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					  Hadron and Hadron-
    Lepton Colliders

             Frank Zimmermann
Special Beam Physics Symposium in Honor of
      Yaroslav Derbenev's 70th Birthday
Jefferson Lab, Newport News, 3 August 2010

 many thanks to J.-P. Delahaye, W. Fischer,
M. Klein, V. Litvinenko, G. Wang, and Y. Zhang
      past, planned but abandoned &
        operating hadron colliders
ISR (p-p) 1970-1983 0.03/0.03 TeV
SPS (p-pbar) 1981-1990 0.3/0.3 TeV
[CHEEP (e± -p) †1978 (?) 0.03/0.3 TeV]
[PEP (e± -p) †1981 (?) 0.015/0.3 TeV]
[TRISTAN (e± -p) †1983 (?) 0.03/0.3 TeV]
ISABELLE/CBA (p-p) †1983 0.4/0.4 TeV
Tevatron (p-pbar) 1987-2011? 1/1 TeV?
HERA (e± ↑ -p) 1991-2007 0.03/1 TeV?
UNK (p-p) †1992 (?) 3/3 TeV
SSC (p-p) †1993 20/20 TeV
RHIC (p↑-p↑ & A-A) 2000-? 0.3/0.3 TeV
LHC (p-p & A-A) 2009-2030? 3.5/3.5 & 7/7 TeV
                                                        HL-LHC
                                        factor 10
                                                            ELIC


                                 factor 30                   LHeC

                          Tevatron is present
CERN ISR held             frontier machine
luminosity world record
for >2 decades




                                                Courtesy W. Fischer
Intersecting Storage Rings 1970-83
         limitations & successes:   – space-charge tune shift &
                                         spread, trapped e−
                                    – proton-electron
                                         instabilities, pressure
                                         bumps
                                    – detector background
                                    – beam brightness from
                                         injector and accumulation
                                    – coherent beam-beam
                                         effects
                                    – missed discovery of the
                                         J/ψ and other new
                                         particles (no central
                                         detector)
                                    – I =38–50 A, coasting
                                         beam, 31 GeV
                                    – L ≈ 2.2 × 1032 cm−2s−1 peak
                                         luminosity
                                    – with bunched beams ξ =
                                         0.0035 per IP (8 crossings)
                                    – first p-pbar collisions
   SppbarS 1981-90
limitations & successes:   – beam-beam interaction
                           – loss of longitudinal Landau
                                     damping
                           – number of antiprotons
                           – hourglass effect
                           – intrabeam scattering
                           – first p-pbar collider
                           – 10× ISR energy (315 GeV)
                           – beam-beam tune shift ξ =
                                     0.005 with 3 crossings
                           – discovery of W and Z
     Tevatron 1987-2011
limitations & successes:   – number of antiprotons
                           – beam-beam interaction incl. long-
                                     range
                           – luminosity lifetime
                           – events per crossing
                           – intrabeam scattering
                           – first superconducting collider
                           – 980 GeV beam energy
                           – p-pbar collisions like SPS
                           – beam-beam tune shift ξ = 0.02!
                           – high-energy e- cooling
                           – discovery of b and t
 HERA 1991-2007
limitations & successes:   – beam from injector
                           – beam-beam interaction
                           – international contributions
                                     “HERA model”
                           – longitudinally polarized e±
                           – first hadron-lepton collider
             RHIC 2001-
limitations & successes:   – intrabeam scattering
                           – beam-beam interaction
                           – luminosity lifetime
                           – electron cloud
                           – events per crossing
                           – longitudinally polarized protons
                           – stochastic cooling
                           – first heavy-ion collider
                           – established existence of
                                     quark-gluon plasma
SSC †1993
        –   87 km circumference
        –   20 TeV beam energy
        –   L=1033 cm-2s-1
        –   halted after 14 miles of
                  tunneling were completed
                  2 billion dollars spent
    –
    Large Hadron Collider 2009-2030(?)
               successes:   – p-p and A-A collider
                            – c.m. energy 14 TeV
                            – design p-p luminosity
                                     1034 cm-2s-1
                            – 1st collisions in 2009




LHC baseline luminosity was pushed in competition with SSC
LHC: design started >26 years ago
      1984

