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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)
Frank Zimmermann, LHCb Upgrade Meeting
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?”).
Frank Zimmermann, LHCb Upgrade Meeting
machine upgrade plan
Frank Zimmermann, LHCb Upgrade Meeting
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
Frank Zimmermann, LHCb Upgrade Meeting
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
Roland Garoby, LHCC 1July ‘08
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
Roland Garoby, LHCC 1July ‘08
extended shutdowns:2012/13 & 2017
Frank Zimmermann, LHCb Upgrade Meeting
machine shutdown plans
Frank Zimmermann, LHCb Upgrade Meeting
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
Frank Zimmermann, LHCb Upgrade Meeting
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
Frank Zimmermann, LHCb Upgrade Meeting
luminosity scenarios in point 8 after phase-2 upgrade
what about
LHCb?
Frank Zimmermann, LHCb Upgrade Meeting
2001 upgrade feasibility study
Frank Zimmermann, LHCb Upgrade Meeting
from 2001 upgrade feasibility study
…
(note:2006 nominaland ultimateparametersare slightlydifferent)
Frank Zimmermann, LHCb Upgrade Meeting
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
Frank Zimmermann, LHCb Upgrade Meeting
• 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?!
Frank Zimmermann, LHCb Upgrade Meeting
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
Frank Zimmermann, LHCb Upgrade Meeting
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)]
Frank Zimmermann, LHCb Upgrade Meeting
• 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
Frank Zimmermann, LHCb Upgrade Meeting
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
Frank Zimmermann, LHCb Upgrade Meeting
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
LHC Upgrade Beam Parameters, Frank ZimmermannFrank Zimmermann, LHCb Upgrade Workshop PAF/POFPA Meeting 20 November 2006
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)
LHC Upgrade Beam Parameters, Frank ZimmermannFrank Zimmermann, LHCb Upgrade Workshop PAF/POFPA Meeting 20 November 2006
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)
LHC Upgrade Beam Parameters, Frank ZimmermannFrank Zimmermann, LHCb Upgrade Workshop PAF/POFPA Meeting 20 November 2006
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
LHC Upgrade Beam Parameters, Frank ZimmermannFrank Zimmermann, LHCb Upgrade Workshop PAF/POFPA Meeting 20 November 2006
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