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Status of Task2.2 HL-LHC Optics and Lattice. Bernhard Holzer for the WP2, Task2.2 Team R. De Maria, S. Fartoukh CERN, Geneva, Switzerland, A. Chancé , B. Dalena , J. Payet , CEA, Gif sur Ivette , France, A. Bogomyagkov , BINP SB RAS, Novosibirsk, Russia
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Status of Task2.2 HL-LHC Optics and Lattice Bernhard Holzer for the WP2, Task2.2 Team R. De Maria, S. Fartoukh CERN, Geneva, Switzerland, A. Chancé, B. Dalena, J. Payet, CEA, Gif surIvette, France, A. Bogomyagkov, BINP SB RAS, Novosibirsk, Russia R. B. Appleby, S. Kelly, M. B. Thomas, The University of Manchester, UK, L. Thompson, The University of Manchester and the Cockcroft Institute, UK, M. Korostelev, K. M. Hock, A. Wolski, University of Liverpool and Cockcroft Institute, UK, C. Milardi, INFN, Frascati, Italy, A. Faus-Golfe, J. Resta Lopez, IFIC (CSIC-UV), Valencia, Spain
Luminosity & Beam Optics Goal: establish & optimise a lattice that is adequate for the luminosity envisaged for the HL-LHC Match a full set of beam optics that corresponds to the experiment desiderata Baseline Version: 150mm triplet aperture
Status: the V1.0 Baseline Optics /afs/cern.ch/eng/lhc/optics/HLLHCV1.0 ... which is clearly the 150mm version for details: MADX sample job (RdM) It contains short cuts ... to the LHC standard optics & lattice (Version V6.503, or called “db5” in the sample job). to the LHC upgrade optics and lattice HLLHCV1.0, or called slhc in the sample job. D2 Q5
Status: the V1.0 Lattice The upgrade lattice used here differs from the LHC standard by: A new triplet with 2 quadrupoles per triplet lens, A s.c. D1 magnet, A shift in D2 by 15m towards the IP, to gain the space needed for the crab cavities A shift of the position of the Q5 by 11m towards the arc to optimise the optics flexibility with a change of the type from MQML to a new proposed MQYL type A small shift of Q4, An additional sextupole in Q10 for IR1&5 The 3 crab cavities per side and beam, IR1&5 A new Q5 in IR6 of the MQYL type A new set of corrector package including a5,b5,a6 New orbit correctors in the triplet and D2
The V1.0 Optics ATS Luminosity base line case: round at βx*=15cm, file=”slhc/opt_round.madx” this is our standard optics, 15cm beta in both planes. the β* in IP2,5 is 10m and 3m respectively (round beams) ATS Luminosity alternatives: round at βx*=10cm, file=”slhc/opt_sround.madx” flat at βx*=30cm, ,βy*=7.5cm file=”slhc/opt_flathv.madx” super flat, βx*=5, βy*=20cm, file=”slhc/opt_sflat.madx” super flat, βx*=20, βy*=5cm, file=”slhc/opt_sflathv.madx” Injection optics: injection ... version 18m: file=”opt_inj_18m.madx" injection ... version 11m: file=”opt_inj_11m.madx" injection ... version 6m: file=”opt_inj.madx" Our standard injection case is still the last in the list, resulting in βx,y*= 6m beta in IP1,5. In all injection files the beta at IP2,8 is put to 10m
The V1.0 Optics Pre-Squeeze optics: two different versions are available: the final pre-squeeze optics: file=”opt_presqueeze.madx", referring to βx,y*= 0.44m at IP1,5 and a pre-pre-squeeze withβx,y*=3.4m file=”opt_presqueeze_3400.madx", with ATS phase advances. Then there is a file, that describes the optics at the end of the ramp it refers to βx,y*=6.0m file=”opt_endoframp.madx". Finally the version for ion operation: Ions Optics with IP15 at βx,y*=0.44m, IP2 and IP8 at βx,y*=50cm file=”opt_presqueeze_3400.madx"
Special Remarks: Fringe Fields court. Luke, Sam, Mathew improving the hard edge model by adding short lenses to model the fringe field effect. nominal LHC, 70mm aperture HL-LHC, 150mm aperture known, but not yet compensated for in te v1.0 data base optics
Special Remarks: HL-LHC Optics in IR2 / IR8 court. A. Bogomyagkov the “ATS Squeece Optics (15cm/15cm/10m/3m) IP8 IP2 Serious Optics changes in the matching section ... But no Lattice Changes foreseen so far.
LatticeOptimisation for Crab Cavities court. B. Dalena Study of additional quadrupoles at Q5 / Q6 / Q7 ... Q4 / Q5 / Q6 in triplet configuration & add. Q7 ... allows for much larger βs at the Crab Cavities add. Quad at Q5: no big change
Special Remarks: Optimisation for Crab Cavities * F F LHC Standard Lattice HL-LHC lattice, V1.0 Provide Space for Crab Installation -> D2 shift -> optimise lattice Q4,5,6 in “triplet configuration” -> optimise optics HL-LHC lattice, Crab Optimised
Special Remarks: Optics Transitions from injection to pre-squeeze, court. Maxim avoid changes in gradient direction running at very low / very high gradients zero crossings (except trim quads) strong differences in the two apertures keep the resulting beta beat as low as possible all curves checked by magnet experts (Per Hagen / EzioTodesco) -> ok
Special Remarks: Optics Transitions from injection to pre-squeeze Optics Transition 6m -> 44cm in 19 steps Δβ/β ≤ 3.7 %
Some Remarks: ... concerning the additional options and efforts that go beyond these baseline optics: Robs and Barbara optimisations, using a triplet like structure in Q4, Q5, Q6 are modifications on top of the lattice (V1.0) that we refer to here. Especially the option of adding a second Q7 to gain margin for the crab cavity voltage is NOT included in this lattice. Anton’s optimisation of the IR2 & IR8optics refer to the study of the phase advance for ALL the HLLHC IR2 and IR8 optics mentioned here. Maxime’s interpolation optics refer to the HLLHC standard injection to pre-squeeze optics mentioned here. The fringe field calculations from Rob/Luke/Sam/Mathew et al refer to this lattice and optics (15cm) but we will need them for fine tuning of any of the optics in the context of the upgrade -> script in MADX. The effect is not rematched yet in V1.0.
Conclusion: IPAC2013 was defined in task2.2 as a deadline to converge the efforts of the different team colleagues. Still there might be room for further detailed modifications. However we would like to freeze the status, including the complete set of optimised beam optics to pass hand over to task 2.3 for field specifications and tolerances. To be determined: Options to improve crab cavity situation, but require additional hardware (Q7)
Lattice Modifications: Summary And finally B. Dalena et al: additional Quadrupole to support Q7 ... crab cavitiy conditions
Lattice & Crab Cavities: Beam Orbit court. R. DeMaria Standard Bump for Crossing angle & beam separation closes at Q5 ... and leads to (varying) orbit offsets at the crab cavity location. -> bump closure by strong dipole magnet at D2. -> Alternative: transverse cavity positioning feedback following the beam orbits
Lattice & Crab Cavities: Beam Orbit A. Dexter/ E. Jensen Frascati Workshop 2012 strong orbit corrector needed in front of D2 for crossing angle bump & separation bump first estimates: