1. SLHC Upgrades CMS Perspectives
Physics cases
Global overview of CMS upgrades
Roadmap/Strategy
16 October 2006
J. Nash - CMS Upgrade Perspective

2. 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)
16 October 2006
J. Nash - CMS Upgrade Perspective

3. 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
Reach vs luminosity, jets + Etmiss channel
16 October 2006
J. Nash - CMS Upgrade Perspective

4. What if no Higgs is found?
Will need to look at WW scattering
Some mechanism required to avoid unitarity violation
Forward Jet Tagging Essential
Fake fwd jet tag (|| > 2) probability
from pile-up (preliminary ...)
ATLAS full simulation
3000 fb-1 (SLHC)
16 October 2006
J. Nash - CMS Upgrade Perspective

5. LHC performance and parameters
n = 3.75 mm in all the options
16 October June EPAC 06
J. Nash - CMS Upgrade PerspectiveW.Scandale, LHC luminosity and energy upgrades

6. J. Nash - CMS Upgrade Perspective
CMS from LHC to SLHC
1032 cm-2 s-1
1033
1035
1034
I. Osborne
With 88 evts/xing
16 October 2006
J. Nash - CMS Upgrade Perspective

7. J. Nash - CMS Upgrade Perspective
CMS Upgrade Issues
These upgrade scenarios put different constraints on the detector
12.5 ns or 75 ns beam crossings
12.5 ns reduces the pile-up in the detector, although out of time pile-up is an issue for detectors (cross-talk from previous bunch)
75 ns puts a very large pile-up, but is “easier” for some of the electronics to cope with (no out of time pile-up - use 25nsec electronics)
Detector issues
Effects on Calorimetry
Noise from pile-up: Bkgd noise increases by 2-5 times
Jet and e,gamma resolution worse
Forward jet tagging - may be compromised by IR changes
Tracking
Pattern recognition, vertex resolution
B-tagging - how much worse with extreme pile-up?
Trigger
12.5 ns pushes some of the front end capabilities
16 October 2006
J. Nash - CMS Upgrade Perspective

8. Radiation environment for trackers
Innermost layers will require new sensor technology (1016 N/cm2)
R. Horisberger
16 October 2006
J. Nash - CMS Upgrade Perspective

9. Tracker occupancy
1034 (18 Min Bias)
1035 (88 Min Bias nsec BX)
Do we want/need an analog or digital readout tracker?
R (cm)
<Nch>/cm2/12.5ns
<Nch>/ (1.28cm)2/12.5ns 8
2.41
3.94 11
1.47 14
0.97
1.59
A. Rose
16 October 2006
J. Nash - CMS Upgrade Perspective

10. Tracking with 500 min Bias events
Study of current CMS tracker for Heavy Ion events
Track density very similar to 75ns running
dnch/dh/crossing ≈ 3000
Tracker occupancy very high
Need more pixel layers
Tracking possible
When tracks are found they are well measured
Efficiency and fake rate suffer
Inner layers of strips reach 30% occupancy on every xing!
Pixel layers
Transverse Impact Parameter Resolution
Momentum Resolution
nhit > 12
Efficiency
Fake Rate
C. Roland
16 October 2006
J. Nash - CMS Upgrade Perspective

11. J. Nash - CMS Upgrade Perspective
B-Tagging
Pile-up overlaps with High Pt event faking a displaced vertex
12.5 ns dnch/dh/crossing ≈ 600 and ≈ 3000 tracks in tracker acceptance
75 ns dnch/dh/crossing ≈ 3000 and ≈ tracks in tracker acceptance
B-tag performance depends on
Vertex resolution
Luminosity/bunch crossing
Size of luminous region (how far apart are the min-bias events)
For 75ns option expect 2-3 min-bias events within 200 mm of any interesting event.
Need simulation to understand how much this reduces b-tagging efficiency
All this pushes for larger area of Pixel coverage, need to look at pixel size as well
16 October 2006
J. Nash - CMS Upgrade Perspective

12. J. Nash - CMS Upgrade Perspective
Level 1 Trigger
Level 1 Trigger has no discrimination for PT > ~ 20 GeV/c
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
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
16 October 2006
J. Nash - CMS Upgrade Perspective

13. J. Nash - CMS Upgrade Perspective
Tracking Trigger?
High momentum tracks are straighter so pixels line up
Search
Window γ
1mm
(y-z)
1cm
Geometrical pT-cut - J. Jones, A. Rose, C. Foudas LECC 2005
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 inside
How to correlate information internally in order to form segments?
Possible topic requiring substantial R&D
“Stacked” pixels which can measure pT of track segments locally
Two layers about 1mm apart that could communicate
16 October 2006
J. Nash - CMS Upgrade Perspective

14. Implementing stacked layers
Single stacked layer gives a PT cut
Two stacked layers give a PT measurement
Cooling
System
Optical
Transceiver
Flip bonded
sensors
Correlator
ASIC
Kevlar-Carbon Fibre
Laminate
Support Structure
Optical fibre to
OptoTX card
Thermal
Epoxy
16 October 2006
J. Nash - CMS Upgrade Perspective

