Programme for Saturday 10 July Understand the RF problems affecting LHC Filling for Physics fill with single10b_4_2_4_rot EOF - ADT feedback Injection studies Physics fill with single9b_6_6_6

Saturday 10 July Morning: 8:00 -12:00 Filling for Physics fill with single10b_4_2_4_rot Injected O.K. 10 bunches of beam 1 and 9 bunches of beam 2 On the request of the 10th bunch of beam 2: LHC-RF got de-synchronised – as last night. Experts investigating. Meanwhile, RF noise on Beam 1 appeared again, creating beam 1 de-bunching (~1e10p in the abort gap). Total losses from the buckets: ~2.5 e11p 12:00 : dump beams (after cleaning some of the beam in the abort gap)

Saturday 10 July

Saturday 10 July RF problems with single10b_4_2_4_rot on bucket number 29700 Philippe and Frederic Request bucket number 29700 Processing of this value: an offset is added and then number cast in a short integer. For value above 29625 there is an overflow and the most significant digit is disregarded resulting in a number which is too small for the bucket selector  common frequency generator is stopped. SPS is locked on the LHC and without this common frequency it will not even take beam from the PS. Fri-Sat night: SPS switched back to its local clock, and beam was re-established in the SPS. LHC RF problem was then solved by sending manually a "NEXT INJECTION RF BUCKET“, which un-blocked the common frequency generator but … did not solve the problem.

Saturday 10 July Saturday morning : Again we logically requested bucket number 29700. Same effects are observed  bucket selector stopped! Had to switch off/on the synchro-crate which hosts this board in SR4 Dry test done with bucket 1  O.K. Test with bucket 29700  same problem. And therefore investigated and understood the problem DO NOT USE bucket number above 29626 Will be fixed on Monday (not needed in this fill)

Saturday 10 July B1 RF noise problems: Philippe and Frederic While investigating, observed big de-bunching on beam 1 with signature similar to last Sunday  RF noise The clock generator module in SR 4 produces the clock used by the RF demodulators. One of this clock (380 MHz) is produced by a Phase Lock Loop which was not locking anymore on beam 1, generating bursts of noise in the loop. Re-tuned it to put it back in the middle of the range. The effects is not caused by temperature but probably humidity. To be monitored periodically. The same module has been in operation in UX45 since Oct. 2008 and showed small drift.

Saturday 10 July 13:30 : Refilling with the single9b_6_6_6, without this 29700 bucket number At the end of injection  beam dump by an electrical glitch caught by the FMCM in IP6 14:30 : re-starting the injection, single9b_6_6_6. 18:30 : at 3.5 TeV, squeezed, right before collapsing the separation bumps, got hit by another electrical glitch on the network which was caught by the FMCM in Pt 1 and 5 and dumped the beams 18:30 : Ramp down combo 20:00 : Towards the end of ramp-down combo, got hit again by an electrical glitch which tripped S67-78. Later on, got hit again by cryo-maintain in S67 (spike in the pressure sensor) 20:00 – 22:00 : Pre-cycle sectors 67 and 78

Saturday 11 to Sunday 12 July 00:30 Injected 9+9 nominal bunches – TI 2 TL and protection device setting-up of Friday successful : IQC does not latched anymore for B1. Ramped and started to squeeze. Orbit feedback was not on and the orbit drifted until the beams were dumped at 2:45 before getting to the 7 m stop point. At about 4 am lost CM in 56 and 67 - this was quickly solved by the cryo piquet and operator so that at 6 am the conditions were already back. 4:15 - 8:00 : WorldFIP communication problem affecting cells 15R4 to 8R4: access in pt 4 – repeater changed. Pre-cycling and preparing LHC for 450 GeV injection

Programme for Sunday 12 July ~11:00 – 23:00 : Injection studies pending readiness of the LINAC source (control problems) Overnight : Physics fill

To Be Done Establish absolute reference orbit with stable beam configuration – Joerg Wenninger EOF: ADT with colliding beams – Wolfgang Hofle Octupoles to zero WS (vs. BLM threshold, also during the ramp) – Bernd Dehning Loss maps – Ralph Assmann Beam time requests: Hump measurements – Gianluigi – 450 GeV, 1.5h Optics measurements – Rogelio Tomas, 450 GeV (8hr) and 3.5 TeV (8h) Beam-beam studies – Werner Herr (few shifts) High/Low gain sensitivity switch (mostly parasitically) ADT: 450 GeV, 8 hrs, to check the noise improvement after going to the high intensity settings, complete the set-up of one missing pick-up

Pending Requests FMCM : re-visit / tests whether the threshold can be relaxed? Access requests: Wire scanner B2: electronics board to change – Anna Guerrero TCLA.B5L3.B2 collimator (during next TS) – Alessandro Masi Check Clock Gen. in Faraday Cage (SR4) – Philippe Baudrenghien In investigation: RSS.A34B1 S34 : No PM by detector due to the low current level in the circuit --> no trigger. PM however from switch confirming self opening (both flags change state). 1st event of this kind in LHC to be studied by EE experts once back from holidays. But tripped again 2 other times