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Progress with Beam

Progress with Beam. Report to LMC, 10.3.2010 Machine Coordination W10: Mike Lamont – Ralph Assmann Thanks to other machine coordinators, EIC’s, operators, system experts, … (especially Mike, Malika and Stefano for some slides). Overall Progress with Beam I.

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Progress with Beam

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  1. Progress with Beam Report to LMC, 10.3.2010 Machine Coordination W10: Mike Lamont – Ralph Assmann Thanks to other machine coordinators, EIC’s, operators, system experts, … (especially Mike, Malika and Stefano for some slides)

  2. Overall Progress with Beam I • All machine systems in operation: cryogenics, magnets, RF, kickers, vacuum, instrumentation, collimation, … • Availability for operation: 45% (week9) and 49% (week10 so far). • Test ramp without beam to 1.18 TeV. • Injection and capture of both beams set up for safe beam. • Beam dump set up for safe beam (further testing requested). • Machine tunes adjusted and controlled to nominal values routinely. • Chromaticity measured and adjusted frequently. • Optics verified and corrected to a maximum beta beat of 20-30%. Almost in specification (OK with better orbit?). • Closed orbit adjusted to an rms of ~0.45 mm (about +-2 mm peak to peak)  factor 2 better than design orbit, if no large BPM offsets. • Dispersion measured and verified (in vertical plane: 3 cm rms).

  3. Overall Progress with Beam II • Spectrometer and compensators set up and corrected with beam. • Nominal separation bumps set up and included into the corrected closed orbit. • Golden reference orbit defined for collimation and machine protection. • Collimation system (all ring collimators) set up with ~0.2mm accuracy. Cleaning and protection hierarchy verified with beam (efficiency: > 99%, limited by BLM resolution with this intensity). • Beam feedback commissioning partially completed, still ongoing. • Luminosity separation knobs tested. • Grazing events delivered to ATLAS and CMS. Many splash events to all experiments.

  4. Typical Picture Very busy beam work by CCC team and many experts (single bunch up to 1e10 p) Very busy hardware work by experts: no beam Note: Short fill lengths related to ongoing work, using up the beam for diagnostics purposes! Low background (except CMS?)

  5. Beta Beating The reproducibility after precycling was excellent. Beam 2 R. Tomas and team

  6. Orbit Established reference orbit “Golden orbit” J. Wenninger

  7. Dispersion Beam 1 M. Meddahi et al

  8. Separation Bumps • Separation bumps – knobs provided by Werner Herr – Stefano Redaelli – Gabriel Mueller - Separation bumps switched on in all IPs Beam1 : Non-closure compared to the case without separation bump is H:0.12 – V:0.15 K.Fuchsberger, M.Meddahi

  9. Beam Dump and Machine Protection Power cut in Point 7 at 01:56 due to emergency stop in RR73 (failure of the emergency stop button). Beams dumped correctly. PIC interlock triggering first, then many others… B. Goddard, R. Schmidt, J. Wenninger, B. Puccio, …

  10. Beta Beat Measurements – Beam 1 Correction done in IP7 R. Tomas and team

  11. Collimation Setup (Good) • Collimator beam based alignment • 2 teams in parallel on beam 1 and 2. • Beam based alignment completed for B1 & B2. Loss maps for assessing efficiency and passive protection to be taken. R.Assmann, R.Bruce, D.Wollmann, S.Readelli

  12. Collimation Setup (Good/Bad) Good Bad (Human Setup Error) R.Assmann, R.Bruce, D.Wollmann, S.Readelli

  13. Some Beam Observations The tune hump is still there (see presentation Ralph Steinhagen), affecting beam lifetime and emittance on the nominal tune working point. For lifetime maybe OK? No source isolated so far. Vertical emittance growth is large (up to 7 micron measured for injected emittance of 1.5 micron). To be studied systematically (calibration of devices, …). Instability with slightly negative chromaticity (seen twice and then fixed by increasing chromaticity by 1 unit). Effect of the transfer line on the loss rate from LHC beam halo.

  14. Evolution of Sudden LHC Beam Loss ~5e9 protons in one bunch for beam 1. Suddenly start of slow loss over 20 s. Then exponential increase until 1/2 – 2/3 of beam lost. Rest of beam self-stabilizes. Seen twice. Fixed by increasing the chromaticity by 1 unit. Case 1 slow loss Case 2 slow loss

  15. Beam Loss IR1: Effect from the Transfer Line Pulsing? factor ~10 increase in IR1 losses at tertiary collimator, during time of SPS extraction! Transfer lines driving and/or exciting beam halo in the LHC!?

  16. This week LHC status

  17. Next week On track towards March 30th date for first 3.5 TeV stable physics! LHC status

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