1. Walter Scandale, Frank Zimmermann 18 January 2007
Baseline Scenario for the LHC Luminosity Upgrade Summary of CARE-HHH LHC-LUMI-06
Walter Scandale, Frank Zimmermann
18 January 2007

2. CARE-HHH APD workshop ‘LUMI 06’ Towards a Roadmap for the Upgrade of the LHC and GSI Accelerator Complex IFIC, Valencia (Spain), October 2006
about 70 participants
including 13 from US-LARP and 2 from KEK
53 presentations, 10 discussions, 4 posters
topics:
interaction-region upgrade
beam parameters
intensity limitations
injector upgrade }
Frank
1st 2.5 days }
Walter
2nd 2.5 days

3. Walter Scandale: Status of LHC Upgrade

4. Roadmap for tracker/trigger upgrades
Jordan Nash: CMS Perspective of Upgrade
Roadmap for tracker/trigger upgrades
Within 5 years of LHC start
New layers within volume of current Pixel tracker which incorporate some tracking information for Level 1 Trigger
“Pathfinder” for full tracking trigger
Elements of new Level 1 trigger
Upgrade to full new tracker system by SLHC (8-10 years from LHC Startup)
Includes full upgrade to trigger system
Target: Summer 2007

5. Inner detector-high luminosity upgrade issues
Per Grafstrom: ATLAS Perspective of Upgrade
Inner detector-high luminosity upgrade issues
x 10 in luminosity  most sensors of inner detector will die in a couple of months
x 10 in luminosity  charged particles in  < 3.2
The TRT will have occupancy close to 100%
For the Inner Detector we are not talking about an “upgrade”
but a complete replacement i.e a NEW Inner Detector
replacement of SS beam pipe by Al or Be
beam pipe (reduced background)
potential slots for “slim” magnets inside ATLAS
“We want maximum annual integrated luminosity
at minimum peak luminosity”

6. Jim Strait: LHC Upgrade from US Perspective
LHC program, including LHC upgrade, is high-priority component of US HEP program.
US participates in R&D towards upgrades of experiments (ATLAS and CMS) and of LHC accelerator.
US contributions to accelerator upgrade focus on IR, in particular on Nb3Sn magnet development; recent successes: fields T reached in different prototype magnets

7. Gian Luca Sabbi: Nb3Sn Quad Development in US

8. Gian Luca Sabbi: Nb3Sn Quad Development in US

9. Tanaji Sen: IR Upgrade with Quadrupoles First

10. Tom Taylor & Ranko Ostojic: Nb3Sn & NbTi Hybrid IR
present
triplet
Nb3Sn
NbTi+
NbTi+
NbTi+
hybrid
upgrade

11. Solution with Modular ‘Triplet’ Layout
Oliver Bruning & R. De Maria: Low-Gradient Triplets
Solution with Modular ‘Triplet’ Layout
b-max below 15 km:
QX1  100T/m
QX2  80 T/m
QX3  100T/m
QX4  80 T/m
peak coil field: 9 T, aperture: 180 mm diameter, 10% operation margin
LHC LUMI 2006; ; Valencia
Oliver Brüning 11

12. Riccardo De Maria: Dipole 1st Optics w Chromaticity
and Dynamic Aperture

13. Tanaji Sen: US Dipole 1st Optics

14. Linear Chromaticity Correction
Angeles Faus-Golfe, R. De Maria, R. Tomas:
Chromaticity Limits
Linear Chromaticity Correction
Limits on Chromaticity Correction

15. Open Midplane Designs With High Temperature Superconductors (HTS)
Ramesh Gupta: Open Midplane Dipoles
and Crab-Cavity Quadrupoles
Open Midplane Designs With High Temperature Superconductors (HTS)
HTS in a hybrid design with Nb3Sn coils
Such magnets could operate at very high field (>16 T)
HTS could tolerate large energy deposition

16. High-Z Liner (Inner Absorber)
Nikolai Mokhov: Handling Collision Debris
High-Z Liner (Inner Absorber)
Liner
Coils
Energy deposition design goal for Nb3Sn
quads is reached with W25Re liner
7.2-mm thick (+1.5mm) in Q1 and 1-mm
thick (+1.5mm) in the rest of triplet
Handling Collision Debris - N. Mokhov

