Frank Zimmermann, LHCb Upgrade Meeting Overview of LHC Machine Upgrade Plans from an LHCb Perspective - Frank Zimmermann LHCb Upgrade Meeting CERN, 5 August

Frank Zimmermann, LHCb Upgrade Meeting

Overview of LHC Machine Upgrade Plans from an

LHCb Perspective-

Frank Zimmermann

LHCb Upgrade Meeting

CERN, 5 August 2008

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-2003-506395)


outline

(1) general LHC upgrade plan

(2) shutdown plans for the machine, i.e. time-windows with longer than normal

shutdown detector access

(3) luminosity scenarios in point 8 after phase 2 (“and maybe phase 1 - if there is a change?”).


machine upgrade plan


Two Strong Reasons for LHC Upgrade

J. Strait 2003

1) after few years, statistical error hardly decreases 2) radiation damage limit of IR quadrupoles (~700 fb-

1) reached by ~2016 time for an upgrade! 3) extending physics potential!

hypothetical luminosity evolution


staged approach to LHC upgrade “phase-1” 2013:

new triplets, D1, TAS, b*=0.25 m in IP1 & 5,reliable LHC operation at ~2-3x luminosity;beam from new Linac4

“phase-2” 2017:target luminosity 10x nominal, possibly Nb3Sn triplet & b*~0.15 m

complementary measures 2010-2017: e.g. long-range beam-beam compensation, crab cavities, new/upgraded injectors, advanced collimators, coherent e- cooling??, e- lenses??

longer term (2020?): energy upgrade, LHeC,…

phase-2 might be just phase-1 plus complementary measures

+ injector upgrade

x

zcR

2

;1

12

“Piwinski angle”

luminosity reduction factor

nominal LHC

constraint crossing angle

qc/2

effective beamsize s→s/Rf

other constraints:beam-beame- cloudcollimation

Name Event Date7

LHC upgrade paths for IP1 & 5

• ultimate beam (1.7x1011 protons/bunch, 25 spacing), b* ~10 cm • early-separation dipoles in side detectors , crab cavities

→ hardware inside ATLAS & CMS detectors, first hadron crab cavities; off- d b

stronger triplet magnetsD0 dipole

small-angle

crab cavity

J.-P. Koutchoukearly separation (ES)

stronger triplet magnets

small-angle

crab cavity

• ultimate LHC beam (1.7x1011 protons/bunch, 25 spacing)• b* ~10 cm • crab cavities with 60% higher voltage

→ first hadron crab cavities, off- d b-beat

L. Evans,W. Scandale,F. Zimmermann

full crab crossing (FCC)

wire

compensator

larger-aperture triplet magnets• 50 ns spacing, longer & more intense bunches

(5x1011 protons/bunch)• b*~25 cm, no elements inside detectors• long-range beam-beam wire compensation

→ novel operating regime for hadron colliders, beam generationF. Ruggiero,

W. Scandale.F. Zimmermann

large Piwinski angle (LPA)

parameter symbol nominal ultimate Early Sep. Full Crab Xing L. Piw Angle

transverse emittance e [mm] 3.75 3.75 3.75 3.75 3.75

protons per bunch Nb [1011] 1.15 1.7 1.7 1.7 4.9

bunch spacing Dt [ns] 25 25 25 25 50

beam current I [A] 0.58 0.86 0.86 0.86 1.22

longitudinal profile Gauss Gauss Gauss Gauss Flat

rms bunch length sz [cm] 7.55 7.55 7.55 7.55 11.8

beta* at IP1&5 *b [m] 0.55 0.5 0.08 0.08 0.25

full crossing angle qc [mrad] 285 315 0 0 381

Piwinski parameter =f qcsz/(2*sx*) 0.64 0.75 0 0 2.0

hourglass reduction 1.0 1.0 0.86 0.86 0.99

peak luminosity L [1034 cm-2s-1] 1 2.3 15.5 15.5 10.7

peak events per #ing 19 44 294 294 403

initial lumi lifetime tL [h] 22 14 2.2 2.2 4.5

effective luminosity (Tturnaround=10 h)

