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Wednesday 9.6

Wednesday 9.6. 08:00: Longitudinal blow up 2 ramps with bunches of 2E10 and blowup in the ramp. Quite successful. 14:00: Preparing new ramp & squeeze with same ref. orbit all along. Re-activated high intensity ramp (last used and corrected 20.05).

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Wednesday 9.6

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  1. Wednesday 9.6 • 08:00: Longitudinal blow up • 2 ramps with bunches of 2E10 and blowup in the ramp. • Quite successful. • 14:00: Preparing new ramp & squeeze with same ref. orbit all along. • Re-activated high intensity ramp (last used and corrected 20.05). • Cloned the settings of the 2E10 squeeze and attached it to the ramp. • 17:00: Ramp. • Excellent quality of the orbit – reference at 450 and 3.5 TeV the same (and old corrections were still quite good). • Orbit FB worked much better (0.12 mm peak excursions). • Orbit corrected back to ~ 50 microns rmswrt injection. Transferred RT trims into the functions for next ramp and for the squeeze. 8:30 meeting

  2. Second ramp Blow up on flat bottom to 1.5 ns. Phase noise excitation (0.4 deg rms) was applied starting after the RF voltage increase at 300 seconds. The bunch lengths were 1.1 ns at the end of the voltage increase and decreased smoothly to around 0.9 ns at the end of the ramp. The bunch profiles remained approximately Gaussian throughout. 8:30 meeting

  3. 3 weeks integrated orbit drift @ 450 GeV Up to 0.6 mm rms 8:30 meeting

  4. Ramp 8:30 meeting

  5. Orbit on flat top after correction Diff. wrt injection 40 to 60 micron rms 8:30 meeting

  6. Longitudinal blowup during the ramp. A bit manual. Some differences between B1 and B2 to be understood. 8:30 meeting

  7. Wednesday 9.6 • 19:00 Squeeze. • Collapse separation bumps. • Decided to use the orbit FB with injection optics (optics change still has problems), deselecting all BPMs from Q4.L to Q4.R. • Squeezed to 9m, 7m and 5m. • Orbit FB worked smoothly, peak RT kicks around 3-4 microrad. • Orbit excursions during entire squeeze less than 70 microns rms, limited to the IR regions. • In cleaning sections the stability was < 50 microns rms. • Transferred RT trims into functions at each point, and cleaned the IR regions for features not corrected by orbit FB. • Super-cool and super-smooth squeeze ! • 23:00 ORB fix for dispersion • OK but must watch out: if the FB strength is too large (no. eigenvalues), the FB can become unstable and drive the correctors (H) all in one direction ! 8:30 meeting

  8. Orbit difference 10/11 m - 5 m 40 to 60 micron rms 8:30 meeting

  9. Wednesday 9.6 • 23:00 High intensity. • Injection of nominal bunches. Longitudinualblowup in the SPS. • Strong horizontal instability. Emittances just after injection around 3 um, growing in H to 10 um in a matter a few minutes. Coherent beam motion. • Re-injected with octupoles to -0.5. Seemed better, H emittance stabilized at 5 um. Ramp with Q and orbit FB. Octupoles removed for ramp. • Smooth ramp – orbit excursions < 0.07 mm rms. • But continuous emittance growth to • B1 : from 4.8/2.9 to 7.4/5.5 • B2: from 5.0/6.8 to 6.7/11.7 • Q’ corrected from 9 to 4-5. Incorporated into ramp. • Beam lifetimes good, > 25 h. Bunch length 0.8-0.9 ns. • Collide: lost ½ of B2 (larger beam) while ramping down separation, close to the end of the process. Forgot to change to collision tunes !!! Arrgh !! 8:30 meeting

  10. Unstable beam 8:30 meeting

  11. Second ramp 8:30 meeting

  12. Profiles.. • Tails… 8:30 meeting

  13. Thursday 10.6 • 06:30 Medium intensity – 8E10 • Looks much better. • Emittances of 3 um at start of ramp, 5 um at end of ramp. • Testing collisions now… • Program for today: • Transverse damper studies. • Longitudinal blowup with nominal bunch. • More ramp and squeeze over-night, prepare 3.5 TeV beam for collimation on Friday morning. 8:30 meeting

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