SUMMARY OF LINEAR COLLIDER TRACKING & VERTEXING R&D

1. SUMMARY OF LINEAR COLLIDER TRACKING & VERTEXING R&D VICTORIA LINEAR COLLIDER WORKSHOP JULY 31 2004 BRUCE SCHUMM UC SANTA CRUZ

2. Important Qualification: Upcoming Technology Decision • Several major tracking challenges will either be required or obviated by the choice of technology. In some sense, this is not the time to be giving this talk! • Novel readout schemes for CCD’s (necessary for cold technology) • Precise z-dimension vertexing from gaseous tracker (to eliminate out-of-time crossings; necessary for warm technology • Fast power-cycling and/or time discrimination of min-I pulses for Si strip tracking (much more challenging for warm technololy) • and so forth… August’s decision will have substantial impact on tracking R&D

3. Vertex Detector R&D When I hear the term `Vertex’ I tend to think… But it’s becoming less obvious that this is the system we’ll end up with…

4. What’s driving Vertexing R&D these days? Note: Most activity is in Europe (LCFI Collaboration, various active pixel scenarios), but North American activity is increasing. • CCD’s are very nice; but can they be read out fast enough (especially for cold technology)? • 50 MHz clock • Column-parallel architecture • `ISIS’ approach? • Radiation hardness? (cm) Need to get thin detectors very close Existing active pixel (APD) solutions typically lack precision (pixel size, material) Ultra-precise scenarios involve very thin detectors (as little as 50 m of Si substrate)

5. What North American groups are active in vertex detector R&D? The Yale/Oregon group has a lengthy and ongoing tradition of critical-path contributions. The LBNL and Purdue efforts are coming into their own after a year or so of ramping up.

6. What are the active groups in North America? Distinguishing parameter: ratio of observed signal loss to expected loss from measured trap clusters Electrons: radiation damage traps not detectable  no expected signal transfer loss n irradiation SLD radiation damage very electron-like  no unmodelled neutron backgrounds Yale/Oregon group has long tradition of critical-path contributions, but LCRD funding will increase scope SLD CCD’s e-irradiation Berkeley, Purdue efforts are coming into their own after a year or so of ramping up Nick Sinev, University of Oregon

7. What North American groups are active in vertex detector R&D? Purdue poised to explore thin pixel sensors in next few months The Yale/Oregon group has a lengthy and ongoing tradition of critical-path contributions. The LBNL and Purdue efforts are coming into their own after a year or so of ramping up. Daniela Bortoletto, Purdue

8. Chris Damerell For the cold technology, readout must take place during the milisecond-scale passage of the spill.

9. Chris Damerell In-situ Storage of Signal Charge (ISIS)  Signal charge shifted into storage register every 50 s, to provide required time slicing.  Noise-free charge storage, ready for readout in 200 ms of calm conditions between trains  Has already been developed for industrial imaging applications Note: not a problem for warm technology, for which bunch train is effectively instantaneous

10. Progress in Active Pixel R&D `Monolithic’ designs (electronics depoited directly onto sensors) – why? • Typical current active pixel detector: • Large-pitch pixel sensor (~100 m or more) • Readout circuitry with fill-factor ~1 • Bump bonds • Servicing and cooling •  Does not achieve ideal impact parameter resolution due to pitch and material burden • A number of different approaches are being explored… • MAPS (Monolithic Active Pixel Sensor) • FAPS (Flexible Active Pixel Sensor) • DEPFET (Depleted Field Effect Transistor) APS • SOI (Silicon on Insulator) APS

11. DEPFET principle and properties DEPFET structure and device symbol Function principle • Field effect transistor on top of fully depleted bulk • All charge generated in fully depleted bulk; assembles underneath the transistor channel; steers the transistor current • Clearing by positive pulse on clear electrode • Combined function of sensor and amplifier Gerhard Lutz, MPI Munich

12. North American Active Pixel Ideas (new initiatives) Industry has been pursuing active pixels for years (high-end digital imaging)  Use this as springboard for HEP R&D Yale/Oregon proposal: use HEP funding (LCRD, SBIR?) to interest private sector in our R&D problems (Sarnoff Corporation) LBNL interdisciplinary proposal: Begin with existing product and Add HEP-specific functionality (fast readout, zero suppression, correlated double-sampling). Eventually, push to current state-of-the-art processes (0.13 m) to permit full functionality on CCD-scale pixel (~20x20 m) Worldwide, active pixel detector activity is growing and broadening

13. What’s driving North American Tracking R&D these days? Gaseous Tracking • Resolution (Higgs recoil mass measurement) • Ion feedback Different readout technologies (GEM, MicroMegas, resistive pads, etc  “MPGD’s”). • Gas mixtures (resolution, backgd) Solid-State Tracking • Low-mass tracking (long shape, power cycling) • Position monitoring • Precise timing / background suppression • Reconsideration of geometry, overall Si strategy

14. Gaseous Tracking R&D Dan Peterson, Cornell Are TPC’s Good for Tracking? • Z-H events • Stand-alone TPC reconstruction (LD design) Answer: Yes. Next questions: what about resolution, ion feedback, track separation resolution, neutron backgrounds?

