Lead Ions in the LHC · 2004-03-12 · 208 Pb82+ +208 Pb82+ →γ 208 Pb82+ +208 Pb81+ +e+ Electron can be captured to a number of bound states, not only 1s. Secondary beam out of

J.M. Jowett, LHC Experiment Accelerator Data Exchange Working Group, 9/2/2004 1

Lead Ions in the LHC Lead Ions in the LHC

Contributors to this talk Contributors to this talk (re(re--run of run of ChamonixChamonix plus some extras): plus some extras):

H. Braun, H. Braun, J.M. Jowett, J.M. Jowett, E. E. MahnerMahner, , K. K. SchindlSchindl, , E. E. ShaposhnikovaShaposhnikova (CERN)(CERN)M. Gresham (Reed College, Portland), M. Gresham (Reed College, Portland),

I. I. PschenichnovPschenichnov (INR, Moscow) (INR, Moscow)

Thanks to: many other CERN colleagues, Thanks to: many other CERN colleagues, I. I. BaishevBaishev, S. , S. StriganovStriganov (FNAL)(FNAL)


Ions for LHC (IIons for LHC (I--LHC) ProjectLHC) Project

�� New INew I--LHC Project Web pages: LHC Project Web pages: –– http://carli.home.cern.ch/carli/ILHC_website/http://carli.home.cern.ch/carli/ILHC_website/

�� Members of the IMembers of the I--LHC Steering Group: LHC Steering Group: –– KarlheinzKarlheinz SchindlSchindl : : Chairman Chairman –– Hans Braun Hans Braun : : Ion collimation in LHC Ion collimation in LHC –– Christian Christian CarliCarli : : Scientific Secretary Scientific Secretary –– Michel Michel ChanelChanel : : Deputy Chairman, LEIR Deputy Chairman, LEIR –– Steven Hancock Steven Hancock : : RF aspects in LEIR and PS RF aspects in LEIR and PS –– Charles Hill Charles Hill : : LinacLinac 3, ECR ion source 3, ECR ion source –– John Jowett John Jowett : : LHC, linkman to experiments LHC, linkman to experiments –– DjangoDjango ManglunkiManglunki : : SPS, operational aspects SPS, operational aspects

Michel Martini Michel Martini : : PS, line to SPS PS, line to SPS –– Stephan Maury Stephan Maury : : Linkman to AC Linkman to AC –– FlemmingFlemming Pedersen Pedersen :: Low level RF all machines Low level RF all machines –– Elena Elena ShaposhnikovaShaposhnikova:: RF aspects SPS and LHC RF aspects SPS and LHC


Plan of talkPlan of talk

�� The IThe I--LHC ProjectLHC Project�� Review new ion parameters Review new ion parameters �� SmallSmall--angle separation schemeangle separation scheme�� Quench limit and ECPPQuench limit and ECPP�� CollimationCollimation�� Vacuum AspectsVacuum Aspects�� Luminosity and beam lifetimeLuminosity and beam lifetime�� Conclusions, implicationsConclusions, implications


Parameters for Lead Ions in LHCParameters for Lead Ions in LHC

�� Revision/verification of all parametersRevision/verification of all parameters–– Started at Started at ChamonixChamonix Workshop 2003Workshop 2003–– SummarisedSummarised in LHC Design Report in LHC Design Report VolVol I, Chapter 21I, Chapter 21

�� Recent changes:Recent changes:–– Introduction of “Early Ion Scheme”Introduction of “Early Ion Scheme”–– Optics update, smallOptics update, small--angle crossing scheme for ALICEangle crossing scheme for ALICE–– Revised lifetimes, IBS, etc.Revised lifetimes, IBS, etc.–– No 200 MHz RF system for capture at injection nowNo 200 MHz RF system for capture at injection now


Nominal scheme parametersNominal scheme parameters


Nominal scheme, lifetime parametersNominal scheme, lifetime parameters


Early scheme ParametersEarly scheme Parameters

Only show parameters that are different from nominal schemeOnly show parameters that are different from nominal scheme


