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J.M. Jowett, Collimation Working Group, 3/4/2006 1
II--LHC ProjectLHC ProjectOverview and StatusOverview and Status
John JowettJohn Jowett
J.M. Jowett, Collimation Working Group, 3/4/2006 2
Heavy Ion Physics ParametersHeavy Ion Physics Parameters
With increasing energy, more partons are available, interact more effectively. Thermalized high-T phase established more quickly and lasts longer.
SPS RHIC LHCCM energy nucleon s u GeV 17 200 5500 μ 28
Charged multiplicity dNchdy 400 800 > 3000 challenge
Energy density e GeV fm3 3 5 15- 60 denserFreeze- out volume Vf fm3 º 103 º 104 º 105 larger
QGP lifetime tQGP fm c b 1 1.5- 4 > 10 longerThermalization time t0 fm c r 1 º 0.2 b 0.1 faster
tQGP t0 1 6 r 30
J.M. Jowett, Collimation Working Group, 3/4/2006 3
II--LHC LongLHC Long--Term PlanningTerm Planning
Baseline: LeadBaseline: Lead--Lead collisionsLead collisions–– ““Early Early PbPb SchemeScheme”” –– much easier to achieve much easier to achieve –– for for
2008 (and 2009?)2008 (and 2009?)Allows study of performance limitations.Allows study of performance limitations.
–– ““Nominal Nominal PbPb SchemeScheme”” by 2009 by 2009 PbPb--PbPb is perceived as posing the most difficult is perceived as posing the most difficult accelerator physics problemsaccelerator physics problems
Future Future ““upgradesupgrades”” not in Baseline: not in Baseline: –– pp--PbPb collisions under studycollisions under study
Effects of revolution frequency difference at injection Effects of revolution frequency difference at injection expected to be expected to be muchmuch weakerweaker than at RHICthan at RHIC
–– lighter ionlighter ion--ion collisions (e.g. Ca, ion collisions (e.g. Ca, ArAr, O, , O, ……) appear ) appear possible without major upgrades, to be studied.possible without major upgrades, to be studied.
J.M. Jowett, Collimation Working Group, 3/4/2006 4
Nominal Nominal vsvs Early Ion Beam in LHCEarly Ion Beam in LHC
Why Early Beam?Why Early Beam?– Easier for injectors, shorter LHC filling time (4
min/ring)– Keep nominal bunch population (7 107 ions/bunch) to
study limitations without risks– A Luminosity of L=5. 1025 cm-2 s-1 (lower by a factor
20) by fewer bunches (1/10) and β* =1 m (factor 1/2) useful for physics (early results)
– Improved Luminosity lifetime because of larger β*
J.M. Jowett, Collimation Working Group, 3/4/2006 5
Nominal vs. Early Ion Beam: Key ParametersNominal vs. Early Ion Beam: Key Parameters
ParameterParameter UnitsUnits Nominal Nominal Early BeamEarly Beam
Energy per nucleonEnergy per nucleon TeV/nTeV/n 2.762.76 2.762.76
Initial Luminosity LInitial Luminosity L00 cmcm--22 ss--11 1 101 102727 5 105 102525
No. bunches/bunch harmonicNo. bunches/bunch harmonic 592/891592/891 62/6662/66
Bunch spacingBunch spacing nsns 99.899.8 13501350
ββ** mm 0.5 (same as p)0.5 (same as p) 1.01.0
Number of Pb ions/bunchNumber of Pb ions/bunch 7 107 1077 7 107 1077
Transv. norm. RMS emittanceTransv. norm. RMS emittance μμmm 1.51.5 1.51.5
Longitudinal emittanceLongitudinal emittance eVeV s/charges/charge 2.52.5 2.52.5
Luminosity halfLuminosity half--life (1,2,3 life (1,2,3 exptsexpts.).) HH 8, 4.5, 38, 4.5, 3 14, 7.5, 5.514, 7.5, 5.5
J.M. Jowett, Collimation Working Group, 3/4/2006 6
Lead Ion Schedule (postLead Ion Schedule (post--Chamonix 2006)Chamonix 2006)
J.M. Jowett, Collimation Working Group, 3/4/2006 7
Electromagnetic Interactions of Heavy ionsElectromagnetic Interactions of Heavy ions
QED effects in the peripheral collisions of heavy ions Rutherford scattering:
++γ++ +⎯→⎯+ 82208822088220882208 PbPbPbPb Copious but harmless
Free pair production:
−+++γ++ +++⎯→⎯+ eePbPbPbPb 82208822088220882208 Copious but harmless
Electron capture by pair production (ECPP)
+++γ++ ++⎯→⎯+ ePbPbPbPb 81208822088220882208 Electron can be captured to a number of bound states, not only 1s.
