SUMMARY OF LINEAR COLLIDER TRACKING &

VERTEXING R&D

VICTORIA LINEAR COLLIDER WORKSHOP

JULY 31 2004

BRUCE SCHUMM

UC SANTA CRUZ

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

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…

Vertex Detector R&D

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

)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)

Need to get thin detectors very close

INSTITUTION PROJECT FUNDED?

Yale/Oregon Broadly-scoped pixel R&D LCRD

Berkeley/LBNL Broadly-scoped pixel R&D LBNL Seed $

Purdue Thin Silicon Sensors (RD50)

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.

INSTITUTION PROJECT FUNDED?

Yale/Oregon Broadly-scoped pixel R&D LCRD

Berkeley/LBNL Broadly-scoped pixel R&D LBNL seed $

Purdue Thin sensors (RD50)

What are the active groups in North America?

Yale/Oregon group has long tradition of critical-path contributions, but LCRD funding will increase scope

Berkeley, Purdue efforts are coming into their own after a year or so of ramping up

Distinguishing parameter: ratio of observed signal loss to expected loss from measured

trap clusters

Nick Sinev, University of Oregon

n irradiation

e- irradiationSLD CCD’s

Electrons: radiation damage traps not detectable no expected signal transfer loss

SLD radiation damage very electron-like no unmodelled neutron backgrounds

INSTITUTION PROJECT FUNDED?

Yale/Oregon Broadly-scoped pixel R&D LCRD

Berkeley/LBNL Broadly-scpoed pixel R&D LBNL Seed $

Purdue Thin Silicon Sensors (RD50)

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.

Purdue poised to explore thin pixel sensors in next few months

Daniela Bortoletto, Purdue

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

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

Note: not a problem for warm technology, for which bunch train is effectively instantaneous

Chris DamerellIn-situ Storage of Signal Charge (ISIS)

Has already been developed for industrial imaging applications

Progress in Active Pixel R&D

`Monolithic’ designs (electronics depoited directly onto sensors) – why?

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

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

DEPFET principle and properties

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

DEPFET structure

and device symbol

Gerhard Lutz, MPI Munich

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 andAdd 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

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

Are TPC’s Good for Tracking?

• Z-H events

• Stand-alone TPC reconstruction (LD design)

Dan Peterson, Cornell

Answer: Yes.

Gaseous Tracking R&D

Next questions: what about resolution, ion feedback, track separation resolution, neutron backgrounds?

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

1st Mass Production of Micromegas

1. Industrially mass produced MICROMEGAS using 3M’s

FLEX circuit technology2. Conical pillars ( 1 mm pitch) to

create a 50 m gap.

-40

-20

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20

40

60

-100 0 100 200 300 400 500 600

PILLAR2.TXT

B

Heig

ht

(mic

ron)

X-direction (micron)

50 micronheight

300 micron wide (mesh side)

35 micron

Presented at ALCW SLAC Jan ’04Now more detail

The flat area that has a contactwith the anode board

70-80 micron(anode side)

Pillar cross section profile

Daniella Bortoletto, Purdue

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

MPI Munich prototype just online

Cornell prototype online soon!

New Prototype Facilities Coming Online Rapidly

And Existing Prototype Facilities Continuing to Break Ground…

Gabe Rosenbaum, UVIC

100 m

B = 0T

B = 0.9T

B = 1.5T

M. Dixit: `TPC developers believe they’re entitled to whatever diffusion permits them’

OK – so you need to work on it a bit…

Double-GEM readout

M. Dixit, Carleton

M. Dixit, Carleton

No magnetic field (B=0)

Jan Timmermans, Nikhef

Jan Timmermans, Nikhef

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

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…

One Pole: A `Gossamer Tracker’

• Minimal material in tracking volume

• Minimal support/servicing material (particularly in `endcap’ region

But can it really do anything?

Steve Wagner, SLAC (preliminary study)

Extend 50 GeV/c pt VXD tracks into Gossamer Tracker

Look as a function of angle from thrust axis in qq events

90%

Dotted lines: all backgrounds included

(1/pt) ~ 2x10-5

(1/pt) ~ 4x10-5

VXD Reconstruction Efficiency(Full Backgrounds)

All tracks

Phys.trks

Reco

Eff.

Clean tracks

Clean in vxd

Extra trks

Energ

Fr. bck

Fake, en. fr fk.

