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Saturday 15 th May

Saturday 15 th May. One bunch 1 e11 per beam 09:57: start ramp Lifetime drops at start of ramp from > 25h to ~7h. Losses seen at momentum collimators ==> initial losses of uncaptured beam as expected.

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Saturday 15 th May

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  1. Saturday 15th May One bunch 1 e11 per beam 09:57: start ramp Lifetime drops at start of ramp from > 25h to ~7h. Losses seen at momentum collimators ==> initial losses of uncaptured beam as expected. Strong emittance growth during the ramp, from the start onwards: 450 GeV 3.5 TeV B1, H: 3.2 ==> 8.8 micron B1, V: 2.6 ==> 5.4 micron B2, H: 3.9 ==> 10.3 micron B2, V: 3.4 ==> 8.2 micron LHC status

  2. Nominal bunch up ramp Losses started at around 1.8 TeV. First losses seen on beam 1. Lifetime drops steeply from ~40 h to 0.04 h. All losses at collimators in IR7 (betatron losses). Losses start to quiet down around 2.6 TeV. No losses of b1 above 3.3 TeV. Losses for b2 continuing all the way to 3.5 TeV, but at lower levels. Lost ~40% of beam during the ramp. Both beam 1 and beam 2 show similar overall intensity loss, even though loss peaks are not correlated in time. Minimum beam lifetime during ramp: ~0.03 hours Beam loss finally reappeared at 3.5 TeV for beam 2 (see below), after end of flat top adjustments. Lost another 30% of beam before being dumped by BPM software interlock. LHC status

  3. Nominal bunch up ramp Orbit well corrected at 3.5 TeV – a lot of history – will try and establish this as baseline for high energy RF - PhilippeFor the beam: Losses do not seem caused by the RF. At 3.5 TeV, fast scope and Bunch-Peak meas show ?quiet? situation and disagree with BQM. On the fast scope B2, probably saturation at the beginning of ramp, generating false satellite bunches For the BQM: At 3.5TeV, measurement is very noisy. Probably caused by the measurement itself as it is not confirmed by Bunch-Pk or fast scope. LHC status

  4. Out of bucket flash at start of ramp LHC status

  5. ~35 Hz LHC status

  6. Qh instabilities saturate the BBQ (> ~ 1 mm amplitudes) LHC status

  7. Bunch length LHC status

  8. Lifetime up the ramp LHC status

  9. LHC status

  10. Re-fill for physics 6 bunches of around 2 e10 per beam Orbit feedback behaved well LHC status

  11. LHC status

  12. Fill 1104 Bit slow getting establishing collisions RT orbit trims make it difficult to correct back to reference orbit without getting radical – had to get beam into collision by hand and then scan LHC status

  13. Fill 1104 All rather boring thereafter LHC status

  14. Today • 14:00 ish - end of fill • 30 mins single beam – CMS BG • Two test ramps • low intensity • measure chromaticity • clean up orbit • high intensity • new orbit • octupoles • Overnight - physics LHC status

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