Secondary beam out of IP, effectively off-momentum”
Pbfor 012.01
1=
−=δ
Zp
Electromagnetic Dissociation (EMD)
Secondary beam out of IP, effectively off-momentum:
Pbfor 108.41
1 3−×−=−
−=δAp
nPb
*)Pb(PbPbPb
82207
82208822088220882208
+
↓
+⎯→⎯+
+
++γ++
(Numerous other changes of ion charge and mass state happen at smaller rates.)
J.M. Jowett, Collimation Working Group, 3/4/2006 8
Nuclear cross sectionsNuclear cross sections
CrossCross--section for section for PbPb totally totally dominated by electromagnetic dominated by electromagnetic processesprocessesValues for nonValues for non--PbPb ions may ions may need upward revision need upward revision
HHe O Ar Kr In Pb
sH
sEMD
sECPP
stot0
200
400
sêbarn
HHe O Ar Kr In Pb
sH sEMD sECPP s tot
Hydrogen 0.105 0 4.25μ 10-11 0.105Helium 0.35 0.002 1.μ 10-8 0.352Oxygen 1.5 0.13 0.00016 1.63016Argon 3.1 1.7 0.04 4.84Krypton 4.5 15.5 3. 23.Indium 5.5 44.5 18.5 68.5Lead 8 225. 280.756 513.756
ECPPEMDHtot
beamfromremovalion for section -crossTotalσ+σ+σ=σ
BFPP(=ECPP) from Meier et al, Phys. Rev. A, 63, 032713 (2001), calculation for Pb-Pbat LHC energy
BFPP(=ECPP) from Meier et al, Phys. Rev. A, 63, 032713 (2001), calculation for Pb-Pbat LHC energy
Need to update
J.M. Jowett, Collimation Working Group, 3/4/2006 9
Luminosity Limit from BFPPLuminosity Limit from BFPP
3700
3705
3710sêm
-0.02-0.0100.010.02
xêm
-0.010
0.01
yêm 3700
3705
3710sêm
00.010.0
0
100
200
300
400
sêm
-0.02 0 0.02
xêm
-0.03
-0.02
-0.01
0
yêm
100
200
300
400
m
Beam screen in one magnetBeam screen in one magnet
IP2IP2
Longitudinal Pb81+ ion distribution on screen
Longitudinal Pb81+ ion distribution on screen
Beam screen
Beam screen
Main Pb82+ beamMain Pb82+ beam
9.5 10 10.5 11 11.5 12
0.2
0.4
0.6
0.8
Secondary Pb81+ beam emerging grom IP and impinging on beam screen
Secondary Pb81+ beam emerging grom IP and impinging on beam screen
82 8 208208 208 82 82 2 8 10 PP Pb Pb ebb ++γ ++ ++ ⎯⎯→ + +
Energy deposition by ion flux may exceeds quench limit of superconducting magnets at nominal luminosity.
Calculations being refined with new ion-matter interaction models in FLUKA
See LHC Project Note 379,
New estimates for dipole quench limit
J.M. Jowett, Collimation Working Group, 3/4/2006 10
Operational Parameter Space for Operational Parameter Space for PbPb IonsIons
0.01 0.05 0.1 0.5 1 5 10
Ib μ
1. × 10 22
1. × 10 23
1. × 10 24
1. × 10 25
1. × 10 26
1. × 10 27
cm 2 s − 1
Visibility threshold on FB
CT
Nominal
Visible o
n BCTDC
Early
-1-2scm/L
A/μbI
Visibility threshold on arc B
PM
BFPP Quench limits ?N
ominal single bunch current
Visible o
n BCTDC
Thresholds for visibility on BPMs and BCTs.