17. Francesco Broggi: Energy Deposition in Triplet
peak power deposition almost constant for all cases

18. Jean-Pierre Koutchouk: Insertion Solutions from Parametric Study

19. Guido Sterbini: D0 and its Integrability
TRIPLETS
vanishing crossing angle & early separation
space for D0 in ATLAS
space for D0 in CMS
Courtesy of M. Nessi, ‘Machine upgrade, ATLAS considerations’, June 2006

20. Emanuele Laface: Q0 with l*=3 m IP 13m
Q0 A
Q0 B Q1 IP
13m
Magnet
Min. Diameter
Gradient
Q0 A
> 40 mm
165 T/m
Q0 B

21. List of R&D topics Continue & expand Nb3Sn magnet R&D
Peter Limon: LHC Luminosity Upgrade Using Quads
List of R&D topics
Continue & expand Nb3Sn magnet R&D
Model quads, Long quadrupoles
More Nb3Sn magnet R&D
Even more aggressive Nb3Sn magnet R&D
What else?
Much more work on energy deposition & cooling
Support structure, alignment techniques, etc.
Lots of detector R&D

22. Ezio Todesco: Scaling Laws for b* in LHC IR
Triplet aperture and length vs b*, technology, l*
Ex.: l*=23 m b*=0.28 cm
Nb-Ti: aperture 94 mm, triplet length 30 m, gradient 160 T/m
Nb3Sn: aperture 81 mm, triplet length 20 m, gradient 275 T/m
Solutions can be found for both materials
Large apertures: is this possible?
Stresses, aberrations ?

23. Rogelio Tomas: IR Upgrade Web Site

24. Ulrich Dorda: Wire Compensation of LR Beam-Beam
current scan
color: amplitude
distance scan
color: tune diffusion

25. Single LR effect at injection (24 GeV p)
Wolfram Fischer: LRBB Compensation RHIC
Single LR effect at injection (24 GeV p)
attempts to improve lifetime, small changes in (Qx,Qy)
wires (2.5m long)
with strong-back
(-profile) 7 support points
NEG coated chambers during assembly

26. Rogelio Tomas: Crab Cavity IR with q=8 mrad

27. Rama Calaga: Crab Cavities

28. Joachim Tuckmantel: Technological Aspects of Crab Cavities
Proposal F. Caspers, similar J. Frisch, SLAC (ILC)
???? Does this really help or not ????

29. emittance growth and luminosity decrement
Kazuhito Ohmi: Beam-Beam Effect with Ext. Noise
emittance growth and luminosity decrement
strong-strong tolerance more severe than weak-strong
turn-to-turn offset jitter tolerance about 0.1%s
build-up of dipole oscillations
bunch by bunch feedback may relax tolerance

30. Functions: Vladimir Shiltsev: Electron Lenses for LHC
#1: LEL as Head-On Compensator at design intensities and with x(2…4?)Np/bunch
#2: LEL as Beam Stabilizer (Tune Spreader) to help design Np=1.15e11
#3: LEL as soft hollow collimator
#4: LEL as soft “beam conditioner”

31. Local cooling limitations
Laurent Tavian: LHC Cryogenic System Upgrade
Local cooling limitations
Scenario
BS cooling loop
1.9 K cooling loop
[W/m/aperture]
[W/m]
Nominal
1.5
0.40
Ultimate
1.7
0.44
Short-bunch 16
0.81
Long-bunch
1.6
0.45
Local limitation
2.4 *
0.9 **
*: limited by the hydraulic impedance of the cooling channels and calculated for a supply pressure (header C) of 3 bar.
**: limited by the sub-cooling heat exchanger capacity
“The Short-bunch scenario requires an increase of the sector cooling
capacity by a factor 4 and shows local limitations in the beam screen
cooling circuits.
These two showstoppers render this scenario cryogenically unfeasible”

