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Thursday 15.7

Thursday 15.7. 04:20 Stable beams 13_8_8_8 Peak luminosity around 1.2E30 cm-2s-1. Dampers on. Intensity and luminosity lifetimes not as good as previous fill. 06:00 TOTEM RPs at 25 sigma vertical plane, 30 sigma hor. plane. Problems with the TOTEM RP FESA server…

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Thursday 15.7

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  1. Thursday 15.7 • 04:20 Stable beams 13_8_8_8 • Peak luminosity around 1.2E30 cm-2s-1. • Dampers on. • Intensity and luminosity lifetimes not as good as previous fill. • 06:00 TOTEM RPs at 25 sigma vertical plane, 30 sigma hor. plane. • Problems with the TOTEM RP FESA server… • 12:00 Damper off, lifetime of beam2 increases by a factor 2-3. Beam2 damper settings not yet fully optimized. • 13:00 Dump beam. • 15:30 Injection – Hump hunting. • Test effects of the GSM. No effect seen on the hump. 8:30 meeting

  2. Lifetime damper ON - OFF 8:30 meeting

  3. Hump vs. GSM signal in the tunnel • Circulating beam (single nominal bunch) available at ~16:25 Started to switch OFF GSM network in the tunnel in the following order: • Sector 12 + TI2 Sector 23 Sector 34 sector 45 Sector 56 Sector 67 Sector 78 Sector 81 + TI8 + UX15 • By 17:24 all GSM transmitters in the tunnel were OFF No significant modification on the hump amplitudeBy 18:00 the GSM network was re-established (for a total interruption of 1.5 h) This test was possible thanks to the contribution of IT/CS (A. Pascal, F. Chapron). G. Arduini et al.

  4. Hump vs. GSM signal in the tunnel • No significant change in amplitude • Typical slow drift in frequency as observed in other occasions. GSM OFF – B2H GSM ON – B2H GSM ON – B2V GSM OFF – B2V

  5. Thursday 15.7 • 18:00 : Prepare for 13 + ½ nominal bunch configuration (LHCf) • LBDS beam position interlocks reconfigured. • Damper noise improvements for beam2. • 20:00 Quench heater of MB in sector 45 discharging. To be fixed before the week-end. • 22:00 CMS reporting overpressure problem in their cavern. • 23:00 Access for CMS • LBDS beam position interlocks reverted to initial situation. Give up on 13 + ½ bunch scheme. • QPS reset on S67. Not pre-cycled. 8:30 meeting

  6. Friday 16.7 • 00:30 Injection • Beams dumped twice by FMCM on RQ5.LR3. M. Zerlauth confirmed that the problem seems to be internal to the FMCM + voltage divider system. • Beam losses at injection, suspected scraping in the SPS, RF loops, energy offsets… • Abnormal bunch length increase in the LHC. Injection losses due to un-bunched beam in the LHC. Large synchro loop errors. • 04:00 RF work at injection. • One explanation : the field in the LHC is off by around 0.3%, but not seen on the trajectories. Still investigating… • SPS : vacuum leak developing in sextant 4 since yesterday evening. 8:30 meeting

  7. Bunch length and losses 8:30 meeting

  8. Friday 16.7 • Restore injection. • Multi-bunch injection. • Access for quench heater PS in S45. • Over the week-end: • Physics • Possibly short loss map measurements at injection. 8:30 meeting

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