1. Name Event Date Name Event Date 1 Univ. “La Sapienza”, Rome, 20–24 March 2006 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios performance limitations, possible scenarios and milestones for the LHC upgrade http://care-hhh.web.cern.ch/care-hhh/ See also slides on Measurements, ideas, curiosities Measurements, ideas, curiosities triplet magnets BBLR

2. Name Event Date Name Event Date 2 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Outline Time scale and potential of an LHC upgrade Time scale and potential of an LHC upgrade LHC commissioning strategy and beam parameters LHC commissioning strategy and beam parameters Machine performance limitations Machine performance limitations Luminosity optimization and upgrade paths Luminosity optimization and upgrade paths Luminosity lifetime: peak vs integrated luminosity Luminosity lifetime: peak vs integrated luminosity LHC luminosity upgrade scenarios: LHC luminosity upgrade scenarios: ultimate performance without hardware changes ultimate performance without hardware changes upgrade of the Interaction Regions upgrade of the Interaction Regions new bunch-shortening RF system and cryogenic loads new bunch-shortening RF system and cryogenic loads collimation, beam-beam compensation and crab cavities collimation, beam-beam compensation and crab cavities milestones and baseline design milestones and baseline design

3. Name Event Date Name Event Date 3 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Time scale of an LHC upgrade L at end of year time to halve error integrated L radiation damage limit ~700 fb -1 the life expectancy of LHC IR quadrupole magnets is estimated to be <10 years owing to high radiation doses the statistical error halving time will exceed 5 years by 2011-2012 therefore, it is reasonable to plan a machine luminosity upgrade based on new low-ß IR magnets before ~2015 design luminosity ultimate luminosity courtesy J. Strait

4. CARE-HHH 03 November 2005 - LHC seminarF. Ruggiero & W.Scandale, LHC luminosity upgrade - report from LHC-LUMI-05 4 luminosity versus energy upgrade Courtesy of Michelangelo Mangano

5. Name Event Date Name Event Date 5 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Chronology of LHC Upgrade studies Summer 2001: two CERN task forces investigate physics potential (CERN-TH- 2002-078) and accelerator aspects (LHC Project Report 626) of an LHC upgrade by a factor 10 in luminosity and 2-3 in energy March 2002: LHC IR Upgrade collaboration meeting http://cern.ch/lhc-proj-IR-upgrade October 2002: ICFA Seminar at CERN on “Future Perspectives in High Energy Physics” 2003: US LHC Accelerator Research Program (LARP) 2004: CARE-HHH European Network on High Energy High Intensity Hadron BeamsCARE-HHH European Network November 2004 : first CARE-HHH-APD Workshop (HHH-04) on “Beam Dynamics in Future Hadron Colliders and Rapidly Cycling High-Intensity Synchrotrons”, CERN-2005-006 September 2005 : CARE-HHH Workshop (LHC-LUMI-05) on “Scenarios for the LHC Luminosity Upgrade” http://care-hhh.web.cern.ch/CARE-HHH/LUMI-05/

6. CARE-HHH 3 November 2005 - LHC seminarF. Ruggiero & W.Scandale, LHC luminosity upgrade - report from LHC-LUMI-05 6 The CARE-HHH Network Roadmap for the upgrade of the European accelerator infrastructure (LHC and GSI accelerator complex) oluminosity and energy upgrade for the LHC opulsed SC high intensity synchrotrons for the GSI and LHC complex oR&D and experimental studies at existing hadron accelerators oselect and develop technologies providing viable design options Coordinate activities and foster future collaborations Disseminate information Coordinate and integrate the activities of the accelerator and particle physics communities, in a worldwide context, towards achieving superior High-Energy High-Intensity Hadron-Beam facilities for Europe Mandate HHH coordination: F. Ruggiero (CERN) & W. Scandale (CERN) 1.Advancement in Acc. Magnet Technology (AMT): L. Rossi (CERN) & L. Bottura (CERN) 2.Novel Meth. for Acc. Beam Instrumentation (ABI): H. Schmickler (CERN) & K. Wittenburg (DESY) 3.Accelerator Physics and Synchrotron Design (APD): F. Ruggiero (CERN) & F. Zimmermann (CERN)

7. Name Event Date Name Event Date 7 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Nominal LHC parameters collision energy dipole peak field injection energy E cm B E inj 2x7 8.3 450 TeV T GeV protons per bunch bunch spacing average beam current N b ∆t I 1.15 25 0.58 10 11 ns A stored energy per beam radiated power per beam 362 3.7 MJ kW normalized emittance rms bunch length nznz 3.75 7.55  m cm beam size at IP1&IP5 beta function at IP1&IP5 full crossing angle **c**c 16.6 0.55 285  m m  rad luminosity lifetime peak luminosity events per bunch crossing LLLL 15.5 10 34 19.2 h cm -2 s -1 integrated luminosity∫ L dt 66.2fb -1 /year

