CMS Upgrades the Role of US Universities

Transcription

1 CMS Upgrades the Role of US Universities Joel Butler, Fermilab US CMS Research Program Manager Presented to the High Energy Physics University Grant Program Subpanel SLAC Jan. 8, 2007 UGPS Jan. 8, 2007, SLAC 1

2 Outline The timing of the SLHC upgrade and associated R&D Scope of SLHC upgrade and R&D Readiness to start R&D How CMS is organizing for this effort Funding required for R&D and construction Role of US universities in CMS upgrade R&D UGPS Jan. 8, 2007, SLAC 2

3 LHC luminosity upgrade: why and when? fast performance ramping Ultimate L Nominal L years 1 2 year Ldt How fast performance is expected to increase: 4 y to nominal L (1x10 34 /cm 2 -s) 4 y to nominal L & 2 y up to ultimate L (2.3x10 34 /cm 2 -s) 4 y to ultimate IR quadrupole lifetime ~ 7-8 years owing to high radiation doses Years to halve errors Radiation damage limit integrated luminosity [fb-1] halving time of the statistical error 5 y already after 4-5 y of operation luminosity upgrade to be planned for the middle of next decade years 0 Somewhere circa 2013, reach the point of diminishing returns and need upgrade!

4 SLHC - Motivations The SLHC is an upgrade to the LHC designed to increase the delivered integrated luminosity by an order of magnitude over the design luminosity of the LHC. ~1000 fb -1 /year cm -2 s -1 peak luminosities Would likely require a long shutdown around 2014 To allow time enough to install new optics for the IR Also gives time for replacement of CMS tracking detectors and other required upgrades Why are we discussing this now before the LHC and experiments have even started operations? long lead times required both for machine R&D and for detector R&D This will be a challenging machine to develop The detectors will require significant upgrades to be able to deliver physics at LHC quality or better Given the time it took to develop detectors for LHC, it is clear we need to start well in advance How far in advance basically NOW! Need to have a project well-enough defined to get the construction project into the funding cycle in a timely way UGPS Jan. 8, 2007, SLAC 4

5 CMS Upgrade Issues These upgrade scenarios put different constraints on the detector Beam crossing interval is NO LONGER AN UNKNOWN (it seems) 50 ns BC Interval is the baseline 25 ns BC Interval (the current baseline) is a fallback This allows electronics/trigger/ daq designs to proceed Detector issues Tracking Pattern recognition, vertex resolution B-tagging - how much worse with factor 20(10) pile-up? Trigger BCI decision leads to design based on existing 40MHz clock. Buffer sizes may need to be enlarged for more interactions distributed in the same number or half the number of crossings. Effects on Calorimetry Noise from pile-up: Background *10 = pile-up noise * 10 Jet and e/γ resolution worse Forward jet tagging - may be compromised by IR changes (IR quads will reach the end of their useful life due to radiation damage this is still an uncertainty but has a relatively narrow impact.) Remaining details of the machine upgrade, such as possible IR modifications for lower β*, are not yet defined and but DO NOT severely limit the type of R&D that can be productively undertaken except in a few instances UGPS Jan. 8, 2007, SLAC 5

6 EPP2010 UGPS Jan. 8, 2007, SLAC 6

7 P5 Upgrade R&D UGPS Jan. 8, 2007, SLAC 7

8 P5 Upgrade Construction The SLHC Upgrade R&D and Construction will go forward and will require significant effort from the US university community and will help sustain and develop its capabilities. UGPS Jan. 8, 2007, SLAC 8

9 SLHC: Detector Challenges 10X higher luminosity 10X higher radiation levels Track occupancy higher, depending on crossing frequency (20X, 10X) The major change and challenge for CMS at the SLHC is an extensive replacement of the TRACKING and TRIGGER TRACKING finer granularity, more channels to control occupancy More radiation hard Tracker information used in Level 1 trigger for first time in CMS TRIGGER/DAQ Doubling the Level 1 trigger latency Adding a new group of tracking triggers at Level 1 Cross component correlation of trigger primitives Some less extensive modifications needed for muon system, and calorimetry are also required Tracking and Trigger are areas where US Universities have made major contributions to CMS both in R&D and construction and should continue to do so UGPS Jan. 8, 2007, SLAC 9