Some things are straightforward Some things are straightforward

�� Beam current and stored energy 100 times lowerBeam current and stored energy 100 times lower–– Many limits to performance of proton beams are not a Many limits to performance of proton beams are not a

problem for lead ion beamsproblem for lead ion beams�� impedanceimpedance--driven collective effectsdriven collective effects�� beambeam--beambeam�� electron cloud (?)electron cloud (?)�� activation and maintenance of collimators activation and maintenance of collimators

�� Same Same geometricalgeometrical transverse beam size and emittance transverse beam size and emittance ⇒⇒ ssome aspects are similarome aspects are similar–– Optics, dynamic aperture, mechanical acceptance, Optics, dynamic aperture, mechanical acceptance,

etc. more or less carry over from protons.etc. more or less carry over from protons.


OpticsOptics

�� Ion optics at injection/ramp Ion optics at injection/ramp –– assumed to be essentially same as protonsassumed to be essentially same as protons

�� Lead ion optics in collisionLead ion optics in collision–– Update for move of Q3 magnets (part of V6.5)Update for move of Q3 magnets (part of V6.5)–– Focus on IR2 (ALICE, Focus on IR2 (ALICE, specialisedspecialised ion experiment)ion experiment)

�� Maintain Maintain ββ*=0.5 m (unlike protons which have *=0.5 m (unlike protons which have ββ*=0.55 m *=0.55 m for reasons of aperture)for reasons of aperture)

–– Ion collisions for ATLAS/CMS may use proton optics Ion collisions for ATLAS/CMS may use proton optics �� Or also squeeze furtherOr also squeeze further

–– Main issue is separationMain issue is separation


Separation in IR2: three illustrative casesSeparation in IR2: three illustrative cases

3100 3200 3300 3400 3500 3600fIP2bump= 17%, fALICE= 100%, qc= 82.2 mrad

-0.005

0

0.005

0.01

y cêm sêm

3100 3200 3300 3400 3500 3600fIP2bump= 42%, fALICE= 100%, qc= -2.8 mrad

-0.005

0

0.005

0.01

y cêm sêm

3100 3200 3300 3400 3500 3600fIP2bump= -65%, fALICE= -100%, qc= 81. mrad

-0.005

0

0.005

0.01

y cêm sêm

Two ways of getting a crossing angle of 80 µrad; one way to get zero crossing angle.

Total separation is superposition of ALICE spectrometer bump and “external” vertical separationBeam 1 / Beam 2

Animation!


Parasitic beamParasitic beam--beam encountersbeam encounters

3200 3250 3300 3350 3400 3450fIP2bump= 17%, fALICE= 100%, qc= 82.2 mrad

-7.5

-5

-2.5

0

2.5

5

7.5

10

Yês 1y sêm

3200 3250 3300 3350 3400 3450fIP2bump= -65%, fALICE= -100%, qc= 81. mrad

-7.5

-5

-2.5

0

2.5

5

7.5

10

Yês 1y sêm

3200 3250 3300 3350 3400 3450fIP2bump= 42%, fALICE= 100%, qc= -2.8 mrad

-7.5

-5

-2.5

0

2.5

5

7.5

10

Yês 1y sêm

Show only vertical separation in units of vertical RMS beam size of Beam 1.

Red lines are possible (ion) encounters (Sb/2)

Zero crossing angle is just about achievable with minimum 3σ separation (strictly need 20 µrad).

Bad!


Aperture (APL program)Aperture (APL program)

All meet the canonical aperture requirements with β*=0.5m


Electromagnetic Interactions of Lead ionsElectromagnetic Interactions of Lead 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=

−=δZp

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.)


Nuclear cross sectionsNuclear cross sections

�� CrossCross--section for section for PbPb totally totally dominated by electromagnetic dominated by electromagnetic processesprocesses

�� Values 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

ECPP values from Meier et al, Phys. Rev. A, 63, 032713 (2001), calculation for Pb-Pbat LHC energy

ECPP values from Meier et al, Phys. Rev. A, 63, 032713 (2001), calculation for Pb-Pbat LHC energy


Involved topic, numerous references …

Extrapolation from SPS measurements at lower energy in Grafström et al, PAC99

Meier et al, Phys. Rev. A, 63, 032713 (2001), calculation for Pb-Pb at LHC energy

Involved topic, numerous references …

Extrapolation from SPS measurements at lower energy in Grafström et al, PAC99

Meier et al, Phys. Rev. A, 63, 032713 (2001), calculation for Pb-Pb at LHC energy

CrossCross--sectionsectionfor ECPPfor ECPP

Electron can be captured to a number of bound states, not only 1s.