Leff [1034 cm-2s-1] 0.46 0.91 2.4 2.4 2.5

Trun,opt [h] 21.2 17.0 6.6 6.6 9.5

effective luminosity (Tturnaround=5 h)

Leff [1034 cm-2s-1] 0.56 1.15 3.6 3.6 3.5

Trun,opt [h] 15.0 12.0 4.6 4.6 6.7

e-c heat SEY=1.4(1.3) P [W/m] 1.07 (0.44) 1.04 (0.59) 1.04 (0.59) 1.04 (0.59) 0.36 (0.1)

SR heat load 4.6-20 K PSR [W/m] 0.17 0.25 0.25 0.25 0.36

image current heat PIC [W/m] 0.15 0.33 0.33 0.33 0.78

gas-s. 100 h (10 h) tb Pgas [W/m] 0.04 (0.38) 0.06 (0.56) 0.06 (0.56) 0.06 (0.56) 0.09 (0.9)

extent luminous region sl [cm] 4.5 4.3 3.7 3.7 5.3

comment nominal ultimate D0 + crab crab wire comp.

larg

e P

iwin

ski angle

(LP

A)

full

crab c

ross

ing (

FCC

)

earl

y se

para

tion (

ES)

Name Event Date9

luminosity leveling

ES orFCC

LPA

averageluminosity

initial luminosity peak may not be useful for physics(set up & tuning?)

experiments prefer ~constant luminosity, less pile up at start of run, higher luminosity at end

ES or FCC: dynamic b squeeze, or dynamic q change (either IP angle bumps or varying crab voltage)LPA: dynamic b squeeze, or dynamic change of bunch length

how can we achieve this?

Name Event Date10

25 ns spacing

50 ns spacing

IP1& 5 event pile up for 25 & 50-ns spacing w/o levelingES orFCC

LPA

Name Event Date11

reasons for injector upgrade

• Need for reliability:• Accelerators are old [Linac2: 1978, PSB:

1975, PS: 1959, SPS: 1976]• They operate far from their design

parameters and close to hardware limits• The infrastructure has suffered from the

concentration of resources on LHC during the past 10 years

• Need for better beam characteristics

Roland Garoby, LHCC 1July ‘08

Name Event Date12

PSB

SPSSPS+

Linac4

(LP)SPL

PS

LHC / SLHC DLHC

Ou

tpu

t en

ergy

160 MeV

1.4 GeV4 GeV

26 GeV50 GeV

450 GeV1 TeV

7 TeV~ 14 TeV

Linac250 MeV

(LP)SPL: (Low Power) Superconducting Proton Linac (4-5 GeV)

PS2: High Energy PS(~ 5 to 50 GeV – 0.3 Hz)

SPS+: Superconducting SPS(50 to1000 GeV)

SLHC: “Superluminosity” LHC(up to 1035 cm-2s-1)

DLHC: “Double energy” LHC(1 to ~14 TeV)

Proton flux / Beam power

present and future injectors

PS2


layout of the new injectorsSPS

PS2

SPL

Linac4

PS

R. Garoby, CARE-HHH BEAM07, October’07; L. Evans, LHCC, 20 Feb ‘08

R. Garoby, LHCC 1 July 2008

ID WBS Task Name

1 Linac4 project start

2 2 Linac systems

3 2.1 Source and LEBT construction, test

4 Drawings, material procurement

5 2.2 RFQ construction, test

6 2.4 Accelerating structures construction

7 Klystron prototypying

8 2.6.2 Klystrons construction

9 2.6.1 LLRF construction

10 2.7 Beam Instrumentation construction

11 2.8 Transfer line construction

12 2.9 Magnets construction

13 2.10 Power converters construction

14 5 Building and infrastructure

15 5.1 Building design and construction

16 5.2,3,4 Infrastructure installation

17 3 PS Booster systems

18 3.1 PSB injection elements construction

19 3.2 PSB beam dynamics analysis

20 4 Installation and commissioning

21 4.1 Test stand operation (3 + 10 MeV)

