Scenarios for the sLHC and the vLHC Walter Scandale, Frank Zimmermann CERN HCP2007 We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3-CT )

outline LHC upgrade: why and when ? beam parameters the two selected scenarios for luminosity upgrade –features, –Bunch structure –IR layout, –merits and challenges luminosity leveling ? summary & recommendations for the sLHC perspective for higher energy hadron collisions –VLHC at FNAL –dLHC and tLHC at CERN –R&D –possible plans

 IR quadrupole lifetime ≥ 8 years owing to high radiation doses  halving time of the statistical error ≥ 5 y already after 4-5 y of operation  luminosity upgrade to be planned by the middle of next decade LHC luminosity upgrade: why and when? How fast performance is expected to increase:  4 y up to nominal L  4 y up to nominal L & 2 y up to ultimate L  4 y up to ultimate

LHC luminosity upgrade: the LARP perspective Courtesy of V. Shiltsev - FNAL

Name Event Date Name Event Date 5 W. Scandale/F. Zimmermann, parametersymbolnominalultimate 12.5 ns, short transverse emittance  [  m] protons per bunch N b [10 11 ] bunch spacing  t [ns] beam current I [A] longitudinal profile GaussGauss Gauss rms bunch length  z [cm] beta* at IP1&5  [m] full crossing angle  c [  rad] Piwinski parameter  c  z /(2*  x *) peak luminosity L [10 34 cm -2 s -1 ] peak events per crossing initial lumi lifetime  L [h] effective luminosity (T turnaround =10 h) L eff [10 34 cm -2 s -1 ] T run,opt [h] effective luminosity (T turnaround =5 h) L eff [10 34 cm -2 s -1 ] T run,opt [h] e-c heat SEY=1.4(1.3) P [W/m] 1.07 (0.44) 1.04 (0.59) (7.85) SR heat load K P SR [W/m] image current heat P IC [W/m] gas-s. 100 h (10 h)  b P gas [W/m] 0.04 (0.38) 0.06 (0.56) (1.13) extent luminous region  l [cm] commentpartial wire c. (heat load induced by Sync.Rad + image current larger than the local heat load capacity) baseline upgrade parameters abandoned at LUMI’06 total heat 15.6 W/m >> 2.4 W/m

Name Event Date Name Event Date 6 W. Scandale/F. Zimmermann, parametersymbol 25 ns, small  * 50 ns, long transverse emittance  [  m] 3.75 protons per bunch N b [10 11 ] bunch spacing  t [ns] 2550 beam current I [A] longitudinal profile GaussFlat rms bunch length  z [cm] beta* at IP1&5  [m] full crossing angle  c [  rad] 0381 Piwinski parameter  c  z /(2*  x *) 02.0 hourglass reduction peak luminosity L [10 34 cm -2 s -1 ] peak events per crossing initial lumi lifetime  L [h] effective luminosity (T turnaround =10 h) L eff [10 34 cm -2 s -1 ] T run,opt [h] effective luminosity (T turnaround =5 h) L eff [10 34 cm -2 s -1 ] T run,opt [h] e-c heat SEY=1.4(1.3) P [W/m] 1.04 (0.59)0.36 (0.1) SR heat load K P SR [W/m] image current heat P IC [W/m] gas-s. 100 h (10 h)  b P gas [W/m] 0.06 (0.56)0.09 (0.9) extent luminous region  l [cm] comment D0 + crab (+ Q0)wire comp. New upgrade scenarios compromises between # of pile up events and heat load injector upgrade Crossing with large Piwinski angle aggressive triplet challenges

LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, PAF/POFPA Meeting 20 November 2006 for operation at beam-beam limit with alternating planes of crossing at two IPs, luminosity equation can be written as  25 ns  50 ns  50 ns where  Q bb = total beam-beam tune shift (the change of F h-g due to hourglass effect is neglected above) Luminosity at the beam-beam limit

Name Event Date Name Event Date 8 W. Scandale/F. Zimmermann, luminosity reduction factor from crossing angle R   0.85 (nominal LHC) Piwinski angle

