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CMS Upgrade Issues
SPC 15 September 2008
SPC - 15/9/20081 J. Nash - CMS SLHC Issues
Topics Potential Physics motivations
Implications for the detectors Tracking detectors
Requirements for phase I Requirements for phase II Tracking Trigger
Muons and Calorimeters Implications for the detector of Upgrades
which place machine elements inside 19m
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SLHC is about the maximizing the output of LHC physics We should be led by getting the best physics
out of any upgraded machine/detector Not by the highest peak luminosity Even maximum integrated luminosity may not be
the most important metric Issues
Integrated luminosity Backgrounds Acceptance Pile-up
Collimation phase 2
Linac4 + IR
upgrade phase 1
New injectors
+ IR upgrade phase 2
Early operation
SPC - 15/9/20084 J. Nash - CMS SLHC Issues
Collimation phase 2
Linac4 + IR
upgrade phase 1
New injectors
+ IR upgrade phase 2
Early operation
SPC - 15/9/20085 J. Nash - CMS SLHC Issues
What are the key timescales/issues? Phase 1
How well do detector components handle the increasing luminosity? Both instantaneous and integrated effects
What detector elements will need replacement/modification to cope? Detectors will record >500 fb-1, can they withstand this?
Phase 2 What detector elements will need replacement? What do machine plans imply for interaction regions Is there a requirement for a long shutdown?
How long – 18 Months? (1 Full calendar year without beam +) When – sometime after the middle of the next decade
Developing and building new tracking detectors will take many years We have to plan this now in order to have any chance of running detectors
with high luminosity ATLAS and CMS now agree on the dates
No sense in having two long shutdowns Reach 700 fb-1(potential limit)
Likely 2017
SPC - 15/9/20086 J. Nash - CMS SLHC Issues
Issues discussed at the CMS May Upgrade workshop What are the “strawmen” for upgrades of
each of the systems? Define the scope of the upgrade projects What is done in Phase I/Phase II
What requires a long shutdown? What can/should we attempt to do before the long
shutdown How should we use the lengthy shutdown in 2013?
When do we need to prepare a LOI For CMS Upgrades For subsystems
When do we need to prepare TDRs
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http://indico.cern.ch/conferenceDisplay.py?confId=28746http://indico.cern.ch/conferenceDisplay.py?confId=28746
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Some Physics themes Different physics channels require different
conditions Three main directions for Phase II
Damn the torpedos - FULL Luminosity Maximum of quality luminosity
Luminosity leveling? Forward acceptance
We won’t know which is the most important until we have first data from the LHC Important not to eliminate a physics opportunity until
we are sure it makes sense to do so We have to be ready to build detectors for any of
these scenarios
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SLHC Physics: Extra gauge bosons
SLHC extends reach for Z’ Cross sections fall with E SLHC gives access to higher E
Good electron resolution required (including understanding saturation)
Just give us the Integrated Luminosity!Just give us the Integrated Luminosity!
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SUSY searches - measurements
SLHC statistics will be vital in reaching understanding of complicated SUSY channels Sparticles seen, but statistics
for reconstruction limited at LHC
Performance of the detector here is vital B-tagging Lepton id
Here we need a lot of Integrated Luminosity, but needs to be high quality. Lower pile-up may be important.
Here we need a lot of Integrated Luminosity, but needs to be high quality. Lower pile-up may be important.
PixelsPixels
J. Nash - CMS SLHC Issues
The pixel 3D hits are ideal seeds for tracking and reconstruction Pattern recognition, all 5 track parameters well constrained
• Excellent position resolution makes pixels essential :
• for primary and secondary vertex reconstruction
• for b and identification
Dark matter candidateSPC - 15/9/200811
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What if no Higgs is found?
Will need to look at WW scattering Some mechanism required to avoid
unitarity violation Forward Jet Tagging Essential
3000 fb-1 (SLHC)
Fake fwd jet tag (|| > 2) probability from pile-up (preliminary ...)