Collimationlimit?
J.M. Jowett, Collimation Working Group, 3/4/2006 11
Optical Parameters at the Optical Parameters at the IPsIPs (Nominal)(Nominal)
= IPopticsTable@"CollisionIons", "LHCB1"D
]//NumberForm=
IP1 IP2 IP5 IP8 IP1.L1βxêm 0.55 0.5 0.55 10. 0.55βyêm 0.55 0.5 0.55 10. 0.55
xcêmm 1.1× 10−9 −3.59× 10−9 0.5 −3.18× 10−9 1.1× 10−9
ycêmm −0.5 5.77× 10−9 2.08× 10−9 −0.5 −0.5pxcêμrad −2.95× 10−6 2.63× 10−6 142. −210. −2.95× 10−6
pycêμrad 143. −10. −7.9× 10−6 −1.81× 10−7 143.
= IPopticsTable@"CollisionIons", "LHCB2"D
]//NumberForm=
IP1 IP2 IP5 IP8 IP1.L1βxêm 0.55 0.5 0.55 10. 0.55βyêm 0.55 0.5 0.55 10. 0.55
xcêmm 4.11× 10−9 3.94× 10−9 0.5 −2.43× 10−8 4.11× 10−9
ycêmm −0.5 −6.01× 10−9 −2.72× 10−9 0.5 −0.5pxcêμrad −2.79× 10−6 5.5× 10−6 −142. 210. −2.79× 10−6
pycêμrad −142. 10. −0.0000107 −2.69× 10−6 −142.
J.M. Jowett, Collimation Working Group, 3/4/2006 12
Optical Parameters at the Optical Parameters at the IPsIPs (Early)(Early)
IPopticsTable@"EarlyCollisionIons", "LHCB1"D
/NumberForm=
IP1 IP2 IP5 IP8 IP1.L1βxêm 2. 1. 2. 10. 2.βyêm 2. 1. 2. 10. 2.
xcêmm −1.11× 10−9 2.29× 10−9 0.322 1.78× 10−9 3.08× 10−9
ycêmm −0.322 2.78× 10−9 3.61× 10−10 −2. −0.322pxcêμrad 2.37× 10−6 −1.83× 10−6 92. −170. 1.86× 10−6
pycêμrad 92. −2.13× 10−6 −1.98× 10−6 8.67× 10−7 92.
IPopticsTable@"EarlyCollisionIons", "LHCB2"D
/NumberForm=
IP1 IP2 IP5 IP8 IP1.L1βxêm 2. 1. 2. 10. 2.βyêm 2. 1. 2. 10. 2.
xcêmm 3.94× 10−9 3.09× 10−9 0.322 −8.36× 10−9 3.94× 10−9
ycêmm −0.322 −4.5× 10−9 −5.35× 10−9 2. −0.322pxcêμrad −1.74× 10−6 1.11× 10−8 −92. 170. −1.74× 10−6
pycêμrad −92. −3.55× 10−7 −1.07× 10−6 −1.13× 10−6 −92.
