Wire , flat beams and beam-beam MDs in 2017

1. LHC MD day 2017, March 31st, 2017 Wire, flat beams and beam-beam MDs in 2017 Y.Papaphilippou Thanks to the Beam-beam and luminosity working group and in particular F.Antoniou, R.Alemany Fernandez, G.Arduini, R.Bruce, X.Buffat, S.Fartoukh, K.Fuchsberger, M.Hostettler, R.Jones, G.Iadarola, N.Karastathis, E.Metral, D.Pellegrini, S.Papadopoulou, T.Pieloni, M.Pojer, S.Redaelli, A.Rossi, B.Salvachua, H.Schmickler, G.Sterbini, G.Trad, R.Tomas, J.Wenninger (CERN), M.Fitterer, A.Patapenka, A.Valishev (FNAL)

2. Outline • Long-range beam-beam effects and wire compensation • Other long-range MDs • Levelling, Head-on beam-beam and noise • Beam-beam and optics • Emittance evolution

3. Long-range Wire Compensation MDs S.Valishev, et al. • Four DC wires embedded in collimators (TCTs) • Two per IP compensating only beam 2 • Installedin IP5 (2017) and in IP1 (2018) • Prove compensation of long range effect • Various observables • Lifetime, halo (special diagnostics), tune-spread • Tests with wires first in IP5 (2017) and then IP1 (2018)

4. Wire impact on single beam • Goal: Test and calibrate the effect of the wires in a single beam (first at injection, then at flat top) • Align wires with respect to the beam by measuring vertical orbit (or coupling) • Measure impact of wires on beam orbit and tune and calibrate theoretical feed-forward functions • Other optics measurements (linear and non-linear chromaticity, beta-beating, tune-spread, RDTs ) • Similar measurementsfor the external wires and with a non-zero vertical position • Estimate impact in lifetime and emittance (tails, halo?) and compensate with other wire (lower priority) G.Sterbini, A.Rossi, et al. • Commissioning • 2X8h already scheduled • If time permits

5. Wire impact on single beam • Goal: Test and calibrate the effect of the wires in a single beam (first at injection, then at flat top) • Align wires with respect to the beam by measuring vertical orbit (or coupling) • Measure impact of wires on beam orbit and tune and calibrate theoretical feed-forward functions • Other optics measurements (linear and non-linear chromaticity, beta-beating, tune-spread, RDTs ) • Similar measurementsfor the external wires and with a non-zero vertical position • Estimate impact in lifetime and emittance (tails, halo?) and compensate with other wire (lower priority) G.Sterbini, A.Rossi, et al. • Commissioning • 2X8h already scheduled • If time permits • Energy: All can be done at 450 GeV. Qualification of tune and orbit feed-forward at6.5 TeV • Beams required: Only beam2. Compatible with parallel studies using beam 1 • Beam composition and intensity: Single nominal bunches of 1.3 x 1011 ppb • Some tests can function already with probe • Emittances: Nominal BCMS, i.e. ~1.5-2.0 μm.rad • Optics: Nominal @ injection with nominal injection tunes, octupoles and chromaticity settings • More exotic options if testing compensation or lifetime impact can be foreseen

6. BBLR Compensation preparation J.Wenninger et al. • Goal: Measure the crossing angle reduction impact on lifetime • Ideally, part of the intensity ramp-up • Synergy with crossing angle levelling setting-up

7. BBLR Compensation preparation J.Wenninger et al. • Goal: Measure the crossing angle reduction impact on lifetime • Ideally, part of the intensity ramp-up • Synergy with crossing angle levelling setting-up • Energy: 6.5 TeV • Beam composition: 2-3 colliding trains in beam1 and 2 (without/with IR8), a few single bunches in beam 2 • With full long-range, PACMAN-L/R, non-colliding • Intensity: Nominal @ 1.25 x 1011 ppb • Emittances: Nominal for trains i.e. 2.5 μm.radfor BCMS, some nominal single bunches and some blown up by ADT to 4-5μm • Optics measurements can be done with pilot • Optics: Nominal @ collision with nominal tunes, octupoles and chromaticity settings • β* of 40 cm, but probably 33 cm when commissioned

8. BBLR Compensation preparation J.Wenninger et al. • Goal: Measure the crossing angle reduction impact on lifetime • Ideally, part of the intensity ramp-up • Synergy with crossing angle levelling setting-up • Energy: 6.5 TeV • Beam composition: 2-3 colliding trains in beam1 and 2 (without/with IR8), a few single bunches in beam 2 • With full long-range, PACMAN-L/R, non-colliding • Intensity: Nominal @ 1.25 x 1011 ppb • Emittances: Nominal for trains i.e. 2.5 μm.radfor BCMS, some nominal single bunches and some blown up by ADT to 4-5μm • Optics measurements can be done with pilot • Optics: Nominal @ collision with nominal tunes, octupoles and chromaticity settings • β* of 40 cm, but probably 33 cm when commissioned • Procedure: • Reduce crossing angle in steps • Measure impact on lifetime of different bunches, while keeping constant orbit and tune • Monitor impact in emittances, luminosity, halo, losses • Measure optics if time permits

9. BBLR Wire Compensation • Goal: Prove BBLR compensation with powering wire when crossing angle reduction impacts beam lifetime • Leading order octupole effect compensation possible with present hardware

