LHC progressSaturday 2nd May 2015

Coordination: Mike Lamont, Wolfgang Hofle

Friday 1st May morning

• Ramp of two probes to 6.5 TeV (hunting 4 MUFOs)– Removed bump before ULO scan (B2, 15R8)– ULO scan with beam scraped to 4s– Losses at -2.5 mm (V); stopped scan at -3 mm– -1 mm in H losses are gone– moved to +2 mm from initial centre position

beams dumped– reminder: ULO bump is +1 mm (V) and -3 mm (H)

Friday 1st May morning

• EDF power glitch during ramp down– RB45 tripped– EPC Piquet diagnosed temporary earth fault due

to power glitch (active filter)– LHCb dipole also tripped

• Access to fix fire detection in ATLAS and US65 • N. Magnin came in to check AC dipole– B1H needs access (before optics measurements)

Friday 1st May afternoon

• ramping up ALICE solenoid (30 kA)– coupling checked (0.002 in B1, 0.004 in B2)– orbit corrected by OFB

• TDI set-up– completed upper jaws of both beams– issue with beam 1 TDI in point 2, LVDT position sensor lower jaw

• 21:11 dumped by access interlock– missing key (“blue”) interlock PX24– piquet: diagnosed bad cable connection at back of distributor box in the rack &

fixed it

• decision to not continue TDI set-up (LVDT issue prevents completion for beam 1)

Friday 1st May night

• 1st ramp to 6.5 TeV for squeeze to 80 cm– succeeded squeeze to 2 m– dumped by SIS interlock on way to 1.5 m: no energy information for

10 s received (telegram); 3rd SIS communication problem• 2nd ramp to 6.5 TeV for squeeze to 80 cm• Squeeze to 80 cm• 5:18 dumped by power cut in point 5, sector 45 & 56 tripped

– 400 V circuit breaker tripped, no 48 V– 7:04 UPS runs out

• vacuum valves closed• communication lost to circuits, collimators, BLMs• cryo start and maintain lost

Bumps (ULO 15R8)

ULO scan (2 probes at 6.5 TeV)

V: -2.7 mm, H: 0 mm V: -2.7 mm, H: -1 mm

Fill 3670

6.5 TeV – vertical scan

- 50 microns

-3.0 mm

6.5 TeV – horizontal scan

-3.0 mm vertical

-1.0 mm

-2.0 mm

Heading for +2 mm

Beams dump

Summary TDI set-up

• Measured angle and centre for the upper jaws in P8 and P2

• got stuck for the lower jaw in P2 due to wrong calibration tables around zero --> requires access to change tables

• during measurement of lower jaw in P8 got stopped by lost key in P2

• will come back to finish measurements on lower jaws for both beams after access for calibration tables in P2

• coupling checked (0.002 in B1, 0.004 in B2)• orbit corrected by OFB

Wolfgang Bartmann, Chiara Bracco

1st squeeze summary• In the end we decided to try the squeeze with bumps, at least for the early

part. Everything went well down to 2m, and it seemed that there was no issue ahead at 1.5m. We skipped the QCHANGE BP and maintained the injection tunes. The differences in the sextupole settings (very small) and tune from the QCHNAGE BP were incorporated at K -level. – Coupling remained low at ~0.004 for both beams (the local triplet correction

obtained at injection is in). – Q' seemed well under control, we made small adjustments to keep it ~4-5 units. – The tunes drifted off for B2H and B1V, they were very stable in B1H and B2V. The

drifts have been incorporated. The tune excursions between the matched points were ~ as expected, and the QFB corrected them very well. We ran with 4k turns at 6.25 Hz.

– One orbit correction in V was performed locally around ATLAS at 7m (incorporated forward as constant delta). Else the OFB maintained the orbit well - with the bumps. Modest RT trims of up to 10 urad around the squeezing IRs.

J. Wenninger, L. Ponce, A. Gorzawski, R. Suykerbuyk

2nd Squeeze summary• We managed to go through the squeeze with the bumps (a last minute decision) - and we made it to 80 cm !! We

also kept the injection tunes to ease life for the QFB - a very good decision.• The main tune drifts are corrected, there are some significant drifts in 2 of the planes (see plots). The QFB

managed to keep the tunes well under control (4K turns at 6.5 Hz), only B2V kept switching OFF in the second attempt.

• Coupling degraded around 1m for B1, increase to ~0.012 (B2 was fine all along, with C- ~0.005). We corrected it with the usual coupling knobs down to 0.005. It remained at that value until the end. To be noted that the local triplet coupling knob determined at injection was kept constant along ramp and squeeze. It seems that it made a good job, we did not observe the large degradations in coupling as in run1.

• Q' was OK around 4-5 units all along, last measurement at 1.2m (we did not have time to measure the end).

• The OFB started to build up large trims around IR1 in B1V between 2m and 1.5m. It is not clear why (BPMs???). We switched the OFB to the 2.5m optics response matrix when we were at 1.5m - worked well. From then on there were no additional large RT trim increases. The RT trims around the other IRs are reasonable / typical for the squeeze. Since the optics is still in undefined state, no RT trim will be incorporated - wait until the beta-beating is corrected.

• Next time we should step through once more. We could use the 2.5m optics for the OFB right from the start of the squeeze, and switch to a 1m optics towards the end. We could also perform optics measurements along the squeeze. For the optics measurements one could ramp down the bumps at the beginning - tdb. We should made the next attempt once more with injection tunes.

J. Wenninger, L. Ponce, A. Gorzawski, R. Suykerbuyk

Squeeze to 80 cm (2nd ramp)

Saturday / Sunday

• Recovery from power cut• TDI LVTD table fixed by remote intervention (A. Masi)

• incoming– Global aperture measurement– Single nominal bunch to 6.5 TeV– Access (AC dipole, TDI, …)– “Virgin B3 ramp” (probe) with RF modulation and tune FB off

(chromaticity measurement)– Squeeze commissioning cont’d– optics measurement (squeezed) – TDI set-up, both beams lower jaw

Pending accesses

• AC dipole (before optics measurements)• BI BLM filters at point 2• BBQ point 4 (fix of on-demand system)• ADT UX45 (not urgent)• BETS point 6