J.M. Jowett, Collimation Working Group, 3/4/2006 13
Beams crossing inside LHC aperture, Nominal, IR2Beams crossing inside LHC aperture, Nominal, IR2
IRcrossingPlot3D@"CollisionsIons", "IR2", 2, 0.25D
CollisionsIons, IR2
3250
3300
3350
3400
3450
sêm
-0.2-0.1
00.1
0.2
xêm
-0.2
-0.1
0
0.1
0.2
yêm
3250
3300
3350
3400
3450
sêm
-0.2-0.1
00.1
J.M. Jowett, Collimation Working Group, 3/4/2006 14
Beams crossing, Beams crossing, Nominal+EARLYNominal+EARLY, IR2 (2, IR2 (2σσ beam)beam)IRcrossingPlot3D@"CollisionIons", "IR2", 2, 0.02D
CollisionIons, IR2
32503300
33503400
3450
sêm
-0.02-0.0100.010.02
xêm
-0.02
-0.01
0
0.01
0.02
yêm
32503300
33503400
3450
EarlyCollisionIons, IR2
32503300
33503400
3450
sêm
-0.02-0.0100.010.02
-0.02
-0.01
0
0.01
0.02
yêm
32503300
33503400
3450
J.M. Jowett, Collimation Working Group, 3/4/2006 15
RFRF
Larger frequency swing than with protons, no problem Larger frequency swing than with protons, no problem Different bunch filling schemesDifferent bunch filling schemesRF noise to be clarified (SPS MD to test continuous use)RF noise to be clarified (SPS MD to test continuous use)Needed to blowNeeded to blow--up longitudinal emittance at collision energy (IBS)up longitudinal emittance at collision energy (IBS)
1 2 3 4 5 6 7Proton momentum TeVê H êcL
400.78
400.782
400.784
400.786
400.788
400.79
fFRê
zHM
1 2 3 4 5 6 7Proton momentum ê HTeVêcL
400.78
400.782
400.784
400.786
400.788
400.79
fFRê
zHM 208Pb82+
p
RFRF 2
ion
ion p
On central orbit:
1
chfm cC
Q p
=⎛ ⎞
+ ⎜ ⎟⎜ ⎟⎝ ⎠
J.M. Jowett, Collimation Working Group, 3/4/2006 16
Optics for the Early and Nominal Ion SchemesOptics for the Early and Nominal Ion Schemes
Same Same geometricalgeometrical transverse beam size and emittancetransverse beam size and emittance–– Optics, dynamic aperture, mechanical acceptance, etc. similar toOptics, dynamic aperture, mechanical acceptance, etc. similar to
protons.protons.Injection and ramp done with Injection and ramp done with exactly the sameexactly the same optics, orbits, optics, orbits, corrections, etc. as for protonscorrections, etc. as for protons–– Should shorten ion commissioning time considerably!Should shorten ion commissioning time considerably!
Colliding in ATLAS, CMS Colliding in ATLAS, CMS ⇒⇒ same squeeze as protonssame squeeze as protonsLeave IR8 in injection configurationLeave IR8 in injection configurationMain difference is that IR2 is squeezed to Main difference is that IR2 is squeezed to –– May May -- or may not or may not -- be operationally convenient to commission be operationally convenient to commission
the ion optics first with lowthe ion optics first with low--intensity protons.intensity protons.Crossing angle at IP2 (1,5?) may be small (includes ALICE muon Crossing angle at IP2 (1,5?) may be small (includes ALICE muon spectrometer, details in Design Report)spectrometer, details in Design Report)–– Aperture requirements somewhat relaxed Aperture requirements somewhat relaxed w.r.tw.r.t. protons. protons–– Operational time for polarity reversalsOperational time for polarity reversals
* 2.,1.,0.5 mβ =
J.M. Jowett, Collimation Working Group, 3/4/2006 17
Plan for Commissioning LHC Rings with Lead Ions (1) Plan for Commissioning LHC Rings with Lead Ions (1)
Assume that protons can be collidedAssume that protons can be collided–– Injection, ramp, squeeze (where applicable) are Injection, ramp, squeeze (where applicable) are
set upset upReRe--commission injection and first turns with single ion commission injection and first turns with single ion ““pilotpilot”” bunch (close to nominal intensity)bunch (close to nominal intensity)–– Adjust BSTAdjust BST–– Energy matching to different SPS cycle, each ringEnergy matching to different SPS cycle, each ring–– Should go quickly (magnetic reproducibilityShould go quickly (magnetic reproducibility……))–– Deal with any difference of geometric beam size from Deal with any difference of geometric beam size from
protons (collimator settings, etc.)protons (collimator settings, etc.)Set up RF and capture (Set up RF and capture (““few shiftsfew shifts””), instrumentation), instrumentation
J.M. Jowett, Collimation Working Group, 3/4/2006 18
Plan for Commissioning LHC Rings with Lead Ions (2) Plan for Commissioning LHC Rings with Lead Ions (2)
ReRe--commission rampcommission ramp–– Should also go quickly (magnetic reproducibility again)Should also go quickly (magnetic reproducibility again)–– Deal with any difference of geometric beam size from protons Deal with any difference of geometric beam size from protons
(collimator settings, etc.)(collimator settings, etc.)Commission squeeze of IP2 (if applicable) Commission squeeze of IP2 (if applicable) –– Including crossing angle with ALICE spectrometer bump Including crossing angle with ALICE spectrometer bump –– (Alignment of IR2 triplet quadrupoles?)(Alignment of IR2 triplet quadrupoles?)–– Could take a few days (see experience with IP1 and IP5)Could take a few days (see experience with IP1 and IP5)
Collide Collide PbPb--PbPb–– ReRe--optimise collimation (how?), measurements, etc.optimise collimation (how?), measurements, etc.