Name Event Date Name Event Date 9 W. Scandale/F. Zimmermann, ns ultra-low-  upgrade scenario stay with ultimate LHC beam (1.7x10 11 protons/bunch, 25 spacing) stay with ultimate LHC beam (1.7x10 11 protons/bunch, 25 spacing)  squeeze  * below ~10 cm in ATLAS & CMS  add early-separation dipoles in detectors, one at ~ 3 m, the other at ~ 8 m from IP  possibly also add quadrupole-doublet inside detector at ~13 m from IP  and add crab cavities (f Piwinski ~ 0), and/or shorten bunches with massive addt’l RF  new hardware inside ATLAS & CMS,  first hadron-beam crab cavities (J.-P. Koutchouk et al)

LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, PAF/POFPA Meeting 20 November 2006 CMS & ATLAS IR layout for 25-ns option ultimate bunch intensity & near head-on collision (R   1) stronger triplet magnets D0 dipole small-angle crab cavity Q0 quad’s l* = 22 m Magnets embedded in the expt. apparatus

LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, PAF/POFPA Meeting 20 November 2006 challenges: D0 dipole deep inside detector (~3 m from IP), Q0 doublet inside detector (~13 m from IP & slim magnet technology), crab cavity for hadron beams (emittance growth ?), 4 parasitic collisions at 4-5  separation, “chromatic beam-beam” Q’ eff ~  z /(4  *   ), poor beam and luminosity lifetime ~  * merits: negligible long-range collisions, reduced geometric luminosity loss, no increase in beam current beyond ultimate 25-ns scenario assessment (accelerator view point)

Name Event Date Name Event Date 12 W. Scandale/F. Zimmermann, ns high intensity upgrade scenario double bunch spacing double bunch spacing  longer & more intense bunches with f Piwinski ~ 2  keep  *~25 cm (achieved by stronger low-  quads alone) do not add any elements inside detectors do not add any elements inside detectors  long-range beam-beam wire compensation  novel operating regime for hadron colliders (W. Scandale, F.Zimmermann & PAF)  add early-separation dipoles, one at ~ 5 m, the other at ~ 9 m from IP Reduce the current Reduce the current Almost head-on crossing angle Almost head-on crossing angle Variant (not yet studied)

LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, PAF/POFPA Meeting 20 November 2006 CMS & ATLAS IR layout for 50-ns option long bunches & nonzero crossing angle & wire compensation wire compensator stronger triplet magnets l* = 22 m

LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, PAF/POFPA Meeting 20 November 2006 merits: no elements in detector, no crab cavities, lower chromaticity, less demand on IR quadrupoles (NbTi possible) challenges: operation with large Piwinski parameter unproven for hadron beams, high bunch charge, beam production and acceleration through SPS, “chromatic beam-beam” Q’ eff ~  z /(4  *   ), larger beam current, wire compensation (established  last validation in RHIC) 50-ns scenario assessment (accelerator view point)

LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, PAF/POFPA Meeting 20 November 2006 IR upgrade optics “compact low-gradient” NbTi,  *=25 cm <75 T/m (Riccardo De Maria, Oliver Bruning) “modular low gradient” NbTi,  *=25 cm <90 T/m (Riccardo De Maria, Oliver Bruning) “low  max low-gradient” NbTi,  *=25 cm <125 T/m (Riccardo De Maria, Oliver Bruning) standard Nb 3 Sn upgrade,  *=25 cm ~ 200 T/m, 2 versions with different magnet parameters (Tanaji Sen et al, Emmanuel Laface, Walter Scandale) + crab-waist sextupole insertions? (LNF/FP7) include sextupoles to compansate the glass-hours effect early separation with  *=8 cm, Nb 3 Sn includes D0; either triplet closer to IP; being prepared for PAC’07 (Jean-Pierre Koutchouk et al) Use of Q0 being finalized for PAC’07 (E. Laface, W.Scandale) compatible with 50-ns upgrade path

LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, PAF/POFPA Meeting 20 November 2006 crab waist scheme minimizes  at s=  x/  c focal plane realization: add sextupoles at right phase distance from IP initiated and led by LNF in the frame of FP7; first beam tests at DAFNE later in 2007 Hamiltonian

LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, PAF/POFPA Meeting 20 November ns spacing 50 ns spacing IP1& 5 luminosity evolution for 25-ns & 50-ns spacing average luminosity initial luminosity peak may not be useful for physics  Turnaround time  10h  Optimized run duration

LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, PAF/POFPA Meeting 20 November ns spacing 50 ns spacing IP1& 5 event pile up for 25-ns and 50-ns spacing

LHC Upgrade Beam Parameters, Frank ZimmermannW. Scandale/F. Zimmermann, PAF/POFPA Meeting 20 November 2006 new upgrade bunch structures 25 ns 50 ns nominal 25 ns ultimate & 25-ns upgrade 50-ns upgrade, no 50 ns 50-ns upgrade with 25-ns collisions in LHCb 25 ns new alternative! new baseline!

LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, PAF/POFPA Meeting 20 November 2006 S-LHCb collision parameters parametersymbol25 ns, offset25 ns, late collision50 ns, satellites collision spacingT coll 25 ns protons per bunchN b [10 11 ] & 0.3 longitudinal profileGaussian flat rms bunch length  z [cm] beta* at LHCb  [m] rms beam size  x,y * [  m] 640 rms divergence  x’,y’ * [  rad] 8013 full crossing angle  c [urad] Piwinski parameter  c  z /(2*  x *) peak luminosityL [10 33 cm -2 s -1 ] effective luminosity (5 h turnaround time)L eff [10 33 cm -2 s -1 ] initial lumi lifetime  L [h] length of lum. region  l [cm] rms length of luminous region:

LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, PAF/POFPA Meeting 20 November 2006 luminosity leveling in IP1&5 experiments prefer more constant luminosity, less pile up at the start of run, higher luminosity at end how could we achieve this? 50-ns higher-  scheme: dynamic  squeeze, and/or dynamic reduction in bunch length (less invasive) 25-ns low-  scheme: dynamic  squeeze or Novel proposal under investigation based on the change the crossing angle (G. Sterbini)

LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, PAF/POFPA Meeting 20 November 2006 beam intensity decays linearly length of run average luminosity leveling equations

LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, PAF/POFPA Meeting 20 November ns, low  *, with leveling 50 ns, long bunches, with leveling events/crossing 300 run time N/A2.5 h av. luminosityN/A2.6x10 34 s -1 cm -2 events/crossing 150 run time 2.5 h14.8 h av. luminosity2.6x10 34 s -1 cm x10 34 s -1 cm -2 events/crossing 75 run time 9.9 h26.4 h av. luminosity2.6x10 34 s -1 cm x10 34 s -1 cm -2 assuming 5 h turn-around time

LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, PAF/POFPA Meeting 20 November ns spacing 50 ns spacing IP1& 5 luminosity evolution for 25-ns & 50-ns spacing with leveling average luminosity

LHC Upgrade Beam Parameters, Frank ZimmermannF. Zimmermann, W. Scandale, PAF/POFPA Meeting 20 November ns spacing 50 ns spacing IP1& 5 event pile up for 25-ns and 50-ns spacing with leveling

Name Event Date Name Event Date 26 W. Scandale/F. Zimmermann, summary two scenarios of L~10 35 cm -2 s -1 for which heat load and #events/crossing are acceptable two scenarios of L~10 35 cm -2 s -1 for which heat load and #events/crossing are acceptable 25-ns option: pushes  *; requires slim magnets inside detector, crab cavities, & high gradient large aperture (Nb 3 Sn) quadrupoles and/or Q0 doublet; attractive if total beam current is limited; transformed to a 50-ns spacing by keeping only 1/2 the number of bunches 25-ns option: pushes  *; requires slim magnets inside detector, crab cavities, & high gradient large aperture (Nb 3 Sn) quadrupoles and/or Q0 doublet; attractive if total beam current is limited; transformed to a 50-ns spacing by keeping only 1/2 the number of bunches 50-ns option: has fewer longer bunches of higher charge ; can be realized with NbTi technology if needed ; compatible with LHCb ; open issues are SPS upgrade & beam-beam effects at large Piwinski angle; luminosity leveling may be done via bunch length and via  * tuning 50-ns option: has fewer longer bunches of higher charge ; can be realized with NbTi technology if needed ; compatible with LHCb ; open issues are SPS upgrade & beam-beam effects at large Piwinski angle; luminosity leveling may be done via bunch length and via  * tuning

Name Event Date Name Event Date 27 W. Scandale/F. Zimmermann, recommendations luminosity leveling should be seriously considered in all cases: luminosity leveling should be seriously considered in all cases: more regular flow of events more regular flow of events moderate decrease in average luminosity moderate decrease in average luminosity long-bunch 50-ns option entails less risk and less uncertainties; however with the drawback of the larger bunch population long-bunch 50-ns option entails less risk and less uncertainties; however with the drawback of the larger bunch population 25-ns option is an optimal back up until we have gained some experience with the real LHC 25-ns option is an optimal back up until we have gained some experience with the real LHC concrete optics solutions, beam-beam tracking studies, and beam-beam machine experiments are needed for both scenarios concrete optics solutions, beam-beam tracking studies, and beam-beam machine experiments are needed for both scenarios