                  “Although the
                  machine operation
                  would become more
                  difficult, it is not
                  unconceivable that
                  the luminosity could
                  eventually approach
                  or even exceed 1033
                  cm-2 s-1 …”
LHC key component: 2-in-1 SC magnet
                     model


                             first proposed
                             by Bob Palmer
                             for
                             ISABELLE/CBA
LHC limit: event pile up



 0.2 events/crossing, 25 ns spacing           2 events/crossing, 25 ns spacing




19 events/crossing, 25 ns spacing           100 events/crossing, 12.5 ns spacing

         pt > 1 GeV/c cut, i.e. all soft tracks removed            I. Osborne
 LHC : stability requires longit. blow up
   Initial meaurement                                E. Shaposhnikova, G. Papotti
  loss of longit. Landau damping                         predicted
    during the ramp (~1.8 TeV)                           loss of Landau damping
                                                                Z/n=0.06 Ohm
  1 ns



   0.2 ns      1.1x1011
               1.05 ns – 0.35 eVs
               (450 GeV, 5 MV)                                      time during ramp
                                                             meaurement with
cures:                                                       controlled blow up,
o increased longitudinal emittance from SPS                  late June 2010
o change in LHC RF voltage profile
o controlled longitudinal blow up on LHC ramp
feedback on bunch length measurement modulates
noise amplitude to control blow-up rate
bunch lengths converge correctly to target ~1.5 ns
      hadron collider integrated
            luminosities
ISR (1970-1983): ? (~1/fb?)
SPS (1982-1990): ~0.02/fb
HERA (1991-2007): 0.8/fb
RHIC : (2000-2009) ~0.2/fb (p-p)
Tevatron (1987-2011): ~10/fb
LHC (now): ~0.001/fb
     LHC goal 2010: 0.1/fb, LHC 2011: 1/fb
     forecast 2020: 300-400/fb, 2030: 3000/fb
   possible future hadron colliders
HL-LHC (p-p & A-A) 2020 7/7 TeV
HE-LHC (p-p & A-A) 2035? 16.5/16.5 TeV
VLHC (p-p) 2035? 100/100 TeV
ELOISATRON (p-p) [when?] 100/100 TeV
NICA (A-A) 2014? 4.5/4.5 GeV/nucleon
ENC (e± ↑ -A↑) 2015? 3/15 GeV
ELIC/MEIC (e± ↑ -p↑, e± ↑ -A↑) 2015? 60/3 GeV
eRHIC (e± ↑ -p↑, e± ↑ -A↑) 2015? 325/20 GeV
LHeC (e± ↑ -p↑, e± ↑ -A↑) 2025? 0.06-0.14/7-16.5 TeV
                      → high luminosity, high energy
   HL-LHC: motivation & status
• reducing statistical errors
• radiation damage limit of IR quadrupoles ~400/fb
• extending physics potential; boost discovery mass reach
  from about 6.5 to 8 TeV

• major revision of LHC upgrade plan in early 2010
• LINAC4 under construction; collimation “phase II” defined;
  Nb-Ti and Nb3Sn low-b quadrupole prototypes under
  development; crab-cavity R&D ongoing ; PS booster
  energy upgrade preparation
• embedded in European & international collaborations
     HL-LHC: example parameters
parameter               symbol                nom.       nom.*    HL-LHC     LPA – 25     LPA – 50
protons per bunch       Nb [1011]               1.15        1.7        1.6          2.6        4.2
bunch spacing           Dt [ns]                  25          50        25           25          50
beam current            I [A]                   0.58       0.43       0.81        1.32        1.06
longitudinal profile                          Gauss       Gauss     Gauss         Flat        Flat
rms bunch length        sz [cm]                 7.55       7.55       7.55        11.8        11.8
beta* at IP1&5          b* [m]                  0.55       0.55       0.14        0.50        0.25
full crossing angle     qc [mrad]               285         285      (509)         339         381
Piwinski parameter      f=qcsz/(2*sx*)          0.65       0.65        0.0          2.0        2.0
tune shift              DQtot                  0.009     0.0136       0.01        0.01        0.01
peak luminosity         L [1034 cm-2s-1]             1      1.1        7.9          4.0        7.4
peak events per #ing                             19          40       150           75         280
initial lumi lifetime   tL [h]                   23          16        4.0        12.4         5.3
effective luminosity
                        Leff [1034 cm-2s-1]     0.55       0.56        1.5          1.9        2.6
(Tturnaround=5 h)
                        Trun,opt [h]            15.2       12.2        9.3        11.3         7.5
e-c heat SEY=1.3        P [W/m]                  0.4        0.1        0.7          1.4        0.8
SR+IC heat 4.6-20 K     PSR+IC [W/m]            0.32       0.30       0.53        0.77        0.82
annual luminosity       Lint[fb-1]               57          58       158          198         274
           paths to high luminosity
                                                                   Piwinski angle
                 1        N 2
                                    luminosity                     = tg(q/2)sz/sx
     L = nb f 0                   
                4s xs y  1 +  2 
                  re b y  N                rb       N 
        y =                        ; x = e x 2   1 +  2 
                                                                      beam-beam
                2gs ys x  1 +  2        2gs x                  tune shifts

