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Friday 15 th February - morning

Friday 15 th February - morning. After a long investigation, having to cope with timing, naming and polarity issues, we are now sure that the Q6 really quenched this morning at 6h10. Arjan Verweij Access I n all areas to change the HW limits on power converters .

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Friday 15 th February - morning

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  1. Friday 15th February - morning • After a long investigation, having to cope with timing, naming and polarity issues, we are now sure that the Q6 really quenched this morning at 6h10. Arjan Verweij • Access • In all areas to change the HW limits on power converters. • BLM thresholds in cell 12L6 changed for fast losses with ADT quench test. • Scope • “There was some misunderstanding for the access in Pt5 were the elevator of PM54 was put in maintenance during the access.” • “Got a phone call from the people accessing Pt.4 because the evacuation alarm went off. TI informs us that the test of the alarms was planned for today. Unfortunately nobody contacted the CCC or checked if the machine was in access mode before starting the test.” LHC status

  2. Friday 15th February - afternoon • 11:55 when switching the magnets ON, we have several of them that tripped: • EPC back in • 13:30 during the precycle, 3 PC tripped: • RPMBB.UA83.RQTD.A78B2 • RPHGA.UA87.RQ10.R8B2 • RPHGA.UA87.RQ10.R8B1 • HW limits problems for the 3 power converters that tripped. • EPC back in • 16:25 RQ10.L8 trip at injection with no beam in. • PIC trigger due to contact problem after hardware limit changed in the last access • EPC back in LHC status

  3. Friday 15th February - evening • 18:45 beam in • calibration of the ADT pickups with different intensities down to 2e8p. After that test of acquisitions and excitation at 450GeV until 20:00. • 20:55 Start ramp • 21:25 Octupoles to zero, chromaticity to ~2 • Found very small losses in MQ12L6 at a trim value of 21.61mm. BPM reading was at 17.89mm. • Retract bump by 2mm for scraping with collimators and vertical excitation. • Excitation with ADT 400%, MKQ 100% intensity: 1.8e8… LHC status

  4. excitation with 1.9e8. BLMs at 35% of dump threshold. LHC status

  5. ADT 200% gain, 4e8p, BLMs at 28% of threshold. LHC status

  6. 23:445 QUENCH! With 8.2e8p (bunch 1092) and 200% ADT gain LHC status

  7. Saturday 16thFebruary – early morning • 23:50 Cryogenics is recovering already. Small event in 12L6. • we observe a propagation of the quench on both sides. • 00:50 Cryo back • impossible to recover QPS on MQ.12L6 The quench heaters are not charging and the Global protection is still active • 03:30 The QPS piquet called back. An expert managed to do the power cycle remotely; access no longer needed. All machine is ON; we prepare for the precycle. • 05:40 Beam 2: three batches of 8 bunches injected to the LHC • (Injection Scheme Single_36b_4_16_16 -> injected 4 bunches+4 bunches, one injection of 4 bunches skipped; repeated twice). LHC status

  8. Saturday 16th February – early morning • 06:05 Flat top • 3 corrector orbit bump in 12L6. • found (very small) losses in 12L6 with 21.13mm nominal bump amplitude (-17.7mm absoulte BPM reading). • Stable losses - excite 1st pilot bunch with more or less the same ADT gain as during the collimator QT but with 1/3 of ADT amplitude LHC status

  9. 15% of ADT excitation strength -> losses up to 2e-3 Gy/s LHC status

  10. excite the same 8 bunches again with 15% of the ADT excitation strength -> QUENCH of 12L6 (QPS) LHC status

  11. Saturday 16th February – early morning • 08:08 Quench • End Run 1 • Ramp-down LHC status

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