Transcript Document 7289258

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
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
Large Hadron Collider (LHC)
c.m. energy 14 TeV
7x Tevatron
design luminosity
1034 cm-2s-1
~100x Tevatron
transverse beam
energy density
1 GJ/mm2
~1000x Tevatron
nominal LHC already a very challenging machine!
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
outline
1) motivation
2) pushing the luminosity
3) beam scenarios & upgrade schemes
- luminous region
- lifetime & integrated luminosity
4) IR upgrade
5) intensity limitations
6) injector upgrade
7) towards higher energy
8) questions to ATLAS
9) summary
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
(1) motivation
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
time scale of an LHC upgrade
Jim Strait, 2003
time to halve error
integrated L
radiation
damage limit
~700 fb-1
L at end of year
ultimate
luminosity
design
luminosity
(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-b IR magnets around ~2014-2015
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
European Accelerator Network on
High Energy
High Intensity
Hadron Beams
http://care-hhh.web.cern.ch/care-hhh/
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. CERN2006-008
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
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
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-b quadrupoles after ~7 years
peak luminosity →4.6x1034 cm-2s-1
• LHC injector upgrade
peak luminosity →9.2x1034 cm-2s-1
• LHC energy upgrade
Eb→13 – 21 TeV (15 → 24 T dipole magnets)
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
(2) pushing the luminosity
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
luminosity
2
b rev
*
nb N f
L
4b 
Fprofile
1 
2
parameters that enter:

 c z
: Piwinski angle
2 x*, y
f rev : revolution frequency
Nb : # protons per bunch
 z : rms bunch length
nb : # bunches per beam
 c : full crossing angle
 : (geometric ) transver se emittance
b * : beta function at collision point
 x*, y  b * : rms transvers e spot size at collision point
for Gaussian bunch
 1
Fprofile  
~ 1.42 for long uniform bunch
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
there are many parameter constraints, for example
 limited by arc aperture and field quality at injection
b* 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 errors
nbNb ~ 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
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
nominal crossing angle “at the edge”
 c z
1
F 
; 
Piwinski angle
2
2 x
1 
luminosity reduction factor
nominal LHC
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
another important constraint is the (head-on) beam-beam
tune shift
Qbb 
N b rp
2
1 
2
total beam-beam tune shift at two
IPs with alternating crossing
Qbb < 0.01- 0.015 , beam-beam limit for
hadron colliders (from SppS experience)
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
for operation at the beam-beam limit
luminosity equation can be rewritten as
injector upgrade
L   nb
  f rev Q 2
LHC +
injector
changes
Machine Plans for SLHC, Frank Zimmermann
r b
2
p
*
bb
1   Fprofile
IR upgrade
2
LHC+
injector
changes
ATLAS Upgrade Workshop, 1 October 2006
(3) beam scenarios &
upgrade schemes
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
parameter
symbol
transverse emittance
 [mm]
3.75
3.75
3.75
7.5
3.75
protons per bunch
Nb [1011]
1.15
1.7
1.7
3.4
6
bunch spacing
t [ns]
25
25
12.5
25
75
beam current
I [A]
0.58
0.86
1.72
1.72
1
Gauss
Gauss
Gauss
Gauss
flat
longitudinal profile
nominal
ultimate
baseline
alternative
backup
rms bunch length
z [cm]
7.55
7.55
3.78
3.78
14.4
beta* at IP1&5
b* [m]
0.55
0.5
0.25
0.25
0.25
full crossing angle
c [murad]
285
315
445
630
430
Piwinski parameter
cz/(2*x*)
0.64
0.75
0.75
0.75
2.8
peak luminosity
L [1034 cm-2s-1]
1
2.3
9.2
9.2
8.9
19
44
88
176
510
22
14
7.2
7.2
4.5
Leff [1034 cm-2s-1]
0.46
0.91
2.7
2.7
2.1
Trun,opt [h]
21.2
17.0
12.0
12.0
9.4
Leff [1034 cm-2s-1]
0.56
1.15
3.6
3.6
2.9
Trun,opt [h]
15.0
12.0
8.5
8.5
6.6
1.07 (0.44)
1.04 (0.59)
13.34 (7.85)
2.56 (2.05)
0.26
events per crossing
Initial lumi lifetime
effective luminosity
(Tturnaround=10 h)
effective luminosity
(Tturnaround=5 h)
tL [h]
e-c heat SEY=1.4(1.3)
P [W/m]
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
0.96
gas-s. 100 h (10 h) tb
Pgas [W/m]
0.04 (0.38)
0.06 (0.56)
0.113 (1.13)
0.11 (1.13)
0.07 (0.7)
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
plus:
can use crab cavities
event pile up tolerable
bunch structure
nominal & ultimate LHC
more (&shorter) bunches
~12.5 ns
upgrade
path 1
25 ns
upgrade
path 2
concerns:
e-cloud
LRBB
impedance
upgrade
path 3
longer (&fewer) bunches
25 ns
bigger (&shorter?)
bunches
concerns:
plus:
limited e-cloud
limited pile up
75 ns
plus:
no e-cloud?
less current
concerns:
event pile up
impedance
impedance heating,
LR compensation,
may need 1-TeV
transitions by bunch merging or splitting;
injector
new rf systems required for cases 1 and 3
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
luminosity upgrade: baseline schemes
0.58 A
1.0
increase Nb
bb
limit?
no
increase F
  
F  1   c *z
  2

yes



2




1/ 2
c>mindue
to LR-bb
BBLR
compensation
crab
cavities
2.3
reduce z
by factor ~2
using higher
frf & lower ||
(larger c ?)
reduce c
(squeeze b*)
0.86 A
4.6
reduce b* by new IR
factor ~2
magnets
0.86 A
if e-cloud, dump &
impedance ok
increase either nb or
(Nb& by factor ~2
peak luminosity gain
beam current 1.72 A
Machine Plans for SLHC, Frank Zimmermann
9.2
use large c
& pass each beam
through separate
magnetic channel
simplified IR design
with large c
ATLAS Upgrade Workshop, 1 October 2006
luminosity upgrade: backup scheme
1.0
decrease F
reduce b* by new IR
factor ~2
magnets
0.58 A
  
F  1   c *z
  2

flatten profile



2




1/ 2
increase zc
increase Nb
reduce #bunches
by 1/3 to limit total
current
2
 Qbb
Nb 
rp F
no
?
yes
8.9
1.0 A
Machine Plans for SLHC, Frank Zimmermann
luminosity gain
beam current
ATLAS Upgrade Workshop, 1 October 2006
due to the crossing angle, colliding long
bunches does not mean the events are spread
out over a large area
2
 2


c
rms length of luminous region




 l2   z2 2 *2x , y 
1
nominal ultimate
l [cm]
4.5
4.3
baseline
2.1
alternative
backup
2.1
3.5
luminous region is largest for nominal LHC
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
optimum run time, integrated luminosity, etc.
1 N b
1 1
N
 n IP L
 c   vac
N b t
nb N b
 V  vac
N b0
N b0
Nb 