22 4.2 Cavities testing, conditioning

23 Cabling, waveguides installation

24 Accelerator installation

25 Klystrons, modulators installation

26 Hardware tests

27 Front-end commissioning

28 4.5 Linac accelerator commissioning

29 Transfer line commissioning

30 PSB modifications

31 4.6 PSB commissioning with Linac4

32 Start physics run with Linac4

01/01

01/05

Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q12007 2008 2009 2010 2011 2012 2013 2014

injector upgrade schedulesynchronized with LHC IR upgrades

LHC IR phase 1

LHC IR phase 2

staged upgrade: peak luminosity in IPs 1 & 5 vs year

collimatio

n phase 2

linac4 + IR

upgrade phase 1

new injectors

+ IR upgrade phase 2

early operatio

n


extended shutdowns:2012/13 & 2017


machine shutdown plans


regular annual shutdown

minimum duration of the annual accelerator shutdown (analysis for 2007 by Simon Baird, ATC mtg. 4 May ‘07)

basic needs:• 6 weeks for mandatory maintenance (legal obligation),• 3 weeks for hardware tests/cold check-out,• 3 weeks for setting-up of the accelerators,

adding up to incompressible minimum duration of 12 weeks of interruption of LHC beam every year, without any major intervention/modification

information from R. Garoby


time slots with >6 months accessin present upgrade schedule:(1) 4th quarter 2012 – 2nd quarter 2013

~7.5 monthsfor PSB cooldown, PSB modifications,PSB commissioning with LINAC4

→ LHC peak luminosity in IP1&5 ~ 2x1034 cm-2s-1

(1-2) ATLAS [& CMS] may need 18 months downtime as early as 2015 (N. Hessey, LHCC 1 July 2008)

(2) mid-November 2016 – end June 2017:~7.5 months

for SPS cooldown, SPS modifications, SPS commissioning with SPL+PS2

→ LHC peak luminosity in IP1&5 ~ 1x1035 cm-2s-1


luminosity scenarios in point 8 after phase-2 upgrade

what about

LHCb?


2001 upgrade feasibility study


from 2001 upgrade feasibility study

…

(note:2006 nominaland ultimateparametersare slightlydifferent)


from 2001 upgrade feasibility study

nominal tune footprintup to 6s with 4 IPs

tune footprint up to 6s with 2 IPs

tune footprint up to 6s with 2 IPs at ultimateintensity

L=1034 cm-2s-1

L=2.3x1034 cm-2s-1

SPS, Tevatron, RHIC experience: beam-beam limit ↔ total tune shift DQ~0.01

going from 4 to 2 IPs we can increase ATLAS&CMS luminosity by factor 2.3

this and all following upgrade studies were based on assumption of only 2 IPs

~0.01

~0.01

~0.01

~0.01


• aim to minimize contribution to beam-beam tune shift (note: DQ is independent of b*)

• aim to provide optimum LHCb luminosity of 2x1033 cm-2s-1/2808 per bunch crossing, or 1/50th of luminosity in IP1 & 5

can we make (upgraded) LHCb compatible with upgraded LHC?!


50-ns upgradewith 25-ns collisionsin LHCb

bunch structures

25 ns

50 ns

nominal

25 ns

ultimate& 25-ns upgrade(ES & FCC)

50-ns upgrade (LPA),no collisions in LHCb!

50 ns25 ns


LHCb recipe for 50-ns scenario • add satellites at 25 ns spacing• these can be produced by highly asymmetric bunch

splitting in the PS (possibly large fluctuation)• in LHCb satellites collide with main bunches • satellite intensity should be lower than 3x1010 p/bunch

to add <5% to beam-beam tune shift and to avoide-cloud problems; 3x1010 ~ 1/16th of main-bunch charge

• b function of ~3 m would result in desired luminosity equivalent to 2x1033 cm-2s-1; easily possible with present IR magnets & layout

[simpler alternative with lower rate: collide displaced 50-ns bunch trains in LHCb @ b*~ 25 m (R. Garoby)]


• here head-on collisions add to beam-beam tune shift of bunches colliding in ATLAS & CMS