ATLAS full simulation
Forward tagging is essentialForward tagging is essential
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Higgs Boson Couplings
Ratios of Higgs couplings to fermions and gauge bosons Independent of uncertainties on tot
Higgs, H and integrated luminosity
Mostly statistics limited at the LHC
Some modes are systematically limited at LHC luminosities - no improvement at SLHC
Some modes are systematically limited at LHC luminosities - no improvement at SLHC
HHZZ
HWWHZZ
WHH
ttH/ttHbb
qqHWWqqH
WHWWWHWW
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Precision Electroweak meaurements
5 parameters describe these TGCs: g1
Z (1 in SM), z, , z(all 0 in SM)
Look in W I , WZ lll W final state probes , WZ probes g1
Z, z, z
Experimental precision can reach 10-3 level at SLHC Compares to SM prediction level
Z
kZ
Z
14 TeV 100 fb-1 28 TeV 100 fb-1 14 TeV 1000 fb-1 28 TeV 1000 fb-1
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Extending MSSM searches, Rare Decays
• rare modes not observable at the LHC HSM Z (BR ~ 10-3), HSM (BR ~ 10-4)
HSM Z l+l- 120 < MH < 150 GeV, LHC with 600 fb-1 signal significance: 3.5 SLHC (two exps, 3000 fb-1each) signal of 11HSM 120 < MH < 140 GeV, LHC (600 fb-1) significance: < 3.5,
SLHC (two exps, 3000 fb-1each) ~ 7
LHC 300 fb-1LHC 300 fb-1
SLHC 3000 fb-1SLHC 3000 fb-1
Can extend region where more than one Higgs is seen (in MSSM)
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Detector ChallengesCMS from LHC to SLHC
10331033
10351035
1032 cm-2 s-1 1032 cm-2 s-1
10341034
I. OsborneI. OsborneThe tracker is the key detector which will require upgrading for SLHC Phase 2
The tracker is the key detector which will require upgrading for SLHC Phase 2
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Radiation environment for trackers
R. HorisbergerR. Horisberger
Except for the very innermost layers many current technologies should survive SLHC
Except for the very innermost layers many current technologies should survive SLHC
CMS Pixel system can be removed in a very short time period
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Trial insertion of Pixel system
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Insertion of the Pixel was done in a fewhours
Insertion of the Pixel was done in a fewhours
Phase I issues for tracking Rough estimate of pixel layer lifetimes
4cm layer should survive a minimum of 200fb-1
Will have to replace the pixel detector during phase I How often? How much to replace? New features
Looking at reducing the material in the replacement pixel detector, and potentially adding a fourth layer
Outer tracker looks robust to survive Phase I
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Limitations in Phase 1Limitations in Phase 1 Radiation damage due to
integrated luminosity. Sensors designed to survive
61014neq/cm2 ( 300 fb-1 ). n-on-n sensors degrade gradually
at large fluences
300 fb-1
500 fb-1
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Dead time will rise to 12% due to increase in peak luminosity
BPIX Options for 2013 replacement/upgrade – R. Horisberger
Option
0
1
2
3
4
5
Cooling
C6F14
C6F14
CO2
CO2
CO2
CO2
Readout
analog 40MHz
analog 40MHz
analog 40MHz
analog 40MHz-tw-pairs
digital 320MHz-tw-pairs
digital 640 MHz-tw-pairs
Pixel ROC
PS46 as now
2x buffers
2x buffers
2x buffers
2xbuffer, ADC160MHz serial
2xbuffer, ADC160MHz serial
Layer/Radii
4, 7, 11cm
4, 7, 11cm
4, 7, 11cm
4, 7, 11cm
4, 7, 11cm
4, 7, 11, 16cm
Modules
768
768
768
768
768
1428
Power
as now
as now
as now
as now
as now
DC-DCnew PS
as 2
008
SPC - 15/9/200822 J. Nash - CMS SLHC Issues
J. Nash - CMS SLHC Issues
CMS - What stays, what goes phase 2
Much of CMS is well shielded andBuilt to last through SLHCMuch of CMS is well shielded andBuilt to last through SLHC
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Reminder what CMS will need to upgrade
This will stay!This will stay!
Barrel crystal calorimterBarrel crystal calorimterHCALHCAL
J. Nash - CMS SLHC Issues
Tracker Readied for Transport to Pt5This will be replacedThis will be replaced
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Key issues for tracker upgrades(Not just more channels!)
Power How to get current needed to the electronics More complicated front ends, more channels may want more
power DC-DC converters, Serial powering
Material Budget Can we build a better/lighter tracker?
From Physics TDR Vol 1 (LHCC 2006-001)From Physics TDR Vol 1 (LHCC 2006-001)
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The effect on physics of large pile-up We need to evaluate how well we can extract
any physics at all in the presence of up to 400 pile-up events per crossing
This is not a trivial study Technically difficult Also depends on geometry of a new tracking device Timescale for full answers is more like years than
months CMS Tracker simulation group has been
creating tools for modeling new tracker designs Expect detailed simulation results from “strawman”
designs in the coming year
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Tracking with 500 min Bias events
Study of current CMS tracker for Heavy Ion events
Track density very similar to 50ns running dnch/d/crossing ≈ 3000 Tracker occupancy very high Need more pixel layers/shorter strips
Tracking possible When tracks are found they are well measured Efficiency and fake rate suffer CPU Intensive
nhit > 12
• Efficiencyo Fake Rate
Momentum Resolution
Transverse Impact
Parameter Resolution
C. RolandC. Roland
Inner layers of strips reach 30% occupancy on every xing!