0
1  n IP LN b t / nb 1  t / t
1  x
1

 N b2
 x t t IBS ( N b ,  x ,  y ,  z ,   ,...)
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:
t~45 h (luminosity lifetime 22 h)
Lpeak=1035 cm-2s-1 in 5616 bunches, Nb~1.7x1011:
t~14 h (luminosity lifetime 7 h)
tgas > 100 h (luminosity lifetime 50 h)
tIBS~105 h (horizontal emittance growth time;
luminosity lifetime 210 h)
burn-off dominates over gas scattering and IBS
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
Lt  
Lˆ
1  t / t 
2
luminosity time evolution
eff
Lave 
→
t
Lˆ t eff Trun
eff
 Trun Trun  Tturnaround
average luminosity
Trun,optimum  t eff Tturnaround optimum run time
Lpeak
beam lifetime Tturnaround
[cm-2 s-1] teff [h]
[h]
1034
1034
1035
1035
Machine Plans for SLHC, Frank Zimmermann
45
45
14
14
10
5
10
5
Trun [h] Int L over
200 days
[fb-1]
21
79
15 6x
97
12
473
8 8x 629
ATLAS Upgrade Workshop, 1 October 2006
(4) IR upgrade
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
IR upgrade
goal: reduce b* by factor 2-5
T. Sen et al., PAC2001
T. Taylor, EPAC02
J. Strait et al., PAC2003
F. Ruggiero et al., EPAC04
options: NbTi ‘cheap’ upgrade, NbTi(Ta), Nb3Sn
new quadrupoles
new separation dipoles
maximize magnet aperture,
minimize distance to IR
factors driving IR design:
• minimize b*
• 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
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
I
R
U
P
G
R
A
D
E
Machine Plans for SLHC, Frank Zimmermann
“quadrupoles
first”
minimum
chromaticity
“dipole first”
reduced # LR collisions;
collision debris hits first dipole
N. Mokhov et al.,
PAC2003
“open midplane s.c.
dipole”
(studied by US LARP)
ATLAS Upgrade Workshop, 1 October 2006
IR schemes with D0 dipole deep inside detector (e.g., ~3 m from IP)
D0 dipole
triplet magnets
D0 dipole
less LR
collisions.
no geometric
lumi. loss
not so short bunches &
near head-on collision
near head-on collision
but large separation
IR schemes with Q0 doublet deep inside detector (7.5 or 13 m from IP)
Q0 doublet
triplet magnets
short bunches &
minimum crossing
angle & BBLR
Machine Plans for SLHC, Frank Zimmermann
Q0 doublet
crab cavities &
large crossing angle
triplet quads
much easier,
less Q’,
could be
combined
with D0
ATLAS Upgrade Workshop, 1 October 2006
higher-luminosity IR optics
web site http://care-hhh.web.cern.ch/carehhh/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
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
(5) intensity limitations
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
ultimate LHC intensity limitations
•
•
•
•
•
•
•
electron cloud
long-range & head-on beam-beam effects
collimator impedance & damage
injectors
beam dump & damage
machine protection
…
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
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]
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
arc heat load vs. spacing, Nb=1.15x1011, ‘best’ model
R=0.5
cooling capacity
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
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 encounters
SPS
Tevatron Run-II
LHC
Machine Plans for SLHC, Frank Zimmermann
9
70
120
ATLAS Upgrade Workshop, 1 October 2006
long-range beam-beam
compensation by wire
prototype wire compensator “BBLR” installed in the SPS
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
crab cavities
crab cavity 100-1000x
more effective than
bunch-shortening rf!
crab voltage compared with bunch-shortening rf
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
crab-cavity timing tolerance jitter tolerances
KEKB
SuperKEKB
70 mm
ILC
Super-LHC
0.24 mm
11 mm
x*
100 mm
c
22 mrad 30 mrad 10 mrad
1 mrad
t
6 ps
0.002 ps
3 ps
0.03 ps