                                                                   neglecting
                                                                   hourglass
Standard scheme:
                                                                   effect
reduce b* and minimimze 

Large Piwinski Angle & “Crab Waist” schemes:
increase N proportionally to :
    1) L grows proportionally to ;                               B.W. Montague, K. Hirata,

    2) y remains constant;
                                                                  O. Napoly, P. Raimondi,
                                                                  F. Ruggiero, F. Zimmermann,

    3) x decreases as 1/
                                                                  M. Zobov, et al
HL-LHC: LHC modifications
     IR upgrade
     (detectors,
     low-b quad’s,
     crab cavities, etc)   SPS enhancements
                           (anti e-cloud coating,RF,
     ~2020-21
                           impedance), 2012-2021




                           Booster energy upgrade
                           1.4 → 2 GeV, ~2015
            Linac4,
            ~2015
  HL-LHC: crab-cavity R&D
conventional, elliptical, “global” crab cavities
BNL                    CI/DL            KEK




               CI/DL           SLAC           JLAB
 KEK




compact, “local” crab cavities
 how to further squeeze LHC’s b*?
• tunnel designed for LEP
• straight sections “too short” even for present LHC
• could Slava Derbenev’s “beam extension section” with
  periodic zooming focusing lattice help to extend the
  final focus into the LHC arcs and reduce b* further?

                                   Guimei Wang,
          beam extension section   Slava Dervenev et al,
                                   PAC 2009
 HL-LHC: present schedule
2010-11: LHC running at 3.5 TeV beam energy; 1/fb
2012(-13): >1 year of stop to prepare LHC for 7 TeV
            and high beam intensity
2013-2014: LHC running; decisions for 2020 IR upgrade
~2016: LINAC4 connection, PSB energy upgrade,
     CMS & ATLAS upgrades, SPS enhancements
2015-20: high-luminosity operation delivering a total of
     300-400/fb (lifetime limit of low-b quadrupoles)
2020-21: HL-LHC, IR upgrade: new low-b quadrupoles &
     crab cavities, major detector upgrades
2021-30: operation at 5x1034/cm2/s w. leveling; 3000/fb
beyond HL-LHC?
 High-Energy LHC: draft parameters
                                               nominal LHC          HE-LHC
beam energy [TeV]                                    7                16.5
dipole field [T]                                   8.33                 20
dipole coil aperture [mm]                           56                  40
#bunches / beam                                   2808                1404
bunch population [1011]                            1.15               1.29
initial transverse normalized emittance [mm]       3.75         3.75 (x), 1.84 (y)
number of IPs contributing to tune shift             3                   2
maximum total beam-beam tune shift                 0.01               0.01
IP beta function [m]                               0.55         1.0 (x), 0.43 (y)
full crossing angle [mrad]                     285 (9.5 sx,y)     175 (12 sx0)
stored beam energy [MJ]                            362                 479
SR power per ring [kW]                              3.6               62.3
longitudinal SR emittance damping time [h]         12.9               0.98
events per crossing                                 19                  76
peak luminosity [1034 cm-2s-1]                      1.0                2.0
beam lifetime [h]                                   46                  13
integrated luminosity over 10 h [fb-1]              0.3                0.5
    HE-LHC: blow up all 3 emittances!?
SR
damping is
“too strong”:
emittance
shrinks
                             controlled blow up
too much
                             to keep DQ=0.01
and                                                    es constant
beam-beam
tune shift
“explodes”
                                  ey           ex
→                           ey
noise injection
to control all three         w. natural e
                                         x
emittances                   SR damping