10 CMS from LHC to SLHC cm -2 s For reference: inner layer of pixels have occupancy of 6X10-4 at LHC so will increase to about 1% (OK from a tracking point of view) UGPS Jan. 8, 2007, SLAC 10

11 SLHC Level Occupancy Degraded performance of algorithms Electrons: reduced rejection at fixed efficiency from isolation Muons: increased background rates from accidental coincidences Larger event size to be read out New Tracker: higher channel count & occupancy large factor Reduces the max level-1 rate for fixed bandwidth readout. Trigger Rates Try to hold max L1 rate at 100 khz by increasing readout bandwidth Avoid rebuilding front end electronics/readouts where possible Limits: readout time (< 10 µs) and data size (total now 1 MB) Use buffers for increased latency for processing, not post-l1a May need to increase L1 rate even with all improvements Greater burden on DAQ Implies raising E T thresholds on electrons, photons, muons, jets and use of less inclusive triggers Need to compensate for larger interaction rate & degradation in algorithm performance due to occupancy Radiation damage -- Increases for part of level-1 trigger located on detector 35 UGPS Jan. 8, 2007, SLAC 11

12 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 Will need to replace existing layers due to expected radiation damage! 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 New Layers Concept New ROC/New Sensor Fabricate Install Full Tracker Monte Carlo Concept New ROC/New Sensor Fabricate UGPS Jan. 8, 2007, SLAC 12

13 Ideas on a new tracker concept? Strawman - A much larger pixel tracker, some triggering layers, more segmented strips 10 cm layer with current pixels (500 ChF/cm 2 ) Around 1m 2 20/40/60 cm layers with bigger pixels (100 Chf/cm 2 ) around 25 m 2 25 MChf Outer layers long pixels/short strips (30 Chf/cm 2 ) Around 170 m 2 50 MChf Some triggering layers. 1 layer for Pt cut only or 2 layers to measure Pt Or perhaps full scale hardware pattern recognition? How much can we re-use to save effort and money? 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 TOB TIB PD UGPS Jan. 8, 2007, SLAC 13 TIB PD TID TEC

14 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 There may not be enough rejection power using the muon and calorimeter triggers to handle the higher luminosity conditions at SLHC Using the studies for HLT applications gives an idea of what could be gained using elements of the tracker in the Level 1 Use of tracking at Level 1 has impact on the architecture of the Level 1 trigger UGPS Jan. 8, 2007, SLAC 14

15 LHC: CMS SLHC Trigger Architecture Level 1: Regional to Global Component to Global L1 Trigger SLHC Proposal: Combine Level-1 Trigger data between tracking, calorimeter & muon at Regional Level at finer granularity Increase the Level 1 latency to 6.4 μsec Transmit physics objects made from tracking, calorimeter & muon regional trigger data to global trigger Implication: perform some of tracking, isolation & other regional trigger functions in combinations between regional triggers New Regional cross-detector trigger crates Leave present L1+ HLT structure intact (except latency) No added levels --minimize impact on CMS readout UGPS Jan. 8, 2007, SLAC 15

16 CMS L1 Algorithm Stages Current for LHC: Trigger Primitive Generator RCT GCT GT Proposed for SLHC (with tracking added): TPG Clustering Correlator Selector Trigger Primitives Tracker L1 Front End e / γ / τ clustering 2x2, φ-strip TPG µ track finder DT, CSC / RPC Regional Track Generator Jet Clustering Missing E T Seeded Track Readout Regional Correlation, Selection, Sorting Global Trigger, Event Selection Manager UGPS Jan. 8, 2007, SLAC 16

17 R&D - starting now Pixel technology Hybrid - cheaper bonding MAPS/SOI - need an answer now if it can be used Geometry How many different sensors Layout of inner/outer pixels Triggering layers How many/where Readout Current ROC to 130 nm New ROC to push Col hit info for stacks Correlator Chip Link and Control technology Effort started at CERN Radiation tolerance and robustness of 130nm/90nm Technology for a very inner layer Different sensor Power/Material DC-DC/Serial power - Some R&D underway UGPS Jan. 8, 2007, SLAC 17