(0.02 ps XFEL!)
IP offset of 0.2 x*
IP offset of
0.6 nm,
~5x10-5 *
tight jitter tolerance might
prevent this scheme
2xmax
t 
nIP c c
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
graphite collimator impedance
renders nominal LHC beam unstable
complex coherent
tune shift plane
+ 43 collimators
stability border(s) from
Landau octupoles
Elias Metral
Machine Plans for SLHC, Frank Zimmermann
resistive wall
& broadband
LHC is limited to 40% of nominal intensity
until “phase-2 collimation”ATLAS Upgrade Workshop, 1 October 2006
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
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
Channeling in flat crystal
2U 0
sin 1
2
 1
(U1  U 2 )  1 
2
sin 2
( pv)1
mv1
( Landau and Lifshitz, Mechanics)
 2  12 
2U 0
( pv)1
U0
Channeled
U0
θ1
U0
θ1
1   L 
2U 0
( pv)1
U0
Y. Ivanov, PNPI
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
Channeling and reflection in
bent crystal
U0
1   L
 2  1 2 
U0
Channeled
θ3
U0
U0
d
R
Reflected
θ1
θ2
 L  3   L 2 
L2 
d
R
d
 3   L
R
U0
Y. Ivanov, PNPI
Machine Plans for SLHC, Frank Zimmermann
reflecting crystals could
serve as primary collimators
ATLAS Upgrade Workshop, 1 October 2006
crystal channeling & reflection demonstrated
in SPS H8 -12.09.2006
Si-strip
detector
65 m behind
Crystal
400 GeV p
unperturbed
or scattered
reflected
channeled
10-mrad
reflection
over 1 mm
distance ↔
~20000 T field!
>99%
efficiency
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
(6) injector upgrade
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
injector upgrade - motivations
raising beam intensity (higher bunch charge,
shorter spacing etc.), for limited geometric
aperture, L~N, may be essential for
alternative scheme
reduction of dynamic effects (persistent
currents, snapback, etc.)
→ improvement of turn-around time by
factor ~2, effective luminosity by ~50%
benefit to other CERN programmes
(n physics, b beams,…)
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
LHC injector upgrade
SPS+
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
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
parameter lists for new injectors under construction
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
Upgraded CERN Complex
fast cycling dipoles for
Super-LHC injectors
Super-LHC
Super-SPS
Super-Transferlines
PS2
PS2?
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
(7) towards higher energy
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
ultimate LHC “upgrade”:
higher beam energy
7 TeV→14 (21) TeV?
R&D on stronger magnets
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
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.
Six institutes: CCLRC/RAL (UK),
CEA/DSM/DAPNIA (France),
CERN/AT (International),
INFN/Milano-LASA &
INFN/Genova (Italy), Twente
University (the Netherlands),
Next European Dipole
European Joint Research
Activity
Wroclaw University (Poland).
Three s.c. wire manufacturers
(also contributing financially):
Alstom/MSA (France),
ShapeMetal Innovation (the
proof-of principle & world record: 16 T at 4.2 K at
LBNL (in 10 mm aperture).
Netherlands), Vacuumschmelze
(now European Advanced
Superconductors, Germany)
18.00
16.00
Magnetic field (T)
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00
0
Machine Plans for SLHC, Frank Zimmermann
2
4
6
8
10
(S. Gourlay, A. Devred)
Training quench number
12
14
16
18
20
22
24
26
28
30
ATLAS Upgrade Workshop, 1 October 2006
proposed design
of 24-T block-coil
dipole for LHC
energy tripler
P. McIntyre, Texas A&M,
PAC’05
magnets are
getting
more efficient!
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
(8) questions to ATLAS
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
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?
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
(9) summary
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
nominal LHC is extremely challenging
three paths to 10x higher luminosity
LHC experience will determine the choice
IR upgrade alone: factor 2-3 increase;
integration of D0 or Q0 in ATLAS?
questions of joint interest
raising beam intensity: factor ~4 gain
new injectors: ~3x higher peak & average
luminosity; 1st step of energy upgrade
vigorous R&D programme needed
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006
Francesco Ruggiero
Machine Plans for SLHC, Frank Zimmermann
2008: LHC Upgrade Conceptual Design Report
2010: LHC Upgrade Technical Design Report
2015: New IR, Beam-Beam Compensation
-2s-1Upgrade Workshop, 1 October 2006
>2015: Luminosity ~5x1034 cmATLAS
thank you for your attention!
Machine Plans for SLHC, Frank Zimmermann
ATLAS Upgrade Workshop, 1 October 2006