Evolution of HE-LHC emittances during physics store with controlled transverse blow
up & constant longitudinal emittance (three thicker lines on top), and natural transverse
emittance evolution due to radiation damping and IBS only (two thinner lines at bottom)
– still for constant longitudinal emittance –, which would lead to an excessive tune shift.
 HE-LHC: luminosity evolution for 20h
peak
luminosity
2x
nominal
LHC
(similar
to KEKB)
with
luminosity
lifetime
~12 h




Time evolution of the HE-LHC luminosity including emittance variation with
controlled transverse & longitudinal blow up and proton burn off.
   HE-LHC: luminosity integral over 20h
integrated
luminosity
~1/fb
per day




Time evolution of the HE-LHC integrated luminosity during a physics store including
emittance variation with controlled blow up and proton burn off.
HE-LHC: CERN complex modifications
                                    HE-LHC
                                     2030-35
                    SPS+,
                    1.3 TeV, 2030-35




                    2-GeV Booster

           Linac4
   HE-LHC: candidate superconductors
                   10000
                                    YBCO B Tape Plane
L. Rossi                                                                                                                                     Data from P. Lee,
                                                                                    YBCO B|| Tape Plane                                      ASC – Florida S.
                                                                                                                                             Univ.
                                                                                                                                           SuperPower tape used
                                                                    RRP Nb3Sn
                                           Nb-Ti                                                                                           in record breaking
                                                                                        Complied from                                      NHMFL insert coil 2007
                   1000                                                                 ASC'02 and
                                                                                        ICMC'03 papers
      JE (A/mm²)




                                                                                        (J. Parrell OI-                    427 filament strand
                                                                                        ST)                                with Ag alloy outer
                                                                                                           2212            sheath tested at
                                                                                                                           NHMFL


                                 MgB2                                                                             YBCO Insert Tape (B|| Tape Plane)
                                                       Maximal JE for
                                                       entire LHC Nb-Ti                                           YBCO Insert Tape (B Tape Plane)
                    100                                strand production
                                                       (CERN-T. Boutboul   Bronze                                 MgB2 19Fil 24% Fill (HyperTech)
                                                       '07)
                               18+1 MgB2/Nb/Cu/Monel                       Nb3Sn                                  2212 OI-ST 28% Ceramic Filaments
                               Courtesy M. Tomsic,
                               2007                                                                               NbTi LHC Production 38%SC (4.2 K)
                                                                               4543 filament High Sn              Nb3Sn RRP Internal Sn (OI-ST)
                                                                                  Bronze-16wt.%Sn-
                                  Domain of iron
                                  dominated
                                                                           0.3wt%Ti (Miyazaki-MT18-               Nb3Sn High Sn Bronze Cu:Non-Cu 0.3
                                                                                            IEEE’04)
                                  magnets
                     10
                           0              5             10            15              20               25    30      35                   40             45
                                                                                                        Applied Field (T)
Interesting zone : 15-24 T ; Possible Superconductors:
Nb3Sn up to 17-18 T (existing, needs improvement)
HTS : either Bi-2212 (existing, needs a lot of improvement) or YBCO existing only in small tapes
(needs a lot of of R&D, however there is some synergy with R&D for energy application at 80 K)
First Nb3Sn Cable Test – Non-impregnated cable
               25



               20
 Current, kA




               15                                                             Nb3Sn


               10
                        WO/self-field corrections
                        W/self-field corrections
               5
                        TQM03 mirror magnet
                        Data from self-field SC transformer           Nb-Ti
               0
                    0        2           4          6        8          10
                                                        Magnetic Field, T      12     14   16



 FNAL US-LARP, Emanuela Barzi et al, last night!
HE-LHC: record dipole field vs time


