summary of linear collider tracking & vertexing r&d victoria linear collider workshop july...
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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
0
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
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
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!
Endplate layout
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
5cm 15cm 25cm0cm
5cm
15cm
0cm
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
0.01
0.1
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
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