machine plans for the lhc upgrade
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Machine Plans for the LHC Upgrade. Frank Zimmermann CERN, AB/ABP. Thanks to Ralph Assmann, Michael Benedikt, Rama Calaga, Ulrich Dorda, Angeles Faus-Golfe, Roland Garoby,Jean-Pierre Koutchouk, Javier Resta, Francesco Ruggiero, Rogelio Tomas, Walter Scandale . Large Hadron Collider (LHC). - PowerPoint PPT PresentationTRANSCRIPT
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
Machine Plans for the LHC Upgrade
Frank ZimmermannCERN, AB/ABP
Thanks to Ralph Assmann, Michael Benedikt, Rama Calaga, Ulrich Dorda, Angeles Faus-Golfe, Roland Garoby,Jean-Pierre Koutchouk, Javier Resta, Francesco Ruggiero, Rogelio Tomas, Walter Scandale
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
Large Hadron Collider (LHC)
c.m. energy 14 TeV7x Tevatron
design luminosity1034 cm-2s-1
~100x Tevatron
transverse beamenergy density1 GJ/mm2
~1000x Tevatron
nominal LHC already a very challenging machine!
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
outline1) motivation 2) pushing the luminosity3) beam scenarios & upgrade schemes
- luminous region- lifetime & integrated luminosity
4) IR upgrade 5) intensity limitations 6) injector upgrade7) towards higher energy 8) questions to ATLAS9) summary
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
(1) motivation
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
time scale of an LHC upgrade
L at end of year
time to halve error
integrated L
radiationdamage limit~700 fb-1
(1) life expectancy of LHC IR quadrupole magnets is estimated to be <10 years due to high radiation doses
(2) statistical error halving time exceeds 5 years by 2011-2012 → it is reasonable to plan a machine luminosity upgrade based
on new low- IR magnets around ~2014-2015
design luminosity
ultimate luminosity
Jim Strait, 2003
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
European Accelerator Network on
November 2004: 1st CARE-HHH-APD Workshop (HHH-2004) on ‘Beam Dynamics in Future Hadron Colliders and Rapidly Cycling High-Intensity Synchrotrons’, Proc. CERN-2005-006
September 2005: 2nd CARE-HHH-APD Workshop (LHC-LUMI-05)on ‘Scenarios for the LHC Luminosity Upgrade’, Proc. CERN-2006-008
October 2006: 3rd CARE-HHH-APD Workshop (LHC-LUMI-06)‘Towards a Roadmap for the Upgrade of the LHC and GSI Accelerator Complex’ .../LUMI-06/LHC-LUMI-06-invitation.pdf
High Energy High Intensity Hadron Beams http://care-hhh.web.cern.ch/care-hhh/
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
upgrade stages• push LHC performance w/o new hardware
luminosity →2.3x1034 cm-2s-1, Eb=7→7.54 TeV• LHC IR upgrade
replace low- quadrupoles after ~7 yearspeak luminosity →4.6x1034 cm-2s-1
• LHC injector upgradepeak luminosity →9.2x1034 cm-2s-1
• LHC energy upgradeEb→13 – 21 TeV (15 → 24 T dipole magnets)
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
(2) pushing the luminosity
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
2*
2
14
profilerevbb FfNnLluminosity
frequency revolution:revf
bunchper protons# :bN
beamper bunches# :bn
emittance se transver)(geometric : pointcollision at function beta :*
angle crossing full :c
lengthbunch rms :z
pointcollision at sizespot e transversrms :**, yx
bunch uniform longfor 42.1~bunchGaussian for 1
profileF
angle Piwinski :2 *
,yx
zc
parameters that enter:
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
limited by arc aperture and field quality at injection limited by final triplet aperture & crossing angle
& long-range beam-beam & collimation & chromatic correction (& beam lifetime)c limited by geometric luminosity loss & long-range
collisions & triplet aperture & triplet field errorsnbNb ~ total current, limited by collimation, machine
protection, beam dump nb limited by electron cloud heating
Nb limited by image-current heating & collimation &