18 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 costing of detector work Including how CMS will organize the effort Submitted to LHCC Allow funding agencies to release funding Target Summer 2007 Next workshop Joint ATLAS-CMS workshop at CERN is Mar 19-21, UGPS Jan. 8, 2007, SLAC 18

19 CMS R&D Proposals SLHC Upgrade Steering Group formed in 2005 This group is charged with Recommending R&D proposals for approval to CMS MB/CB Planning SLHC workshops Outreach to collaboration Interaction/Co-ordination with Machine and ATLAS on SLHC matters Regular Reporting to MB/CB R&D Proposals get a stamp of CMS approval before going to funding agencies UGPS Jan. 8, 2007, SLAC 19

20 4 th 4 th CMS SLHC Upgrade Workshop Perugia Apr 3, Agenda Technology Session I Optical links, power, rapid prototyping New Pixel Layers Performance requirements at SLHC, Radiation Damage, MAPS. Technology Session II New materials: diamond, high O2 silicon, amorphous silicon Trigger Upgrades Tracking Trigger concept, L1 Pixel Trigger, new trigger technologies, TTC replacement Technology Session III 130nm technology Other Issues Calorimeter, muon upgrades UGPS Jan. 8, 2007, SLAC 20

21 SLHC Upgrade Steering Group Members Technical Coordination : EC (chair, Jordan Nash), DTC Representatives from Tracker, ECAL, HCAL, Muons and Level-1 Trigger Nominated by PMs Tracker : G. Hall (TK Upgrade Working Group has been formed) Level-1 Trigger: W. Smith (Trigger Upgrade Working Group) ECAL : P. Busson HCAL: D. Baden CPT: D. Acosta US CMS university MUONS: M. Dallavalle faculty Electronics WG Conveners Micro Electronics (A. Marchioro) Opto Electronics (F. Vasey) Radiation Expert - TBD SP/DSP/TC (Ex-Officio) Others as needed UGPS Jan. 8, 2007, SLAC 21

22 Proposed CMS Working Sub-Groups for Tracker Upgrade Performance and detector layout Sensor material and operation Outer tracker readout system definition Pixel system and triggering Manufacture and material budget Tracker upgrade is a large part of the total SLHC upgrade. The Tracker community is now actively organizing for the upgrade effort. The US wants to play a large role. UGPS Jan. 8, 2007, SLAC 22

23 CMS Detector Replacements M&S Only Inner Tracker 30 MChf Outer Tracker 90 MChf Level 1 Trigger 20 MChf DAQ 10 MChf Other Front Ends 10 MChf Infrastructure 15 MChf Total Across collaboration ~ 900 FTE!!!!! 175 MChf Materials Cost for Collaboration (CORE) UGPS Jan. 8, 2007, SLAC 23

24 USCMS Upgrade Budget Profile US Funding Metric - Draft USCMS Upgrade Budget Total = $150M $M Other Trigger/DAQ Tracker Pixel Major activity in Pixel replacement frontloads budget profile. Major items are Tracker replacements - pixels and strips plus triggering ability in order to confront the much greater trigger rates. US CMS is ~ 33% of the collaboration, would be expected to cover that fraction of upgrades and the upgrade R&D. Expect heavy involvement in new pixel, new tracker, track trigger, trigger upgrades. Exact contributions must be worked out in the future with our funding agencies Assume intermediate Pixel Detector 2011, full SLHC Startup 2014 UGPS Jan. 8, 2007, SLAC 24

25 Guesstimate of Scale of Resources for CMS SLHC Upgrade A personal guess (not representing anyone but myself) of the required R&D funding is 10-15% of the construction cost ~ $15-~20M for R&D Time scale is driven by opportunity afforded by intermediate pixel detector replacement The full R&D for the final detector does not need to be done in time for the intermediate replacement, but some of it is certainly necessary UGPS Jan. 8, 2007, SLAC 25

26 Current R&D Funding in US CMS R&D budget held by RPM Limited R&D budget in each subsystem, probably amounting to $1M/yr total after 07 including use of engineers and technicians for upgrade when not occupied in maintenance This funding level does not get us where we need to be (remedial actions discussed at end of talk) AY $k AY K$ US CMS Upgrade R&D M&O Cost Estimate FY02-FY08 Total $2,706,893 AY$ 1,400 1,200 1, WBS 20. FY02 FY03 FY04 FY05 FY06 FY07 FY08 Subsystem R&D Costs (FY04 - FY08 Total = $2.4M) FY04 FY05 FY06 FY07 FY08 Labor M&S Trig SiTrk HCAL EMU ECAL FPix UGPS Jan. 8, 2007, SLAC 26