Electron can be captured to a number of bound states, not only 1s.


C.f. 204 barn used in previous discussions

[ ]

[ ]

[ ]

barn 281

barn 533.076.9)1()3(

barn 533.076.92.88.28.225

)2()2()3()2()1(

ECPP

2/3ECPP2/1ECPP

ECPPECPPECPPECPP

≈

+++σζ≈

++++++≈

+σ+σ++σ+σ+σ=σ

L

L

L

L

L

s

ppsss

Use Meier et al’s result for Pb-Pb at LHC energy:

CrossCross--section for ECPPsection for ECPP

3ECPP

ECPP)1()(

nsns σ

≈σ


Main and ECPP secondary beamsMain and ECPP secondary beams

0

100

200

300

400

sêm

-0.02

0

0.02

xêm-0.03

-0.02

-0.01

0

yêm0.02

0

5σ beam envelopes, emerging to right of IP2

Collimation of secondary beam seems difficult.

Beam screen

Uncorrected strong chromatic effects of low-b insertion⇒ cannot use linear beam sizes for Pb71+ beam


Secondary beam spotSecondary beam spot

3700

3705

3710

sêm

-0.02-0.01

00.01

0.02

xêm

-0.01

0

0.01

yêm 3700

3705

3710

sêm

0.0100.01

0.02

m/s

m/y

m/x

9.5 10 10.5 11 11.5 12

0.2

0.4

0.6

0.8

Energy deposition by ion flux from ECPP exceeds nominal quench limit of superconducting magnets by factor 2 at nominal luminosity. DIRECT LIMIT ON LUMINOSITY.

m 4.1m 1length shower with quadratureIn m, 1over Dilution

≈≈dl Beam screen in a

dispersion suppressor dipole

Pb/m/s 108 is ive)(conservatlimit Quench 4×

Plan to improve heat deposition estimate with FLUKA calculations.


Collimation for Collimation for PbPb ionsions

�� 208208PbPb82+82+ ionion--graphite interactions compared with pgraphite interactions compared with p--graphite interactions.graphite interactions.

From Hans Braun


FLUKA calculations from Vasilis Vlachoudisfor dump kicker single module prefire

Robustness of collimator against mishapsRobustness of collimator against mishaps

–The higher Ionisation loss makes the energy deposition at the impact side almost equal to proton case, despite 100 times less beam power.

–Similar damage potential.

From Hans Braun


The probability to convert a 208Pb nucleus into a neighboring nucleus. Impact on graphite at LHC collision energy.

Cleaning efficiencyCleaning efficiency

From Hans Braun


Simulation of collimation (Hans Braun)Simulation of collimation (Hans Braun)

� Model of ion fragmentation, linear optics, collimators and beam aperture

� Suppose beam lifetime is down to 12 min– due to non-luminosity processes, e.g., IBS, beam-gas,

resonances, … � Collimators tend to put ion fragments on trajectories

with large momentum errors and small betatron amplitude –– but the secondary collimators are designed to cut

betatron amplitudes� Acts like one-stage system� Worrying results at collision energy (following slides)

– Various hot-spots around ring� Seems OK at injection energy


570 580 590 600 610 620 630

0

5

10

15

20P' (W

/m)

distance from TCP.D6L7.B1 (m)

Fractional heat load in dispersion suppressor, τ=12min

MQ

.10R

7.B1

MQ

TLI.1

0R7.

B1

MB.

A11

R7.B

1

MB.

B11

R7.B

1

MQ

.11R

7.B1

MQ

TLI.1

1R7.