8. Name Event Date Name Event Date 8 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Peak luminosity at the beam-beam limit L~ I/  * Total beam intensity I limited by electron cloud, collimation, injectors Minimum crossing angle depends on beam intensity: limited by triplet aperture Longer bunches allow higher bb-limit for N b /  n : limited by the injectors Less ecloud and RF heating for longer bunches: ~50% luminosity gain for flat bunches longer than  * Event pile-up in the physics detectors increases with N b Luminosity lifetime at the bb limit depends only on  * ⇒ reduce T turnaround to increase integrated lumi LHC upgrade paths/limitations I=0.86 A I=1.72 A nominal ultimate I=0.58 A larger crossing angle longer bunches bb limit more bunches

9. Name Event Date Name Event Date 9 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios The peak LHC luminosity can be multiplied by:  factor 2.3 from nominal to ultimate beam intensity (0.58  0.86 A)  factor 2 (or more?) from new low-beta insertions with ß* = 0.25 m T turnaround ~10 h  ∫Ldt ~ 3 x nominal ~ 200/(fb*year) Expected factors for the LHC luminosity upgrade Major hardware upgrades (LHC main ring and injectors) are needed to exceed ultimate beam intensity. The peak luminosity can be increased by:  factor 2 if we can double the number of bunches (maybe impossible due to electron cloud effects) or increase bunch intensity and bunch length T turnaround ~10 h  ∫Ldt ~ 6 x nominal ~ 400/(fb*year) Increasing the LHC injection energy to 1 TeV would potentially yield:  factor ~2 in peak luminosity (2 x bunch intensity and 2 x emittance)  factor 1.4 in integrated luminosity from shorter T turnaround ~5 h thus ensuring L~10 35 cm -2 s -1 and ∫Ldt ~ 9 x nominal ~ 600/(fb*year)

10. Name Event Date Name Event Date 10 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Challenge of a Cold Machine

11. Name Event Date Name Event Date 11 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios LHC Cleaning System (R. Assmann) 43 Pilot No collimation Single-stage cleaning Two-stage cleaning (phase 1) Two-stage cleaning (phase 2)

12. Name Event Date Name Event Date 12 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Collimation & Machine Protection

13. Name Event Date Name Event Date 13 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Constraints for LHC commissioning uOnly 8/20 LHC dump dilution kickers available during the first two years of operation  total beam intensity in each LHC ring limited to 1/2 of its nominal value uAccording to SPS experience and to electron cloud simulations, the initial LHC bunch intensity N b can reach and possibly exceed its nominal value for 75 ns bunch spacing, while it may be limited to about 1/3 of its nominal value for 25 ns spacing uMachine protection and collimation favours initial operation with lower beam power and lower transverse beam density. Simple graphite collimators may limit maximum transverse energy density to about 1/2 of its nominal value uEmittance preservation from injection to physics conditions will require a learning curve  do not assume transverse emittance smaller than nominal, even for reduced bunch intensity uInitial operation with relaxed parameters is strongly favoured  higher ß*, reduced crossing angle, and fewer parasitic collisions

14. Name Event Date Name Event Date 14 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios LHC beam commissioning Mike Lamont, Chamonix 2005 workshop No parasitic encounters No crossing angle No long range beam-beam Larger aperture Instrumentation Good beam for RF, Vacuum… Lower energy densities Reduced demands on beam dump system Collimation Machine protection Luminosity 10 30 cm -2 s -1 at 18 m 2 x 10 31 cm -2 s -1 at 1 m 43 on 43 with 3 to 4 x 10 10 ppb to 7 TeV

15. Name Event Date Name Event Date 15 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios PhaseR1/2 Time [days]Total 1Injection212 2First turn236 3Circulating beam236 4450 GeV: initial commissioning248 5450 GeV: detailed measurements248 6450 GeV: 2 beams122 7Nominal cycle155 8Snapback – single beam236 9Ramp – single beam248 10Single beam to physics energy224 11Two beams to physics energy133 12Establish Physics122 13Commission squeeze244 14Physics partially squeezed TOTAL 60 LHC beam commissioning Mike Lamont, Chamonix 2005 workshop

16. Name Event Date Name Event Date 16 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios parameterunits75 ns spacing25 ns spacingnominal number of bunches protons per bunch n b N b [10 11 ] 936 0.9 2808 0.4 2808 1.15 normalized emittance rms bunch length rms energy spread  n [µm]  z [cm]  E [10 -4 ] 3.75 7.55 1.13 3.75 7.55 1.13 3.75 7.55 1.13 IBS growth time beta at IP full crossing angle  x IBS [h] ß*[m]  c [  rad] 135 1.0 250 304 0.55 285 106 0.55 285 luminosity lifetime peak luminosity events per crossing  L [h] L [10 34 cm -2 s -1 ] 22 0.12 7.1 26 0.12 2.3 15 1.0 19.2 ∫ over 200 runs L dt L int [fb -1 ]9.39.566.2 Steps to reach nominal LHC luminosity Possible scenarios with 75 ns and 25 ns bunch spacing for early LHC runs with integrated luminosity of about 10 fb -1 in 200 fills, assuming an average physics run time T run = 14 h and T turnaround =10 h.