27 Role of US Universities US universities played a significant role in R&D for CMS detector More than 90% of the physics power of US CMS is based in the universities. In particular, 100% of the graduate students and 90% of the Post docs are in the university community These are the groups whose position allows them to focus intensely on the experiment They will play a perhaps even more significant role in the SLHC upgrade because The main issues are tracking and trigger Optimizations depend on detailed simulations The focus will be on small scale R&D, radiation hardness studies, test beam measurements and detailed testing These activities do not require substantial large-scale engineering or manufacturing infrastructure They can gain much from collaboration with engineering and scientific resources at the universities University R&D is cost effective because of the availability of effort from graduate students and RAs and advantageous overhead Universities have 85% of the PhDs and 100% of the students Electronics design can also be carried out at universities and labs Engineers who are needed (and funded) to carry out M&O existing detector can be used (and funded), when not busy with that, to do R&D for SLHC UGPS Jan. 8, 2007, SLAC 27

28 Some US R&D on Current Detector ECAL Collaboration with Hamamatsu to develop a rad-hard APD for use in ECAL (Minnesota) HCAL Development of HPD in collaboration with DEP. (Minnesota) Development of manufacturing design and techniques for HCAL optics (Rochester) Development of low profile optical connectors (UIC) Development of air-powered radioactive source drives (Purdue) Development of Cerenkov calorimeter based on quartz fibers (TTU/Iowa/Iowa State/BU) Development of low-cost quartz fibers. (Iowa in collaboration with Poly Micro) Pixels Development of radiation hard sensors Development of Radiation hard sequencer for pixel readout Testing and input to Pixel Readout Chip development Trigger large effort expert on this committee! UGPS Jan. 8, 2007, SLAC 28

29 USCMS R&D Activities Optical Links: Study next generation optical links. Important for new tracker. Joint project with CMS/ATLAS HCAL: Replacements for high eta HE region. Collaboration with RDMS EMU: Studies of EMU Trigger functionality at SLHC luminosity. Pixel: Starting to think through Pixel Replacement, Pixel Trigger. First Dedicated Workshop Oct 10-12, 2006 at FNAL. Trigger/DAQ: Upgrade studies for higher frequency operation UGPS Jan. 8, 2007, SLAC 29

30 US Tracker R&D Interests Prototyping this year Hamamatsu is interested in SOI. Designing sensor test pieces Study individual & ganged pixels: probed, in cosmics, in test beam Follow up with test pieces having some initial basic readout circuitry. Studying new pair modules and rod supports, cooling (UCSB) Calculate heat-loads and cooling requirements. Prototypes for comparisons with calculations Study performance of various configurations Use GEANT, simulate events and run pattern recognition. Activity in new materials with RD50 (Rochester, Purdue,FNAL) MCz sensors produced, work done in collaboration with pixel group Telescope under construction for study of sensors Will coordinate with US Pixel group on future R& Would like to ramp up to make a substantial contribution. For current tracker we are a substantial part of final production (roughly 50%) and integration (roughly 25%) and we will also be a major part of operation (roughly 25%). For SLHC we should continue at the same level of involvement, but it is critically important that we participate in the R&D, design, and construction from the beginning. We are coordinating with our international CMS collaborators. UGPS Jan. 8, 2007, SLAC 30