Inner layers of strips reach 30% occupancy on every xing!
Pixel layersPixel layers
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Level 1 Trigger
The trigger/daq system of CMS will require an upgrade to cope with the higher occupancies and data rates at SLHC
One of the key issues for CMS is the requirement to include some element of tracking in the Level 1 Trigger One example: There may not be
enough rejection power using the muon and calorimeter triggers to handle the higher luminosity conditions at SLHC
Adding tracking information at Level 1 gives the ability to adjust PT thresholds
Single electron trigger rate also suffers Isolation criteria are insufficient
to reduce rate at L = 1035 cm-
2.s-1
Level 1 Trigger has no discrimination for PT > ~ 20 GeV/c
Level 1 Trigger has no discrimination for PT > ~ 20 GeV/c
Tracking needed for L1 trigger@ 1035
Muon L1 trigger rate
Single electron trigger rate
Isolation criteria are insufficient to reduce rate at L = 1035 cm-2.s-1
5kHz @ 1035
L = 1034
L = 2x1033
MH
z
Standalone Muon trigger resolution insufficient
We need to get another x200
(x20) reduction for single
(double) tau rate!
Amount of energy carried by tracks around tau/jet direction
(PU=100)
Cone 10o-30o
~dET/dcos τ
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Concepts:Tracking Trigger
Why not use the inner tracking devices in the trigger? Number of hits in tracking devices on each trigger is enormous Impossible to get all the data out in order to form a trigger How to correlate information internally in order to form
segments? Topic requiring substantial R&D
“Stacked” layers which can measure pT of track segments locally Two layers about 1mm apart that could communicate
Cluster width may also be a handle
SearchWindow
γ
Geometrical pT-cut - J. Jones, A. Rose, C. Foudas LECC 2005
High momentum tracks are straighter so pixels line up
High momentum tracks are straighter so pixels line up
Pairs of stacked layers can give a PT measurement
Pairs of stacked layers can give a PT measurement
Example PT module
Geoff HallVertex 200832
Such a design has potential for inexpensive assembly, using wire bonding, with low risk and easy prototyping
2 x 2.5mm
12.8mm64 x 2
Data out
128 x100µmx 2x2.5mm
Correlator
data
Pt - Trigger for TOB layers
2mm
Strip Read Out Chip2 x 100 pitch withon-chip correlator
Hybrid
50mm strips
1mm
2mm
2 x DC coupled Strip detectorsSS, 100 pitch ~8CHF/cm2
wire bonds
spacer
W.E. / R.H.
track angular resolution ~20mrad good Pt resolution
Two-In-One DesignR HorisbergerW Erdmann
33
Vertex 200834
More Realistic Strawman A A working idea from Carlo and Alessia
Take current Strawman A and remove 1 “TIB” and 2 “TOB” layers
Strawman A r-phi view Strawman A r-phi view
(RecHit ‘radiography’)(RecHit ‘radiography’)
4 inner pixels
2 TIB strixelsAdjust chn count
2 TIB short stripsRemove 1
2 TOB strixelsAdjust chn count
4 TOB short stripsRemove 2
Vertex 200835
More Realistic Strawman B Adjust granularity (channel count) of Strawman B layers
Keep the TEC for now until someone can work on the endcaps
Strawman B r-phi view Strawman B r-phi view (RecHit ‘radiography’)(RecHit ‘radiography’)
r-z view r-z view
Endcap CSC Muon Phase 1 Upgrade (ME4/2)
R-Z cross-section
“Empty” YE3 ready for ME4/2SPC - 15/9/200836 J. Nash - CMS SLHC Issues
Phase 1 : Muons ME4/2 upgrade motivation
Compare 3/4 vs. 2/3 stations: (Triggering on n out of n stations is inefficient and uncertain)
Recent simulation with & without the ME4/2 upgrade: The high-luminosity Level 1 trigger threshold is reduced from 48 18
GeV/c
Target Rate 5 kHz
Rick Wilkinson, Ingo BlochSPC - 15/9/200837 J. Nash - CMS SLHC Issues
The start up RPC endcap systemThe start up RPC endcap system
SLHC workshop, CERN, May 2008 G. Iaselli on behalf of CMS RPC SLHC workshop, CERN, May 2008 G. Iaselli on behalf of CMS RPC groupgroup
Three stations up to = 1.6 Three stations up to = 1.6
RE 1/1
RE 1/2
RE 1/3
RE 2/1
RE 2/2
RE 2/3
RE 3/1
RE 3/2
RE 3/3
RE 4/1
RE 4/2
RE 4/3
No. of chambers 36*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2
RE i/3
REi/2REi/1
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RPC trigger efficiencyRPC trigger efficiency
SLHC workshop, CERN, May 2008 G. Iaselli on behalf of CMS RPC SLHC workshop, CERN, May 2008 G. Iaselli on behalf of CMS RPC groupgroup
Trigger CMS TDR, four stations Importance of high restoration Importance of high restoration
CMSSW 1.7.5, three stations
Importance of four stations restoration Importance of four stations restoration
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CMS HCALsHad Barrel: HB
Had Endcaps:HE
Had Forward: HF
HB
HE
HF
HO
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HF Damage
Tower 1 loses 60% of light during LHC, down to 4% of original after SLHC.
