sextupoles • Conducting proton-only studies to implement in final configuration • New circuits to run at zero current except @ low-β • Need short access to flip polarity of some elements when ready • Could be operational in ~1 month • Simulation results in Alex Valishev’s slides 2007 DOE Tevatron Operations Review – R. Moore

  26. Luminosity Projections • Refer to slides in R. Dixon’s talk • Projections assume ≈100 store hrs/week on average • Takes into account possible unplanned downtime (failures) • Based on current pbar stacking rate, appear on track to deliver 5.5-6.5 fb-1 total • Likely need increased stacking rates to go higher • Approaching design 320 μb-1/s peak luminosity • Consult with experiments if higher is OK for them • Goal is to maximize integrated luminosity on tape 2007 DOE Tevatron Operations Review – R. Moore

  27. Peak Pbar Stacking Rates Integrated Luminosity We’re in this area now 2.6 fb-1 ≈22 mA/hr March ‘07 2007 DOE Tevatron Operations Review – R. Moore

  28. One Example of Model Parameters • In general, weekly integrated luminosity ≈ independent of store length in 20-30 hr range → flexible running schemes • Pbar stacking rate important factor 2007 DOE Tevatron Operations Review – R. Moore

  29. Summary • Tevatron delivering record peak and delivered luminosity • Great start-up following long 13-week shutdown • Higher beam intensities to HEP, improved lifetime • Protons suffering more from beam-beam effects • Operationally challenging to stay in desired tune space when pbar intensities vary from store-to-store • Implementing 2nd order chromaticity compensation circuits • Should improve lifetimes in collisions • Prerequisite for investigating ½ integer working point • Maximize integrated luminosity to CDF and D0 • On track for 5.5-6.5 fb-1 at current pbar stacking rates • Let’s find the Higgs! 2007 DOE Tevatron Operations Review – R. Moore

  30. Backup Slides 2007 DOE Tevatron Operations Review – R. Moore

  31. NuMI (120 GeV) MiniBoone (8 GeV) A1 Line P1 Line 2007 DOE Tevatron Operations Review – R. Moore

  32. FY Integrated Luminosity 2007 DOE Tevatron Operations Review – R. Moore

  33. FY07 Peak Luminosity 2007 DOE Tevatron Operations Review – R. Moore

  34. FY05-FY07 Weekly Integrated Luminosity 5 store running average scaled to 1 week 2007 DOE Tevatron Operations Review – R. Moore

  35. FY 2007 Average Store Hours per Week 2007 DOE Tevatron Operations Review – R. Moore

  36. Machine Studies and Maintenance • Averaged ≈6.5 hrs / week since last shutdown • Does not include parasitic studies • Exploit natural breaks in machine operation • Lost stores, pbar stacks, etc. • Exploit end-of-store studies • Focus on specific, well-prepared studies • Be efficient, prevent unnecessary quenches/downtime • Start with proton-only stores before trying in HEP • If we really need study time to implement something new for HEP, will get the time • e.g., proton-only for commissioning new sextupole circuits 2007 DOE Tevatron Operations Review – R. Moore

  37. Proton #1 [E9] Proton #19 [E9] Pbar Int. [E9] Pbar cog [bkts] Proton #22 [E9] Proton #34 [E9] Lifetime of a proton bunch degrades when it has a parasitic crossing with pbar bunch near B13 Bunch-by-Bunch Proton Losses @ 150 GeV 2007 DOE Tevatron Operations Review – R. Moore

  38. New Injection Helix blue – oldred – present Separation in σ • Increased separation at “worst” parasitic crossing Parasitic Crossing Number (from B0) 2007 DOE Tevatron Operations Review – R. Moore

  39. New Collision Helix • After adding the A17H and B48V separators in 2006 shutdown blue – oldred – present Separation in σ Distance from B0 [m] 2007 DOE Tevatron Operations Review – R. Moore

  40. Better Lifetime  More Delivered Luminosity Based on luminosity lifetime fits and adjusting to 24 hour store duration 2007 DOE Tevatron Operations Review – R. Moore

  41. Separation at IPs with different cogging at injection S2min Injection cogging ncog=61 S1min ncog - cogging w.r.t. the collision one, ncog=0 Measured helix and optics used, reference emittance 15mmmrad 2007 DOE Tevatron Operations Review – R. Moore

  42. Beam-Beam Resonance Strengths vs Injection Cogging 5Qx Nominal values @ injection ncog=61 (before change) Collision cogging: ncog=0 ncog=-2 is the best for 7Qy ncog=10 is good for 5Qx while not bad for 7Qy Now implemented for ramp 7Qy ncog Yuri Alexahin RDTs (Resonance Driving Terms) calculated for 3 amplitude 2007 DOE Tevatron Operations Review – R. Moore

  43. Kautzky Valve Poppets • During quench, pressure forces valve open, allows He to escape • Poppet can break off, remain in closed position • 1 similar failure in 20 years, then 2 in three months • Replaced all ≈1200 He Kautzky valve poppets during 2006 shutdown • No poppet failures since replacement Broken poppet from B17 spool Kautzky valve Closed Kautzky valve 2007 DOE Tevatron Operations Review – R. Moore

  44. Online Luminosity Evolution Fits • Bunch-by-bunch lumi and beam intensities, too • Different fit functions and results stored in database, spreadsheets, etc. • Useful for Run Coordinator to determine end-of-store time 2007 DOE Tevatron Operations Review – R. Moore

  45. Holes from arcing D32-5 dipole beam tube Flashover in Feeder 46B cubicle D32-5 Dipole Failure in Oct 2006 • Mouse caused feeder fault • Glitch → D3 quench response • Dipole failed during quench • Previous D3 quench 9/11/02 • Failure lying in wait? 2007 DOE Tevatron Operations Review – R. Moore

  46. Tevatron Electron Lenses (TEL) • TEL-1 installed 2001; repaired & reinstalled 2006 • Used mainly to clean abort gap • Few studies demonstrating (horz) compensation on pbars (2003) • Test bed for electron gun designs • TEL-2 installed 2006 • Used as spare abort gap cleaner • Successful (vertical) tune-shifting on protons during HEP! TEL-2 on P12 TEL-2 2007 DOE Tevatron Operations Review – R. Moore

  47. TEL-2 in Action P12/24/36 lowest vertical tune (PACMAN) P12 intensity [E9] TEL-2 ON P12 P36 intensity [E9] TEL-2 off • TEL-2 increases proton lifetime by raising vertical tune away from 7/12 • TEL-1 could do same for horz tune on leading bunches of train • Little emittance growth, little/no increase in losses • Currently doing studies with TEL-1 while TEL-2 cleans abort gap • Could try simultaneous operation to level bunch tunes to help lifetime • TEL-2 Marx generator suffers from radiation damage – added steel shielding 2007 DOE Tevatron Operations Review – R. Moore

  48. IPM • Detectors installation completed during 2006 shutdown • Waiting for full complement of production electronics • Observed TBT quadrupole oscillations on injection • Will improve transfer line matching, emittance dilution Proton Bunch Injection Oscillations Protons & Pbars at Injection 2 RMS size [mm] 1 0 20 Turn # 2007 DOE Tevatron Operations Review – R. Moore

  49. Peak Pbar Stacking Rates Peak Luminosity 2007 DOE Tevatron Operations Review – R. Moore

  50. Peak Pbar Stacking Rates Delivered Luminosity per Week 2007 DOE Tevatron Operations Review – R. Moore

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