5 hit, bad tim.,0.1GeV

94.6%

99.3%

87.1%

93.4%

93.9%

98.6%

186 77.1

GeV

14

4.0Gev

5 hit, good tim.,0.1GeV

95%

99%

90.8%

96%

99.9%

99.9%

164 69.6

GeV

6

1.7Gev

6 hit, bad tim.,0.2GeV

98%

99.5%

89.4%

95.6%

99.3%

99.5%

70 35.3

GeV

2

1.8Gev

6 hit, good tim.,0.2GeV

97.3%

98.5%

76.2%

96.4%

99.9%

99.9%

0.9 0.57

GeV

9

4GeV

Nick Sinev, University of Oregon Simulated tt events

Update on BackgroundsNew 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

J. Jaros

Bunch Crossing : hadrons background

0BX 1BX 4 BX 18 BX

Integrating over several BX hadronic backgrounds reduces the resolution on ΔmH from 75 MeV (1BX) to 92 MeV (18 BX)

Mass measurement of light Higgs boson (mH=120 GeV) Hbb, Zqq 4 jets reconstruction

from K. Desch

How you address this problem (intrinsic timing; dedicated timing components…) is very technology-dependent

Bill Cooper, Marcel Demarteau, Michael Hrycyk, FNAL

Rich Partridge, Brown

These drawings are misleading; both groups gave substantial thought to tiling, axial/stereo issues, readout, mechanics, etc (based on considerable expertise from D0)

cos = 0

p (GeV/c)

p/p

2 (

GeV

/c-1)

LD 3/01`Gossamer’

Short shaping-time

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?

LPNHE Preamp

Santa Cruz ASIC power cycle

60 s

60 s

8 ms

Long-ladder (long shaping-time) readout R&D at LPNHE Paris

and UC Santa Cruz

Both will submit September or October

LPNHE design optimized for cold technology; UCSC for warm; also complementary analog and digital readout schemes

The International SiLC Group The International SiLC Group (Acknowledged by DESY PRC May 03)(Acknowledged by DESY PRC May 03)

BNLWayne St.U.

U. Of Michigan

SLACUCSanta Cruz

-SCIPP

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)

Korean Institutes

Tokyo U.HAMAMATSU

USA: Europe:

Asia:

Substantial international group with increasing coordination in both hardware and simulation; a lot of non-American interest in Si!!

BUT: Wayne State not funded by UCLC/LCRD

for Si Drift R&D

Just one example: testing of SiLC

sensors in Vienna

Your TPC here!!

SiLC also involved in Si component support for

TESLA/LD designs

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 andincorporation of new effort

Whom: Due to limited space, attendance restricted to homo sapiens only.

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…

Ekhard von Toerne, Kansas State

Reconstructing K0S in SiD with

assistance from Calorimeter

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.

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.

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.

Global cooperation seems to be on the rise, and for now, many interesting threads are being explored for both the warm and cold scenarios.

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

Tracking efficiency for Pt=50 GeV track, as a function of angle from thrust axis, for qq events

Steve Wagner

Simulated Tracking Performance for Long Shaping-Time SD Tracker

PERFECT

GOOD

Two curves are with/without machine backgrounds

90%

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

Tracking Performance of SD Tracker with 10cm Ladder Segmentation

PERFECT

GOOD

Steve Wagner

90%

With coarse spatial sep-aration, backgrounds are substantially mitigated.

This is really lower bound on performance:• Study imposes `extra track’ within jet• Algorithm not yet fully sophisticated• Temporal segmentation

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!

High B-field limits transverse diffusion Better resolution

Peter Wienemann, DESY

Endplate layout

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5cm 15cm 25cm0cm

5cm

15cm

0cm

Toshi Abe, John Jaros

Occupancies vs. R

10-3 at inner radius

Toshi Abe, John Jaros

Charged Particle Occupancies/Train

• Pairs and hads dominate. Most are < 1%.

• Worst Case: Pairs forward occupancy ~3% in Layer 1at smallest radii.

0.001

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1O

ccu

pa

ncy/T

rain

(%

)

54321

Layer

Pairs (Forward) Pairs (barrel) gg->hadrons (Forward) gg->hadrons (Barrel) gg->muons (Forward) gg->muons (Barrel)

J. Jaros

Get some of Dan Peterson’s slides!

Joe Goldstein, Rutherford Labs

Chris Damerell

INSTITUTION PROJECT FUNDED?

Yale/Oregon Broadly-scoped pixel R&D $$$

Oklahoma/Boston CCD Readout ASIC 0

Purdue Thin Silicon Mechanics 0

KEY:

0 No funding

$ Nominal funding

$$ Significant funding

$$$ More significant funding

INSTITUTION PROJECT FUNDED?

Oklahoma Forward tracking reconstr. 0

Louisiana Tech Gem-based forward tracking $$

Hampton Straw-tube forward tracking 0

MIT Gem sensor development $$

Indiana Sci-fi R&D for inter. tracker $

Cornell/Purdue Generic TPC test facility 0

Michigan Laser alignment; physics sim $$

South Carolina Silicon detector tracking 0

Santa Cruz Microelectronics for SiLC $$$

Wayne State Silicon drift detector R&D 0

Wayne State Negative-ion TPC 0