17. Name Event Date Name Event Date 17 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Luminosity optimization Collisions with full crossing angle  c reduce luminosity by a geometric factor F maximum luminosity below beam-beam limit ⇒ short bunches and minimum crossing angle (baseline scheme) H-V crossings in two IP’s ⇒ no linear tune shift due to long range total linear bb tune shift also reduced by F peak luminosity for head-on collisions round beams, short Gaussian bunches transverse beam size at IP I = n b f rev N b total beam current long range beam-beam collective instabilities synchrotron radiation stored beam energy normalized emittance N b /  n beam brightness head-on beam-beam space-charge in the injectors transfer dilution

18. Name Event Date Name Event Date 18 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios If bunch intensity and brightness are not limited by the injectors or by other effects in the LHC (e.g. electron cloud) ⇒ luminosity can be increased without exceeding beam-beam limit  Q bb ~0.01 by increasing the crossing angle and/or the bunch length Express beam-beam limited brilliance N b /ε n in terms of maximum total beam-beam tune shift  Q bb, then At high beam intensities or for large emittances, the performance will be limited by the angular triplet aperture

19. Name Event Date Name Event Date 19 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Minimum crossing angle Beam-Beam Long-Range collisions: perturb motion at large betatron amplitudes, where particles come close to opposing beam cause ‘diffusive’ (or dynamic) aperture, high background, poor beam lifetime increasing problem for SPS, Tevatron, LHC, i.e., for operation with larger # of bunches higher beam intensities or smaller  * require larger crossing angles to preserve dynamic aperture and shorter bunches to avoid geometric luminosity loss  baseline scaling:  c ~1/√  *,  z ~  * dynamic aperture caused by n par parasitic collisions around two IP’s angular beam divergence at IP

20. Name Event Date Name Event Date 20 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Schematic of a super-bunch collision, consisting of ‘head-on’ and ‘long-range’ components. The luminosity for long bunches having flat longitudinal distribution is ~1.4 times higher than for conventional Gaussian bunches with the same beam-beam tune shift and identical bunch population (see LHC Project Report 627)

21. Name Event Date Name Event Date 21 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Schematic of reduced electron cloud build up for a long bunch. Most electrons do not gain any energy when traversing the chamber in the quasi-static beam potential [after V. Danilov] negligible heat load

22. Name Event Date Name Event Date 22 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Scenarios for the luminosity upgrade uultimate performance without hardware changes (phase 0) umaximum performance with only IR changes (phase 1) umaximum performance with “major” hardware changes (phase 2) Phase 0: steps to reach ultimate performance without hardware changes: 1)collide beams only in IP1 and IP5 with alternating H-V crossing 2)increase N b up to the beam-beam limit  L = 2.3 x 10 34 cm -2 s -1 3)increase the dipole field to 9T (ultimate field)  E max = 7.54 TeV The ultimate dipole field of 9 T corresponds to a beam current limited by cryogenics and/or by beam dump/machine protection considerations.  beam-beam tune spread of 0.01 L = 10 34 cm -2 s -1 in ATLAS and CMS Halo collisions in ALICE Low-luminosity in LHCb Nominal LHC performance 

23. Name Event Date Name Event Date 23 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Phase 1: steps to reach maximum performance with only IR changes 1)Modify the insertion quadrupoles and/or layout  ß* = 0.25 m 2)Increase crossing angle  c by √2   c = 445 µrad 3)Increase N b up to ultimate intensity  L = 3.3 x 10 34 cm -2 s -1 4)Halve  z with high harmonic RF system  L = 4.6 x 10 34 cm -2 s -1 5)Double the no. of bunches n b (and increase  c )  L = 9.2 x 10 34 cm -2 s -1 excluded by electron cloud? Step 5 belongs to Phase 2  Step 4) requires a new RF system providing uan accelerating voltage of 43 MV at 1.2 GHz ua power of about 11 MW/beam ulongitudinal beam emittance reduced to 1.8 eVs uhorizontal Intra-Beam Scattering (IBS) growth time decreases by ~ √2  Operational consequences of step 5)  exceeding ultimate beam intensity u upgrade LHC cryogenics, collimation, RF and beam dump systems u the electronics of all LHC beam position monitors should be upgraded u possibly upgrade SPS RF system and other equipment in the injectors Scenarios for the luminosity upgrade

24. 24 luminosity upgrade: baseline scheme increase N b bb limit? restore F no yes  c >  min due to LR-bb crab cavities BBLR compen- sation reduce  z by factor ~2 using higher f rf & lower  || (larger  c ?) 2.3 reduce  c (squeeze  *) use large  c & pass each beam through separate magnetic channel reduce  * by factor ~2 new IR magnets increase n b by factor ~2 if e-cloud, dump & impedance ok 9.2 1.0 4.6 simplified IR design with large  c peak luminosity gain 1.72 A 0.86 A 0.58 A 0.86 A beam current or decouple L and F

25. 25 luminosity upgrade: Piwinski scheme reduce  * by factor ~2 new IR magnets decrease F increase  z  c increase N b no ? yes reduce #bunches to limit total current? flatten profile? 7.715.5 1.0 0.86 A1.72 A luminosity gain beam current superbunches? 0.58 A

