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Programme for VDM measurements Friday Oct 15. Phase I: Getting ready 06:00 Started BI checks without beam (BCT) 07:03 S81+LHCb dipole tripped => precycle needed …. delay 09:45 Started filling… some probs with XPOC & filling scheme 11:35 16 bunches ready at 450 GeV , checked ,
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Programme for VDM measurements Friday Oct 15 Phase I: Getting ready 06:00 Started BI checks without beam (BCT) 07:03 S81+LHCb dipole tripped => precycle needed …. delay 09:45 Started filling… some probs with XPOC & filling scheme 11:35 16 bunches ready at 450 GeV, checked , 12:05 Ramp started 12:42 Squeeze started 13:05 Squeeze finished 13:12 Collapsed, optimize IPs…
Programme for VDM measurements Friday Oct 15 Phase II: VDM scans proper 13:43 Started IP8 vdm scans 14:58 Finished IP8 vdm scans 15:18 Started IP5 scans 16:17 Finished IP5 scans 16:31 Started IP2 scans 17:50 Finished IP2 scans IP5: +1 hour Oct 1
Programme for VDM measurements Friday Oct 15 Phase III: complementary measurements 17:55 Started IP8 length scale calibration 18:05 Finished IP8 length scale calibration 18:10 Started IP5 length scale calibration 18:26 Beam dump LBDS vac gauge off ???... one plane done, other plane just started Could not do (30 minutes more!): • longitudinal scan • Simon’s check of parallel IP optimisation • and ALICE length scale calibration (no Silicon tracker)
Overview whole programme CMS scans LHCb scans ALICE scans
Overview all scans LHCb scans CMS scans ALICE scans
Did it go well ? • Phase I: expected ~3hours , took ~7hours (3 ¾ hours lost by Pt8 trip) • Phase II and III: What was originally planned to take ~5 ½ hours of stable beams was compressed into ~ 4 ¾ hours • (excluding what could not be done due to dump) • Beams were good, some more ghost charge (satellite bunches) than usual ? • should not be a problem for this time (on the contrary?)
Summary • Very good beam conditions (emittance, charge, special pattern…) • but 3-4h delay du to pt 8 trip • Completed all VDM • Excellent support and participation from BI, OP, ABP, … • online indications that beam current errors are small • Still to do: • length scale calibrations in IP5 and IP2 • can be done in physics • longitudinal scan tests • can be done in physics, but better test once in a low intensity fill ? MANY THANKS