32. Frank Z., W. Scandale: HHH IR Ranking Proposal
Low-gradient large-aperture NbTi magnets with large l*
Risk -, Return +
Quad 1st “pushed” NbTi: tailored aperture & length, 2x better cooling, ~20% higher field
NbTi-Nb3Sn hybrid scheme
Quad 1st Nb3Sn
Quad 1st with detector-integrated dipole
Detector-integrated quadrupole
Quad 1st flat beam
Separate-channel quad 1st Nb3Sn or NbTi plus crab cavities
Dipole first options with Nb3Sn
Pulsed or dc beam-beam compensator
Risk -, Return ++
Electron lens
Risk -, Return +
Risk +, Return ++
Risk ++, Return +++
Risk ++, Return +++
Risk +, Return +++
Risk -, Return ++
Risk +++, Return +
retain options with
perceived lowest risk
or highest return
(in red)
Risk +++, Return +
Risk +++, Return ++

33. Vladimir Shiltsev: IR Ranking Conclusions 1

34. Summary IR Upgrade Ranking
Oliver Bruning: IR Ranking Conclusions 2
Summary IR Upgrade Ranking
(personal observations for discussion)
increased triplet aperture helps for almost everything:
 allows lower * (luminosity)
 allows larger crossing angle (beam-beam)
 allows larger collimator gap opening
(impedance and beam intensity)
 more room for absorber material and liners
decreased L* provides smaller -max:
(field quality, DA and mechanical aperture)
increased gradient provides more compact final focus:
 allows lower -max (field quality and DA and aperture)
LHC LUMI 2006; ; Valencia
Oliver Brüning 34

35. baseline upgrade parameters 2001-2005 abandoned at LUMI’06
symbol
nominal
ultimate
12.5 ns, short
transverse emittance
e [mm]
3.75
protons per bunch
Nb [1011]
1.15
1.7
bunch spacing
Dt [ns] 25
12.5
beam current
I [A]
0.58
0.86
1.72
longitudinal profile
Gauss
rms bunch length
sz [cm]
7.55
3.78
beta* at IP1&5
b* [m]
0.55
0.5
0.25
full crossing angle
qc [mrad]
285
315
445
Piwinski parameter
f=qcsz/(2*sx*)
0.64
0.75
peak luminosity
L [1034 cm-2s-1] 1
2.3
9.2
peak events per crossing 19 44 88
initial lumi lifetime
tL [h] 22 14
7.2
effective luminosity
(Tturnaround=10 h)
Leff [1034 cm-2s-1]
0.46
0.91
2.7
Trun,opt [h]
21.2
17.0
12.0
(Tturnaround=5 h)
0.56
3.6
15.0
8.5
e-c heat SEY=1.4(1.3)
P [W/m]
1.07 (0.44)
1.04 (0.59)
13.34 (7.85)
SR heat load K
PSR [W/m]
0.17
image current heat
PIC [W/m]
0.15
0.33
1.87
gas-s. 100 h (10 h) tb
Pgas [W/m]
0.04 (0.38)
0.06 (0.56)
0.113 (1.13)
comment
partial wire c.
baseline
upgrade
parameters
abandoned at
LUMI’06
total heat load far exceeds maximum local cooling capacity of 2.4 W/m
(SR and image current heat load well known)

36. two new upgrade scenarios compromises between heat load and # pile up
parameter
symbol
25 ns, small b*
50 ns, long
transverse emittance
e [mm]
3.75
protons per bunch
Nb [1011]
1.7
4.9
bunch spacing
Dt [ns] 25 50
beam current
I [A]
0.86
1.22
longitudinal profile
Gauss
Flat
rms bunch length
sz [cm]
7.55
11.8
beta* at IP1&5
b* [m]
0.08
0.25
full crossing angle
qc [mrad]
381
Piwinski parameter
f=qcsz/(2*sx*)
2.0
hourglass reduction
0.99
peak luminosity
L [1034 cm-2s-1]
15.5
10.7
peak events per crossing
294
403
initial lumi lifetime
tL [h]
2.2
4.5
effective luminosity
(Tturnaround=10 h)
Leff [1034 cm-2s-1]
2.4
2.5
Trun,opt [h]
6.6
9.5
(Tturnaround=5 h)
3.6
3.5
4.6
6.7
e-c heat SEY=1.4(1.3)
P [W/m]
1.04 (0.59)
0.36 (0.1)
SR heat load K
PSR [W/m]
0.36
image current heat
PIC [W/m]
0.33
0.78
gas-s. 100 h (10 h) tb
Pgas [W/m]
0.06 (0.56)
0.09 (0.9)
comment
D0 + crab (+ Q0)
wire comp.
two new
upgrade
scenarios
compromises
between
heat load
and # pile up
events