15. Several North American groups have long history of tackling critical issues in international TPC R&D effort Carleton University (readout testing and optimization) University of Victoria (readout testing and optimization) Berkeley (In support of many NA and European groups Others are just getting off the ground with their LC hardware effort Cornell (new TPC prototype test facility) Purdue (Micropattern detector development) MIT (GEM manufacture) All in all, North American effort is coming into its own and will make substantial contributions as WW effort organizes

16. Daniella Bortoletto, Purdue 1st Mass Production of Micromegas • Industrially mass produced • MICROMEGAS using 3M’s FLEX circuit technology • 2. Conical pillars ( 1 mm pitch) to create a 50 mm gap. 35 micron The flat area that has a contact with the anode board Pillar cross section profile 50 micron height 70-80 micron (anode side) 300 micron wide (mesh side) Presented at ALCW SLAC Jan ’04 Now more detail

17. Mike Ronan, LBNL, for Berkeley/Saclay/Orsay group

18. New Prototype Facilities Coming Online Rapidly MPI Munich prototype just online Cornell prototype online soon!

19. And Existing Prototype Facilities Continuing to Break Ground… M. Dixit: `TPC developers believe they’re entitled to whatever diffusion permits them’ B = 0T Double-GEM readout B = 0.9T 100 m B = 1.5T Gabe Rosenbaum, UVIC OK – so you need to work on it a bit…

20. M. Dixit, Carleton

21. M. Dixit, Carleton No magnetic field (B=0)

22. Jan Timmermans, Nikhef

23. Jan Timmermans, Nikhef

24. Jan Timmermans, Nikhef Readout microMegas multiplier with 55x55 m2 pixel MediPix chip Clear depiction of ionization path, -ray Optimal (?) for pattern recognition, two-track separation, dE/dX

25. Overall Status of Gaseous Tracking R&D Effort Substantial headway remains to be made Results from existing prototypes are encouraging Soon will have ~ ½ dozen facilities: duplication of effort to the untrained eye, but probably critical in exploring the parameter space of good ideas Solid State Tracking…

26. One Pole: A `Gossamer Tracker’ • Minimal material in tracking volume • Minimal support/servicing material (particularly in `endcap’ region But can it really do anything?

27. Extend 50 GeV/c pt VXD tracks into Gossamer Tracker Look as a function of angle from thrust axis in qq events Dotted lines: all backgrounds included (1/pt) ~ 2x10-5 (1/pt) ~ 4x10-5 90% Steve Wagner, SLAC (preliminary study)

28. Nick Sinev, University of Oregon Simulated tt events VXD Reconstruction Efficiency (Full Backgrounds)

29. J. Jaros Update on Backgrounds New estimates of hadrons yield 56 events/ NLC train (192 bunches). (T. Barklow SLAC ALCPG 1/04) Occupancies/Train8600 e+e- pairs 35k’s (~MeV) 154 +- pairs 56 had events

30. 0BX 1BX 4 BX 18 BX from K. Desch Bunch Crossing :   hadrons background Mass measurement of light Higgs boson (mH=120 GeV) Hbb, Zqq  4 jets reconstruction Integrating over several BX hadronic backgrounds reduces the resolution on ΔmHfrom 75 MeV (1BX) to 92 MeV (18 BX) How you address this problem (intrinsic timing; dedicated timing components…) is very technology-dependent

31. Bill Cooper, Marcel Demarteau, Michael Hrycyk, FNAL These drawings are misleading; both groups gave substantial thought to tiling, axial/stereo issues, readout, mechanics, etc (based on considerable expertise from D0) Rich Partridge, Brown

32. cos = 0 Short shaping-time p/p2 (GeV/c-1) `Gossamer’ LD 3/01 p (GeV/c) These designs would employ ~10cm tiling for z segmentation. In addition, short ladders  less noise  short shaping time  good (5 nsec) timing to solve pile-up problem. But: price to pay in terms of momentum resolution at intermediate pt (extra electronics and cabling); do we care?