26. Name Event Date Name Event Date 26 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Various LHC upgrade options parametersymbolnominalultimateshorter bunch longer bunch no of bunchesnbnb 2808 5616936 proton per bunchN b [10 11 ]1.151.7 6.0 bunch spacing∆t sep [ns]25 12.575 average currentI [A]0.580.861.721.0 normalized emittance  n [µm] 3.75 longit. profileGaussian flat rms bunch length  z [cm] 7.55 3.7814.4 ß* at IP1&IP5ß* [m]0.550.500.25 full crossing angle  c [µrad] 285315445430 Piwinski parameter  c  z /(2  * ) 0.64 0.75 2.8 peak luminosityL [10 34 cm -2 s -1 ]1.02.39.28.9 events per crossing194488510 luminous region length  lum [mm] 44.942.821.836.2

27. Name Event Date Name Event Date 27 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Heat loads per beam aperture for various LHC upgrade options parametersymbolnominalultimate shorter bunch longer bunch protons per bunchN b [10 11 ]1.151.7 6.0 bunch spacing∆t sep [ns]25 12.575 average currentI [A]0.580.861.721.0 longitudinal profileGaussian flat rms bunch length  z [cm] 7.55 3.7814.4 Average electron-cloud heat load at 4.6–20 K in the arc for R=50% and δ max =1.4 (in parentheses for δ max =1.3) P ecloud [W /m] 1.07 (0.44) 1.04 (0.59) 13.34 (7.85) 0.26 (0.26) Synchrotron radiation heat load at 4.6–20 K P  [W /m]0.170.250.500.29 Image currents power at 4.6–20 KP  [W /m]0.150.331.870.96 Beam-gas scattering heat load at 1.9 K for 100-h beam lifetime (in parentheses for a 10-h lifetime). It is assumed that elastic scattering (~40% of the total cross section) leads to local loss. P gas [W /m] 0.038 (0.38) 0.056 (0.56) 0.113 (1.13) 0.066 (0.66)

28. Name Event Date Name Event Date 28 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Events per bunch crossing and beam lifetime due to nuclear p-p collisions  bb =60 mb total inelastic cross section beam intensity halving time due to nuclear p-p collisions at two IP’s with total cross section  TOT =110 mb luminosity lifetime: assumes radiation damping compensates diffusion exponential luminosity lifetime due to nuclear p-p interactions nuclear scattering lifetime at the beam-beam limit depends only on  * !

29. Name Event Date Name Event Date 29 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Optimum run time and effective luminosity The optimum run time and the effective luminosity are universal functions of T turnaround /  L When the beam lifetime is dominated by nuclear proton- proton collisions, then  L~  N /1.54 and the effective luminosity is a universal functions of T turnaround /  

30. Name Event Date Name Event Date 30 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Effective luminosity for various upgrade options parametersymbolnominalultimateshorter bunch longer bunch protons per bunchN b [10 11 ]1.151.7 6.0 bunch spacing∆t sep [ns]25 12.575 average currentI [A]0.580.861.721.0 longitudinal profileGaussian flat rms bunch length  z [cm] 7.55 3.7814.4 ß* at IP1&IP5ß* [m]0.550.500.25 full crossing angle  c [µrad] 285315445430 Piwinski parameter  c  z /(2  * ) 0.64 0.75 2.8 peak luminosityL [10 34 cm -2 s -1 ]1.02.39.28.9 events per crossing194488510 IBS growth time  x IBS [h] 106724275 nuclear scatt. lumi lifetime  N /1.54 [h] 26.5178.55.2 luminosity lifetime (  gas =85 h)  L [h] 15.511.26.54.5 effective luminosityL eff [10 34 cm -2 s -1 ]0.40.82.41.9 (T turnaround =10 h)T run [h] optimum14.612.38.97.0 effective luminosityL eff [10 34 cm -2 s -1 ]0.51.03.32.7 (T turnaround = 5 h)T run [h] optimum10.89.16.75.4

31. Name Event Date Name Event Date 31 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Interaction Region upgrade factors driving IR design: minimize  * minimize effect of LR collisions large radiation power directed towards the IRs accommodate crab cavities and/or beam-beam compensators. Local Q’ compensation scheme? compatibility with upgrade path goal: reduce  * by at least a factor 2 maximize magnet aperture, minimize distance to IR options: NbTi ‘cheap’ upgrade, NbTi(Ta), Nb 3 Sn new quadrupoles new separation dipoles

32. Name Event Date Name Event Date 32 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios IR ‘baseline’ schemes short bunches & minimum crossing angle & BBLR crab cavities & large crossing angle triplet magnets crab cavity BBLR

33. Name Event Date Name Event Date 33 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios alternative IR schemes dipole first & small crossing angle triplet magnets dipole magnets dipole first & large crossing angle & long bunches or crab cavities triplet magnets dipole reduced # LR collisions collision debris hit D1