31 Pixel Workshop Attendance G. Landsberg, M. Narain Brown University C. da Via Brunel University, London K. Ecklund University of Buffalo, NY J. Nash CERN J. Adelman, E. Brubaker University of Chicago I. Redondo CIEMAT, Madrid M. Bunce, K. Stenson, S. Wagner University of Colorado J. Alexander, J. Thom Cornell University D. E. Pellett University of California, Davis J. Incandela University of California, Santa Barbara B. Baldin, K. Burkett (WG2 co-lead), J. Butler, G. Cardoso, H. Cheung (WG3 co-lead), D. Christian, M. Demarteau, E. Gottschalk (WG3 co-lead), J. Howell, M. Johnson, U. Joshi, S. Kwan (WG1 co-lead), V. Pavlicek, L. Spiegel, P. Tan, M. Turqueti, L. Uplegger, M. Wang, Jin-yuan Wu, R. Yarema Fermilab, Batavia IL, USA M. Bruzzi Universita di Firenze C. Gerber University of Illinois, Chicago Campus J. Jones Imperial College, London C. Newsom, L. Perera University of Iowa T. Bolton Kansas State University A. Bean University of Kansas L. Cremaldi Louisiana State University S. Eno, N. Hadley University of Maryland Dominguez (WG2 co-lead), M. Eads, S. Malik University of Nebraska, Lincoln, NE, USA W. Erdmann, R. Horisberger, H. Kaestli, D. Kotlinski, T.Rohe Paul Scherer Institute X. Huang, A. Lopez University of Puerto Rico K. Arndt, G. Bolla, D. Bortoletto (WG1 co-lead), M. Jones, P. Merkel, I. P. Shipsey Purdue University V. Cuplov, N. Parashar Purdue University, Calumet E. Bartz, S. Schnetzer Rutgers University M. Artuso Syracuse University M. Swartz Johns Hopkins University S. Spanier University of Tennessee P. Sheldon Vanderbilt University W. Smith, S. Dasu University of Wisconsin Note: participation by members of Silicon Strip group, Trigger group, as well as US and European CMS pixel groups. The CMS SLHC program leader attended. Members of ATLAS and RD50 also participated. UGPS Jan. 8, 2007, SLAC 31

32 Summary of CMS Pixel Group Preparatory Workshop on Upgrades Major Findings 1 Interest of US groups in pixel/tracker upgrades: An important aspect of the workshop was to determine the level of interest in the pixel groups for carrying out this R&D, and to determine whether other collaborators in CMS share this interest. The attendance at the workshop was excellent. More then 50 people participated in some phase of the activities. When asked by their working group leader, most expressed a desire to work on upgrade R&D and on the upgrade projects Urgency to begin R&D The design and construction of the tracking and trigger systems for CMS took a decade. The upgrades are less extensive, but by necessity, more ambitious and complex. It is necessary to begin the R&D very soon Relationship to definition of the SLHC machine upgrade The overall luminosity goals for the SLHC are defined. However, key details such as the bunch crossing interval are not yet specified. Early efforts in SLHC R&D should concentrate on key areas that do not depend on characteristics of the upgraded LHC that have not yet been fixed or should address technology issues that occur under any of the potential upgrade scenarios Relationship to other CMS and LHC efforts While this workshop was hosted by the CMS pixel group, it was attended by members of the Silicon Strip Tracker and the Trigger Groups. While the current detector has two tracking technologies, pixels to about 15 cm in radius and strips from 20 cm on out, the upgraded detector may have more technologies and may have different transition radii. Some layers may be introduced specifically to facilitate triggering. The pixel group should participate in the Tracking Upgrade and in CMS upgrade workshops and activities as well as activities involving other LHC experiments Possible opportunities for external collaboration to develop new technologies The short time scale, the complexity, and the cost of the new technologies that are likely to be needed for the SLHC upgrade strongly argue for collaboration with other LHC experiments and with industry. UGPS Jan. 8, 2007, SLAC 32

33 General recommendations The Pixel Upgrade effort should be part of the overall CMS Tracking upgrade effort, which is in turn part of the CMS SLHC upgrade effort. Either through the tracking upgrade or by some other arrangement, the Pixel Upgrade effort must maintain close collaboration with the trigger upgrade. The Pixel Subgroup should adopt a formal structure and organization to pursue the SLHC R&D. The group structure adopted for the pixel workshop could provide the basis for this organization. A simulation package that permits one to easily modify the geometry of the tracking system and to add layers of different types is essential to developing the tracking and trigger upgrades. The package should permit a prompted reconstruction with a method for adding alignment errors, inefficiencies, confusion, backgrounds, and noise. The existing CMS simulation packages should be evaluated for their suitability to this task before one considers developing a new program UGPS Jan. 8, 2007, SLAC 33