Need to review time requirements with proton experience.Need to review time requirements with proton experience.Provide > 4 weeks of physics with Early Scheme for ALICE, ATLAS,Provide > 4 weeks of physics with Early Scheme for ALICE, ATLAS,
CMS.CMS.DonDon’’t forget MD time (t forget MD time (→→ Nominal SchemeNominal Scheme) with ) with PbPb ions ions
J.M. Jowett, Collimation Working Group, 3/4/2006 19
Synchrotron RadiationSynchrotron Radiation
LHC is the first proton storage ring in which synchrotron radiation plays a noticeable role, (mainly as a heat load on the cryogenic system) It is also the first heavy ion storage ring in which synchrotron radiation has significant effects on beam dynamics. – Surprisingly, perhaps, some of these effects are
stronger for lead ions than for protons.– Nucleus radiates coherently:
pp
p EAZE
mAcErZ
mcErU =
ρ
π=
ρπ
= ion346
4ion
2
3ion
6
4ionion ,
34
34
per turnlossradiation n Synchrotro
J.M. Jowett, Collimation Working Group, 3/4/2006 20
Synchrotron RadiationSynchrotron Radiation
Scaling with respect to protons Scaling with respect to protons in same ring, same magnetic in same ring, same magnetic fieldfield
–– Radiation damping for Radiation damping for PbPb is is twice as fast as for protonstwice as fast as for protons
Many very soft photonsMany very soft photonsCritical energy in visible Critical energy in visible spectrumspectrum
20 40 60 80Z
0.5
1
1.5
2
tpÅÅÅÅÅÅÅÅÅÅÅtion
Radiation damping enhancement for all stable isotopes
Lead is (almost) best, deuteron is worst.
J.M. Jowett, Collimation Working Group, 3/4/2006 21
Evolution during a fillEvolution during a fill
( ) ( ) ( )
( ) ( )( ) ( )( )
( )
( ) ( )( ) ( ) ( )( )
( )
= −
ε = −ε
ε
ε =
ε
ε
ε
ε
τ
ε
τ
⎛ ⎞ σ− σ⎜ ⎟
−
πβ
ε
⎠ ε⎝∑
radi
2
tot exp 0
*
luminosi
IBS
IBS
Bj-M in MAD, full lattic
ty b
a
beam-gas
tioe
urn-of
n
f
, ,
,
4
,
2
4
g bg b b
x
x b x l
x
x
l
bg
x
lx
b
b
l x l
x
x
t
T
t
t
N t
t
n f N
N t t
t
T N t tt
n v N tt
t( )+ RF
Injected RF noise
damping
D t
0 2 4 6 8 10têh
1μ10-10
2μ10-10
3μ10-10
4μ10-10
5μ10-10
6μ10-10
7μ10-10
e xêm
No radiation damping, DRF=0
Radiation damping, DRF>0
=expNo. of experiments: 0, 31,2,n0 2 4 6 8 10
têh
2μ1026
4μ1026
6μ1026
8μ1026
1μ1027
Lêmc-2
s-1
0 2 4 6 8 10têh
1μ10-10
2μ10-10
3μ10-10
4μ10-10
5μ10-10
6μ10-10
e xêm
Nominal initial εx
=expNo. of experiments: 0, 31,2,n
Nominal initial εx
Blown-up initial εx
Blown-up initial εx
=expNo. of experiments: 0, 31,2,n
J.M. Jowett, Collimation Working Group, 3/4/2006 22
Luminosity evolution during a fill: Early schemeLuminosity evolution during a fill: Early scheme
0 2 4 6 8 10têh
1μ10-10
2μ10-10
3μ10-10
4μ10-10
5μ10-10
e xêm
0 2 4 6 8 10têh
1μ107
2μ107
3μ107
4μ107
5μ107
6μ107
7μ107
N b
expNo. of experiments: 0, 3,1,2n =Assuming good vacuum conditions, but including all effects.