                         13-T Nb3Sn dipole w. 6-T
                         HTS insert - EuCARD FP7
                                HE-LHC: a 20 T dipole
  •   50 mm aperture                                            • Operational current: 18 KA
  •   20 Tesla operational field
        – Inner layers: High Tc                                 • Operational current density: 400
          superconductor                                          A/mm2
        – Outer layers: Nb3Sn                                   • 20% operational margin (more
  •   To be explored for cost reduction:                          than LHC)               15 m
      outer layer in Nb-Ti and Nb3Sn
                                                                • Next step: Twin dipole + yoke
              200                              HTS                reduction
                                               Nb3 Sn

                                                                                                       HTS                               Nb3 Sn
              100                                                                   500

                                                                                    400
      y(mm)




                                                                                    300
                 0
                                                                                                               41° 49’ 55” N – 88 ° 15’ 07” W
                                                                               200
                                                        40° 53’ 02” N – 72 ° 52’ 32” W
                                                                                    100
              -100

                                                                           y (mm)
                                                                                      0

                                                                                    -100
              -200                                                      1 Km                                                        1.9 Km
                                                                           -200
                  -200   -100     0      100    200
                                x (mm)                                              -300

                                                                                    -400

                                                                                    -500
                                                                                        -500 -400 -300 -200 -100     0      100 200 300 400 500

Lay-out by E. Todesco (CERN)                                                                                       x (mm)



L. Rossi (CERN), P. McIntyre (Texas A&M)
    HE-LHC: high-field magnet issues
                                     Use of Nb-Ti (pink), Nb3Sn
Tripler 24 T by P. McIntyre (Texas   (red) and HTS (green).
A&M), PAC 2005                       What are the issues?
                                     • Stress management
                                     • Uniformity of the SC,
                                        especially for HTS
                                     • Cost : 4-4.5 G$ for the HE-
                                        LHC magnet system (L. Rossi,
                                       CERN edms n. 745391)
                                     • Handling of the synchrotron
                                       radiation power. VLHC
                                       solutions (cold fingers are
                                       envisaged but no R&D or
                                       conceptual design done so far…)

                                                                   L. Rossi
a short digression
(for completeness)
future ion-ion colliders: parameters
          Parameters                  NICA     RHIC II   LHiC
          Energy (GeV/Nucleon)       1-4.5      100      2760
          Luminosity (1027cm-2s-1)     1         4        1
          Ion species                Au-Au     Au-Au     Pb-Pb
Ions      Number of bunches            34       111      592
          Ions/bunch (107)            100       100       7
          Emittances H/V ([μm]       30/0.03     2.5      1.5
          Stored energy (MJ)                     0.4      3.8


          Energy(Gev/Nucleon)        12-25      250
Protons   Luminosity (1030cm-2s-1)     1.1      300      LHC
          Polarisation (%)             70        70

                                                           J.-P.
                                                           Delahaye,
                                                           ICHEP’10
let’s turn to lepton-hadron colliders
future hadron-lepton colliders L vs E




                                                     •




                            V. Litvinenko, IPAC’10
                        ENC at FAIR

Taking advantage of
the “existing” FAIR /
HESR
15 GeV proton ring




                                      J.-P.
                                      Delahaye,
                                      ICHEP’10
                                     ELIC at JLAB                                           Taking advantage of the
                                                                                            existing CEBAF 12 GeV
   MEIC first stage collider
                                                                                            electron accelerator
   Serves as a large booster to
                                                                                                 Circumference            m    1800
   the full energy collider ring                 p
                                                                                Ion
                                                                     SRF                              Radius              m    140
                                                     prebooster               Sources
                                                                     Linac
             p
                                                         p                                             Width              m    280
                                                                                                      Length              m    695
                                       MEIC
        ELIC
                                      collider
                                                                                                      Straight            m    306
       collider
                                       ring                                      electron ring
        ring                                                                                      Interaction Point


                 e                                   e


            e                  six “figure-8” rings
                               for polarization (Slava)
                  injector                                                          Ion ring
                                                                                                         Vertical crossing

                             12 GeV CEBAF
                                                             Stage           Max. Energy         Ring Size            Ring Type       IP
                                                                               (GeV/c)              (m)                                #
                                                                             p          e         p          e        p        e