34 Comments 2007 R&D will be mostly simulation studies and participation in common activities such as RD50 For some issues. it is premature to spend large quantities of money before 08, when we start to get operational experience with LHC We will, however, have to make some decisions before we have all the information we might like to have. Need infusion of money starting in 08 to hold this schedule. (First pixel replacement in 2011; SLHC in 2014.) Out year budgets will have to include a larger share of R&D Close collaboration with ATLAS important to control costs (chip submission in 130nm process, optical link development, new sensor material development.) UGPS Jan. 8, 2007, SLAC 34

35 Near-term Steps and Conclusion Will appoint a US CMS Upgrade R&D Coordinator Will reevaluate portion of budget from 08 and forward that is devoted to SLHC R&D Changes will have to be carefully evaluated due to needs of ongoing program and data analysis Will try to encourage and support US Universities to pursue other funding opportunities, such as competing for R&D grants Will try to achieve maximum synergy with other efforts, especially at FNAL, including ILC Will work with our colleagues in DOE and NSF to try to improve the budget I anticipate breakthroughs that will encourage national investment in the LHC program! Outreach will be a vehicle for making the case. The LHC and SLHC will provide the outstanding physics research and detector R&D opportunities that will sustain the US HEP academic community and keep it at the forefront of HEP research as we hopefully prepare for the ILC. UGPS Jan. 8, 2007, SLAC 35

36 Backup Slides UGPS Jan. 8, 2007, SLAC 36

37 Radiation environment for trackers R. Horisberger UGPS Jan. 8, 2007, SLAC 37

38 Signal efficiency versus fluence for various sensor technologies UGPS Jan. 8, 2007, SLAC 38

39 Data loss in pixel readout chip assuming that there are no buffer size limitations. Mask costs for different CMOS processes Data loss at different radii for SLHC luminosity. Increase in power density of electronics over the years. UGPS Jan. 8, 2007, SLAC 39

40 Preliminary study of the integrated material distribution of the tracker as a function of h. The left-hand plot shows the number of radiation lengths separately for the contributions of different components, including services. The plot on the right shows the number of radiation lengths separated by the sub-detector of the tracker. Efficiency for reconstructing single pions with PT = 1, 10, and 100 GeV/c in the tracker. The left-hand plot shows the algorithmic efficiency, where the denominator contains tracks with at least two pixels hits and hits in at least eight tracker layers. The plot on the right shows the overall efficiency, including the effect of tracks that interact in the inner layers and do not reach the outside of the tracker. UGPS Jan. 8, 2007, SLAC 40

41 Tracking trigger might have a few layers, perhaps between the current Pixel Detector and the Inner Strips, that identify hi-p t track candidates to associate with calorimeter and muon trigger primitives. HLT single-muon trigger rates as a function of the pt threshold for a luminosity of 1034 information available at cm-2s-1. The rates are shown for L1, L2, and L3, with and without isolation for L2 and L3 (HLT). The rate generated in the simulation is also shown. At L2, using the HLT, a muon must be reconstructed in the muon system and have an valid extrapolation to the collision vertex. At L3 a muon must have more than 5 silicon hits in total in the pixel and strip tracking system [vii]. UGPS Jan. 8, 2007, SLAC 41

42 US CMS tracker group: Overview Currently, deeply involved in installation and commissioning. We have begun a few projects for SLHC Studying general layout, prototyping some rad-hard sensors, developing lightweight mechanics Would like to ramp up to make a substantial contribution. For current tracker we are a substantial part of final production (roughly 50%) and integration (roughly 25%) and we will also be a major part of operation (roughly 25%). For SLHC we should continue at the same level of involvement, but it is critically important that we participate in the R&D, design, and construction from the beginning. We are coordinating with our international CMS collaborators. UGPS Jan. 8, 2007, SLAC 42

43 Straw-man Layout Example 12 Measurement Layers Organized in 3 Super-Layers Fewer but more poweful layers with pixels at small radii, long pixels or short strips elsewhere. Each Super-Layer = Stack of 2 Sensor Pairs (4 measurement layers / Super-Layer) Inner Super-Layer ~ 10-20cm Middle Super-Layer ~ 60cm Possible High Pt Discrimination Scheme Stacks of Sensor Pairs, improved local Pt measurement Outer Super-Layer ~ 100cm M. Mannelli at Perugia Workshop UGPS Jan. 8, 2007, SLAC 43 43