Tevatron Operations Since the Shutdown

1. Tevatron Operations Since the Shutdown Ron Moore Fermilab – Tevatron Dept.

2. Shutdown/Startup Work • No big upgrades, but lots of maintenance • Warmed up 4 houses for vacuum work • Found/replaced unexpectedly a few (electrically) bad components • Unroll ~60 dipoles, lattice quads (including D16-1 ≈20 mrad) • Move CDF and D0 triplets to move IP and lower corrector currents • Adjusted CDF again after start-up since IP far off (?) • Start up with new helical orbits (horz & vert collision, vert injection) • Goal was to eliminate proton loss during helix transition in squeeze • Had to revert after high pbar loss in new transition R. Moore - FNAL

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5. As good as ever… R. Moore - FNAL

6. Losses during Squeeze • Proton loss is driven by beam-beam effects • New helix more complicated that initially thought • Flip horz collision helix in short arc to eliminate B17H separator polarity change • Also need vert collision helix flip to allow initiating collisions in usual way • Flip vert injection helix to prevent C17V separator polarity change in squeeze • Lost ~1/3 pbars during new helix transition in squeeze of 1st 36x36 store • Phase changes of helix allowed horz and vert separation minima to coincide • Nearly head-on collisions in many places around the ring • Some improvements made, but not good enough  revert to old helix scheme • Made improvements after tuning-up and making orbit bumps to reduce losses at CDF and D0 R. Moore - FNAL

7. Shot 5802 – (Smaller) Proton Loss during Squeeze Low-β LBSEQ Proton Intensity [109] Proton Loss @ Helix Transition Pbar Intensity [109] LBSEQ 14 D11 BLM [Rad/s] Loss Spikes CDF BLM [Rad/s] R. Moore - FNAL

8. Improved Proton Efficiency in Squeeze R. Moore - FNAL

9. HEP • Luminosity ramping up with beam intensities • D0 luminosity lower than expected • Made 3% improvement with alpha-bumps (horz and vert β* offset longitudinally) • Still not understood completely R. Moore - FNAL

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13. Lifetimes in HEP • Pbar lifetime is improved – almost entirely luminous • Proton lifetime suffering from small pbar emittances • Pbars 3-4 times smaller than protons • Greater fraction of proton bunch sees strongest beam-beam force • Highest head-on tune shifts for protons > 0.024 • Trying to blow-up pbars last few stores (missteering at injection) R. Moore - FNAL

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15. Proton Burn Rates – Store 5802 Mary Convery Measured burn rate Non-luminous burn rate Non-luminous losses dominate early in HEP Burn rate from luminosity R. Moore - FNAL

16. Jerry Annala R. Moore - FNAL

17. 5 store running average R. Moore - FNAL

18. Summary • Post-shutdown start-up longer than desired • Adjust CDF quads (again) and revert to old helix • Beam losses at injection, ramp, squeeze as good or better • Luminosity ramping up with beam intensities • Proton lifetime early in HEP is an issue • Exacerbated by small pbar transverse emittances • Want higher intensities to push integrated luminosity • 15-20% more protons and pbars to return to pre-shutdown • Get back to > 40 pb-1 per week reliably R. Moore - FNAL

19. Pbars in the Squeeze R. Moore - FNAL

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