34. Name Event Date Name Event Date 34 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios

35. 35 Dipoles first and doublet focusing IPD1 D2 Q1 Q2 Features Requires beams to be in separate focusing channels Fewer magnets Beams are not round at the IP Polarity of Q1 determined by crossing plane – larger beam size in the crossing plane to increase overlap Opposite polarity focusing at other IR to equalize beam-beam tune shifts Significant changes to outer triplet magnets in matching section. Focusing symmetric about IP Tanaji Sen, Doublet optics

36. Name Event Date Name Event Date 36 CERN F. Ruggiero LHC upgrade scenarios Flat beams Interesting approach, flat beams could increase luminosity by ~20-30% with reduced crossing angle Symmetric doublets studied by J. Johnstone (FNAL) require separate magnetic channels, i.e. dipole-first, Crab cavities or special quads Tune footprints are broader than for round beams, since there is only partial compensation of parasitic beam-beam encounters by the H/V crossing scheme. More work needed to evaluate nonlinear resonance excitation. Probably requires BBLR compensation Recently S. Fartoukh has found a more interesting flat beam solution with anti-symmetric LHC baseline triplets

37. 37 Beam aspect ratio vs triplet aperture (1/5) Beam screen orientation for H/V scheme S. Fartoukh, ABP-RLC meeting, 28-10-2005 Effect of increasing the beam aspect ratio at the IP (and decreasing the vert. X-angle) Effect of decreasing the beam aspect ratio at the IP (and increasing the vert. X-angle)  In both cases, H-separation of about 9.5*max(  x,b1,  x,b2 )  In both cases, V-separation of about 9.5*max(  y,b1,  y,b2 )  Find the optimum matching between beam-screen and beam aspect ratio

38. 38 Pushing the luminosity by 10-20% Case  x * [cm]  y * [cm]  * [  rad] n1 in the triplet Geometric loss factor [%] L/L nom Nominal r=1.0    55cm 55.00 285~783.91.00 Flat r=2.0    55cm 110.0027.50201~795.11.13 Flat r=1.6    55cm 88.0034.37225~7.592.71.10 Flat r~1.7    51cm 88.0030.00225~792.71.18  All these cases being allowed by the nominal LHC hardware:layout, power supply, optics antisymmetry, b.s. orientation in the triplets (only changing the present H/V scheme into V/H scheme)! S. Fartoukh, ABP-RLC meeting, 28-10-2005

39. Name Event Date Name Event Date 39 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios ‘cheap’ IR upgrade short bunches & minimum crossing angle & BBLR triplet magnets each quadrupole individually optimized (length & aperture) reduced IP-quad distance from 23 to 22 m conventional NbTi technology:  *=0.25 m is possible BBLR in case we need to double LHC luminosity earlier than foreseen

40. Name Event Date Name Event Date 40 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios quadrupole-first and dipole-first solutions based on conventional NbTi technology and on high-field Ni 3 Sn magnets, possibly with structured SC cable energy deposition, absorbers, and quench limits schemes with Crab cavities as an alternative to the baseline bunch shortening RF system at 1.2 GHz to avoid luminosity loss with large crossing angles early beam separation by a “D0” dipole located a few metres away from the IP (or by tilted experimental solenoids?) may allow operation with a reduced crossing angle. Open issues: compatibility with detector layout, reduced separation at first parasitic encounters, energy deposition by the collision debris local chromaticity correction schemes flat beams, i.e. a final doublet instead of a triplet. Open issues: compensation of long range beam-beam effects with alternating crossing planes Several LHC IR upgrade options are being explored :

41. Name Event Date Name Event Date 41 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Crab cavities vs bunch shortening Crab cavities combine advantages of head-on collisions and large crossing angles require lower voltages compared to bunch shortening RF systems but tight tolerance on phase jitter to avoid emittance growth KEKBSuper- KEKB ILCSuper- LHC x*x*100  m70  m0.24  m11  m cc +/- 11 mrad +/-15 mrad +/-5 mrad +/- 0.5 mrad tt 6 ps3 ps0.03 ps0.08 ps Comparison of timing tolerances

42. Name Event Date Name Event Date 42 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Crab Cavities

43. Name Event Date Name Event Date 43 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Motivation of Beam-Beam compensation studies Provide more LHC luminosity earlier Space is reserved in the LHC for the wires. An early test in RHIC will determine the effectiveness of the compensation and possibly address the challenges to the compensation. If effective, will allow a smaller crossing angle and more beam intensity. Provide direction to an IR upgrade path If compensation is proven to be effective, then the quadrupole-first option, possibly with flat beams, seems to be a more natural path for the IR upgrade. Otherwise, the dipole-first option will be more attractive.

44. Name Event Date Name Event Date 44 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Lessons from the SPS experiments Compensating 1 wire with another wire at nearly the same phase “works” Compensation is tune dependent Current sensitivity Alignment sensitivity Equivalent crossings in the same plane led to better lifetimes than alternating planes Beam lifetime  ~ d 3 d is the beam-wire distance Higher power law expected given the proximity of high order resonances Both wires on 1 wire on Nearly perfect compensation No wires activated

45. Name Event Date Name Event Date 45 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios 2 nd prototype BBLR in the CERN SPS has demonstrated benefit of compensation G. Burtin, J. Camas, J.-P. Koutchouk, F. Zimmermann et al.