15. Key issues for tracker upgrades
Power
How to get current needed to the electronics
More complicated front ends will want more power
DC-DC converters, Serial powering
Material Budget
Can we build a better/lighter tracker?
Tracker R&D focus
Performance and detector layout
Sensor material and operation
Outer tracker readout system definition
Pixel system and triggering
Manufacture and material budget
16 October 2006
J. Nash - CMS Upgrade Perspective

16. J. Nash - CMS Upgrade Perspective
Calorimeters/Muons
ECAL
Crystal calorimeter electronics designed to operate in SLHC conditions
Electronics for barrel is not accessible without disassembly of the barrel
HCAL
Scintillator may suffer damage for >2
R & D required
Finer granularity
HF some very high  towers lost
HF and shielding system issues with new insertion
MUON
system front end electronics look fairly robust at SLHC
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
16 October 2006
J. Nash - CMS Upgrade Perspective

17. Issues with Bunch crossing timing
Assume new tracker and trigger electronics can cope with the choice of bunch timing
Electronics for other detectors
ECAL - not easily accessible
HCAL - can be changed
MUONS - can be changed
Situation for 12.5ns or 25ns very different from 10ns or 15 ns
Electronics clocked at 40 Mhz
QPLL which synchronizes links to this clock has a very narrow frequncy lock
Can clock system at 40 Mhz and cope with 12.5ns
75 ns should not be a problem
16 October 2006
J. Nash - CMS Upgrade Perspective

18. Ideas on a new tracker concept?PD
TIB
TOB
Strawman - A much larger pixel tracker, some triggering layers, more segmented strips
10 cm layer with current pixels (500 ChF/cm2)
Around 1m2
20/40/60 cm layers with bigger pixels (100 Chf/cm2)
around 25 m2
25 MChf
Outer layers long pixels/short strips (30 Chf/cm2)
Around 170 m2
50 MChf
Some triggering layers.
1 layer for Pt cut only or 2 layers to measure Pt
Or perhaps full scale hardware pattern recognition?
This is the at the limit of affordability - How much can we re-use?
Can we use the TOB mechanical structures (a copy at least)
Can we re-use services
Re-use of some of the TOB - at least the concept if not the actual modules
TOB
TID
TIB
TEC PD
16 October 2006
J. Nash - CMS Upgrade Perspective

19. Roadmap for tracker/trigger upgrades
Within 5 years of LHC start
New layers within the volume of the current Pixel tracker which incorporate some tracking information for Level 1 Trigger
Room within the current envelope for additional layers
Possibly replace existing layers
“Pathfinder” for full tracking trigger
Proof of principle, prototype for larger system
Elements of new Level 1 trigger
Utilize the new tracking information
Correlation between systems
Upgrade to full new tracker system by SLHC (8-10 years from LHC Startup)
Includes full upgrade to trigger system
16 October 2006
J. Nash - CMS Upgrade Perspective

20. CMS Detector Replacements
Inner Tracker
30 MChf
Outer Tracker
90 MChf
Level 1 Trigger
20 MChf
DAQ
10 MChf
Other Front Ends
Infrastructure
15 MChf
Total
175 MChf
Materials Cost for Collaboration (CORE)
Across collaboration
~ 900 FTE
16 October 2006
J. Nash - CMS Upgrade Perspective

21. J. Nash - CMS Upgrade Perspective
SLHC R&D:Next steps
Expression of Interest
Reasonably brief document (40 pages)
Section authors identified
Brief case for upgrade
Outlines scope of upgrade work
What detectors/Timescale
To be submitted by End 2006
Circulated to collaboration September CMS Week
Prepare funding agencies
Letter of Intent
A larger document
More complete physics case
Includes organization and rough costings of detector work
Including how CMS will organize the effort
Submitted to LHCC
Allow funding agencies to “release” funding
Target Summer 2007
16 October 2006
J. Nash - CMS Upgrade Perspective

22. Alternative IP Schemes
triplet magnets
dipole magnets
triplet magnets
dipole
dipole first & small crossing angle
dipole first & large crossing angle &
long bunches or crab cavities
New options for IR optics consider bringing magnetic elements literally into CMS
Important to understand background induced in trackers
May have very severe consequences for forward calorimetry
16 October 2006
J. Nash - CMS Upgrade Perspective

23. CMS IP Upgrade Triplet moves closer to IP Dipole inside end disks
16 October 2006
J. Nash - CMS Upgrade Perspective

24. J. Nash - CMS Upgrade Perspective
Conclusions
SLHC will be a challenging machine for the detector as well as the machine
CMS at SLHC will require a substantially larger pixel detector
We may also need to understand how to form tracks with these detectors at 40 MHz as input to the Level 1
R&D required is substantial
Needs to start now
Needs to be focused
Important to converge on tracker design requirements
Crucial input on machine designs affect the detector design
Physics will also have a role in defining the upgraded detector
16 October 2006
J. Nash - CMS Upgrade Perspective