B1

Maximum for continous loss,corresponds to local collimation inefficiency of 1.61 10-3m-1

Pb208

Pb207

Pb206

Pb205

Pb204

Pb203

Tl204

Tl203

Tl202

Tl201

Tl200

Tl199

Tl198

Hg201

Hg200

Hg199

Nominal ILHC beam at collision

From Hans Braun


0 5 10 15 20 25

0

10

20

30

IP1 IP2 IP3 IP4 IP5 IP6 IP7 IP8 IP1

P' (W/m

)

Distance from IP1 (km)

Loss map

0

500

1000

1500

TCP

.6L3

.B1

TCS

.5L3

.B1

TCS

.A4R

3.B

1

TCS

.B4R

3.B

1

TCS

.A5R

3.B

1

TCS

.B5R

3.B

1

TCS

.C5R

3.B

1

TCP

.D6L

7.B

1

TCP

.C6L

7.B

1

TCP

.B6L

7.B

1

TCP

.A6L

7.B

1

TCS

.C6L

7.B

1

TCS

.B6L

7.B

1

TCS

.A6L

7.B

1

TCS

.B5L

7.B

1

TCS

.A5L

7.B

1

TCS

.B4L

7.B

1

TCS

.A4L

7.B

1

TCS

.A4R

7.B

1

TCS

.B4R

7.B

1

TCS

.C4R

7.B

1

TCS

.D4R

7.B

1

TCS

.E4R

7.B

1

TCS

.F4R

7.B

1

TCS

.G4R

7.B

1

TCS

.A5R

7.B

1

TCS

.B5R

7.B

1

P CO

LL (W

)Collimator load distribution

0 20 40 60 80 100 120 140 1600

2

4

6x 10

4

NTURN

Time development after first impact on collimatorparticles lost on collimatorsparticles lost elsewhereparticles in beam

Nominal ILHC beam at collision


Interaction of Interaction of PbPb ions with residual gasions with residual gas

�� Losses due to nuclear scattering on residual gasesLosses due to nuclear scattering on residual gases–– Atoms in residual gases (6 usual suspects in Design Atoms in residual gases (6 usual suspects in Design

Report for protons) have Z≤8. Report for protons) have Z≤8. –– For simplicity, discuss only the dominant inelastic For simplicity, discuss only the dominant inelastic

nuclear scattering (leave out elastic and nuclear scattering (leave out elastic and electromagnetic contributions, EMD, ECPP which are electromagnetic contributions, EMD, ECPP which are smaller). Somewhat optimistic!smaller). Somewhat optimistic!

–– Dominant beamDominant beam--gas lifetime:gas lifetime:is independent of intensity is independent of intensity

–– Multiple Coulomb scattering on residual gas also Multiple Coulomb scattering on residual gas also causes emittance growth (similar to protons, not causes emittance growth (similar to protons, not treated here).treated here).

–– Lost ions are a heat load:Lost ions are a heat load:

ii

i nc ∑∈

σ=τ gasesbg

1

bgτ=Zec

EIkP bbbg


Inelastic nuclear cross sectionsInelastic nuclear cross sections

�� CrossCross--sections of protonsections of proton--nucleus and nucleusnucleus and nucleus--nucleus inelastic interactions nucleus inelastic interactions at ~10 GeV/n, assumed similar at 2.75 TeV/n (as is the case for at ~10 GeV/n, assumed similar at 2.75 TeV/n (as is the case for protons)protons)–– Simple formula, V.S. Barashenkov, 1993Simple formula, V.S. Barashenkov, 1993

( )

( ) ( )

barn. 038.0 where

215.285.1,,, :AA

1215.21

85.1, :pA

0

2

2

2

1

13/1

23/1

1

3/1213/1

23/1

102211in21

2

3/1

3/13/1

0in

=σ

−

−−+

+++σ=σ

−

−+

++σ=σ

AZ

AZ

AAAAAAAZAZ

AZ

AAAAZ

Comparison with earlier Hard-sphere overlap model (Bradt & Peters 1950)

20 40 60 80Z

2

4

6

8

σêbarnPb, Barashenkov

Pb, Hard-sphere

pA, BarashenkovpA, Hard-sphere


Required gas pressuresRequired gas pressures

Gas σin nêm−3 τbgêh PbgêHWêmLH2 3.75 1.03× 1015 2.4 0.0165He 2.48 8.2× 1014 4.55 0.00872CH4 10.9 2.14× 1014 3.96 0.01H2O 7.52 2.33× 1014 5.28 0.00752CO 7.22 1.65× 1014 7.76 0.00512CO2 11. 1.07× 1014 7.89 0.00503