The VLHC versus the LHC energy upgrade

Fermilab-TM-2149 June 11, Design Study for a Staged Very Large Hadron Collider

 Build a long tunnel.  Fill it with a “cheap” 40 TeV collider.  Later, upgrade to a 200 TeV collider in the same tunnel. –Spreads the cost –Produces exciting energy-frontier physics sooner & cheaper –Allows time to develop cost-reducing technologies for Stage 2 –vigorous R&D program in magnets and underground construction required. This is a time-tested formula for success Main Ring  Tevatron LEP  LHC The two Stages of the VLHC

Parameters of the VLHC

 Cost estimate ~ 4 G$ ono detectors (2 halls included), ono EDI, ono indirect costs, ono escalation, ono contingency  2001 prices and c.a technology. oNo cost reduction assumed from R&D oCost almost independent of the choice of the B-field  Stage-1 at 40 TeV and luminosity olarge tunnel to be build in the Fermilab area ototal construction time ~ 10 years oLogistics and management complex oonly 20 MW of refrigeration power, comparable to the Tevatron. osignificant money and time saving by building the VLHC at FNAL Cost drivers for the stage-1 (at FNAL)

30cm support tube/ vacuum jacket Cryo-lines 100kA return bus vacuum chambers SC transmission line (100 kA)  2-in-1 warm iron  Superferric: 2T B- field  100kA Transmission Line  Combined function dipole (no quadrupoles needed)  65m Length  Self-contained including Cryogenic System and Electronics Cabling  Warm Vacuum System Transmission line magnet for Stage-1

 The Stage-2 VLHC can reach 200 TeV and 2x10 34 or possibly significantly more in the 233 km tunnel. oA large-circumference ring is a great advantage for Stage-2 oA high-energy, high B-field (B > 12 T) VLHC in a small- circumference ring may not be realistic (too much synchrotron radiation). oTo demonstrate feasibility and to reduce cost, there is the need for R&D in the following items  high-field magnet,  vacuum in presence of large radiated power  efficient tunneling  photon stopper. Stage-2

 Superconducting magnets based on Nb 3 Sn Stage-2 Dipole Single-layer common coilStage-2 Dipole Warm-iron Cosine Q Magnets for Stage-2

Synchrotron radiation

Beam screen  There is an optimal size of the coolant pipe and of the beam screen temperature for a given synchrotron emission regime

 Synchrotron radiation masks look promising.  Preliminary tests already performed at FNAL.  They will decrease refrigerator power and permit higher energy and luminosity.  They are practical only in a large- circumference tunnel. Photon stoppers

P SR <10 W/m/beam peak t L > 2 t sr Interaction per cross < 60 L units cm -2 s -1 Optimum Dipole Field The cutoffs are  field too low, not enough damping,  field too high, too much synchrad power so required aperture too large. Luminosity scale

LHC energy doubler 14*14 TeV  dipole field B nom = 16.8 T, B design = T (10-15% margin) osuperconductor - Nb 3 Sn o10-13 T field demonstrated in several 1-m long Nb3Sn dipole models oDLHC magnet parameters well above the demonstrated Nb3Sn magnet technology  R&D and construction time and cost estimates o10+ years for magnet technology development and demonstration oMagnet production by industry ~ 8-10 years oHigh cost for R&D and construction (cost of dipoles > 3GCHF ?)

LHC energy tripler 21*21 TeV  dipole field B nom = 25 T, B design = T (10-15% margin) osuperconductor - HTS-BSCCO (low demand) or Nb 3 Sn oMagnet technology to be fully demonstrated oDLHC magnet parameters well above the demonstrated Nb3Sn magnet technology  Large aperture dipole to accommodate an efficient beam screen  R&D and construction time and cost/risk estimates o20++ years for magnet technology development and demonstration oExtremely high R&D and construction cost and risk  SC cable to be developed,  Magnetic coil stress requires innovative dipole cross section oMagnet production by industry (?) ?? years

LHC, sLHC, DLHC perspective

VLHC perspective