46. Name Event Date Name Event Date 46 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Lessons from RHIC experiment Study at injection energy with 1 bunch and 1 parasitic interaction per beam There is an effect to compensate, even with 1 parasitic Drop in lifetime seen for beam separations < 7 σ Effect is very tune dependent How important are machine nonlinearities and other time dependent effects? Did they change with the beam-beam separation ?

47. Name Event Date Name Event Date 47 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Wire compensation at RHIC Compensation of 1 wire by another wire worked well in the SPS under LHC conditions. Real test of the compensation principle requires 2 beams Beam studies in RHIC show that parasitic interactions have strong influence on beam loss Favorable location for wire has been found in IR6, phase advance to parasitic ~6 degrees at top energy Proposed wire location Location of parasitic

48. Name Event Date Name Event Date 48 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Milestones for future LHC Upgrade machine studies 2006: installation and test of a beam-beam long range compensation system at RHIC to be validated with colliding beams 2006/2007: new SPS experiment for crystal collimation, complementary to Tevatron results 2006: installation and test of Crab cavities at KEKB to validate higher beam-beam limit and luminosity with large crossing angles 2007: if KEKB test successful, test of Crab cavities in a hadron machine (RHIC?) to validate low RF noise and emittance preservation 2007-2009: LHC running-in and first machine studies on collimation and beam-beam

49. Name Event Date Name Event Date 49 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Tentative conclusions for the LHC IR Upgrade We do need a back-up or intermediate IR upgrade option based on NbTi magnet technology. What is the maximum luminosity? A vigorous R&D programme on Nb 3 Sn magnets should start at CERN asap, in parallel to the US-LARP programme, to be ready for 10 35 luminosity in ~2015 Alternative IR layouts (quadrupole-first, dipole- first, D0, flat beams, Crab cavities) will be rated in terms of technological and operational risks/advantages

50. Name Event Date Name Event Date 50 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Towards a baseline design Define a Baseline, i.e. a forward looking configuration which we are reasonably confident can achieve the required LHC luminosity performance and can be used to give an accurate cost estimate by mid-end 2006 in a “Reference Design Report” Identify Alternative Configurations and rate them in terms of technological and operational risks/advantages Identify R&D (at CERN and elsewhere) To support the baseline To develop the alternatives Following the approach proposed by Barry Barish for the ILC, we propose to:

51. Name Event Date Name Event Date 51 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Reference LHC Luminosity Upgrade: workpackages and tentative milestones

52. Name Event Date Name Event Date 52 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios LHC upgrade scenarios Summary The upgrade scenario currently assumed as baseline includes a reduction of  * to 0.25 m, an increased crossing angle and a new bunch-shortening RF system. The upgrade scenario currently assumed as baseline includes a reduction of  * to 0.25 m, an increased crossing angle and a new bunch-shortening RF system. The corresponding peak luminosity with ultimate beam intensity is 4.6x10 34 cm -2 s -1 at two IP’s. Electron cloud effects and/or cryogenic heat loads may exclude the possibility to double the number of bunches. The corresponding peak luminosity with ultimate beam intensity is 4.6x10 34 cm -2 s -1 at two IP’s. Electron cloud effects and/or cryogenic heat loads may exclude the possibility to double the number of bunches. Milestones for future LHC Upgrade machine studies include RHIC tests on Long Range Beam-Beam compensation and possibly on crab cavity operation, after KEKB tests, SPS and Tevatron studies on crystal assisted collimation, as well as collimation, electron cloud, and beam-beam studies at the LHC itself. Milestones for future LHC Upgrade machine studies include RHIC tests on Long Range Beam-Beam compensation and possibly on crab cavity operation, after KEKB tests, SPS and Tevatron studies on crystal assisted collimation, as well as collimation, electron cloud, and beam-beam studies at the LHC itself. Several LHC IR upgrade options are currently being explored: we need to converge to a baseline configuration and identify a few alternative options. Several LHC IR upgrade options are currently being explored: we need to converge to a baseline configuration and identify a few alternative options.

53. Name Event Date Name Event Date 53 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Additional Slides

54. Name Event Date Name Event Date 54 CERN F. Ruggiero LHC upgrade scenarios Alternative ways to avoid luminosity loss 1)Reduce crossing angle and apply “wire” compensation of long range beam-beam effects 2)Crab cavities ⇒ large crossing angles to avoid long range bb effects w/o luminosity loss. Potential of boosting the beam-beam tune shift (factor 2-3 predicted for KEKB, what about LHC?) 3)Early beam separation by a “D0” dipole located a few metres away from the IP, as recently suggested by JPK at the LHC-LUMI-05 workshop. The same effect could be obtained by tilted experimental solenoids, but the experiments don’t seem to like the idea. A potential drawback of 2) and 3) is that  Q bb is no longer reduced by the geometric factor F ⇒ lower beam-beam limit?