Gas σin nêm−3 PH300KLênTorr PH5KLêPa PbgêHWêmLH2 0.09 1.03× 1015 32. 7.11× 10−8 0.0377He 0.113 8.2×1014 25.5 5.66× 10−8 0.0377CH4 0.433 2.14× 1014 6.65 1.48× 10−8 0.0377H2O 0.397 2.33× 1014 7.24 1.61× 10−8 0.0377CO 0.56 1.65× 1014 5.14 1.14× 10−8 0.0377CO2 0.868 1.07× 1014 3.32 7.37× 10−9 0.0377

Protons with lifetime 100h

Lead ions with pressure that gave proton lifetime 100h

Gas σin nêm−3 PH300KLênTorr PH5KLêPa PbgêHWêmLH2 3.75 2.47× 1013 0.768 1.71× 10−9 0.000397He 2.48 3.73× 1013 1.16 2.58× 10−9 0.000397CH4 10.9 8.47× 1012 0.263 5.85× 10−10 0.000397H2O 7.52 1.23× 1013 0.383 8.5× 10−10 0.000397CO 7.22 1.28× 1013 0.399 8.86× 10−10 0.000397CO2 11. 8.43× 1012 0.262 5.82× 10−10 0.000397

Lead ions with lifetime 100h


0.1 1 10 100 1000 10000 100000101

102

103

104

105

106

107

108

Pb27+

BNL (AGS) BNL (RHIC) CERN (LINAC 3) CERN (SPS) GSI (HLI) GSI (HLI) GSI (SIS 18)

PRELIMINARY

In49+

Au79+

U28+Pb53+

Zn10+

Au31+

η eff [

mol

ecul

es/io

n]

Ion energy [MeV/u]

HeavyHeavy--ion induced ion induced desorptiondesorption data:data:New OverviewNew Overview

15 From Edgar Mahner


Electron Cloud effect with ions ?Electron Cloud effect with ions ?

�� Key parameters are charge/bunch and bunch spacingKey parameters are charge/bunch and bunch spacing–– We do not expect electron cloud effects with We do not expect electron cloud effects with PbPb ions. ions.

0.01 0.02 0.03 0.041êSb

2µ 1010

4µ 1010

6µ 1010

8µ 1010

1µ 1011

NbQion

Pb nominalPb early

RHIC with ecloud

LHC p nominal

LHC p no electron cloud (FZ simulation)


Longitudinal parametersLongitudinal parameters

Longitudinal emittance at injection from SPS has been reduced since we no longer have 200 MHz RF system for capture.


IntraIntra--beam scatteringbeam scattering

Injection Collision


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 photons�� Critical 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.


Damping partition number variationDamping partition number variation

�� Allows us to switch some radiation damping from Allows us to switch some radiation damping from longitudinal into horizontal motionlongitudinal into horizontal motion–– Heavily used at LEP, PETRA, TRISTAN, … Heavily used at LEP, PETRA, TRISTAN, … –– Overcome IBS, shrinking horizontal emittance to Overcome IBS, shrinking horizontal emittance to

maximisemaximise integrated luminosityintegrated luminosity–– Price of a few mm negative closed orbit in arc Price of a few mm negative closed orbit in arc QFsQFs ––

needs further studyneeds further study

( ) ( )

( ) ( )( ) dssDsKI

III

ff

II

II

dUdJ

x

sss

ss

2

18

23

42

RF

RF

2

8

2

4

,10 ,2

1 ,22log:orbitclosedofdeviation momentumh number witpartition dampingallongitudin ofVariation

∫=

≈ρπ

≈

∆η

−=δδ++≈δδ

=δ

−

ε

( ) ( ) ( ) ( )( ) ( )030motionbetatron horizontalfor rateDamping

xsxsxsx JJ αδ−=αδ=δα ε


Luminosity and beam lifetimeLuminosity and beam lifetime

�� InitialInitial beam (intensity) lifetime due to beambeam (intensity) lifetime due to beam--beam beam interactions (noninteractions (non--exponential decay) exponential decay)

–– where where nnexpexp is the number of experiments illuminatedis the number of experiments illuminated�� But luminosity may be limited by experiment or quench But luminosity may be limited by experiment or quench

limitlimit

ββ**--tuning during collision to tuning during collision to maximisemaximise integrated integrated luminosity luminosity –– especially if especially if NNbb can be increased.can be increased.