pile-up events
there are many parameter constraints, for example
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
x
zcF
2
;1
12
Piwinski angle
luminosity reduction factor
nominal LHC
nominal crossing angle “at the edge”
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
212
pbbb
rNQ
Qbb < 0.01- 0.015 , beam-beam limit for
hadron colliders (from experience)SpSp
total beam-beam tune shift at two IPs with alternating crossing
another important constraint is the (head-on) beam-beam tune shift
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
profilebb
p
revb FQrfnL 22
*2 1
for operation at the beam-beam limitluminosity equation can be rewritten as
IR upgrade
injector upgrade
LHC +injectorchanges
LHC+injectorchanges
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
(3) beam scenarios & upgrade schemes
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
parameter symbol nominal ultimate baseline alternative backuptransverse emittance [m] 3.75 3.75 3.75 7.5 3.75
protons per bunch Nb [1011] 1.15 1.7 1.7 3.4 6bunch spacing t [ns] 25 25 12.5 25 75beam current I [A] 0.58 0.86 1.72 1.72 1longitudinal profile Gauss Gauss Gauss Gauss flat
rms bunch length z [cm] 7.55 7.55 3.78 3.78 14.4beta* at IP1&5 [m] 0.55 0.5 0.25 0.25 0.25
full crossing angle c [murad] 285 315 445 630 430
Piwinski parameter cz/(2*x*) 0.64 0.75 0.75 0.75 2.8peak luminosity L [1034 cm-2s-1] 1 2.3 9.2 9.2 8.9events per crossing 19 44 88 176 510
Initial lumi lifetime L [h] 22 14 7.2 7.2 4.5
effective luminosity (Tturnaround=10 h)
Leff [1034 cm-2s-1] 0.46 0.91 2.7 2.7 2.1Trun,opt [h] 21.2 17.0 12.0 12.0 9.4
effective luminosity (Tturnaround=5 h)
Leff [1034 cm-2s-1] 0.56 1.15 3.6 3.6 2.9Trun,opt [h] 15.0 12.0 8.5 8.5 6.6
e-c heat SEY=1.4(1.3) P [W/m] 1.07 (0.44) 1.04 (0.59) 13.34 (7.85) 2.56 (2.05) 0.26
SR heat load 4.6-20 K PSR [W/m] 0.17 0.25 0.5 0.5 0.29
image current heat PIC [W/m] 0.15 0.33 1.87 3.74 0.96gas-s. 100 h (10 h) b Pgas [W/m] 0.04 (0.38) 0.06 (0.56) 0.113 (1.13) 0.11 (1.13) 0.07 (0.7)
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
bunch structure
25 ns
nominal & ultimate LHC
~12.5 ns
more (&shorter) bunches
concerns:e-cloudLRBBimpedance
upgrade path 1
upgrade path 3
75 nsconcerns:event pile upimpedance
longer (&fewer) bunches
transitions by bunch merging or splitting;new rf systems required for cases 1 and 3
plus:can use crab cavitiesevent pile up tolerable
plus:no e-cloud?less current
upgrade path 2
25 nsbigger (&shorter?) bunches concerns:
impedance heating,LR compensation,may need 1-TeVinjector
plus:limited e-cloudlimited pile up
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
luminosity upgrade: baseline schemes
increase Nb
bblimit?
increase F2/12
*21
zcF
no
yes
c>mindue to LR-bb
crab cavities
BBLRcompen-sation
reduce z
by factor ~2using higherfrf & lower ||
(largerc ?)
2.3reduce c
(squeeze *)
use large c
& pass each beamthrough separatemagnetic channel
reduce * byfactor ~2
new IRmagnets
increase either nb or (Nb& by factor ~2
if e-cloud, dump &impedance ok
9.2
1.0
4.6
simplified IR design with large c
peak luminosity gain1.72 A
0.86 A
0.58 A
0.86 A
beam current
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
luminosity upgrade: backup scheme
reduce * byfactor ~2
new IRmagnets
decrease F2/12
*21
zcF
increase zc
increase Nb
no bb
pb Q
FrN
2
?
yes
reduce #bunchesby 1/3 to limit total current
flatten profile
8.9
1.0
1.0 A
luminosity gain
beam current
0.58 A
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
2
,*
2
22 221
yx
c
zl
rms length of luminous region
due to the crossing angle, colliding long bunches does not mean the events are spread out over a large area
nominal ultimate baseline alternative backupl [cm] 4.5 4.3 2.1 2.1 3.5
luminous region is largest for nominal LHC
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
optimum run time, integrated luminosity, etc.