37. PAF/POFPA Meeting 20 November 2006
for operation at beam-beam limit
with alternating planes of crossing at two IPs,
luminosity equation can be written as
↑↑ 50 ns
↓ 50 ns
↓↓ 25 ns
↓ 50 ns
where DQbb = total beam-beam tune shift
PAF/POFPA Meeting 20 November 2006

38. 25-ns upgrade scenario
stay with ultimate LHC beam (1.7x1011 protons/bunch, 25 spacing)
squeeze b* to ~10 cm in ATLAS & CMS
add early-separation dipoles in detectors starting at ~ 3 m from IP
possibly also add quadrupole-doublet inside detector at ~13 m from IP
and add crab cavities (fPiwinski~ 0)
→ new hardware inside ATLAS & CMS detectors, first hadron-beam crab cavities
(J.-P. Koutchouk et al)

39. CMS & ATLAS IR layout for 25-ns option
stronger triplet magnets
D0 dipole
Q0 quad’s
small-angle
crab cavity
ultimate bunches & near head-on collision
merits:
negligible long-range collisions,
no geometric luminosity loss
challenges:
D0 dipole deep inside detector (~3 m from IP),
Q0 doublet inside detector (~13 m from IP),
crab cavity for hadron beams (emittance growth)
PAF/POFPA Meeting 20 November 2006

40. 50-ns upgrade scenario double bunch spacing
longer & more intense bunches with fPiwinski~ 2
keep b*~25 cm (achieved by stronger low-b quads alone)
do not add any elements inside detectors
long-range beam-beam wire compensation
→ novel operating regime for hadron colliders

41. CMS & ATLAS IR layout for 50-ns option
stronger triplet magnets
wire
compensator
long bunches & nonzero crossing angle & wire compensation
merits:
no elements in detector, no crab cavities,
lower chromaticity
challenges:
operation with large Piwinski parameter unproven for
hadron beams, high bunch charge, larger beam current
PAF/POFPA Meeting 20 November 2006

42. PAF/POFPA Meeting 20 November 2006
IP1& 5 luminosity evolution for 25-ns and 50-ns spacing
25 ns
spacing
50 ns
spacing
average
luminosity
PAF/POFPA Meeting 20 November 2006

43. PAF/POFPA Meeting 20 November 2006
IP1& 5 event pile up for 25-ns and 50-ns spacing
50 ns
spacing
25 ns
spacing
PAF/POFPA Meeting 20 November 2006

44. PAF/POFPA Meeting 20 November 2006
old upgrade bunch structure
nominal
25 ns
ultimate
25 ns
12.5-ns upgrade
12.5 ns
abandoned
at LUMI’06
PAF/POFPA Meeting 20 November 2006

45. PAF/POFPA Meeting 20 November 2006
new upgrade bunch structures
nominal
25 ns
new alternative!
ultimate
& 25-ns upgrade
25 ns
50-ns upgrade, no
50 ns
new baseline!
50-ns upgrade
with 25-ns
collisions
in LHCb
50 ns
25 ns
PAF/POFPA Meeting 20 November 2006

46. Outcome of LUMI’06 Part 1 IR upgrade and beam parameters
quadrupole 1st preferred over dipole 1st
pushed NbTi or Nb3Sn still pursued, or hybrid solution - new
slim magnets inside detector (“D0 and Q0”) – new
wire compensation ~established; electron lens – new
crab cavities: large angle rejected; small-angle – new
12.5-ns scenario strongly deprecated
e-cloud/pile-up compromise: 25-ns w b*~8 cm, or 50-ns spacing long bunches – new
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 )