Tower 2 down to 23% after SLHC.
SLHC “kills” a few high eta towers.
Andre Gribushin
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Calorimeters/Muons Phase 2 ECAL
Crystal calorimeter electronics designed to operate in SLHC conditions
VPT in Endcap and Endcap crystals themselves may darken at SLHC Very difficult to replace – Highly
activated HCAL
HF may be blocked by potential changes to the interaction region
HF/HE vital in looking for WW scattering Both Calorimeters suffer degraded resolution
at SLHC affects electron ID, Jet resolutions –
simulations needed Increased segmentation for HCAL may
help – SiPM• MUON– system front end electronics look fairly robust at SLHC
• Cathode Strip Chambers/RPC Forward : Drift Tubes /RPC Barrel
• Trigger electronics for the muon systems would most likely need to be replaced/updated
– Some Electronics is “less” radiation hard (FPGA)– Coping with higher rate/different bunch crossing frequency
– May have to limit coverage in ( > 2) due to radiation splash
• This effect will be known better after first data taking, potential additional cost of chamber replacement
Upgrade Scope
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Documents
Phase I Upgrades
Phase 2 Upgrades
SPC - 15/9/2008J. Nash - CMS SLHC Issues 44
Next Steps Produce an Integrated project plan for Phase I
Large number of systems expect to produce upgrades many of which involved interleaved installation issues
Some of these are already rather advanced and need to be integrated into the planning
Define timescales/scopes for reviews of each upgrade PDR > ESR/EDR > PRR?
Request milestones/deliverables down to level … for each project TDR > Production > Installation > Start to track these milestones
Will require resources
SPC - 15/9/2008J. Nash - CMS SLHC Issues 45
Planning for Phase 2 Too early for detailed planning of phase 2 upgrades Must understand the overall scope of the upgrade
This is driven by the geometry/functionality of the new tracker Simulations will be vital in understanding
Tracker TP should focus the direction of upgrades in other systems which may depend on tracker functionality For example the inclusion of tracking information in the trigger
Build a detailed plan by the time of the phase 2 TDRs Will also have a much clearer idea of the machine timescales
However a key issue which may come up earlier than this is the date of the long shutdown
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Implications of Early Separation
Could we do this without replacing HF? No way without obscuring part of the
detector But perhaps lower eta region still usable
Will the HF still be useful at SLHC
SPC - 15/9/2008J. Nash - CMS SLHC Issues 48
What about maintenance?
These wheels move for maintenance
These wheels move for maintenance
Triplet moves closer to IPTriplet moves closer to IP
Either D0 has to clear the EE, or it has to move for
maintenance
Either D0 has to clear the EE, or it has to move for
maintenance
Forward beampipe
thin pipe 13-16 m believed good for 1034 ppCASTOR & TOTEM easily installed/removed for specialruns (eg heavy ion), interspersed with high lumi pp
LHC
SLHC
wide pipe (400mm) after HF and in its shadowSPC - 15/9/200849 J. Nash - CMS SLHC Issues
Infrastructure modifications: Yoke
Reinforced Shielding inside forward muons: up to ~2 automatically implies replacement of inner CSC, RPC
(alternatives with protection from new high HE/EE not considered)
Supplement YE4 wall with borated polythene
Improve shielding of HF PMT’s
possibility of increased YE1-YE2 separation toinsert another detector layer?
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CMS Upgrade Management
SPC - 15/9/200851 J. Nash - CMS SLHC Issues
Conclusions CMS is progressing on defining the scope of
phase 1 and phase 2 upgrades A substantial program of R&D is well
underway The coming years will see development of
detailed project plans for the upgrades Need to work with the LHCC to understand the
transition from phase 1 to phase 2
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