55. 55 Back to the Xing angle issue Q1 Q2 Q3 Orbit corrector An “easy” way to reduce or cancel the Xing angle at the IP and gain 20% to 50% in luminosity. Is it possible for the detectors? J.-P. Koutchouk, LHC-LUMI-05

56. Name Event Date Name Event Date 56 CERN F. Ruggiero LHC upgrade scenarios New idea: D0 magnet a few meters away from the IP Advantages Cheap and elegant solution to increase luminosity No need of a new bunch shortening RF system Cleans collision debris from Q1? Possible drawbacks Reduced separation at first few parasitic encounters? Collision debris and background in the experiments? Compatibility with detector layout and integration into the experiments

57. Name Event Date Name Event Date 57 CERN F. Ruggiero LHC upgrade scenarios LR beam-beam compensation: remarks and open issues Simulations of LR compensation with 2 wires indicate that lifetime is recovered over a wide tune range but not for all tunes. The measured SPS lifetime is 5 ms x (d/  ) 5. Extrapolation to LHC beam-beam distance (9.5  ) would predict 6 minutes beam lifetime! Tevatron observations with electron lens show cubic dependence. Further SPS tests at different energy are needed. Lifetimes predicted by simulation codes are much larger than those observed, even though sensitivity to parameters seems correct. Needs further understanding and beam tests, e.g. at RHIC. For extreme PACMAN bunches there is overcompensation which causes the footprint to flip over or to increase instead of shrinking. To avoid degraded lifetime for PACMAN bunches, the wire should be pulsed train by train. It is rather challenging to make a pulsed wire for BB compensation: the required average pulse rate is 439 kHz and the turn-by-turn amplitude stability 10 -4. Experiments at RHIC (Fischer) with a single LR encounter show that the BB effect is visible starting from a 5  separation, consistent with Tevatron and Daphne observations, but contrary to LHC simulations and possibly earlier observations at the SPS collider.

58. 58 RHIC experiment Studied at injection energy with 1 bunch and 1 parasitic interaction per beam There is an effect to compensate, even with 1 parasitic Drop in lifetime seen for beam separations < 7 σ Effect is very tune dependent SPS :   (d/  ) 5 Tevatron:  ~ d 3 RHIC :  ~ d 4 or d 2 [measured 04/28/05, scan 4]

59. Name Event Date Name Event Date 59 CERN F. Ruggiero LHC upgrade scenarios LHC-LUMI-05 workshop: some conclusions on the IR Upgrade Local correction à la Raimondi, via dispersion inside triplet magnets and two pairs of sextupoles, can correct chromaticity and geometric aberrations  look for a solution that can be implemented and removed anytime by varying quads and sexupole strengths Three IR layout options were identified that should be studied in more detail: 1) dipole-first based on Nb3Sn technology with ℓ* = 19 m 2) quad-first layout based on Nb3Sn technology ℓ * = 19 m 3) low gradient quad-first layout based on NbTi technology Still need to fix ℓ* and required length for TAS upgrade. Agreement to assume ℓ* = 19 m as a reasonable estimate CARE-HHH web repository with optics solutions is very desirable  we should all use the same input (MADX) Update the 3 proposals by the end of 2005

60. Name Event Date Name Event Date 60 CERN F. Ruggiero LHC IR Upgrades, LARP Workshop, WG1 summary Energy Deposition Issues in LHC IR Upgrades, N. Mokhov (FNAL) All three aspects, i.e. i) quench limit, ii) radiation damage (magnet lifetime), and iii) dynamic heat load on the cryo system should be simultaneously addressed in the IR magnet design. i) and ii) are linked Peak power deposition at non-IP end of IR magnets ~proportional to ∫Bdℓ  FDFD “quadruplet” focusing? Estimated dipole field with TAS in quad-first option to reduce peak energy deposition “well below” quench limits  15-20 Tm for magnetic TAS Estimated thickness of internal absorbers  a 5 mm thick SS absorber reduces peak power by a factor ~2 Impact of orbit corrector D0 inside the experiment on energy deposition in downstream magnets, including detector solenoid field  more work needed, modest impact of solenoid field on energy deposition (more from fringe fields)

61. Name Event Date Name Event Date 61 CERN F. Ruggiero LHC IR Upgrades, LARP Workshop, WG1 summary Action items/comments on energy deposition, Nikolai Mokhov Refine and test scaling law for energy deposition in IR magnets with MARS simulations (including dependence on ℓ*) Introduce quench limits to JPK’s spreadsheet for NbTi and Nb 3 Sn Address radiation damage/lifetime issues in all IR magnet design analyses: 7 years at 10 34 become 8 months at 10 35 with currently used materials  new (ceramic type) materials for 10 35 ? Launch R&D program on beam tests for SC and insulating materials asap: BNL, FNAL, MSU Arrive at a clear picture on Dynamic Heat Load limits. How serious is the current 10 W/m limit or 120 W on each side of IR? This becomes 100 W/m and 1.2 kW for 10 35. Cooling scheme? Cryoplant capability?