10. BBLR Wire Compensation • Goal: Prove BBLR compensation with powering wire when crossing angle reduction impacts beam lifetime • Leading order octupole effect compensation possible with present hardware • Energy: 6.5 TeV • Partially squeezed optics @ injection could be envisaged (simulation work to be done and optics commissioning overhead) • Beam composition • A few single bunches (around 3-4) in beam 2 (weak beam) spaced far enough for machine protection (abort gap kicker rise time) • With full long-range, 1 non-colliding • As many trains in beam 1 • Intensity: Nominal of 1.25 x 1011ppb for beam 1 (or highest possible from SPS) • Emittances: Nominal for trains i.e. 2.5 μm.radfor BCMS, some nominal single bunches and some blown up by ADT to 4-5μm

11. BBLR Wire Compensation • Goal: Prove BBLR compensation with powering wire when crossing angle reduction impacts beam lifetime • Leading order octupole effect compensation possible with present hardware • Energy: 6.5 TeV • Partially squeezed optics @ injection could be envisaged (simulation work to be done and optics commissioning overhead) • Beam composition • A few single bunches (around 3-4) in beam 2 (weak beam) spaced far enough for machine protection (abort gap kicker rise time) • With full long-range, 1 non-colliding • As many trains in beam 1 • Intensity: Nominal of 1.25 x 1011ppb for beam 1 (or highest possible from SPS) • Emittances: Nominal for trains i.e. 2.5 μm.radfor BCMS, some nominal single bunches and some blown up by ADT to 4-5μm • Optics: Nominal @ collision with nominal tunes, octupoles and chromaticity settings • β* of 40 cm, but probably 33 cm if commissioned • Un-squeezed optics in IR1 (only if commissioned for IR compensation MD) • Crossing angle: • Start with nominal in both IR1 and 5, no collisions in IR2 and 8 • Moving only one IR crossing angle could be envisaged

12. BBLR Compensation procedure • Inject and ramp up a few bunches in beam 2 to commission orbit and tune feed-forward with wire (ideally during commissioning phase) and blow-up effect of ADT • Compatible with parallel tests in beam 1 • Inject, ramp-up and collide strong (beam 1) and weak beam (beam 2) • Set internal TCT/L jaw at 5-6σcol(including other collimation adjustments enabling this) • Reduce crossing angle in steps, while keeping orbit and tune constant • Observe lifetime reduction and ramp-up the current of each wire in steps, observing lifetime recovery in colliding weak beam • Monitor emittance, luminosity, halo, losses • Repeat the test with different weak beam flavours (Pacman-L, Pacman-R, without HO and non-colliding)

13. BBLR Compensation procedure • Measure optics, e.g. beta-beating, coupling, chromaticity, tune spread, RDTs, with wire compensation • Repeat the test with IR1 crossing angle fixed and/or separated in IR1 • Repeat the test using the wires in external jaw • If time permits • Inject and ramp up a few bunches in beam 2 to commission orbit and tune feed-forward with wire (ideally during commissioning phase) and blow-up effect of ADT • Compatible with parallel tests in beam 1 • Inject, ramp-up and collide strong (beam 1) and weak beam (beam 2) • Set internal TCT/L jaw at 5-6σcol(including other collimation adjustments enabling this) • Reduce crossing angle in steps, while keeping orbit and tune constant • Observe lifetime reduction and ramp-up the current of each wire in steps, observing lifetime recovery in colliding weak beam • Monitor emittance, luminosity, halo, losses • Repeat the test with different weak beam flavours (Pacman-L, Pacman-R, without HO and non-colliding)

14. Other Long-range B-B MDs D.Pellegrini, G.Iadarola, et al. S.Fartoukh et al. • Round optics (operational but also pushed β*) • LR limits (crossing angle vs. lifetime and losses) • Different chromaticity, octupole and triplet corrector settings • IP1/5 phase advance scan • Higher intensity/brightness tests (ultimate 25ns, BCMS, 50ns) • Tune-scan (during physics fills) • Flat optics • Passive compensation of tune during leveling • LR limits (crossing angle vs. lifetime and losses) • ATS telescopic optics • LR limits (crossing angle vs. lifetime and losses) • Octupole compensation

15. Head-on B-B and noise J.Wenninger, et al. X.Buffat, T.Pieloni, et al. M.Fitterer, et al. • Leveling by separation (and β*) • In parallel plane (HV in IR1/5), or crossing plane (VH in IR1/5), or skew plane (45deg/135 deg) • End (or beginning) of fill MD with trains or during intensity ramp up • Head-on beam-beam limit and high frequency noise on colliding beams • Emittance growth for “single” colliding bunches with different brightness against noise levels and damper gain • Effect of low frequency noise • Mimicking triplet eigen-frequencies with ADT • Effect 50Hz noise (PC filters) • Short test at injection and/or in conjunction with other MDs

16. Beam-Beam and optics T.Pieloni, R.Tomas, et al. • Beta-beating driven by beam-beam • Pilot vs High-brightness bunch • Beta-beating measurement and correction • Injection and then flat top • Chromaticity variation due to LRs • Measure chromaticity of pilot vs train • Vary crossing angle • Can be combined with tune-spread measurements @ collision

17. Emittance evolution S.Papadopoulou et al. M.Hostettler et al. • Evolution of the beam distribution through the LHC cycle • Single bunches with different brightness and profile measurements • Can be parasitic (transverse and longitudinal profile logging) • Observation of single beam parameter evolution at flat top • Non-colliding bunches emittance evolution (parasitic MDs) • Stability (different chromaticity and octupoles) • Dependence on number of LRs • “OP scans” for determining emittance through luminosity • Parasitic MDs • Beam stability for scans at IP1 • Perform scans at both IPs simultaneously • Impact of longitudinal profiles

18. Summary COM: Commissioning, IR: Intensity Ramp-up, BoF: Beginning of Fill, P: Physics

19. Summary Total of 11 (+5) MD shifts COM: Commissioning, IR: Intensity Ramp-up, BoF: Beginning of Fill, P: Physics