Transcript Machine Plans for the LHC Upgrade (check title)

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. timewindows 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
hypothetical luminosity
evolution
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!
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
+ injector
upgrade
complementary measures 2010-2017:
e.g. long-range beam-beam compensation,
crab cavities, new/upgraded injectors, advanced
collimators, coherent e- cooling??, e- lenses??
phase-2 might be just phase-1 plus complementary measures
longer term (2020?): energy upgrade, LHeC,…
Frank Zimmermann, LHCb Upgrade Meeting
constraint crossing angle
c z
“Piwinski angle”
R 
; 
2
2 x
1 
1
luminosity reduction factor
nominal LHC
c/2
effective beam
size →/R
other constraints:
beam-beam
e- cloud
collimation
LHC upgrade paths for IP1 & 5
early separation (ES)
D0 dipole
•
•
J.-P. Koutchouk
stronger triplet
magnets
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
large Piwinski
angle (LPA)
F. Ruggiero,
W. Scandale.
F. Zimmermann
full crab crossing (FCC) L.W.Evans,
Scandale,
stronger triplet
magnets
•
•
•
F. Zimmermann
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
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 generation
parameter
symbol
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
Gauss
Gauss
Gauss
Gauss
Flat
longitudinal profile
nominal
ultimate
Early Sep.
Full Crab Xing
L. Piw Angle
rms bunch length
z [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
c [mrad]
285
315
0
0
381
Piwinski parameter
cz/(2*x*)
0.64
0.75
0
0
2.0
1.0
1.0
0.86
0.86
0.99
1
2.3
15.5
15.5
10.7
19
44
294
294
403
22
14
2.2
2.2
4.5
hourglass reduction
peak luminosity
L [1034 cm-2s-1]
peak events per #ing
initial lumi lifetime
tL [h]
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
l [cm]
4.5
4.3
3.7
3.7
5.3
D0 + crab
crab
wire comp.
comment
nominal
ultimate
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
luminosity leveling
ES or
FCC
LPA
average
luminosity
how can we achieve this?
ES or FCC: dynamic b squeeze, or dynamic  change (either
IP angle bumps or varying crab voltage)
LPA: dynamic b squeeze, or dynamic change of bunch length
IP1& 5 event pile up for 25 & 50-ns spacing w/o leveling
ES or
FCC
25 ns
spacing
50 ns
spacing
LPA
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
present and future injectors
Proton flux / Beam power
50 MeV
160 MeV
Output energy
1.4 GeV
4 GeV
26 GeV
50 GeV
450 GeV
1 TeV
7 TeV
~ 14 TeV
Linac2
Linac4
PSB
(LP)SPL
PS
PS2
SPS
LHC /
SLHC
SPS+
(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)
DLHC
Roland Garoby, LHCC 1July ‘08
layout of the new injectors
SPS
PS2
SPL
PS
Linac4
R. Garoby, CARE-HHH BEAM07, October’07; L. Evans, LHCC, 20 Feb ‘08
injector upgrade schedule
synchronized with LHC IR upgrades
R. Garoby,
LHCC 1 July 2008
LHC IR phase 1
LHC IR
phase 2
new
injectors +
IR upgrade
phase 2
early
operation
collimation
phase 2
linac4 + IR
upgrade
phase 1
Roland Garoby, LHCC 1July ‘08
extended shutdowns:
2012/13 & 2017
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 access
in present upgrade schedule:
(1) 4th quarter 2012 – 2nd quarter 2013
~7.5 months
for 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
Frank Zimmermann, LHCb Upgrade Meeting
2001 upgrade feasibility study
Frank Zimmermann, LHCb Upgrade Meeting
PAF/POFPA Meeting 20
November 2006
from 2001 upgrade feasibility study
…
(note:
2006 nominal
and ultimate
parameters
are slightly