33. Long-ladder (long shaping-time) readout R&D at LPNHE Paris and UC Santa Cruz 60 s 8 ms Both will submit September or October 60 s LPNHE Preamp Santa Cruz ASIC power cycle LPNHE design optimized for cold technology; UCSC for warm; also complementary analog and digital readout schemes

34. The International SiLC Group (Acknowledged by DESY PRC May 03) BNL Wayne St.U. U. Of Michigan SLAC UCSanta Cruz -SCIPP USA: Helsinki U. (Fin) Obninsk St. U. (Ru) IEKP Karlsruhe (Ge) Charles U. Prague (CZ) Ac. Sciences.Wien (Au) LPNHE-Paris (F) U. de Genève (CH) Torino U. (I) INFN-Pisa (I) La Sapienza-Rome (I) CNM-Barcelona (Es) Cantabria U. (Es) Valencia IFIC (Es) Europe: Korean Institutes Tokyo U. HAMAMATSU Asia: BUT: Wayne State not funded by UCLC/LCRD for Si Drift R&D Substantial international group with increasing coordination in both hardware and simulation; a lot of non-American interest in Si!!

35. Just one example: testing of SiLC sensors in Vienna SiLC also involved in Si component support for TESLA/LD designs Your TPC here!!

36. Silicon Tracking: Special Organization Session When: 13:30 – 15:00 Today Where: VIB East (or West if East is occupied) Why: Exploit rare face-to-face opportunity for (inter)national coordination and incorporation of new effort Whom: Due to limited space, attendance restricted to homo sapiens only.

37. Much interesting and critical work is underway, but something’s missing: much work in the area of… Simulation Studies Many of the technologies that are being pursued will probably be shown to work. How will we know which path(s) to choose? Numerous questions (many of them raised 5-10 years ago) remain with us today. Some of these will be challenging to answer, involving the combination of sophisticated tracking and clustering algorithms. However, it seems as if tools and frameworks are reaching the point that we can begin to address some of these, and progress is being made…

38. Ekhard von Toerne, Kansas State What efficiency for K0S vs. decay length can be achieved? Plus: How much material can be tolerated before tracks enter Cal? What are requirements on tracking efficiency (especially for high momentum tracks in jets) for adequate Eflow? etc…. Answering these questions (and a number of others) must be central focus of design studies. Reconstructing K0S in SiD with assistance from Calorimeter

39. In Summary Technology choice will have big impact on tracking R&D. The sooner the decision comes, the better. In the mean time, domestic effort is growing substantially. Global cooperation seems to be on the rise, and for now, many interesting threads are being explored for both the warm and cold scenarios. Simulation studies remain somewhat behind, but it now seems that they are beginning to move forward. We need to refine our list of simulation goals and ensure that critical issues are addressed.

40. Some things: Need for low-p resolution Need for PID from tracking Pattern recognition and its effect on Eflow Rest of Jaros’ list Track-separation resolution

42. Simulated Tracking Performance for Long Shaping-Time SD Tracker GOOD Tracking efficiency for Pt=50 GeV track, as a function of angle from thrust axis, for qq events Steve Wagner PERFECT Two curves are with/without machine backgrounds 90%

43. Simulation Studies (Much of this on to-do lists!) • What does it take to reconstruct tracks in dense jets with an all- silicon tracker? • What sort of segmentation is necessary in the forward direction? • What resolution is required in the forward direction? • What is physics impact of coulomb-scattering limitations on resolution at intermediate momenta (benchmark process?)? • How much endplate material can we get away with before we degrade the energy flow measurment? • Can an all-silicon tracker reconstruct K0’s and kinks with a little help from our friends (CAL)? • How do LC backgrounds impact tracker design? • Effect of photon conversion in tracker on energy flow

44. Tracking Performance of SD Tracker with 10cm Ladder Segmentation GOOD With coarse spatial sep-aration, backgrounds are substantially mitigated. PERFECT Steve Wagner • This is really lower bound on performance: • Study imposes `extra track’ within jet • Algorithm not yet fully sophisticated • Temporal segmentation 90%

45. Activities of the SiLC (Silicon for the Linear Collider) Group Meeting in Paris April 21 2004 (during LCWS) • Series of phone meetings: • June 14 • June 30 • July 14 • Hardware • Updates of independent activity • Some talk about mutual test beam run • Simulation • Identification and coordination of critical simulation issues • Material before calorimeter • Forward tracking tools • But effort still in need of bolstering!

46. High B-field limits transverse diffusion  Better resolution Peter Wienemann, DESY