Particles per bunch
Transverse emittance
0 2 4 6 8 10têh
1μ1025
2μ1025
3μ1025
4μ1025
5μ1025
Lêmc-2
s-1
Luminosity
Increasing number Increasing number of experiments of experiments reduces beam and reduces beam and luminosity lifetime luminosity lifetime butbut we can still we can still keep fills for a long keep fills for a long time (useful if turntime (useful if turn--round time is long).round time is long).
Arc BPM visibility threshold
* 1 mβ =
J.M. Jowett, Collimation Working Group, 3/4/2006 23
0 2 4 6 8 10têh
1μ107
2μ107
3μ107
4μ107
5μ107
6μ107
7μ107
N b
0 2 4 6 8 10têh
1μ10-10
2μ10-10
3μ10-10
4μ10-10
5μ10-10
e xêm
Luminosity evolution: Nominal schemeLuminosity evolution: Nominal scheme
expNo. of experiments: 0, 3,1,2n =
An “ideal” fill, starting from design parameters giving nominal luminosity.
Particles per bunch
Transverse emittance
0 2 4 6 8 10têh
2μ1026
4μ1026
6μ1026
8μ1026
1μ1027
Lêmc-2
s-1
Luminosity
Increasing number Increasing number of experiments of experiments reduces beam and reduces beam and luminosity lifetime.luminosity lifetime.
BPM visibility threshold
J.M. Jowett, Collimation Working Group, 3/4/2006 24
SummarySummary
II--LHC Project remains on track for LHC Project remains on track for PbPb--PbPb collisions with collisions with ““Early SchemeEarly Scheme”” at end 2008at end 2008–– See talk by S. See talk by S. MauryMaury at Chamonix 2006at Chamonix 2006–– No serious performance limits expectedNo serious performance limits expected
Move towards Move towards PbPb--PbPb nominal parameters from 2009nominal parameters from 2009–– Various performance limits, including collimationVarious performance limits, including collimation
This is just the first step in the ion programmeThis is just the first step in the ion programme
J.M. Jowett, Collimation Working Group, 3/4/2006 25
ConclusionsConclusions
US DOE/NSAC Review 2004: US DOE/NSAC Review 2004: –– ““LHC will open up a new regime of ultraLHC will open up a new regime of ultra--relativistic relativistic
heavyheavy--ion physics with significant opportunities for ion physics with significant opportunities for new discoveries.new discoveries.””
AddedAdded--value for the worldvalue for the world--wide investment in LHC.wide investment in LHC.Operation of LHC with lead ions limited by new effects, Operation of LHC with lead ions limited by new effects, qualitatively different from protons qualitatively different from protons –– Several effects important around design luminosity. Several effects important around design luminosity. –– Challenge to achieve design luminosity.Challenge to achieve design luminosity.
Extensive future programme, colliding Extensive future programme, colliding pp--PbPb, , ArAr--ArAr, O, O--O, O, pp--ArAr, p, p--O, O, …… with further challenges.with further challenges.