different)
Frank Zimmermann, LHCb Upgrade Meeting
from 2001 upgrade feasibility study
~0.01
~0.01
~0.01
~0.01
nominal tune footprint
up to 6 with 4 IPs
L=1034 cm-2s-1
tune footprint up to 6
with 2 IPs
tune footprint up to 6
with 2 IPs at ultimate
intensity
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
Frank Zimmermann, LHCb Upgrade Meeting
can we make (upgraded) LHCb
compatible with upgraded LHC?!
• 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
Frank Zimmermann, LHCb Upgrade Meeting
bunch structures
nominal
25 ns
ultimate
& 25-ns upgrade
(ES & FCC)
25 ns
50-ns upgrade (LPA),
no collisions in LHCb!
50 ns
50 ns
25 ns
Frank Zimmermann, LHCb Upgrade Meeting
50-ns upgrade
with 25-ns
collisions
in LHCb
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 avoid
e-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
LHCb schemes for 25-ns scenario
• 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
Frank Zimmermann, LHCb Upgrade Meeting
LHCb collisions with transverse offset d
luminosity:
L = L0 exp (-d2/(42))
tune shift:
DQ LHCb = 2 DQIP1or5 / (d/)2
suppose tune shift from LHCb should be less
than 10% of that from CMS or ATLAS → d>4.5  ;
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 4-5 offset collisions:
• offset stability
• interference with LHC collimation
• effect on beam lifetime
• effect on detector background
experience at RHIC, SPS, HERA and Tevatron was
discouraging (see slides with examples presented
at LHCB Upgrade Workshop of January 2007);
but interpretation of past results and their application
to LHC is a bit controversial
Frank Zimmermann, LHCb Upgrade Meeting
LHCb luminosity for 25 ns with offset & 50 ns
50 ns
spacing,
satellites
25 ns
spacing,
4.5 offset,
b*~0.08 m
LHCb 50-ns luminosity decays 2x more slowly
than 25-ns luminosity or that at ATLAS and CMS
Frank
LHC
Zimmermann,
Upgrade Beam
LHCb
Parameters,
Upgrade Workshop
Frank Zimmermann
PAF/POFPA Meeting 20 November 2006
tune shift during store for 25-ns & 50-ns spacing
50 ns
spacing
change
DQ ~
-0.0033
25 ns
spacing
LHCb 25-ns collisions from middle of each store?! b*~3 m
(5 h turnaround time is assumed)
Frank
LHC
Zimmermann,
Upgrade Beam
LHCb
Parameters,
Upgrade Workshop
Frank Zimmermann
PAF/POFPA Meeting 20 November 2006
LHCb luminosity for 25-ns late collisions & 50 ns
50 ns
spacing,
b*~3 m,
satellites
25 ns
spacing,
b* ~ 3 m,
no transverse
offset
(5 h turnaround time is assumed)
PAF/POFPA Meeting 20 November 2006
Frank
LHC
Zimmermann,
Upgrade Beam
LHCb
Parameters,
Upgrade Workshop
Frank Zimmermann
LHCb collision parameters
parameter
symbol
collision spacing
Tcoll
protons per bunch
Nb [1011]
longitudinal profile
25 ns, offset
25 ns, late collision
50 ns, satellites
25 ns
25 ns
25 ns
1.7
1.7
4.9 & 0.3
Gaussian
Gaussian
flat
rms bunch length
z [cm]
7.55
7.55
11.8
beta* at LHCb
b* [m]
0.08
3
3
rms beam size
x,y* [mm]
6
40
40
rms divergence
x’,y’* [mrad]
80
13
13
full crossing angle
c [urad]
550
180
180
Piwinski parameter
cz/(2*x*)
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
l [cm]
5.3
5.3
8.0
rms length of luminous region:
(in cases w/o transverse offset)
Frank
LHC
Zimmermann,
Upgrade Beam
LHCb
Parameters,
Upgrade Workshop
Frank Zimmermann
2
 2


c




2
2
2
 l   z 2 * x , y 
1
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 50ns 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
Frank
LHC
Zimmermann,
Upgrade Beam
LHCb
Parameters,
Upgrade Workshop
Frank Zimmermann
PAF/POFPA Meeting 20 November 2006