                                                               Low           12       5 (11)          630         Warm        Warm    1


J.-P.                                                        Medium          60       5 (11)          630         Cold        Warm    2
Delahaye,                                                                                                                      40
ICHEP’10                                                      High           250        10            1800        Cold        Warm    4
Taking advantage of the
existing RHIC 130 GeV/u   eRHIC at BNL
Au ring


                                         First stage
                                         4 Gev e- X
                                         250 GeV p
                                         100 GeV/u Au




             J.-P.
             Delahaye,                        41
             ICHEP’10
                               Taking advantage of the
                LHeC at CERN   existing LHC proton ring
                               7 TeV (to 16.5 TeV in HE)

                                           RR LHeC:
                                           new ring
                                           in LHC tunnel,
                                           with bypasses
                                           around
                                           experiments



LR LHeC:                              RR LHeC
recirculating                         e± injector
linac with
                                      10 GeV,
energy
                                      10 min. filling time
recovery



                                                    42
LHeC: ring-ring configuration
Newly built
magnets
installed on top of
the LHC bypassing
LHC experiments.




10 GeV injector into
bypass of P1              10 33 cm -2 s -1,  L =100 fb -1,E e= 60GeV
2 1010e (LEP: 4 1011)
~10 min filling time
synchronous ep + pp
                                                              M. Klein
LHeC: linac-ring “erl” baseline
Also presented in CDR:
60 GeV pulsed 1032cm-2s-1
140 GeV pulsed 5 1031

Note: CLIC x LHC ~1030
due to different time
structure (0.5 vs 50ns)                 erl         10-GeV linac
                                                                           injector
                                      dump
Max. Power: 100 MW
                                                       1.0 km



                                                   2.0 km                   LHC p




                                                    10-GeV linac   IP


                                        Energy recovery (94%),
             M. Klein,                  β*=10cm
             J. Osborne,
             F. Zimmermann
                             10 33 cm -2 s -1,  L =100 fb -1,E e= 60GeV
       LHeC: linac-ring configurations
p-60                                             erl         10-GeV linac
                 1.67 km                LHC p
                                                                                   injector
   0.34 km                                      dump

                                                                1.0 km
  injector   30-GeV linac     IP        dump

       “least expensive"                                    2.0 km                  LHC p




p-140                                                        10-GeV linac   IP   high
                                                                                 luminosity


              2.0 km                                             LHC p
                                   3.9 km



  injector                  70-GeV linac               IP            dump
             high
             energy
p-140’                                 7.8 km
                                                                                   IP

                               140-GeV linac                                                  dump
injector
             future hadron-lepton colliders
         Parameters          ENC        ELIC       eRHIC                  LHeC
option                        RR         RR          LR           RR              LR
P-A/e- energy [GeV]          15/3.3      60/3       325/20      7000/60      7000/60
√(s) [GeV]                     14        27        160-102       1296            1296
luminosity [1032 cm-2s-1]      2         400         140          17              10
P/e- polarization [%]        80/80                  70/80         /40             /90
P/e- bunch popul. [109]      5.4/23     11/60       200/24      170/26       170/2.0
P/e- bunch length [mm]       0.3/0.1      5         49/20         /10            /0.3
P/e- bunch interval [ns]       19                     74         25-50           25-50
P/e- tr. emit. gex,y [μm]               0.8/75    1200/25000 3.75/580,290    3.75/50
IP beam size sx,y [μm]                                           30, 16           7
full crossing angle [mrad]                                       0.93             0
geometric reduction Hhg                                          0.77            0.91
Energy Recovery efficien.       -         -          94?           -             94%
average current [mA]                   860/4800     420/50        131             6.6    J.-P.
                                                                                         Delahaye,
tot. wall plug power[MW]                                          100            100     ICHEP’10
  LHeC: highest-energy ERL option




High luminosity LHeC with nearly 100% energy efficient ERL.
The main high-energy e- beam propagates from left to right.
In the 1st linac it gains ~150 GeV (N=15), collides with the
hadron beam and is then decelerated in the second linac.
Such ERL could push LHeC luminosity to 1035 cm-2s-1 level.