• potential ways out:– collisions with transverse offset– collide at LHCb only in later part of each store,

when the beam-beam tune shift from IP1 & 5 has decreased (H. Dijkstra)

more “exotic” / advanced (need studies):– “electron lenses” for tune-shift compensation– flat-beam “crab-waist” collisions for DQx~0

LHCb schemes for 25-ns scenario


L = L0 exp (-d2/(4s2))

LHCb collisions with transverse offset d

luminosity:

DQ LHCb = 2 DQIP1or5 / (d/ )s 2tune shift:

suppose tune shift from LHCb should be less than 10% of that from CMS or ATLAS → d>4.5 s ;then luminosity L ~ 0.006 L0

if we wish LLHCb~0.01 LIP1or5 (~1-2x1033 cm-2s-1)

we need b* ~0.08 m → IR triplet upgrade!

offset collisions w/o IR upgrade LLHCb ~ 4x1031 cm-2s-1


other concerns for 4-5s offset collisions:

• offset stability • interference with LHC collimation• effect on beam lifetime • effect on detector background

experience at RHIC, SPS, HERA and Tevatron wasdiscouraging (see slides with examples presented at LHCB Upgrade Workshop of January 2007); but interpretation of past results and their applicationto LHC is a bit controversial

LHC Upgrade Beam Parameters, Frank ZimmermannFrank Zimmermann, LHCb Upgrade Workshop PAF/POFPA Meeting 20 November 2006

LHCb luminosity for 25 ns with offset & 50 ns

25 ns spacing,4.5s offset,b*~0.08 m

50 ns spacing,satellites

LHCb 50-ns luminosity decays 2x more slowlythan 25-ns luminosity or that at ATLAS and CMS


25 ns spacing

50 ns spacing

tune shift during store for 25-ns & 50-ns spacing

changeDQ ~-0.0033

LHCb 25-ns collisions from middle of each store?! b*~3 m (5 h turnaround time is assumed)


LHCb luminosity for 25-ns late collisions & 50 ns

25 ns spacing,b* ~ 3 m,no transverseoffset

50 ns spacing,b*~3 m,satellites

(5 h turnaround time is assumed)


LHCb collision parametersparameter symbol 25 ns, offset 25 ns, late collision 50 ns, satellites

collision spacing Tcoll 25 ns 25 ns 25 ns

protons per bunch Nb [1011] 1.7 1.7 4.9 & 0.3

longitudinal profile Gaussian Gaussian flat

rms bunch length sz [cm] 7.55 7.55 11.8

beta* at LHCb *b [m] 0.08 3 3

rms beam size sx,y* [mm] 6 40 40

rms divergence sx’,y’* [mrad] 80 13 13

full crossing angle qc [urad] 550 180 180

Piwinski parameter =f qcsz/(2*sx*) 3.3 0.18 0.28

peak luminosity L [1033 cm-2s-1] 1.15 2.1 2.4

initial lumi lifetime tL [h] 1.8 2.8 9

length of lum. region sl [cm] 5.3 5.3 8.0

rms length of luminous region:(in cases w/o transverse offset)

2

,*

2

222

21

yx

c

zl


summary• time slots for LHCb upgrade: annual shutdown: > 3 months;

phase-1 2012/13: > 7 months; ATLAS/CMS upgrade: 2015/16/17? ~18 months; phase-2 2016/17: > 7 months

• three paths to 10x higher luminosity in IP1&5: 25-ns or 50-ns bunch spacing; early LHC experience may decide

• original upgrade plans did not consider LHCb, however LHCb can be made compatible

• 50-ns upgrade: satellite bunches at 25 ns could yield desired LHCb luminosity nearly transparently

• 25-ns upgrade: LHCb collisions with transverse offset + LHCb IR upgrade not too promising; better: late collisions with b*~3 m; e- lenses & crab-waist option to be studied

Documents

Frank Zimmermann, LHCb Upgrade Meeting Overview of LHC Machine Upgrade Plans from an LHCb Perspective - Frank Zimmermann LHCb Upgrade Meeting CERN, 5 August