62. Name Event Date Name Event Date 62 CERN F. Ruggiero LHC IR Upgrades, LARP Workshop, WG1 summary Potential impact of novel magnet technology for IR elements, Peter McIntyre Designs have been suggested for novel magnet technology to mitigate limitations from heat deposition and radiation damage from deposition of secondary particles in the quadrupole triplet and separation dipole. One example is an ironless quadrupole using structured-cable Nb3Sn conductor, which could provide 390 T/m gradient at a location as close as 12 m from the IP, and compatibility with supercritical helium flowing throughout the coils. A second example is a 9 T levitated-pole dipole for D1, which would open the transverse geometry so that secondaries are swept into a room-temperature flux return. In order to evaluate the potential benefit of these concepts it is necessary to model the heat deposition and radiation damage in the more compact geometries, and to examine potential interference with the performance of the detectors. Of particular importance is to undertake a consistent examination of the impact of reducing ℓ* on the ensemble of issues that impact achievable  * the interface of the IR with the machine lattice (chromaticity and dispersion, multipole errors, orbit errors, etc.), and the strategy for accommodating long-range beam-beam effects. Also of interest is to evaluate the pros and cons of the alternatives for operating temperature (superfluid, two-phase, or supercritical cooling) for the IR elements that must operate with substantial heat loads.

63. 63 Latest design: 9 Tesla @ 4.5 K Support each pole piece using tension struts (low heat load).56 mm clear aperture All windings are racetracks. Only pole tip winding is Nb 3 Sn. All others are NbTi.

64. Name Event Date Name Event Date 64 CERN F. Ruggiero LHC upgrade scenarios Dipole-First optics (R. De Maria) matched optics solution for dipole-first layout for Beam1 and Beam2 with squeeze and tunability study: 18 km  -max requires additional Q’ correction dispersion of 15 cm from D1/D2 arrangement for free could be increased for D’ ≠ 0 at the IP dispersion changes sign left and right from IP S. Fartoukh proposed a `kissing scheme’ could allow equal signs of D but vertical D is quite small optics study relies on Nb3Sn technology:  10 m long dipole magnets with B = 15 T  quadrupole magnets with 260 T/m and 80 mm aperture  11 T coil field  IR layout provides magnetic TAS for “free”

65. Name Event Date Name Event Date 65 CERN F. Ruggiero LHC upgrade scenarios Alternative Dipole-First optics (O.Brüning) proposal of a low-gradient solution that could be realized with NbTi technology 18 km  -max requires additional Q’ correction maximum gradient of 70 T/m allows more than 200 mm diameter with a peak coil field of 5.5 T Dispersion inside the triplet could be increased for D’ ≠ 0 at the IP Layout still requires an improved TAS absorber

66. Name Event Date Name Event Date 66 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios CERN: the World’s Most Complete Accelerator Complex (not to scale)

67. Name Event Date Name Event Date 67 CERN F. Ruggiero LHC beam performance and luminosity upgrade scenarios Injector chain for 1 TeV proton beams injecting at 1 TeV into the LHC reduces dynamic effects of persistent currents, i.e.: n persistent current decay during the injection flat bottom n snap-back at the beginning of the acceleration  easier beam control  decreases turn-around time and hence increases integrated luminosity L 0 [cm -2 s -1 ]  L [h] T turnaround [h] T run [h] ∫ 200 days L dt [fb - 1 ] gain 10 34 151014.6 66 x1.0 10 34 15 510.8 85 x1.3 10 35 6.110 8.5 8.5 434 x6.6 10 35 6.1 5 6.5 6.5 608 x9.2 with  gas = 85 h and  x IBS = 106 h (nom)  40 h (high-L)

68. Name Event Date Name Event Date 68 CERN F. Ruggiero LHC upgrade scenarios Injector chain for 1 TeV proton beams injecting in LHC more intense proton beams with constant brightness, within the same physical aperture  will increase the peak luminosity proportionally to the proton intensity at the beam-beam limit, peak luminosity L is proportional to normalized emittance  n = , unless limited by the triplet aperture an increased injection energy (Super-SPS) allows a larger normalized emittance  n in the same physical aperture, thus more intensity and more luminosity at the beam-beam limit. the transverse beam size at 7 TeV would be larger and the relative beam-beam separation correspondingly lower: long range beam-beam effects have to be compensated.

69. Name Event Date Name Event Date 69 CERN F. Ruggiero LHC upgrade scenarios LHC injector complex upgrade CERN is preparing a road map for an upgrade of its accelerator complex to optimize the overall proton availability in view of the LHC luminosity upgrade and of all other physics users Scenarios under consideration include a new proton linac (Linac 4, 160 MeV) to overcome space charge limitations at injection in the PS Booster and a new Superconducting PS reaching an energy of 50-60 GeV This would open the possibility of a more reliable production of higher-brightness beams for the LHC, with lower transmission losses in the SPS thanks to the increased injection energy It would also offer the opportunity to develop new fast pulsing SC magnets in view of a Super-SPS, injecting at 1 TeV into the LHC