2
0
0
0
,...),,,,(11
/1/1
111
bzyxbIBS
x
x
b
bbIP
bb
vacvacbb
IPb
b
NNt
tN
ntNLnN
N
VNc
NnLn
tN
N
collisions, gas scattering
intensity evolution for collisions only
intrabeam scattering (IBS) growth
burn-off collision lifetime with ~100 mbarn, nIP~2: Lpeak=1034 cm-2s-1 in 2808 bunches, Nb~1.15x1011:
~45 h (luminosity lifetime 22 h)Lpeak=1035 cm-2s-1 in 5616 bunches, Nb~1.7x1011:
~14 h (luminosity lifetime 7 h)gas > 100 h (luminosity lifetime 50 h)IBS~105 h (horizontal emittance growth time;
luminosity lifetime 210 h)burn-off dominates over gas scattering and IBS
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
Lpeak [cm-
2 s-1]beam lifetime eff [h]
turnaround [h] Trun [h] Int L over 200 days[fb-1]
1034 45 10 21 79 1034 45 5 15 97 1035 14 10 12 473 1035 14 5 8 629
2/1
ˆ
efftLtL
luminosity time evolution
turnaroundrunruneff
runeffave TTT
TLL
ˆaverage luminosity
turnaroundeffoptimumrun TT ,→ optimum run time
6x
8x
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
(4) IR upgrade
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
factors driving IR design: • minimize * • minimize effect of LR collisions• large radiation power directed towards the IRs• crab cavities or beam-beam compensators, • integration of elements inside detector• compatibility with upgrade path
IR upgradegoal: reduce * by factor 2-5
maximize magnet aperture,minimize distance to IR
options: NbTi ‘cheap’ upgrade, NbTi(Ta), Nb3Sn new quadrupoles new separation dipoles
T. Sen et al., PAC2001T. Taylor, EPAC02J. Strait et al., PAC2003F. Ruggiero et al., EPAC04
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
IR
UPGRADE
reduced # LR collisions;collision debris hits first dipole
N. Mokhov et al., PAC2003
“open midplane s.c. dipole”
(studied by US LARP)
“dipole first”
“quadrupolesfirst”
minimumchromaticity
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
not so short bunches & near head-on collision
triplet magnetsD0 dipole
near head-on collisionbut large separation
triplet magnets
D0 dipole
IR schemes with D0 dipole deep inside detector (e.g., ~3 m from IP)
IR schemes with Q0 doublet deep inside detector (7.5 or 13 m from IP)
short bunches & minimum crossing angle & BBLR
crab cavities & large crossing angle
crab cavitytriplet
magnetstriplet magnetsBBLRQ0 doublet
Q0 doublet
triplet quadsmuch easier,less Q’,could be combinedwith D0
less LRcollisions.no geometriclumi. loss
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
higher-luminosity IR opticsweb site
http://care-hhh.web.cern.ch/care-hhh/SuperLHC_IRoptics/IRoptics.html
Candidate solutions:Combined function NbTi magnets with large l* (O. Bruning)Dipole first options with Nb3Sn (CERN & FNAL)Quad 1st Nb3Sn (T. Sen)Quad 1st “pushed” NbTi (O. Bruning, R. Ostojic, F. Ruggiero)Quad 1st with detector-integrated dipole (J.-P. Koutchouk)Quad 1st flat beam (S. Fartoukh)Quad 1st Nb3Sn or NbTi plus crab cavities (R.Tomas & F.Z.)Detector-integrated quadrupole doublet (E. Laface, W. Scandale, et al)
Rating criteria: aperture, energy deposition, technology, chromatic correction, beam-beam compensation,…,risks, development time scales, operational difficulties
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
(5) intensity limitations
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
ultimate LHC intensity limitations
• electron cloud• long-range & head-on beam-beam effects• collimator impedance & damage• injectors • beam dump & damage• machine protection• …
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
electron cloud in the LHC
schematic of e- cloud build up in the arc beam pipe,due to photoemission and secondary emission
[Courtesy F. Ruggiero]
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
arc heat load vs. spacing, Nb=1.15x1011, ‘best’ model
cooling capacity
R=0.5
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
long-range beam-beam collisions perturb motion at
large transverse amplitudes, where particles come close to opposing beam
may cause high background, poor beam lifetime
increasing problem for SPS, Tevatron, LHC,...
#LR encountersSPS 9Tevatron Run-II 70LHC 120
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
long-range beam-beam compensation by wire
prototype wire compensator “BBLR” installed in the SPS
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
crab voltage compared with bunch-shortening rf
crab cavity 100-1000x more effective than bunch-shortening rf!
crab cavities
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
KEKB Super-KEKB
ILC Super-LHC
x* 100 m 70 m 0.24 m 11 m
c 22 mrad 30 mrad 10 mrad 1 mrad
t 6 ps 3 ps 0.03 ps 0.002 ps
IP offset of 0.2 x*
IP offset of 0.6 nm, ~5x10-5 *
crab-cavity timing tolerance jitter tolerances
cIPcnxtmax2
(0.02 ps XFEL!)