Pb-Pbwith scm 10 nominalfor hour4.22 1-2-27

exptotexp

==σ

=τ LnLn

Nk bbNL

2

02

20

2

* by varying luminosity same havecan

*4*4

b

n

bbbb

N

fNkfNkL

∝β⇒

γεβπ

=σπ

=


Nominal scheme, lifetime parameters (again)Nominal scheme, lifetime parameters (again)


Operational parameter space Operational parameter space with lead ionswith lead ions

0.01 0.05 0.1 0.5 1 5 10Ib µ

1. × 1022

1. × 1023

1. × 1024

1. × 1025

1. × 1026

1. × 1027

cm 2s−1

Visibility threshold on FB

CT

Nominal

Visible o

n BCTDC

Early

-1-2scm/L

A/µbI

Visibility threshold on arc B

PM

ECPP Quench limitN

ominal single bunch current

Visible o

n BCTDC

Thresholds for visibility on BPMs and BCTs.


ConclusionsConclusions

�� Operation of LHC with lead ions limited by diverse effects, ofteOperation of LHC with lead ions limited by diverse effects, often n qualitatively different from protonsqualitatively different from protons

�� ECPP leading to magnet quench limits luminosityECPP leading to magnet quench limits luminosity�� Poor collimation efficiency, large particle losses in dispersionPoor collimation efficiency, large particle losses in dispersion

compressor, limit on total currentcompressor, limit on total current–– Either keep > 40 min lifetime for nominal Ion parameters in Either keep > 40 min lifetime for nominal Ion parameters in

collision (!) or reduce beam currentcollision (!) or reduce beam current�� “Early scheme” will allow relatively safe commissioning, access “Early scheme” will allow relatively safe commissioning, access good good

initial physicsinitial physics–– Reduced risk of magnet quenches from ECPPReduced risk of magnet quenches from ECPP–– Reduced heat deposition related to collimationReduced heat deposition related to collimation

�� But But PbPb ions require much lower vacuum pressure than protonsions require much lower vacuum pressure than protons–– Independent of beam intensity! Independent of beam intensity!

�� Restricted to a small range of operational parameters below the Restricted to a small range of operational parameters below the nominal luminositynominal luminosity–– Do everything possible to expand it!Do everything possible to expand it!


ImplicationsImplications

�� Some effects (collimation,…) limit Some effects (collimation,…) limit total beam current total beam current but but there are no hard limits on single bunch currentthere are no hard limits on single bunch current–– More luminosity by distributing current in fewer More luminosity by distributing current in fewer

bunchesbunches–– Optimum filling scheme may be somewhere between Optimum filling scheme may be somewhere between

Early (kb=62) and Nominal (kb=592)Early (kb=62) and Nominal (kb=592)–– Possibility of running with, Possibility of running with, e.ge.g, 100, 100--300 bunches 300 bunches

should be kept in mind by injectors, all LHC systems should be kept in mind by injectors, all LHC systems and the experiments.and the experiments.

�� Do everything possible to increase singleDo everything possible to increase single--bunch currentbunch current–– Push all limits in injector chainPush all limits in injector chain

�� Many uncertainties to be resolved with further workMany uncertainties to be resolved with further work–– ECPP heating, EMD losses, vacuum, collimation, RF ECPP heating, EMD losses, vacuum, collimation, RF

noise, …noise, …

Documents

Lead Ions in the LHC · 2004-03-12 · 208 Pb82+ +208 Pb82+ →γ 208 Pb82+ +208 Pb81+ +e+ Electron can be captured to a number of bound states, not only 1s. Secondary beam out of