LHC report Friday 22 nd June 2016 Coordination: Wolfgang Hofle and Mike Lamont

Since Wednesday 00:00

Wednesday Wednesday 00:00 to 16:45 – Stable beam fill :45 ADJUST for halo measurements 19:45 Back into Stable Beams – BA3/SPS RF down due to SPS transformer overheating (+ other issues in injectors) – Still on back-up transformer

Thursday 21 st July 02:15 OP dump of #5105 – 639 pb -1 in 27h22m – Peak 1.23e34 cm -2 s -1 – BCMS – no blow-up in PS 04:07 probes in after some delay (power converter problem in TI2.) New filling scheme: 25ns_2076b_2064_1681_1772_96bpi_23inj with reduced batch spacing for LHC (900ns) and SPS (250ns) MKI8 interconnect – With 1.18e11 p/b average, reached 6.00e-8 at the last but 1 injection of beam 2.

Thursday 21 st July 06:00 Stable beams #5106 MKI8 delays adjusted so that the kick waveform does not touch circulating beam. (Mike Barnes) MKI8D-Q5 SIS vacuum threshold increase from 6.0e-8 mbar to 6.3e-8 mbar (Mike Barnes)

Friday 22 nd July 00:30 OP dump of #5106 – 495 pb -1 in 18h33 – Peak 1.19e34 cm -2 s -1 01:20 injecting MKI8 interconnect vacuum before last injection just at the limit (~1.19e11/ppb) – had asked PSB to reduced twice Ib while filling – Linac2 also not in the best of shapes 03:35 Stable beams #5107 – Peak 1.11e34 cm -2 s -1

Halo studies ith 2072b in ADJUST, managed to do inward (down to 3.5 sigma) followed by outward TCP jaw movements for both beams and planes. Losses never exceeded 30% of warning limits. Got very clean measurements in general except some fluctuations in losses in B2H. From a preliminary analysis, the diamond BLM data looks good, to be analyzed later in detail offline. Diffusion speed seems faster for horizontal planes in both beams than in vertical. TCP collimators put back to stable beams positions. Gianluca Valentino and team

Latest MKI parameters rise time: < 900 ns (i.e. 360 buckets) flat top: = 4040 ns – (i.e buckets, 3020 is to be used for not having bunches in buckets that are not xyz1) fall time: < 3500 ns – (i.e buckets, apparently there is a very small bump in the end of the waveform which is hard to measure, but better be avoided). Given these updated numbers Delphine has modified her algorithm to correctly position pilot

MKI vacuum Thursday afternoon Mike Barnes increased the MKI8D-Q5 SIS vacuum threshold from 6.0e-8 mbar to 6.3e-8 mbar. Please note that the MKI SIS (interconnect) vacuum thresholds must NEVER be masked. If it is ever required to change these thresholds, e.g. for a special scrubbing run, the thresholds can be modified by a person with the appropriate RBAC role. Hence there is no need to mask the thresholds.

3 peaks spaced by 25ns Kicked circulating Injected 5 ns recapture. ~ 850 ns Florian Burkart

Histogram produced during the PRERAMP beam mode, shows the bunch structure of the full machine Subtraction of 2 histograms before and after the B2 injection, the time difference between the 2 histograms is 1.1 second (~12k turns) Loss from the injected bunches 2 peaks spaced by 25ns Kicked circulating Losses in the inj gap Chen Xu

Lumi lifetime ML

Turn around time Michi Hostettler

RF - incoming The tests that we would still like to do in Physics are the following: 1. Apply sinusoidal modulation at arrival to flat top, to see how different the distribution is when shaped by band-limited noise vs. modulation 2. Apply band-limited noise at about 0.95 ns at flat top to compare with the bunch flattening we've done using sinusoidal modulation 3. We've observed that since the target bunch length for the ramp has been decreased from 1.15 ns to 1.1 ns, there are a few bunches that have significantly shorter or longer bunch length than targeted. Therefore we'd like to try to keep the target at a higher value in the first half of the ramp and lower it only towards the end of the ramp and see whether the situation can be improved. 4. As for the recurrent application of the flattening, we should also test it, but maybe we can do it once the modulation is implemented in FESA (hopefully by the end of this week or next week at the latest), to test both things at the same time. Helga

Summary Proposal for a reduction of the AGK window length at the MKI level from 4460 buckets (288 bunches) to 2790 buckets (144 bunches) endorsed by (r)MPP up to end of 2016 First possible date for implementation is Monday Two full shifts needed for implementation and re-validation The gain in instantaneous luminosity (IP 1 / 5) for the fills with reduced AGK window would be 7% The estimated gain in total integrated luminosity for 2016 is around 3% if implementation done before MD1 (r)MPP recommends LMC to approve this modification for implementation ahead of MD1 Detailed technical review of proposed implementation in MPP on FRI 22/07 (r)MPP recommends to continue the studies for a safe implementation of a variable AGK window as an operational parameter after EYETS16-17 Etienne Carlier LMC 20/7/2016

Incoming Stable Beam over the weekend 2 shifts for AGK Monday plus access in parallel Possibly back into physics depending on the timing – otherwise OP measurements (coupling, Q’ in ramp, squeeze etc). MD starts 07:00 Tuesday