tight jitter tolerance might prevent this scheme
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
graphite collimator impedance renders nominal LHC beam unstable
stability border(s) fromLandau octupoles
complex coherent tune shift plane
+ 43 collimators
resistive wall& broadband
Elias Metral LHC is limited to 40% of nominal intensity until “phase-2 collimation”
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
LHC phase-2 collimation options• high chromaticity and/or transverse feedback
(poor lifetime & emittance growth)• consumable low-impedance collimators (rotating
metal wheels; prototype from US LARP / SLAC to be installed in 2008)
• nonlinear collimation; pairs of sextupoles to deflect halo particles to larger amplitudes & open collimator gaps
• use crystals to bend halo particles to larger amplitudes & open collimator gaps
several proposed solutions
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
Channeling in flat crystal
U0
U0
U0
U0
θ1θ1
Channeled
1
0212 )(
2pvU
1
01 )(
2pvU
L
1
0212
12
1
)(21)(21
sinsin
pvUUU
mv
( Landau and Lifshitz, Mechanics)
Y. Ivanov, PNPI
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
Channeling and reflection in bent crystal
U0
U0
U0
U0
U0
θ1
θ3
θ2
Reflected
Channeled
LL Rd 3
2
Rd
212
Rd
LL 23
L 1
Y. Ivanov, PNPIreflecting crystals couldserve as primary collimators
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
crystal channeling & reflection demonstrated in SPS H8 -12.09.2006
Si-strip detector65 m behindCrystal
400 GeV p
10-rad reflectionover 1 m distance ↔~20000 T field!
>99% efficiency
channeledreflected
unperturbedor scattered
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
(6) injector upgrade
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
injector upgrade - motivationsraising beam intensity (higher bunch charge, shorter spacing etc.), for limited geometric aperture, L~N, may be essential for alternative scheme
reduction of dynamic effects (persistentcurrents, snapback, etc.)
→ improvement of turn-around time byfactor ~2, effective luminosity by ~50%
benefit to other CERN programmes ( physics, beams,…)
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
LHC injector upgradeSPS+
extraction energy 450 GeV →1 TeV PS2 or PS2+
extraction energy 26 GeV → 50 or 75 GeV LHC+
injection energy 450 GeV → 1 TeV
Super ISR is alternative to Super PS
Superferric ring “pipetron” in LHC tunnel is alternative to Super SPS – issue: detector bypass
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
parameter lists for new injectors under construction
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
PS2?
Super-SPS
Super-LHC
Super-Transferlines
Upgraded CERN Complexfast cycling dipoles for
Super-LHC injectors
PS2
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
(7) towards higher energy
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
ultimate LHC “upgrade”: higher beam energy
7 TeV→14 (21) TeV?
R&D on stronger magnets
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Training quench number
Mag
netic
fiel
d (T
)
Next European Dipole
Six institutes: CCLRC/RAL (UK), CEA/DSM/DAPNIA (France), CERN/AT (International), INFN/Milano-LASA & INFN/Genova (Italy), Twente University (the Netherlands), Wroclaw University (Poland).Three s.c. wire manufacturers (also contributing financially): Alstom/MSA (France), ShapeMetal Innovation (the Netherlands), Vacuumschmelze (now European Advanced Superconductors, Germany)
proof-of principle & world record: 16 T at 4.2 K at LBNL (in 10 mm aperture).
(S. Gourlay, A. Devred)
develop and construct a large-aperture (up to 88 mm), high-field (up to 15 T) dipole magnet model that pushes the technology well beyond present LHC limits.
European Joint Research Activity
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
proposed design of 24-T block-coil
dipole for LHCenergy tripler
P. McIntyre, Texas A&M, PAC’05
magnets are getting more efficient!
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
(8) questions to ATLAS
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
questions to ATLAS
• is the back up solution with peak pile up of 500 events per crossing a viable option?
• can “slim" s.c. magnets be installed deep inside the upgraded ATLAS detector, and, if so, under which boundary conditions, such as envelope, volume, material, or fringe field?
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
(9) summary
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
nominal LHC is extremely challengingthree paths to 10x higher luminosityLHC experience will determine the choice IR upgrade alone: factor 2-3 increase; integration of D0 or Q0 in ATLAS?
questions of joint interestraising beam intensity: factor ~4 gainnew injectors: ~3x higher peak & average luminosity; 1st step of energy upgradevigorous R&D programme needed
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
Francesco Ruggiero 2008: LHC Upgrade Conceptual Design Report2010: LHC Upgrade Technical Design Report2015: New IR, Beam-Beam Compensation>2015: Luminosity ~5x1034 cm-2s-1
ATLAS Upgrade Workshop, 1 October 2006Machine Plans for SLHC, Frank Zimmermann
thank you for your attention!