                                               V. Litvinenko,
                                               2nd LHeC workshop
                                               Divonne 2009
the icing on the cake
  some trends in hadron colliders
beam cooling
 stochastic cooling (RHIC l.&v.)
 electron cooling (Tevatron, ENC, ELIC)
 coherent electron cooling ((e)RHIC, HL-LHC?)
 synchrotron-radiation damping (HE-LHC)
beam-beam compensation
 long-range compensation [wire] (RHIC, LHC)
 e-lens compensation (Tevatron, RHIC, LHC)
new performance limitations
 burn-off and pile up (LHC, RHIC?)
 electron cloud (RHIC, LHC)
 machine protection, collimator cleaning (LHC)
advanced cooling concepts (Slava)
dispersive electron cooling with beam adapter and
circulator cooler for ELIC (EPAC2000, 2002)
-“overwhelms” IBS and produces very bright ion
       bunches
coherent electron cooling for RHIC, eRHIC, LHC etc.
(1980, EPAC’08 & PRL 2009, with V. Litvinenko)
- provides cooling times ≤ 1 h
open questions for hadron colliders
total beam-beam tune-shift limit
 Sp-pbarS 0.01-0.015, Tevatron 0.02, LHC design 0.01,
      ELIC/MEIC design 0.045 (see next slide)
 simulation codes successful for B factories find no beam-
      beam limit for LHC ?!
 dependence of beam-beam tune-shift limit on
      Piwinski angle? (see next next slide)
 dependence on phase advance between IP’s?

IR design
 minimum possible b*? beam extension section?
 local chromatic correction?
 feasibility of crab-waist scheme for hadrons?
 feasibility of crab cavities for hadrons?
Tevatron head-on beam-beam tune shift vs. time




                                       A .Valishev et al
dependence of tune shift limit on crossing angle?
                           historical experiments
   f~0.45
                           at SppbarS

                           K. Cornelis, W. Herr, M. Meddahi,
                           “Proton Antiproton Collisions at a
             qc=500 mrad
                           Finite Crossing Angle in the SPS”,
                           PAC91 San Francisco


tests up to f>0.7
showed (almost) no                 f>0.7
additional
beam-beam effect

present nominal LHC:
                                               qc=600 mrad
f~0.64,                                        small emittance
“phase-I” upgrade:
f~1.25!
            more open questions
damping equilibrium & optimization
 equilibrium distribution with IBS, cooling or radiation
damping, noise injection and       beam-beam
 “optimum” emittances?

boosting beam-beam limit
 circular modes and beam adapters (Slava)
 hollow beam collisions (Slava)
 beam-beam compensation


               LHC L-R wire    layout of
               compensator        RHIC
               prototype       electron
               in CERN SPS          lens
         still more open questions

longitudinal emittance & bunch length
 intentional longitudinal blowup throughout CERN complex
      - space charge, Landau damping of higher-order
      modes, IBS, m-wave instability

 ELIC/MEIC considers much smaller emittance and bunch
     lengths (sz ~5 mm compared with ~76 mm for LHC)

 with smaller longitudinal emittance in LHC we would not
     need crab cavities
                 proton bunch parameters
                 SPS    HERA   RHIC   Tevatron   LHC        ELIC/MEIC   ERHIC
                                                 (design)   (design)    (design)
beam energy      315    920    250    980        7000       60          325
[GeV]
bunch            1.3    0.7    1.1    2.8        1.15       0.11        2
population
[1011]
norm. transv.    3.0    5.0    2.5    3.0        3.75       0.8         0.2
emittance [mm]
norm. longit.    0.65   1.3    2.0    6.0        2.5        ~0.001      0.2
emittance                                                   - 0.01 ?
(4szsE) [eVs]
“p-s density”    0.22   0.02   0.09   0.05       0.03       17-170      250
[1011/mm2/eVs]                                              (cooling)   (cooling)
rms bunch        18     21     60     50         7.65       0.5         4.9
length [cm]
bunch spacing    ~7000 192     108    396        25         2           83
[ns]
                 conclusions
hadron and hadron-lepton colliders have performed
exceedingly well in the past

 they might profit from synchrotron radiation
     and advanced cooling schemes (how?)→
     new regime of beam dynamics!

 they promise further substantial
     advancements in energy and luminosity at
     sustainable power levels
Happy
Birthday,
Slava!



there is still
lots to do!

				
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